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Neurosurgery

Neurosurgery is a specialized field focused on the surgical management of pathologies of the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification, spine Spine The human spine, or vertebral column, is the most important anatomical and functional axis of the human body. It consists of 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae and is limited cranially by the skull and caudally by the sacrum. Vertebral Column: Anatomy, spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy, and peripheral nerves Peripheral Nerves The nerves outside of the brain and spinal cord, including the autonomic, cranial, and spinal nerves. Peripheral nerves contain non-neuronal cells and connective tissue as well as axons. The connective tissue layers include, from the outside to the inside, the epineurium, the perineurium, and the endoneurium. Nervous System: Histology. General neurosurgery includes cases of trauma and emergencies. There are a number of specialized neurosurgical practices, including oncologic neurosurgery, spinal neurosurgery, and pediatric neurosurgery. Common neurosurgery cases treat tumors, masses, herniations, various types of hemorrhages, and radicular pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways. Although neurosurgery is a surgical specialty, neurosurgeons must be very competent in neurology, critical care, trauma care, and radiology.

Last updated: Jul 6, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Anatomy

The surgeon needs to be aware of the important structures at the site where the surgery occurs, being especially careful not to damage delicate neurovascular structures.

Bones of the cranial dome

  • Frontal Frontal The bone that forms the frontal aspect of the skull. Its flat part forms the forehead, articulating inferiorly with the nasal bone and the cheek bone on each side of the face. Skull: Anatomy
  • Parietal Parietal One of a pair of irregularly shaped quadrilateral bones situated between the frontal bone and occipital bone, which together form the sides of the cranium. Skull: Anatomy
  • Temporal
  • Occipital Occipital Part of the back and base of the cranium that encloses the foramen magnum. Skull: Anatomy

Bones of the cranial floor

  • Sphenoid
  • Ethmoid

Meninges Meninges The brain and the spinal cord are enveloped by 3 overlapping layers of connective tissue called the meninges. The layers are, from the most external layer to the most internal layer, the dura mater, arachnoid mater, and pia mater. Between these layers are 3 potential spaces called the epidural, subdural, and subarachnoid spaces. Meninges: Anatomy

Table: Meninges Meninges The brain and the spinal cord are enveloped by 3 overlapping layers of connective tissue called the meninges. The layers are, from the most external layer to the most internal layer, the dura mater, arachnoid mater, and pia mater. Between these layers are 3 potential spaces called the epidural, subdural, and subarachnoid spaces. Meninges: Anatomy
Layer Characteristics
Epidural space Epidural space Space between the dura mater and the walls of the vertebral canal. Epidural Hemorrhage
  • Potential space between the dura mater Dura mater The outermost of the three meninges, a fibrous membrane of connective tissue that covers the brain and the spinal cord. Meninges: Anatomy and skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy/ vertebral column Vertebral column The human spine, or vertebral column, is the most important anatomical and functional axis of the human body. It consists of 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae and is limited cranially by the skull and caudally by the sacrum. Vertebral Column: Anatomy
  • Contains blood vessels and fat
  • Site of blood collection in cases of middle meningeal artery Middle Meningeal Artery Epidural Hemorrhage injury → epidural hematoma Hematoma A collection of blood outside the blood vessels. Hematoma can be localized in an organ, space, or tissue. Intussusception
Dura mater Dura mater The outermost of the three meninges, a fibrous membrane of connective tissue that covers the brain and the spinal cord. Meninges: Anatomy
  • Divided into 2 layers:
    • Superficial periosteal layer
    • Inner meningeal layer
  • Grows adhered to the periosteum Periosteum Thin outer membrane that surrounds a bone. It contains connective tissue, capillaries, nerves, and a number of cell types. Bones: Structure and Types of the calvaria
  • Blood supply: middle meningeal artery Middle Meningeal Artery Epidural Hemorrhage
  • Nerve supply:
    • Trigeminal nerve Trigeminal nerve The 5th and largest cranial nerve. The trigeminal nerve is a mixed motor and sensory nerve. The larger sensory part forms the ophthalmic, mandibular, and maxillary nerves which carry afferents sensitive to external or internal stimuli from the skin, muscles, and joints of the face and mouth and from the teeth. Most of these fibers originate from cells of the trigeminal ganglion and project to the trigeminal nucleus of the brain stem. The smaller motor part arises from the brain stem trigeminal motor nucleus and innervates the muscles of mastication. The 12 Cranial Nerves: Overview and Functions branches: innervate supratentorial structures
    • Cervical nerves (C2 and C3): innervate infratentorial structures
Subdural space Subdural space Potential cavity which separates the arachnoid mater from the dura mater. Subdural Hemorrhage
  • Potential space between the arachnoid mater Arachnoid mater A delicate membrane enveloping the brain and spinal cord. It lies between the pia mater and the dura mater. It is separated from the pia mater by the subarachnoid cavity which is filled with cerebrospinal fluid. Meninges: Anatomy and the dura mater Dura mater The outermost of the three meninges, a fibrous membrane of connective tissue that covers the brain and the spinal cord. Meninges: Anatomy
  • Site of blood collection in cases of injury to bridging veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology → subdural hematoma Hematoma A collection of blood outside the blood vessels. Hematoma can be localized in an organ, space, or tissue. Intussusception
Arachnoid mater Arachnoid mater A delicate membrane enveloping the brain and spinal cord. It lies between the pia mater and the dura mater. It is separated from the pia mater by the subarachnoid cavity which is filled with cerebrospinal fluid. Meninges: Anatomy
( leptomeninges Leptomeninges Meninges: Anatomy)
  • Outer layer of the subarachnoid space Subarachnoid space The space between the arachnoid membrane and pia mater, filled with cerebrospinal fluid. It contains large blood vessels that supply the brain and spinal cord. Subarachnoid Hemorrhage
  • Avascular Avascular Corneal Abrasions, Erosion, and Ulcers
  • Arachnoid trabeculae: web-like strands that separate the arachnoid and pia mater Pia mater The innermost layer of the three meninges covering the brain and spinal cord. It is the fine vascular membrane that lies under the arachnoid and the dura mater. Meninges: Anatomy
Subarachnoid space Subarachnoid space The space between the arachnoid membrane and pia mater, filled with cerebrospinal fluid. It contains large blood vessels that supply the brain and spinal cord. Subarachnoid Hemorrhage
  • Arachnoid/pacchionian granulations: allow CSF to enter from the subarachnoid space Subarachnoid space The space between the arachnoid membrane and pia mater, filled with cerebrospinal fluid. It contains large blood vessels that supply the brain and spinal cord. Subarachnoid Hemorrhage into the venous system
  • CSF: produced by the choroid plexus Choroid plexus A villous structure of tangled masses of blood vessels contained within the third, lateral, and fourth ventricles of the brain. It regulates part of the production and composition of cerebrospinal fluid. Ventricular System: Anatomy and contained in the subarachnoid space Subarachnoid space The space between the arachnoid membrane and pia mater, filled with cerebrospinal fluid. It contains large blood vessels that supply the brain and spinal cord. Subarachnoid Hemorrhage
  • Site of blood collection in cases of saccular aneurysm Aneurysm An aneurysm is a bulging, weakened area of a blood vessel that causes an abnormal widening of its diameter > 1.5 times the size of the native vessel. Aneurysms occur more often in arteries than in veins and are at risk of dissection and rupture, which can be life-threatening. Thoracic Aortic Aneurysms rupture → subarachnoid hemorrhage Subarachnoid Hemorrhage Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage
Pia mater Pia mater The innermost layer of the three meninges covering the brain and spinal cord. It is the fine vascular membrane that lies under the arachnoid and the dura mater. Meninges: Anatomy
( leptomeninges Leptomeninges Meninges: Anatomy)
  • Inner layer of the subarachnoid space Subarachnoid space The space between the arachnoid membrane and pia mater, filled with cerebrospinal fluid. It contains large blood vessels that supply the brain and spinal cord. Subarachnoid Hemorrhage
  • Adherent to the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification
  • Confers shiny appearance
  • Highly vascularized
Cross-sectional view of the head showcasing the meningeal layers

Cross-sectional view of the head showcasing the meningeal layers

Image by Lecturio.

Ventricular system Ventricular System The ventricular system is an extension of the subarachnoid space into the brain consisting of a series of interconnecting spaces and channels. Four chambers are filled with cerebrospinal fluid (CSF): the paired lateral ventricles, the unpaired 3rd ventricle, and the unpaired 4th ventricle. Ventricular System: Anatomy

The ventricular system Ventricular System The ventricular system is an extension of the subarachnoid space into the brain consisting of a series of interconnecting spaces and channels. Four chambers are filled with cerebrospinal fluid (CSF): the paired lateral ventricles, the unpaired 3rd ventricle, and the unpaired 4th ventricle. Ventricular System: Anatomy is composed of the following structures:

  • Lateral ventricles Lateral ventricles Cavity in each of the cerebral hemispheres derived from the cavity of the embryonic neural tube. They are separated from each other by the septum pellucidum, and each communicates with the third ventricle by the foramen of monro, through which also the choroid plexuses (choroid plexus) of the lateral ventricles become continuous with that of the third ventricle. Ventricular System: Anatomy:
    • Body:
      • Spans the frontal Frontal The bone that forms the frontal aspect of the skull. Its flat part forms the forehead, articulating inferiorly with the nasal bone and the cheek bone on each side of the face. Skull: Anatomy, parietal Parietal One of a pair of irregularly shaped quadrilateral bones situated between the frontal bone and occipital bone, which together form the sides of the cranium. Skull: Anatomy, temporal, and occipital Occipital Part of the back and base of the cranium that encloses the foramen magnum. Skull: Anatomy lobes 
      • Extends from the interventricular foramen of Monro Foramen of Monro Ventricular System: Anatomy to the splenium of the corpus callosum.
    • Anterior horn Anterior horn One of three central columns of the spinal cord. It is composed of gray matter spinal laminae VIII and ix. Brown-Séquard Syndrome: in the frontal lobe Frontal lobe The part of the cerebral hemisphere anterior to the central sulcus, and anterior and superior to the lateral sulcus. Cerebral Cortex: Anatomy
    • Posterior horn Posterior horn One of three central columns of the spinal cord. It is composed of gray matter spinal laminae i-vi. Brown-Séquard Syndrome: curves posteromedially into the occipital lobe Occipital lobe Posterior portion of the cerebral hemispheres responsible for processing visual sensory information. It is located posterior to the parieto-occipital sulcus and extends to the preoccipital notch. Cerebral Cortex: Anatomy
    • Inferior horn
      • Largest compartment of the lateral ventricle
      • Extends forward into the temporal lobe Temporal lobe Lower lateral part of the cerebral hemisphere responsible for auditory, olfactory, and semantic processing. It is located inferior to the lateral fissure and anterior to the occipital lobe. Cerebral Cortex: Anatomy
  • 3rd ventricle: midline, slit-like cavity
  • Cerebral aqueduct Cerebral aqueduct Narrow channel in the mesencephalon that connects the third and fourth cerebral ventricles. Ventricular System: Anatomy: small tube extending throughout the dorsal quarter of the midbrain Midbrain The middle of the three primitive cerebral vesicles of the embryonic brain. Without further subdivision, midbrain develops into a short, constricted portion connecting the pons and the diencephalon. Midbrain contains two major parts, the dorsal tectum mesencephali and the ventral tegmentum mesencephali, housing components of auditory, visual, and other sensorimotor systems. Brain Stem: Anatomy in the midline and surrounded by the periaqueductal gray
  • 4th ventricle: between the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification stem and the cerebellum Cerebellum The cerebellum, Latin for “little brain,” is located in the posterior cranial fossa, dorsal to the pons and midbrain, and its principal role is in the coordination of movements. The cerebellum consists of 3 lobes on either side of its 2 hemispheres and is connected in the middle by the vermis. Cerebellum: Anatomy
Ventricular system isolated from brain

Ventricular system Ventricular System The ventricular system is an extension of the subarachnoid space into the brain consisting of a series of interconnecting spaces and channels. Four chambers are filled with cerebrospinal fluid (CSF): the paired lateral ventricles, the unpaired 3rd ventricle, and the unpaired 4th ventricle. Ventricular System: Anatomy isolated from the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification:
Note the lateral ventricles Lateral ventricles Cavity in each of the cerebral hemispheres derived from the cavity of the embryonic neural tube. They are separated from each other by the septum pellucidum, and each communicates with the third ventricle by the foramen of monro, through which also the choroid plexuses (choroid plexus) of the lateral ventricles become continuous with that of the third ventricle. Ventricular System: Anatomy, the 3rd ventricle in the center, and the 4th ventricle toward the bottom.

Image by Lecturio.

Arterial supply of the head

The arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology that supply the skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy and its contents can be divided into 2 large groups.

  • The external group is made up of the branches of the external carotid artery External carotid artery Branch of the common carotid artery which supplies the exterior of the head, the face, and the greater part of the neck. Carotid Arterial System: Anatomy
  • The internal group is made up of branches of the circle of Willis Circle of Willis A polygonal anastomosis at the base of the brain formed by the internal carotid, proximal parts of the anterior, middle, and posterior cerebral arteries, the anterior communicating artery and the posterior communicating arteries. Subarachnoid Hemorrhage:
    • Anterior cerebral artery Anterior cerebral artery Artery formed by the bifurcation of the internal carotid artery. Branches of the anterior cerebral artery supply the caudate nucleus; internal capsule; putamen; septal nuclei; gyrus cinguli; and surfaces of the frontal lobe and parietal lobe. Cerebrovascular System: Anatomy
    • Middle cerebral artery Middle cerebral artery The largest of the cerebral arteries. It trifurcates into temporal, frontal, and parietal branches supplying blood to most of the parenchyma of these lobes in the cerebral cortex. These are the areas involved in motor, sensory, and speech activities. Cerebrovascular System: Anatomy
    • Posterior cerebral artery Posterior cerebral artery Artery formed by the bifurcation of the basilar artery. Branches of the posterior cerebral artery supply portions of the occipital lobe; parietal lobe; inferior temporal gyrus, brainstem, and choroid plexus. Cerebrovascular System: Anatomy
Major branches of the external carotid artery

Major branches of the external carotid artery External carotid artery Branch of the common carotid artery which supplies the exterior of the head, the face, and the greater part of the neck. Carotid Arterial System: Anatomy

Image by BioDigital, edited by Lecturio

Dural venous sinuses Dural venous sinuses Cerebrovascular System: Anatomy

The venous drainage system of the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification is located between the endosteal and meningeal layers of dura mater Dura mater The outermost of the three meninges, a fibrous membrane of connective tissue that covers the brain and the spinal cord. Meninges: Anatomy. These vessels are lined by endothelium Endothelium A layer of epithelium that lines the heart, blood vessels (vascular endothelium), lymph vessels (lymphatic endothelium), and the serous cavities of the body. Arteries: Histology and have no valves or smooth muscle cells in their walls. 

The following sinuses are in contact with the bones of the skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy:

  • Superior sagittal Sagittal Computed Tomography (CT) sinus
  • Transverse sinus Transverse sinus The two large endothelium-lined venous channels that begin at the internal occipital protuberance at the back and lower part of the cranium and travels laterally and forward ending in the internal jugular vein (jugular veins). One of the transverse sinuses, usually the right one, is the continuation of the superior sagittal sinus. The other transverse sinus is the continuation of the straight sinus. Cerebrovascular System: Anatomy
  • Sigmoid Sigmoid A segment of the colon between the rectum and the descending colon. Volvulus sinus
Venous sinuses of the middle and posterior fossa

Venous sinuses Venous sinuses Veins: Histology of the middle and posterior fossa
IJV: internal jugular vein Internal jugular vein Parapharyngeal Abscess

Image by Lecturio.

Vertebral column Vertebral column The human spine, or vertebral column, is the most important anatomical and functional axis of the human body. It consists of 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae and is limited cranially by the skull and caudally by the sacrum. Vertebral Column: Anatomy

  • 33 vertebrae placed in series and connected by intervertebral disks and ligaments
  • Vertebral column Vertebral column The human spine, or vertebral column, is the most important anatomical and functional axis of the human body. It consists of 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae and is limited cranially by the skull and caudally by the sacrum. Vertebral Column: Anatomy segmentation Segmentation Gastrointestinal Motility
    • Cervical: 7
    • Thoracic: 12
    • Lumbar: 5
    • Sacral: 5
    • Coccygeal: 4 (3–5)
  • The vertebrae form the spinal canal Spinal Canal The cavity within the spinal column through which the spinal cord passes. Spinal Cord Injuries, which houses the spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy and spinal nerves Spinal nerves The 31 paired peripheral nerves formed by the union of the dorsal and ventral spinal roots from each spinal cord segment. The spinal nerve plexuses and the spinal roots are also included. Spinal Cord: Anatomy 
  • Intervertebral foramina (neuroforamen or neural foramen): foramen for the spinal nerves Spinal nerves The 31 paired peripheral nerves formed by the union of the dorsal and ventral spinal roots from each spinal cord segment. The spinal nerve plexuses and the spinal roots are also included. Spinal Cord: Anatomy exiting the vertebral column Vertebral column The human spine, or vertebral column, is the most important anatomical and functional axis of the human body. It consists of 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae and is limited cranially by the skull and caudally by the sacrum. Vertebral Column: Anatomy  between 2 spinal vertebrae
Intervertebral disk

The intervertebral disk space is highlighted in this image.

Image: “ Intervertebral disc Intervertebral disc Any of the 23 plates of fibrocartilage found between the bodies of adjacent vertebrae. Vertebral Column: Anatomy” by Phil Schatz. License: CC BY 4.0

Vertebrae

  • Components:
    • Body (anterior)
    • Vertebral arch Vertebral arch Vertebral Column: Anatomy (lateral and posterior) formed by the vertebral pedicles, laminae, and spinous processes
    • Spinous processes: 
      • Transverse (lateral)
      • Articular (superior and inferior, form the facets)
      • Spinous (posterior) 
  • Foramina:
    • Vertebral: Large central openings in vertebrae that collectively form the vertebral, or spinal, canal, which contains:
      • Spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy
      • Nerve roots
      • Blood vessels
    • Intervertebral foramina (neuroforamen or neural foramen): opening for the spinal nerves Spinal nerves The 31 paired peripheral nerves formed by the union of the dorsal and ventral spinal roots from each spinal cord segment. The spinal nerve plexuses and the spinal roots are also included. Spinal Cord: Anatomy 
  • Intervertebral disks:
    • Components:
      • Annulus fibrosus Annulus Fibrosus Spinal Disk Herniation
      • Nucleus Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (cell nucleolus). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the endoplasmic reticulum. A cell may contain more than one nucleus. The Cell: Organelles pulposus
      • Cartilaginous end plates anchor the disks to the adjacent vertebrae
Superior view (left) and anterior view (right) of a lumbar vertebra-01

Components of vertebrae

Image by BioDigital, edited by Lecturio

Craniotomy/Craniectomy

Definition

  • Craniotomy: surgical procedure that aims to access the cranial cavity and operate directly on the cerebral parenchyma by removing a bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types flap from the skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy.
  • Craniectomy: a craniotomy in which the bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types flap is used as a template for a titanium or acrylic plate or is stored for later reimplantation. 
  • Cranioplasty: surgical procedure to reconstruct the skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy by placing the bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types flap, or a synthetic replacement, into position during a 2nd intervention.

Classification

  • Hemicraniectomy: removal of bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types in a single hemisphere 
  • Bilateral craniectomy: removal of a single bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types flap from both hemispheres

Depending on the location, a craniotomy is:

  • Supratentorial
  • Infratentorial

Indications

  • Craniotomy:
    • Brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast/ tumor Tumor Inflammation removal
    • Blood clot treatment
    • Removing a foreign body Foreign Body Foreign Body Aspiration
    • Implantation Implantation Endometrial implantation of embryo, mammalian at the blastocyst stage. Fertilization and First Week of a device with therapeutic intent (e.g., deep brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification stimulation in the treatment of Parkinson disease Parkinson disease Parkinson’s disease (PD) is a chronic, progressive neurodegenerative disorder. Although the cause is unknown, several genetic and environmental risk factors are currently being studied. Individuals present clinically with resting tremor, bradykinesia, rigidity, and postural instability. Parkinson’s Disease)
  • Craniectomy:
    • Elevated intracranial pressure Intracranial Pressure Idiopathic Intracranial Hypertension ( ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP)) refractory to medical intervention
    • Traumatic brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification injury
    • Stroke
    • Chiari malformation
    • Brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification herniation Herniation Omphalocele: pathologic displacement Displacement The process by which an emotional or behavioral response that is appropriate for one situation appears in another situation for which it is inappropriate. Defense Mechanisms of intracranial structures due to an increased pressure gradient Pressure gradient Vascular Resistance, Flow, and Mean Arterial Pressure between the intracranial compartments

Contraindications Contraindications A condition or factor associated with a recipient that makes the use of a drug, procedure, or physical agent improper or inadvisable. Contraindications may be absolute (life threatening) or relative (higher risk of complications in which benefits may outweigh risks). Noninvasive Ventilation

  • Severe cardiopulmonary disease
  • Severe systemic collapse (e.g., sepsis Sepsis Systemic inflammatory response syndrome with a proven or suspected infectious etiology. When sepsis is associated with organ dysfunction distant from the site of infection, it is called severe sepsis. When sepsis is accompanied by hypotension despite adequate fluid infusion, it is called septic shock. Sepsis and Septic Shock, adrenal crisis Adrenal crisis Adrenal crisis is the acute decompensation of adrenal function that can be triggered by another disease, surgery, stress, or increased glucocorticoid inactivation. Adrenal Insufficiency and Addison’s Disease, massive hemorrhage)
  • Abnormal coagulation parameters

Operative care

When used for decompression, the craniotomy/craniectomy procedure turns the intracranial compartment from a semirigid shape into an elastic Elastic Connective Tissue: Histology container.

  1. An incision is made on the scalp. A local anesthetic with epinephrine Epinephrine The active sympathomimetic hormone from the adrenal medulla. It stimulates both the alpha- and beta- adrenergic systems, causes systemic vasoconstriction and gastrointestinal relaxation, stimulates the heart, and dilates bronchi and cerebral vessels. Sympathomimetic Drugs may be administered at the incision site to prevent heavy bleeding of the scalp.
  2. Subcutaneous tissue Subcutaneous tissue Loose connective tissue lying under the dermis, which binds skin loosely to subjacent tissues. It may contain a pad of adipocytes, which vary in number according to the area of the body and vary in size according to the nutritional state. Soft Tissue Abscess and muscles are dissected to expose the skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy.
  3. Retractors are placed on the edges of the incision to expose the work area.
  4. Burr holes are made in the skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy to mark the corners of the skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy segment to be removed. 
  5. The burr holes are linked using a craniotome, creating a bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types flap.
  6. The dura is separated from the bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types.
  7. After separating the bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types flap from the dura, it is elevated and then removed. At this time, the bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types flap can be:
    • Kept on the surgical table until reimplantation
    • Discarded (requires immediate intraoperative reconstruction with synthetic materials)
    • Placed within an abdominal subcutaneous incision
    • Preserved in a tissue bank
  8. The dura is cut and retracted to expose the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification to perform the specific intervention.
  9. The intended procedure is performed on the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification parenchyma.
  10. The bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types flap is reattached to the rest of the skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy using plates and screws.
  11. The incision on the scalp is closed by layers using absorbable sutures Absorbable Sutures Surgical Instruments and Sutures.
    • The surgeon is careful to ensure adequate homeostasis Homeostasis The processes whereby the internal environment of an organism tends to remain balanced and stable. Cell Injury and Death before closing the scalp. 
    • The surgeon can decide to leave a subdural or subgaleal drain in place.
  12. The skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions is closed using nonabsorbable sutures Nonabsorbable Sutures Surgical Instruments and Sutures
  13. The skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions is cleansed of any residue (e.g., blood, adipose tissue Adipose tissue Adipose tissue is a specialized type of connective tissue that has both structural and highly complex metabolic functions, including energy storage, glucose homeostasis, and a multitude of endocrine capabilities. There are three types of adipose tissue, white adipose tissue, brown adipose tissue, and beige or “brite” adipose tissue, which is a transitional form. Adipose Tissue: Histology)
  14. A sterile Sterile Basic Procedures gauze and skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions dressing are placed over the surgical wound. 
Intraoperative images of craniotomy

Intraoperative images of craniotomy:
A: The 2-part craniotomy is elevated to reveal intact dura spanning the transverse sinus Transverse sinus The two large endothelium-lined venous channels that begin at the internal occipital protuberance at the back and lower part of the cranium and travels laterally and forward ending in the internal jugular vein (jugular veins). One of the transverse sinuses, usually the right one, is the continuation of the superior sagittal sinus. The other transverse sinus is the continuation of the straight sinus. Cerebrovascular System: Anatomy.
B: The inner concavity of the 2-part bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types flap is seen. The Penfield #4 instrument points to the imprint of the transverse sinus Transverse sinus The two large endothelium-lined venous channels that begin at the internal occipital protuberance at the back and lower part of the cranium and travels laterally and forward ending in the internal jugular vein (jugular veins). One of the transverse sinuses, usually the right one, is the continuation of the superior sagittal sinus. The other transverse sinus is the continuation of the straight sinus. Cerebrovascular System: Anatomy.
C: The 2 bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types pieces have been fixed to each other on the internal surface; here, the external convexity is restored with an excellent anatomic cosmetic result.

Image: “Intraoperative Images of Craniotomy” by Department of Neurological Surgery, University of California, San Francisco. License: CC BY 30

Cranioplasty

  • The timing for cranioplasty depends on the individual’s clinical status and is left to the surgeon’s discretion (at least 6 weeks to 3 months after injury).
  • Some surgeons wait up to 6 months, depending on the individual’s underlying medical issues.
  • Autologous bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types should be used whenever possible (cheaper than synthetic materials), especially in young individuals owing to skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy growth. 
  • Rehabilitation can be started and continued while the individual is wearing a helmet. 

Prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas

  • Depends on the underlying condition
  • When performed for decompression, neurologic recovery has been reported in the weeks following the procedure (e.g., improved motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology strength and language function)

Complications

  • Intracranial hematomas (subdural, epidural, subarachnoid)
  • Heavy bleeding
  • Dural sinus perforation Perforation A pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force. Esophagitis
  • Postcraniotomy headache Headache The symptom of pain in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of headache disorders. Brain Abscess
  • Neurologic deficit
  • Hydrocephalus Hydrocephalus Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial. Subarachnoid Hemorrhage: potentially life-threatening condition caused by the excess accumulation of CSF within the ventricular system Ventricular System The ventricular system is an extension of the subarachnoid space into the brain consisting of a series of interconnecting spaces and channels. Four chambers are filled with cerebrospinal fluid (CSF): the paired lateral ventricles, the unpaired 3rd ventricle, and the unpaired 4th ventricle. Ventricular System: Anatomy. Hydrocephalus Hydrocephalus Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial. Subarachnoid Hemorrhage can be classified as communicating, which is caused by either impaired CSF absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption or excess CSF production, or noncommunicating, which is caused by a structural blockage in CSF flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure
  • Seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures: abnormal, excessive and hypersynchronous firing of neurons Neurons The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the nervous system. Nervous System: Histology. Seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures can be generalized (involving both hemispheres and compromising awareness) or focal (involving a single area of the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification and not compromising awareness)
  • Stroke: refers to the injury undergone by brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification tissue after interruption of blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure ( ischemic stroke Ischemic Stroke An ischemic stroke (also known as cerebrovascular accident) is an acute neurologic injury that occurs as a result of brain ischemia; this condition may be due to cerebral blood vessel occlusion by thrombosis or embolism, or rarely due to systemic hypoperfusion. Ischemic Stroke) or active hemorrhage ( hemorrhagic stroke Hemorrhagic stroke Stroke due to rupture of a weakened blood vessel in the brain (e.g., cerebral hemispheres; cerebellum; subarachnoid space). Subarachnoid Hemorrhage), which has characteristic neurologic clinical features
  • Coma Coma Coma is defined as a deep state of unarousable unresponsiveness, characterized by a score of 3 points on the GCS. A comatose state can be caused by a multitude of conditions, making the precise epidemiology and prognosis of coma difficult to determine. Coma: clinical state characterized by unarousability and unresponsiveness to external stimuli
  • Surgical site infection Surgical site infection Infection occurring at the site of a surgical incision. Surgical Complications
  • Osteomyelitis Osteomyelitis Osteomyelitis is an infection of the bone that results from the spread of microorganisms from the blood (hematogenous), nearby infected tissue, or open wounds (non-hematogenous). Infections are most commonly caused by Staphylococcus aureus. Osteomyelitis of the bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types flap: inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types due to infection (most commonly by bacterial agents)
  • Bacterial, viral, fungal meningitis Meningitis Meningitis is inflammation of the meninges, the protective membranes of the brain, and spinal cord. The causes of meningitis are varied, with the most common being bacterial or viral infection. The classic presentation of meningitis is a triad of fever, altered mental status, and nuchal rigidity. Meningitis: inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the leptomeninges Leptomeninges Meninges: Anatomy due to an infectious Infectious Febrile Infant agent
  • Air embolism Air embolism Blocking of a blood vessel by air bubbles that enter the circulatory system, usually after trauma; surgical procedures, or changes in atmospheric pressure. Nonthrombotic Embolism: embolization Embolization A method of hemostasis utilizing various agents such as gelfoam, silastic, metal, glass, or plastic pellets, autologous clot, fat, and muscle as emboli. It has been used in the treatment of spinal cord and intracranial arteriovenous malformations, renal arteriovenous fistulas, gastrointestinal bleeding, epistaxis, hypersplenism, certain highly vascular tumors, traumatic rupture of blood vessels, and control of operative hemorrhage. Gastrointestinal Bleeding of gas bubbles within the circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment leading to blockage of arterial or venous blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure 

Ventriculostomy

Definition

A ventriculostomy is an opening created to communicate the cerebral ventricles with a sterile Sterile Basic Procedures extracranial space. The therapeutic goal is drainage of CSF contained within the ventricles, decompression of intracranial spaces, and a decrease in the ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP).

Indications

  • Acute symptomatic hydrocephalus Hydrocephalus Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial. Subarachnoid Hemorrhage
  • ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP) monitoring
  • Intraoperative brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema: swelling Swelling Inflammation of the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification that occurs during another intracranial procedure

Contraindications Contraindications A condition or factor associated with a recipient that makes the use of a drug, procedure, or physical agent improper or inadvisable. Contraindications may be absolute (life threatening) or relative (higher risk of complications in which benefits may outweigh risks). Noninvasive Ventilation

  • Use of anticoagulants Anticoagulants Anticoagulants are drugs that retard or interrupt the coagulation cascade. The primary classes of available anticoagulants include heparins, vitamin K-dependent antagonists (e.g., warfarin), direct thrombin inhibitors, and factor Xa inhibitors. Anticoagulants
  • Bleeding disorders Bleeding disorders Hypocoagulable conditions, also known as bleeding disorders or bleeding diathesis, are a diverse group of diseases that result in abnormal hemostasis. Physiologic hemostasis is dependent on the integrity of endothelial cells, subendothelial matrix, platelets, and coagulation factors. The hypocoagulable states result from abnormalities in one or more of these contributors, resulting in ineffective thrombosis and bleeding. Hypocoagulable Conditions
  • Scalp infection
  • Brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease

Operative care

  1. Kocher’s point is identified 1–2 cm anterior to the coronal suture Coronal suture Cranial suture, or a type of fibrous joint, between the frontal and parietal bones. Skull: Anatomy in the midpupillary line.
  2. An incision is made on the scalp. A local anesthetic with epinephrine Epinephrine The active sympathomimetic hormone from the adrenal medulla. It stimulates both the alpha- and beta- adrenergic systems, causes systemic vasoconstriction and gastrointestinal relaxation, stimulates the heart, and dilates bronchi and cerebral vessels. Sympathomimetic Drugs may be administered at the incision site to prevent heavy bleeding of the scalp.
  3. Subcutaneous tissue Subcutaneous tissue Loose connective tissue lying under the dermis, which binds skin loosely to subjacent tissues. It may contain a pad of adipocytes, which vary in number according to the area of the body and vary in size according to the nutritional state. Soft Tissue Abscess and muscles are dissected to expose the skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy.
  4. A burr hole Burr Hole Subdural Hemorrhage is made in the skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy using a craniotome (craniostomy).
  5. The dura is carefully perforated.
  6. A pliable catheter with a rigid internal stylet is passed through the burr hole Burr Hole Subdural Hemorrhage and through the cerebral parenchyma into the ventricle. 
  7. The stylet is removed and adequate placement of the catheter is confirmed with CSF flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure.
  8. The catheter is directed under the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions to a sterile Sterile Basic Procedures exit site in the scalp, a few centimeters away from the burr hole Burr Hole Subdural Hemorrhage
  9. The catheter is connected to a sterile Sterile Basic Procedures drainage system. 

Complications

  • Vascular injury
  • Intracranial hemorrhage Intracranial hemorrhage Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most sahs originate from a saccular aneurysm in the circle of willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage
  • Blockage of catheter lumen by air, blood, and/or debris
  • Failure to tap ventricle or catheter misplacement
  • Ventriculitis: inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the ventricles due to a pathogen 
  • Pneumocephalus: a collection of air within the cranial vault Cranial Vault Increased Intracranial Pressure (ICP) 

Ventriculoperitoneal (VP) Shunt

Definition

A VP shunt is a surgically created communication Communication The exchange or transmission of ideas, attitudes, or beliefs between individuals or groups. Decision-making Capacity and Legal Competence between the cerebral ventricles and the peritoneal cavity Peritoneal Cavity The space enclosed by the peritoneum. It is divided into two portions, the greater sac and the lesser sac or omental bursa, which lies behind the stomach. The two sacs are connected by the foramen of winslow, or epiploic foramen. Peritoneum: Anatomy. The aim of this treatment is to drain CSF within the ventricles and decrease ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP).

Indications

  • Congenital Congenital Chorioretinitis or acquired hydrocephalus Hydrocephalus Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial. Subarachnoid Hemorrhage
  • Craniosynostosis Craniosynostosis Craniosynostosis is the premature fusion of 1 or more cranial sutures during the 1st year of life. Craniosynostosis is classified as simple or complex, and can be caused by environmental factors or genetic syndromes. Craniosynostosis 
  • Dandy-Walker syndrome
  • Idiopathic Idiopathic Dermatomyositis intracranial hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension

Contraindications Contraindications A condition or factor associated with a recipient that makes the use of a drug, procedure, or physical agent improper or inadvisable. Contraindications may be absolute (life threatening) or relative (higher risk of complications in which benefits may outweigh risks). Noninvasive Ventilation

  • Infection over the entry site
  • Infected CSF
  • Allergy Allergy An abnormal adaptive immune response that may or may not involve antigen-specific IgE Type I Hypersensitivity Reaction to shunt components (e.g., silicone)

Operative care

  1. A U- or C-shaped incision is made on:
    1. Kocher’s point for a frontal Frontal The bone that forms the frontal aspect of the skull. Its flat part forms the forehead, articulating inferiorly with the nasal bone and the cheek bone on each side of the face. Skull: Anatomy approach
    2. Keen’s point (2.5–3 cm superior and posterior to the pinna) for a parieto-occipital approach.
  2. Subcutaneous tissue Subcutaneous tissue Loose connective tissue lying under the dermis, which binds skin loosely to subjacent tissues. It may contain a pad of adipocytes, which vary in number according to the area of the body and vary in size according to the nutritional state. Soft Tissue Abscess and muscles are dissected to expose the skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy.
  3. A burr hole Burr Hole Subdural Hemorrhage is made in the skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy using a craniotome.
  4. The dura is carefully perforated.
  5. A catheter is passed through the burr hole Burr Hole Subdural Hemorrhage into the ventricle with a stylet. 
  6. The catheter is cut to a premeasured length, and CSF samples are collected.
  7. The catheter is connected to the valve and secured with silk sutures.
  8. An incision in the abdomen and the peritoneal cavity Peritoneal Cavity The space enclosed by the peritoneum. It is divided into two portions, the greater sac and the lesser sac or omental bursa, which lies behind the stomach. The two sacs are connected by the foramen of winslow, or epiploic foramen. Peritoneum: Anatomy is accessed.
  9. A shunt passer is used to pass the peritoneal catheter between the abdominal and cranial incisions.
  10. The peritoneal catheter is connected to the valve and secured with silk sutures.
  11. Patency of the peritoneal catheter is confirmed by the flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure of CSF. 
  12. The distal end of the peritoneal catheter is introduced into the peritoneal cavity Peritoneal Cavity The space enclosed by the peritoneum. It is divided into two portions, the greater sac and the lesser sac or omental bursa, which lies behind the stomach. The two sacs are connected by the foramen of winslow, or epiploic foramen. Peritoneum: Anatomy.
Illustration of a ventriculoperitoneal shunt in a baby

Ventriculoperitoneal shunt in an infant with important structures, such as the valve, reservoir Reservoir Animate or inanimate sources which normally harbor disease-causing organisms and thus serve as potential sources of disease outbreaks. Reservoirs are distinguished from vectors (disease vectors) and carriers, which are agents of disease transmission rather than continuing sources of potential disease outbreaks. Humans may serve both as disease reservoirs and carriers. Escherichia coli, and burr hole Burr Hole Subdural Hemorrhage, labeled

Image by Lecturio.

Complications

  • Shunt infection
  • Intracerebral or intraventricular hemorrhage Intraventricular hemorrhage Bleeding within the cerebral ventricles. It is associated with intraventricular trauma, aneurysm, vascular malformations, hypertension and in very low birth weight infants. Intracerebral Hemorrhage
  • Malposition of the shunt
  • Abdominal perforation Perforation A pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force. Esophagitis
  • Erosion Erosion Partial-thickness loss of the epidermis Generalized and Localized Rashes of the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions by the shunt
  • Shunt nephritis: a rare, reversible immune complex–mediated inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy secondary to shunt infection
  • Shunt disconnection
  • Shunt obstruction
  • Abdominal CSF collections (pseudocyst)
  • Shunt breakage
  • Catheter perforation Perforation A pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force. Esophagitis of viscera
  • Inguinal hernia Hernia Protrusion of tissue, structure, or part of an organ through the bone, muscular tissue, or the membrane by which it is normally contained. Hernia may involve tissues such as the abdominal wall or the respiratory diaphragm. Hernias may be internal, external, congenital, or acquired. Abdominal Hernias
  • Seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures (focal or generalized)

Spinal Cord Decompression Surgery (SCDS)

Definition

Spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy decompression surgery Decompression surgery A surgical operation for the relief of pressure in a body compartment or on a body part. Cranial Nerve Palsies is a group of surgical interventions performed in the vertebral column Vertebral column The human spine, or vertebral column, is the most important anatomical and functional axis of the human body. It consists of 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae and is limited cranially by the skull and caudally by the sacrum. Vertebral Column: Anatomy with the goal of alleviating direct compression Compression Blunt Chest Trauma on the spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy

Decompression techniques include:

  • Laminectomy
  • Diskectomy/microdiskectomy
  • Corpectomy
  • Foraminotomy
  • Osteophyte Osteophyte Bony outgrowth usually found around joints and often seen in conditions such as arthritis. Osteoarthritis removal

Decompression techniques are classified as direct (permits visualization of the dural sac) and indirect (does not permit visualization of the dural sac).

Indications

  • Nerve root compression Compression Blunt Chest Trauma due to intervertebral disk herniation Herniation Omphalocele causing radiculopathy Radiculopathy Disease involving a spinal nerve root which may result from compression related to intervertebral disk displacement; spinal cord injuries; spinal diseases; and other conditions. Clinical manifestations include radicular pain, weakness, and sensory loss referable to structures innervated by the involved nerve root. Rheumatoid Arthritis
  • Spinal canal Spinal Canal The cavity within the spinal column through which the spinal cord passes. Spinal Cord Injuries stenosis Stenosis Hypoplastic Left Heart Syndrome (HLHS) causing spinal claudication (may be congenital Congenital Chorioretinitis or acquired)
  • Cauda equina syndrome Cauda Equina Syndrome Compressive lesion affecting the nerve roots of the cauda equina (e.g., compression, herniation, inflammation, rupture, or stenosis), which controls the function of the bladder and bowel. Symptoms may include neurological dysfunction of bladder or bowels, loss of sexual sensation and altered sensation or paralysis in the lower extremities. Ankylosing Spondylitis

Contraindication

Spinal instability is a contraindication for SCDS.

Operative care

Spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy decompression surgery Decompression surgery A surgical operation for the relief of pressure in a body compartment or on a body part. Cranial Nerve Palsies is performed as a combination of different procedures according to the needs in each individual case. The following are among the most commonly performed decompression techniques. 

Laminectomy (open approach):

  1. A posterior midline incision is made. The extent of the incision depends on the number of laminae to be removed.
  2. The subcutaneous soft tissues and paraspinal muscles are dissected and retracted. 
  3. Dissection continues until the ligamentum flavum is reached, which is resected using a Woodson elevator and spatula.
  4. Once the spinous processes and laminae are fully exposed, they are sharply debulked and dissected with a rongeur to expose the spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy dura and spinal nerve roots.
  5. The compressive lesion (e.g., spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy tumor Tumor Inflammation, bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types fragments, foreign bodies) is removed.
  6. Interbody cages may be used to stabilize the spine Spine The human spine, or vertebral column, is the most important anatomical and functional axis of the human body. It consists of 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae and is limited cranially by the skull and caudally by the sacrum. Vertebral Column: Anatomy after the laminectomy.

Diskectomy (open approach):

  1. A posterior incision is made parallel to the midline ipsilateral to the defect.
  2. The subcutaneous soft tissues and paraspinal muscles are dissected and retracted down to the laminar junction.
  3. A Cobb elevator is used to continue the dissection to the facet joints.
  4. The ligamentum flavum is released from its attachment Attachment The binding of virus particles to virus receptors on the host cell surface, facilitating virus entry into the cell. Virology on the anterior aspect of the lamina of the superior vertebra using a curette.
  5. The ligamentum is incised and retracted with a Penfield elevator to gain visualization of the nerve root.
  6. The nerve root is retracted medially using a Penfield elevator to visualize the intervertebral space and the herniated disk.
  7. Herniated tissue is removed.
  8. If indicated, a total disk replacement is performed. 

These procedures may also be done in a minimally invasive fashion; however, such procedures are beyond the scope of this review. 

Spinal cord decompression surgery

Illustration showing different procedures for spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy decompression surgery Decompression surgery A surgical operation for the relief of pressure in a body compartment or on a body part. Cranial Nerve Palsies

Image by Lecturio.

Complications

  • Dural sac tear
  • Nerve root injury 
  • CSF leak Csf Leak Le Fort Fractures
  • Spinal instability
  • Surgical site infection Surgical site infection Infection occurring at the site of a surgical incision. Surgical Complications and wound dehiscence Wound dehiscence Pathologic process consisting of a partial or complete disruption of the layers of a surgical wound. Wound Healing
  • Meningitis Meningitis Meningitis is inflammation of the meninges, the protective membranes of the brain, and spinal cord. The causes of meningitis are varied, with the most common being bacterial or viral infection. The classic presentation of meningitis is a triad of fever, altered mental status, and nuchal rigidity. Meningitis

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