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Motor Neuron Lesions

Upper motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology 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 (UMNs) and lower motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology 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 (LMNs) combine to form a neuronal circuit for movement. UMNs are responsible for carrying motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology information from the cerebral cortex Cerebral cortex The cerebral cortex is the largest and most developed part of the human brain and CNS. Occupying the upper part of the cranial cavity, the cerebral cortex has 4 lobes and is divided into 2 hemispheres that are joined centrally by the corpus callosum. Cerebral Cortex: Anatomy and 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 to 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 LMNs carry motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology information from UMNs in 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 to the skeletal muscles Skeletal muscles A subtype of striated muscle, attached by tendons to the skeleton. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles. Muscle Tissue: Histology for movement. Upper motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron lesions cause damage to 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 above the motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology nuclei of the cranial nerves Cranial nerves There are 12 pairs of cranial nerves (CNs), which run from the brain to various parts of the head, neck, and trunk. The CNs can be sensory or motor or both. The CNs are named and numbered in Roman numerals according to their location, from the front to the back of the brain. The 12 Cranial Nerves: Overview and Functions in 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 or the 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 cells in 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. These lesions present clinically with symptoms of weakness, spasticity Spasticity Spinal Disk Herniation, clonus Clonus Ehrlichiosis and Anaplasmosis, and hyperreflexia. Causes include stroke, 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, 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 cancer, infectious Infectious Febrile Infant and inflammatory disorders, and metabolic and neurodegenerative disorders. Lower motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron lesions affect Affect The feeling-tone accompaniment of an idea or mental representation. It is the most direct psychic derivative of instinct and the psychic representative of the various bodily changes by means of which instincts manifest themselves. Psychiatric Assessment the nerve fibers Nerve Fibers Slender processes of neurons, including the axons and their glial envelopes (myelin sheath). Nerve fibers conduct nerve impulses to and from the central nervous system. Nervous System: Histology traveling from the 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 of 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 to the peripheral muscle. These lesions present clinically with muscle weakness, atrophy Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation, and hyporeflexia Hyporeflexia Duchenne Muscular Dystrophy, with sensation remaining intact. Diagnosis is made by clinical neurologic exam, and management is mostly supportive, but some newer therapies have recently become available.

Last updated: Jul 6, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Overview

Definition

Upper motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron (UMN) lesions originate in the cerebral cortex Cerebral cortex The cerebral cortex is the largest and most developed part of the human brain and CNS. Occupying the upper part of the cranial cavity, the cerebral cortex has 4 lobes and is divided into 2 hemispheres that are joined centrally by the corpus callosum. Cerebral Cortex: Anatomy or 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 cause damage to 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 above the motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology nuclei of the cranial nerves Cranial nerves There are 12 pairs of cranial nerves (CNs), which run from the brain to various parts of the head, neck, and trunk. The CNs can be sensory or motor or both. The CNs are named and numbered in Roman numerals according to their location, from the front to the back of the brain. The 12 Cranial Nerves: Overview and Functions (CNs) in 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 or the 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 cells in 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 (SC).
Lower motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron (LMN) lesions affect Affect The feeling-tone accompaniment of an idea or mental representation. It is the most direct psychic derivative of instinct and the psychic representative of the various bodily changes by means of which instincts manifest themselves. Psychiatric Assessment the nerve fibers Nerve Fibers Slender processes of neurons, including the axons and their glial envelopes (myelin sheath). Nerve fibers conduct nerve impulses to and from the central nervous system. Nervous System: Histology traveling from the 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 of the SC to the peripheral muscle.

Anatomy and physiology

  • CNS controls the skeletal muscles Skeletal muscles A subtype of striated muscle, attached by tendons to the skeleton. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles. Muscle Tissue: Histology via 2 types of motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology 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:
    • UMNs: further divided into pyramidal and extrapyramidal tracts Extrapyramidal tracts Uncrossed tracts of motor nerves from the brain to the anterior horns of the spinal cord, involved in reflexes, locomotion, complex movements, and postural control. Spinal Cord: Anatomy
    • LMNs 
  • UMN pyramidal tract:
    • Direct pathway Direct Pathway Huntington Disease between cerebral cortex Cerebral cortex The cerebral cortex is the largest and most developed part of the human brain and CNS. Occupying the upper part of the cranial cavity, the cerebral cortex has 4 lobes and is divided into 2 hemispheres that are joined centrally by the corpus callosum. Cerebral Cortex: Anatomy and SC
    • Carries signals for voluntary movements only
    • Motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology areas of the cerebral hemispheres innervate muscles on the contralateral side of the body.
    • Divided into:
      • Corticospinal tract (whose fibers synapse Synapse The junction between 2 neurons is called a synapse. The synapse allows a neuron to pass an electrical or chemical signal to another neuron or target effector cell. Synapses and Neurotransmission with 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)
      • Corticobulbar tract (whose fibers synapse Synapse The junction between 2 neurons is called a synapse. The synapse allows a neuron to pass an electrical or chemical signal to another neuron or target effector cell. Synapses and Neurotransmission with CNs in 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) 
  • UMN extrapyramidal tract:
    • Indirect connection:  fibers pass through the tegmentum rather than the medullary pyramid
    • Involved in:
      • Initiation and coordination Coordination Cerebellar Disorders of voluntary movements
      • Involuntary movements such as reflexes (pyramidal system controls voluntary movements only)
  • LMNs: 
    • Found in the 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/ventral SC or at the CN nuclei in 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
    • Exist in both the central and peripheral nervous systems
    • Classification:
      • Branchial muscles innervated by CNs V, VII, IX, and X
      • Visceral: autonomic sympathetic (fight-or-flight response) and parasympathetic (rest and digest) innervation to the smooth muscles Smooth muscles Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. Muscle Tissue: Histology, glands, and GI tract
      • Lower motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology 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 do not directly innervate the viscera but contribute to the CN functions that regulate these responses.
      • Somatic: directly innervate skeletal muscles Skeletal muscles A subtype of striated muscle, attached by tendons to the skeleton. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles. Muscle Tissue: Histology for contraction/movement

Etiologies of motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron lesions

  • Hereditary
    • UMN: hereditary spastic paraplegia 
    • LMN: 
  • Sporadic Sporadic Selective IgA Deficiency 
    • UMN: 
      • Primary lateral sclerosis Sclerosis A pathological process consisting of hardening or fibrosis of an anatomical structure, often a vessel or a nerve. Wilms Tumor
      • 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
      • 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 transection
      • Brown-Séquard syndrome Brown-Séquard syndrome Brown-Séquard syndrome (BSS) is a rare neurologic injury that causes hemisection of the spinal cord, resulting in weakness and paralysis of one side of the body and sensory loss on the opposite side. Brown-Séquard Syndrome 
    • LMN: poliomyelitis Poliomyelitis Poliomyelitis is an infectious disease caused by the poliovirus. Transmission occurs through the fecal-oral route and through respiratory aerosols. The majority of patients will be asymptomatic or have a mild, abortive presentation with flu-like symptoms. Those who develop nonparalytic poliomyelitis will develop signs and symptoms of aseptic meningitis. A very minor proportion of patients will progress to paralytic poliomyelitis. Poliovirus/Poliomyelitis 
    • Both UMN and LMN: 
  • Immune-mediated 
    • UMN: none
    • LMN: 
      • Multifocal Multifocal Retinoblastoma motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuropathy Neuropathy Leprosy
      • Chronic inflammatory demyelinating polyneuropathy Polyneuropathy Polyneuropathy is any disease process affecting the function of or causing damage to multiple nerves of the peripheral nervous system. There are numerous etiologies of polyneuropathy, most of which are systemic and the most common of which is diabetic neuropathy. Polyneuropathy ( CIDP CIDP A slowly progressive autoimmune demyelinating disease of peripheral nerves and nerve roots. Clinical manifestations include weakness and sensory loss in the extremities and enlargement of peripheral nerves. The course may be relapsing-remitting or demonstrate a step-wise progression. Protein is usually elevated in the spinal fluid and cranial nerves are typically spared. Guillain-barre syndrome features a relatively rapid progression of disease which distinguishes it from this condition. Polyneuropathy)
      • Guillain-Barré syndrome Guillain-Barré syndrome Guillain-Barré syndrome (GBS), once thought to be a single disease process, is a family of immune-mediated polyneuropathies that occur after infections (e.g., with Campylobacter jejuni). Guillain-Barré Syndrome
Umn vs lmn lesions

Upper motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron (UMN) and lower motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron (LMN) pathways

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Clinical Presentation

UMN lesions above the decussation manifest as motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology symptoms on the contralateral side of the body, whereas lesions below the pyramidal decussation present on the ipsilateral side of the body. Pathologic mechanisms of LMN lesions involve axonal degeneration and cell death Cell death Injurious stimuli trigger the process of cellular adaptation, whereby cells respond to withstand the harmful changes in their environment. Overwhelmed adaptive mechanisms lead to cell injury. Mild stimuli produce reversible injury. If the stimulus is severe or persistent, injury becomes irreversible. Apoptosis is programmed cell death, a mechanism with both physiologic and pathologic effects. Cell Injury and Death of the LMN.

Signs associated with upper motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron lesions

  • Weakness
  • Clonus Clonus Ehrlichiosis and Anaplasmosis
  • No fasciculations Fasciculations Involuntary contraction of the muscle fibers innervated by a motor unit. Fasciculations may be visualized as a muscle twitch or dimpling under the skin, but usually do not generate sufficient force to move a limb. They may represent a benign condition or occur as a manifestation of motor neuron disease or peripheral nervous system diseases. Polyneuropathy
  • Increased tone
    • Spasticity Spasticity Spinal Disk Herniation 
    • Clasp-knife rigidity Rigidity Continuous involuntary sustained muscle contraction which is often a manifestation of basal ganglia diseases. When an affected muscle is passively stretched, the degree of resistance remains constant regardless of the rate at which the muscle is stretched. This feature helps to distinguish rigidity from muscle spasticity. Megacolon 
  • Hyperreflexia
  • Positive Babinski sign Babinski sign A reflex found in normal infants consisting of dorsiflexion of the hallux and abduction of the other toes in response to cutaneous stimulation of the plantar surface of the foot. In adults, it is used as a diagnostic criterion, and if present is a neurologic manifestation of dysfunction in the central nervous system. Posterior Cord Syndrome: extension Extension Examination of the Upper Limbs (dorsiflexion) of the big toe and fanning of the other toes
  • Pseudobulbar palsy Pseudobulbar palsy A syndrome characterized by dysarthria, dysphagia, dysphonia, impairment of voluntary movements of tongue and facial muscles, and emotional lability. This condition is caused by diseases that affect the motor fibers that travel from the cerebral cortex to the lower brain stem (i.e., corticobulbar tracts); including multiple sclerosis; motor neuron disease; and cerebrovascular disorders. Atypical Parkinsonian Syndromes:
    • Slurred speech Slurred Speech Cerebellar Disorders
    • Dysphagia Dysphagia Dysphagia is the subjective sensation of difficulty swallowing. Symptoms can range from a complete inability to swallow, to the sensation of solids or liquids becoming “stuck.” Dysphagia is classified as either oropharyngeal or esophageal, with esophageal dysphagia having 2 sub-types: functional and mechanical. Dysphagia
    • Dysarthria Dysarthria Disorders of speech articulation caused by imperfect coordination of pharynx, larynx, tongue, or face muscles. This may result from cranial nerve diseases; neuromuscular diseases; cerebellar diseases; basal ganglia diseases; brain stem diseases; or diseases of the corticobulbar tracts. The cortical language centers are intact in this condition. Wilson’s Disease
    • Tongue Tongue The tongue, on the other hand, is a complex muscular structure that permits tasting and facilitates the process of mastication and communication. The blood supply of the tongue originates from the external carotid artery, and the innervation is through cranial nerves. Lips and Tongue: Anatomy spasticity Spasticity Spinal Disk Herniation
    • Pseudobulbar affect Affect The feeling-tone accompaniment of an idea or mental representation. It is the most direct psychic derivative of instinct and the psychic representative of the various bodily changes by means of which instincts manifest themselves. Psychiatric Assessment: emotional manifestations, including uncontrollable episodes of crying, laughing, and anger

Signs associated with lower motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron lesions

  • Weakness
  • Atrophy Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation
  • Fasciculations Fasciculations Involuntary contraction of the muscle fibers innervated by a motor unit. Fasciculations may be visualized as a muscle twitch or dimpling under the skin, but usually do not generate sufficient force to move a limb. They may represent a benign condition or occur as a manifestation of motor neuron disease or peripheral nervous system diseases. Polyneuropathy:
  • Decreased tone
  • Hyporeflexia Hyporeflexia Duchenne Muscular Dystrophy
  • Bulbar palsy Bulbar Palsy Locked-in Syndrome
    • Symptoms related to impaired function of the lower CNs (IX, X, XI, and XII)
    • Involves impairment of muscles used for chewing, swallowing Swallowing The act of taking solids and liquids into the gastrointestinal tract through the mouth and throat. Gastrointestinal Motility, and tongue Tongue The tongue, on the other hand, is a complex muscular structure that permits tasting and facilitates the process of mastication and communication. The blood supply of the tongue originates from the external carotid artery, and the innervation is through cranial nerves. Lips and Tongue: Anatomy movements

Summary of clinical findings in upper and lower motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron lesions

Table: Clinical findings that help differentiate upper motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron (UMN) from lower motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron (LMN) lesions
Clinical finding UMN lesion LMN lesion
Muscle tone Muscle tone The state of activity or tension of a muscle beyond that related to its physical properties, that is, its active resistance to stretch. In skeletal muscle, tonus is dependent upon efferent innervation. Skeletal Muscle Contraction
  • Spastic
  • Rigid
Hypotonic Hypotonic Solutions that have a lesser osmotic pressure than a reference solution such as blood, plasma, or interstitial fluid. Renal Sodium and Water Regulation
Muscle mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast No change Muscle wasting Muscle Wasting Duchenne Muscular Dystrophy present
Fasciculation None Present
Tendon reflexes Hyperreflexia Hyporeflexia Hyporeflexia Duchenne Muscular Dystrophy/ areflexia Areflexia Duchenne Muscular Dystrophy
Electromyographic findings Normal nerve conduction Abnormal nerve conduction

Diagnosis

It is important to differentiate central from peripheral nervous system Peripheral nervous system The nervous system outside of the brain and spinal cord. The peripheral nervous system has autonomic and somatic divisions. The autonomic nervous system includes the enteric, parasympathetic, and sympathetic subdivisions. The somatic nervous system includes the cranial and spinal nerves and their ganglia and the peripheral sensory receptors. Nervous System: Anatomy, Structure, and Classification lesions on exam.

History

  • Onset of disease 
  • Progression (rapid versus gradual)  
  • Symptoms as above

Physical exam

  • Muscle examination:
    • Muscle bulk: Inspect for atrophy Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation seen with LMN lesions.
    • Muscle tone Muscle tone The state of activity or tension of a muscle beyond that related to its physical properties, that is, its active resistance to stretch. In skeletal muscle, tonus is dependent upon efferent innervation. Skeletal Muscle Contraction: Inspect for spasticity Spasticity Spinal Disk Herniation or rigidity Rigidity Continuous involuntary sustained muscle contraction which is often a manifestation of basal ganglia diseases. When an affected muscle is passively stretched, the degree of resistance remains constant regardless of the rate at which the muscle is stretched. This feature helps to distinguish rigidity from muscle spasticity. Megacolon seen with UMN lesions.
    • Inspect for fasciculations Fasciculations Involuntary contraction of the muscle fibers innervated by a motor unit. Fasciculations may be visualized as a muscle twitch or dimpling under the skin, but usually do not generate sufficient force to move a limb. They may represent a benign condition or occur as a manifestation of motor neuron disease or peripheral nervous system diseases. Polyneuropathy.
    • Test for symmetric versus asymmetric weakness.
    • Test for proximal (LMN/ 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) versus distal (due to peripheral nerve lesions) weakness.
  • Complete neurologic exam:

Diagnostic tests Diagnostic tests Diagnostic tests are important aspects in making a diagnosis. Some of the most important epidemiological values of diagnostic tests include sensitivity and specificity, false positives and false negatives, positive and negative predictive values, likelihood ratios, and pre-test and post-test probabilities. Epidemiological Values of Diagnostic Tests

  • Electromyography Electromyography Recording of the changes in electric potential of muscle by means of surface or needle electrodes. Becker Muscular Dystrophy (EMG): 
  • Nerve conduction study:
    • Normal in UMN lesion
    • Abnormal in LMN lesion
  • Lumbar puncture Lumbar Puncture Febrile Infant
  • Laboratory tests to rule out other causes:
  • MRI imaging to evaluate for:
    • 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 SC tumors
    • Stroke
    • Inflammatory disorders
    • Infectious Infectious Febrile Infant 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 or SC lesions
    • Multiple sclerosis Sclerosis A pathological process consisting of hardening or fibrosis of an anatomical structure, often a vessel or a nerve. Wilms Tumor

Genetic tests

  • Used for identifying genes Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. DNA Types and Structure involved in some UMN and LMN syndromes:
    • Spinal muscular atrophy Spinal Muscular Atrophy Spinal muscular atrophy (SMA) is a spectrum of autosomal recessive syndromes characterized by progressive proximal muscle weakness and atrophy, possibly due to degeneration of the anterior horn cells in the spinal cord and motor nuclei in the lower brainstem. Spinal Muscular Atrophy
    • Spinobulbar muscular atrophy Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation 
    • Some causes of familial ALS ALS Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, is a sporadic or inherited neurodegenerative disease of upper motor neurons (UMNs) and lower motor neurons (LMNs). ALS is the most common progressive motor neuron disease in North America, primarily affecting men and individuals of Caucasian ethnicity. Amyotrophic Lateral Sclerosis
  • Includes next-generation sequencing:
    • A modern DNA-sequencing technology to study genetic variation associated with certain diseases 
    • Entire genome Genome The complete genetic complement contained in the DNA of a set of chromosomes in a human. The length of the human genome is about 3 billion base pairs. Basic Terms of Genetics can be sequenced in 1 day.

Management

There is no standard treatment for motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron diseases, but there are some medical and surgical methods available to treat the sequelae of UMN and LMN lesions and help individuals maintain their quality Quality Activities and programs intended to assure or improve the quality of care in either a defined medical setting or a program. The concept includes the assessment or evaluation of the quality of care; identification of problems or shortcomings in the delivery of care; designing activities to overcome these deficiencies; and follow-up monitoring to ensure effectiveness of corrective steps. Quality Measurement and Improvement of life.

Supportive management

  • Physical therapy Physical Therapy Becker Muscular Dystrophy:
    • Stretching and strengthening exercises to reduce stiffness
    • Prevent and treat contractures Contractures Prolonged shortening of the muscle or other soft tissue around a joint, preventing movement of the joint. Wound Healing.
    • Help improve posture.
    • Prevent joint immobility.
    • Slow muscle weakness and atrophy Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation.
  • Speech therapy Speech Therapy Treatment for individuals with speech defects and disorders that involves counseling and use of various exercises and AIDS to help the development of new speech habits. Myotonic Dystrophies:
    • Helps with chewing and swallowing Swallowing The act of taking solids and liquids into the gastrointestinal tract through the mouth and throat. Gastrointestinal Motility difficulties
    • Speech synthesizers
  • Assistive devices:
    • Mobility Mobility Examination of the Breast aids AIDS Chronic HIV infection and depletion of CD4 cells eventually results in acquired immunodeficiency syndrome (AIDS), which can be diagnosed by the presence of certain opportunistic diseases called AIDS-defining conditions. These conditions include a wide spectrum of bacterial, viral, fungal, and parasitic infections as well as several malignancies and generalized conditions. HIV Infection and AIDS: canes, wheelchairs, motorized scooters
    • Braces, orthotics
  • Other therapies:
    • Feeding tubes may be required to maintain good nutrition.
    • Noninvasive positive pressure ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing or assisted ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing: for severe muscle weakness in the neck Neck The part of a human or animal body connecting the head to the rest of the body. Peritonsillar Abscess, throat Throat The pharynx is a component of the digestive system that lies posterior to the nasal cavity, oral cavity, and larynx. The pharynx can be divided into the oropharynx, nasopharynx, and laryngopharynx. Pharyngeal muscles play an integral role in vital processes such as breathing, swallowing, and speaking. Pharynx: Anatomy, and chest

Medication

  • Muscle relaxers for spasticity Spasticity Spinal Disk Herniation:
    • Baclofen Baclofen A gamma-aminobutyric acid derivative that is a specific agonist of gaba-b receptors. It is used in the treatment of muscle spasticity, especially that due to spinal cord injuries. Its therapeutic effects result from actions at spinal and supraspinal sites, generally the reduction of excitatory transmission. Spasmolytics
    • Tizanidine Tizanidine Spasmolytics
    • Dantrolene Dantrolene Skeletal muscle relaxant that acts by interfering with excitation-contraction coupling in the muscle fiber. It is used in spasticity and other neuromuscular abnormalities. Although the mechanism of action is probably not central, dantrolene is usually grouped with the central muscle relaxants. Spasmolytics
    • Botulinum toxin Botulinum toxin Toxic proteins produced from the species Clostridium botulinum. The toxins are synthesized as a single peptide chain which is processed into a mature protein consisting of a heavy chain and light chain joined via a disulfide bond. The botulinum toxin light chain is a zinc-dependent protease which is released from the heavy chain upon endocytosis into presynaptic nerve endings. Once inside the cell the botulinum toxin light chain cleaves specific snare proteins which are essential for secretion of acetylcholine by synaptic vesicles. This inhibition of acetylcholine release results in muscular paralysis. Botulism injections: treat muscle stiffness Muscle Stiffness Ion Channel Myopathy by weakening overactive muscles
  • For excess salivation (antisialogogues):
    • Amitriptyline Amitriptyline Tricyclic antidepressant with anticholinergic and sedative properties. It appears to prevent the reuptake of norepinephrine and serotonin at nerve terminals, thus potentiating the action of these neurotransmitters. Amitriptyline also appears to antagonize cholinergic and alpha-1 adrenergic responses to bioactive amines. Tricyclic Antidepressants (a tricyclic antidepressant Antidepressant Antidepressants encompass several drug classes and are used to treat individuals with depression, anxiety, and psychiatric conditions, as well as those with chronic pain and symptoms of menopause. Antidepressants include selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), and many other drugs in a class of their own. Serotonin Reuptake Inhibitors and Similar Antidepressants with anticholinergic Anticholinergic Anticholinergic drugs block the effect of the neurotransmitter acetylcholine at the muscarinic receptors in the central and peripheral nervous systems. Anticholinergic agents inhibit the parasympathetic nervous system, resulting in effects on the smooth muscle in the respiratory tract, vascular system, urinary tract, GI tract, and pupils of the eyes. Anticholinergic Drugs properties causing dry mouth)
    • Glycopyrrolate Glycopyrrolate A muscarinic antagonist used as an antispasmodic, in some disorders of the gastrointestinal tract, and to reduce salivation with some anesthetics. Anticholinergic Drugs
    • Atropine Atropine An alkaloid, originally from atropa belladonna, but found in other plants, mainly solanaceae. Hyoscyamine is the 3(s)-endo isomer of atropine. Anticholinergic Drugs
    • Botulinum toxin Botulinum toxin Toxic proteins produced from the species Clostridium botulinum. The toxins are synthesized as a single peptide chain which is processed into a mature protein consisting of a heavy chain and light chain joined via a disulfide bond. The botulinum toxin light chain is a zinc-dependent protease which is released from the heavy chain upon endocytosis into presynaptic nerve endings. Once inside the cell the botulinum toxin light chain cleaves specific snare proteins which are essential for secretion of acetylcholine by synaptic vesicles. This inhibition of acetylcholine release results in muscular paralysis. Botulism injections into the salivary glands Salivary glands The salivary glands are exocrine glands positioned in and around the oral cavity. These glands are responsible for secreting saliva into the mouth, which aids in digestion. There are 3 major paired salivary glands: the sublingual, submandibular, and parotid glands. Salivary Glands: Anatomy to stop drooling Drooling Peritonsillar Abscess
  • Disease-specific medications:
    • ALS ALS Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, is a sporadic or inherited neurodegenerative disease of upper motor neurons (UMNs) and lower motor neurons (LMNs). ALS is the most common progressive motor neuron disease in North America, primarily affecting men and individuals of Caucasian ethnicity. Amyotrophic Lateral Sclerosis: New drugs available may provide protection against further damage to motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology 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 and prevent disease progression.
    • Spinal muscular atrophy Spinal Muscular Atrophy Spinal muscular atrophy (SMA) is a spectrum of autosomal recessive syndromes characterized by progressive proximal muscle weakness and atrophy, possibly due to degeneration of the anterior horn cells in the spinal cord and motor nuclei in the lower brainstem. Spinal Muscular Atrophy: Some new gene Gene A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Basic Terms of Genetics therapies are available.
    • Multiple sclerosis Sclerosis A pathological process consisting of hardening or fibrosis of an anatomical structure, often a vessel or a nerve. Wilms Tumor: immunomodulators and immunosuppressants Immunosuppressants Immunosuppressants are a class of drugs widely used in the management of autoimmune conditions and organ transplant rejection. The general effect is dampening of the immune response. Immunosuppressants

Surgery

  • If individual has voluntary control of extremities: can lengthen spastic muscles to increase the individual’s level of function
  • If individual is not able to use extremities: may need muscle origin release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology, myotomy, tenotomy, neurectomy, or arthrodesis

Clinical Relevance

Syndromes with upper motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron lesion features

  • Stroke: also known as a cerebrovascular accident Cerebrovascular accident 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. Stroke can be ischemic (cerebral blood vessel occlusion by thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus or embolism) or less commonly hemorrhagic (intracranial bleeding). The clinical presentation includes neurologic symptoms with varying degrees of motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology and sensory Sensory Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology loss corresponding to the 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 affected and the extent of the tissue damage. Diagnosis is made by physical examination and imaging. Management depends on whether it is a thrombotic or hemorrhagic event.
  • Brown-Séquard syndrome Brown-Séquard syndrome Brown-Séquard syndrome (BSS) is a rare neurologic injury that causes hemisection of the spinal cord, resulting in weakness and paralysis of one side of the body and sensory loss on the opposite side. Brown-Séquard Syndrome: refers to hemisection Hemisection Brown-Séquard Syndrome of the SC secondary to injury, most commonly from penetrating trauma. Other etiologies include blunt trauma, disc herniation Herniation Omphalocele, hematoma Hematoma A collection of blood outside the blood vessels. Hematoma can be localized in an organ, space, or tissue. Intussusception, and malignancy Malignancy Hemothorax. The clinical presentation of Brown-Séquard syndrome Brown-Séquard syndrome Brown-Séquard syndrome (BSS) is a rare neurologic injury that causes hemisection of the spinal cord, resulting in weakness and paralysis of one side of the body and sensory loss on the opposite side. Brown-Séquard Syndrome is with weakness and paralysis of 1 side of the body and sensory Sensory Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology loss on the opposite side. The UMN lesion syndrome manifests ipsilaterally and below the level of the hemisection Hemisection Brown-Séquard Syndrome.  
  • Primary lateral sclerosis Sclerosis A pathological process consisting of hardening or fibrosis of an anatomical structure, often a vessel or a nerve. Wilms Tumor (PLS): UMN neurodegenerative disorder. Primary lateral sclerosis Sclerosis A pathological process consisting of hardening or fibrosis of an anatomical structure, often a vessel or a nerve. Wilms Tumor is considered to be sporadic Sporadic Selective IgA Deficiency, although there are some subtypes with genetic heritability. The disorder presents similarly to ALS ALS Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, is a sporadic or inherited neurodegenerative disease of upper motor neurons (UMNs) and lower motor neurons (LMNs). ALS is the most common progressive motor neuron disease in North America, primarily affecting men and individuals of Caucasian ethnicity. Amyotrophic Lateral Sclerosis, although with slower progression and without any LMN findings initially. The majority of people with PLS will progress to ALS ALS Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, is a sporadic or inherited neurodegenerative disease of upper motor neurons (UMNs) and lower motor neurons (LMNs). ALS is the most common progressive motor neuron disease in North America, primarily affecting men and individuals of Caucasian ethnicity. Amyotrophic Lateral Sclerosis within 4 years of symptom onset. There is no cure for PLS, and management is supportive, similar to that for ALS ALS Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, is a sporadic or inherited neurodegenerative disease of upper motor neurons (UMNs) and lower motor neurons (LMNs). ALS is the most common progressive motor neuron disease in North America, primarily affecting men and individuals of Caucasian ethnicity. Amyotrophic Lateral Sclerosis
  • Hereditary spastic paraplegia ( HSP HSP Henoch-Schönlein purpura (HSP), also known as immunoglobulin A vasculitis, is an autoimmune small-vessel vasculitis that typically presents as a tetrad of abdominal pain, arthralgia, hematuria, and purpuric rash. Henoch-Schönlein Purpura): neurodegenerative disorder presenting with bilateral lower extremity weakness and spasticity Spasticity Spinal Disk Herniation. This disorder is a hereditary cause of UMN lesions. In addition to the UMN signs, HSP HSP Henoch-Schönlein purpura (HSP), also known as immunoglobulin A vasculitis, is an autoimmune small-vessel vasculitis that typically presents as a tetrad of abdominal pain, arthralgia, hematuria, and purpuric rash. Henoch-Schönlein Purpura may present with cognitive impairment, ataxia Ataxia Impairment of the ability to perform smoothly coordinated voluntary movements. This condition may affect the limbs, trunk, eyes, pharynx, larynx, and other structures. Ataxia may result from impaired sensory or motor function. Sensory ataxia may result from posterior column injury or peripheral nerve diseases. Motor ataxia may be associated with cerebellar diseases; cerebral cortex diseases; thalamic diseases; basal ganglia diseases; injury to the red nucleus; and other conditions. Ataxia-telangiectasia, and peripheral neuropathy Peripheral Neuropathy Neurofibromatosis Type 2. Management is similar to that for ALS ALS Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, is a sporadic or inherited neurodegenerative disease of upper motor neurons (UMNs) and lower motor neurons (LMNs). ALS is the most common progressive motor neuron disease in North America, primarily affecting men and individuals of Caucasian ethnicity. Amyotrophic Lateral Sclerosis, but HSP HSP Henoch-Schönlein purpura (HSP), also known as immunoglobulin A vasculitis, is an autoimmune small-vessel vasculitis that typically presents as a tetrad of abdominal pain, arthralgia, hematuria, and purpuric rash. Henoch-Schönlein Purpura has a better 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; progression of the disease is much slower and symptoms are usually limited to the lower extremities. 
  • Vitamin B12 deficiency: may arise because of insufficient intake, gastrectomy, and autoimmune destruction of gastric parietal cells Parietal cells Rounded or pyramidal cells of the gastric glands. They secrete hydrochloric acid and produce gastric intrinsic factor, a glycoprotein that binds vitamin B12. Stomach: Anatomy, among others. This deficiency manifests clinically as fatigue Fatigue The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli. Fibromyalgia and peripheral neuropathy Peripheral Neuropathy Neurofibromatosis Type 2 and even has psychiatric features. The diagnosis is confirmed through megaloblastic anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types on CBC and measurement of serum B12 levels. Management is via removing barriers to 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 plus supplementation.

Syndromes with lower motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron lesion features

  • Poliomyelitis Poliomyelitis Poliomyelitis is an infectious disease caused by the poliovirus. Transmission occurs through the fecal-oral route and through respiratory aerosols. The majority of patients will be asymptomatic or have a mild, abortive presentation with flu-like symptoms. Those who develop nonparalytic poliomyelitis will develop signs and symptoms of aseptic meningitis. A very minor proportion of patients will progress to paralytic poliomyelitis. Poliovirus/Poliomyelitis: infectious Infectious Febrile Infant disease caused by poliovirus Poliovirus Poliomyelitis is an infectious disease caused by the poliovirus. This virus is a member of the Picornaviridae family. It is a small, single-stranded, positive-sense RNA virus without a lipid envelope. Transmission occurs through the fecal-oral route and, occasionally, through respiratory aerosols. Poliovirus/Poliomyelitis affecting the 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 cells via 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. Transmission of poliomyelitis Poliomyelitis Poliomyelitis is an infectious disease caused by the poliovirus. Transmission occurs through the fecal-oral route and through respiratory aerosols. The majority of patients will be asymptomatic or have a mild, abortive presentation with flu-like symptoms. Those who develop nonparalytic poliomyelitis will develop signs and symptoms of aseptic meningitis. A very minor proportion of patients will progress to paralytic poliomyelitis. Poliovirus/Poliomyelitis occurs through the fecal–oral route and through respiratory aerosols Aerosols Colloids with a gaseous dispersing phase and either liquid (fog) or solid (smoke) dispersed phase; used in fumigation or in inhalation therapy; may contain propellant agents. Coxiella/Q Fever. A very small proportion of individuals will progress to paralytic poliomyelitis Poliomyelitis Poliomyelitis is an infectious disease caused by the poliovirus. Transmission occurs through the fecal-oral route and through respiratory aerosols. The majority of patients will be asymptomatic or have a mild, abortive presentation with flu-like symptoms. Those who develop nonparalytic poliomyelitis will develop signs and symptoms of aseptic meningitis. A very minor proportion of patients will progress to paralytic poliomyelitis. Poliovirus/Poliomyelitis with neurologic progression. Diagnosis is by clinical presentation, viral culture Viral culture West Nile Virus, PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR), and serology Serology The study of serum, especially of antigen-antibody reactions in vitro. Yellow Fever Virus. Current antivirals are ineffective, and management is supportive. The 2 available vaccines have almost eradicated this disease worldwide. 
  • Guillain-Barré syndrome Guillain-Barré syndrome Guillain-Barré syndrome (GBS), once thought to be a single disease process, is a family of immune-mediated polyneuropathies that occur after infections (e.g., with Campylobacter jejuni). Guillain-Barré Syndrome ( GBS GBS An acute inflammatory autoimmune neuritis caused by t cell- mediated cellular immune response directed towards peripheral myelin. Demyelination occurs in peripheral nerves and nerve roots. The process is often preceded by a viral or bacterial infection, surgery, immunization, lymphoma, or exposure to toxins. Common clinical manifestations include progressive weakness, loss of sensation, and loss of deep tendon reflexes. Weakness of respiratory muscles and autonomic dysfunction may occur. Polyneuropathy): immune-mediated neuropathy Neuropathy Leprosy that may occur after a bacterial or viral infection or less frequently after a triggering event such as immunization or trauma. Guillain-Barré syndrome Guillain-Barré syndrome Guillain-Barré syndrome (GBS), once thought to be a single disease process, is a family of immune-mediated polyneuropathies that occur after infections (e.g., with Campylobacter jejuni). Guillain-Barré Syndrome is characterized by acute, symmetric, ascending neuromuscular paralysis that can progress to respiratory failure Respiratory failure Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation. Respiratory failure may be acute or chronic and is classified as hypoxemic, hypercapnic, or a combination of the two. Respiratory Failure. Diagnosis is based on clinical presentation, exam, and CSF findings. Management is mostly supportive and may require either plasma Plasma The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation. Transfusion Products exchange or IV immunoglobulin Iv Immunoglobulin Dermatomyositis
  • Spinal muscular atrophy Spinal Muscular Atrophy Spinal muscular atrophy (SMA) is a spectrum of autosomal recessive syndromes characterized by progressive proximal muscle weakness and atrophy, possibly due to degeneration of the anterior horn cells in the spinal cord and motor nuclei in the lower brainstem. Spinal Muscular Atrophy (SMA): spectrum of autosomal recessive Autosomal recessive Autosomal inheritance, both dominant and recessive, refers to the transmission of genes from the 22 autosomal chromosomes. Autosomal recessive diseases are only expressed when 2 copies of the recessive allele are inherited. Autosomal Recessive and Autosomal Dominant Inheritance syndromes characterized by progressive proximal muscle weakness Proximal Muscle Weakness Lambert-Eaton Myasthenic Syndrome and atrophy Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation. Spinal muscular atrophy Spinal Muscular Atrophy Spinal muscular atrophy (SMA) is a spectrum of autosomal recessive syndromes characterized by progressive proximal muscle weakness and atrophy, possibly due to degeneration of the anterior horn cells in the spinal cord and motor nuclei in the lower brainstem. Spinal Muscular Atrophy is due to degeneration of the 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 cells in the SC and motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology nuclei in the lower 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. There are 5 clinical types of SMA, each with its distinctive clinical presentation. Initial diagnosis is made clinically and confirmed with genetic testing Genetic Testing Detection of a mutation; genotype; karyotype; or specific alleles associated with genetic traits, heritable diseases, or predisposition to a disease, or that may lead to the disease in descendants. It includes prenatal genetic testing. Myotonic Dystrophies. Management is mostly supportive, and the 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 clinical type. 
  • Spinobulbar muscular atrophy Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation (Kennedy disease): X-linked X-linked Genetic diseases that are linked to gene mutations on the X chromosome in humans or the X chromosome in other species. Included here are animal models of human X-linked diseases. Common Variable Immunodeficiency (CVID) disorder of 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 SC LMNs that classically presents in men ages 20–50 and worsens progressively over time. Manifestations of this disease are facial and limb-girdle muscle atrophy Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation and weakness, tremor Tremor Cyclical movement of a body part that can represent either a physiologic process or a manifestation of disease. Intention or action tremor, a common manifestation of cerebellar diseases, is aggravated by movement. In contrast, resting tremor is maximal when there is no attempt at voluntary movement, and occurs as a relatively frequent manifestation of parkinson disease. Myotonic Dystrophies, fasciculations Fasciculations Involuntary contraction of the muscle fibers innervated by a motor unit. Fasciculations may be visualized as a muscle twitch or dimpling under the skin, but usually do not generate sufficient force to move a limb. They may represent a benign condition or occur as a manifestation of motor neuron disease or peripheral nervous system diseases. Polyneuropathy, mild cognitive impairment, and some associated endocrinopathies. Diagnosis is made with lab and genetic testing Genetic Testing Detection of a mutation; genotype; karyotype; or specific alleles associated with genetic traits, heritable diseases, or predisposition to a disease, or that may lead to the disease in descendants. It includes prenatal genetic testing. Myotonic Dystrophies and also electromyography Electromyography Recording of the changes in electric potential of muscle by means of surface or needle electrodes. Becker Muscular Dystrophy and nerve conduction velocity testing (EMG/NCV). Management is supportive.

Syndromes with both upper and lower motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology neuron features

  • Amyotrophic lateral sclerosis Sclerosis A pathological process consisting of hardening or fibrosis of an anatomical structure, often a vessel or a nerve. Wilms Tumor ( ALS ALS Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, is a sporadic or inherited neurodegenerative disease of upper motor neurons (UMNs) and lower motor neurons (LMNs). ALS is the most common progressive motor neuron disease in North America, primarily affecting men and individuals of Caucasian ethnicity. Amyotrophic Lateral Sclerosis): also known as Lou Gehrig disease. Amyotrophic lateral sclerosis Sclerosis A pathological process consisting of hardening or fibrosis of an anatomical structure, often a vessel or a nerve. Wilms Tumor is a sporadic Sporadic Selective IgA Deficiency or inherited neurodegenerative disease of UMNs and LMNs. This disease is characterized by the coexistence of UMN and LMN signs and symptoms that lead to weakness and difficulty speaking and swallowing Swallowing The act of taking solids and liquids into the gastrointestinal tract through the mouth and throat. Gastrointestinal Motility. The diagnosis is made clinically. Management is supportive and symptomatic, with a poor 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 and low 5-year survival.
  • Multiple sclerosis Sclerosis A pathological process consisting of hardening or fibrosis of an anatomical structure, often a vessel or a nerve. Wilms Tumor ( MS MS Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease that leads to demyelination of the nerves in the CNS. Young women are more predominantly affected by this most common demyelinating condition. Multiple Sclerosis): chronic inflammatory autoimmune disease leading to CNS demyelination Demyelination Multiple Sclerosis. The clinical presentation of MS MS Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease that leads to demyelination of the nerves in the CNS. Young women are more predominantly affected by this most common demyelinating condition. Multiple Sclerosis varies widely depending on the site of lesions, but it typically involves neurologic symptoms affecting vision Vision Ophthalmic Exam, motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology function, and autonomic function. The diagnosis is based on clinical findings, MRI imaging, and CSF examination. Management involves corticosteroids Corticosteroids Chorioretinitis for acute exacerbations and disease-modifying agents.

References

  1. Emos, M.C., Agarwal, S. (2020). Neuroanatomy, upper motor neuron lesion. StatPearls. Retrieved August 8, 2021,  from https://www.ncbi.nlm.nih.gov/books/NBK537305/
  2. Javed, K., Daly, D.T. (2020). Neuroanatomy, lower motor neuron lesion. StatPearls. Retrieved August 8, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK539814/
  3. Fullam, T., Statland, J. (2021). Upper motor neuron disorders: primary lateral sclerosis, upper motor neuron dominant amyotrophic lateral sclerosis, and hereditary spastic paraplegia. Brain Sciences 11:611. https://doi.org/10.3390/brainsci11050611
  4. Garg, N., et al. (2017). Differentiating lower motor neuron syndromes. Journal of Neurology, Neurosurgery, and Psychiatry 88:474–483. https://pubmed.ncbi.nlm.nih.gov/28003344/
  5. Miller, M.L. (2021). Approach to the patient with muscle weakness. UpToDate. Retrieved August 18, 2021, from  https://www.uptodate.com/contents/approach-to-the-patient-with-muscle-weakness
  6. Zayia, L.C., Tadi, P. (2021). Neuroanatomy, motor neuron. StatPearls. Retrieved August 8, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK554616/
  7. Ratti, E. (2015). Motor Neuron Diseases. DeckerMed Medicine. Retrieved August 8, 2021. http://dx.doi.org/10.2310/PSYCH.6266
  8. Elman, L.B., McCluskey, L. (2021).  Diagnosis of amyotrophic lateral sclerosis and other forms of motor neuron disease. UpToDate. Retrieved August 20, 2021, from  https://www.uptodate.com/contents/diagnosis-of-amyotrophic-lateral-sclerosis-and-other-forms-of-motor-neuron-disease

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