Peripheral Nerve Injuries in the Upper Extremity

Peripheral nerve damage affecting the upper extremities is a common occupational injury and also occurs in individuals who participate in recreational sports. Injuries can affect the axillary, musculocutaneous, median, ulnar, or radial nerves. The most common causes of these injuries are overuse, compression or entrapment, or nerve trauma; degenerative or demyelinating disorders; radiation therapy; and mass lesions. Clinical presentation is with motor and/or sensory deficits. Diagnosis is made clinically and based on electrodiagnostic and imaging studies. Treatment in most cases is conservative, although surgical intervention may occasionally be necessary.

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Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

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Overview

Anatomy

The brachial plexus is a network of nerves that originates in the posterior triangle of the neck and passes to the axilla Axilla The axilla is a pyramid-shaped space located between the upper thorax and the arm. The axilla has a base, an apex, and 4 walls (anterior, medial, lateral, posterior). The base of the pyramid is made up of the axillary skin. The apex is the axillary inlet, located between the 1st rib, superior border of the scapula, and clavicle. Axilla and Brachial Plexus. The brachial plexus is formed by the spinal nerve roots C5 to T1, which then divides and branches to provide all of the somatic innervation and some sympathetic innervation to the upper extremities.

  • Formed from the anterior rami of spinal nerve roots C5 to T1
  • Divided into trunks → divisions → cords, branches, and nerves
    • Upper trunk: formed by the C5 and C6 roots
    • Middle trunk: formed by the C7 root
    • Lower trunk: formed by the C8 and T1 roots
  • Divisions: Each trunk divides into an anterior and posterior part.
  • Cords, branches, and nerves
    • Lateral cord branches into:
      • Musculocutaneous nerve
      • Median nerve
    • Posterior cord branches into:
      • Axillary nerve
      • Subscapular nerve
      • Thoracodorsal nerve
      • Radial nerve
    • Medial cord branches into:
      • Median nerve
      • Ulnar nerve
      • Medial cutaneous nerves of the arm Arm The arm, or "upper arm" in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). Arm and forearm Forearm The forearm is the region of the upper limb between the elbow and the wrist. The term "forearm" is used in anatomy to distinguish this area from the arm, a term that is commonly used to describe the entire upper limb. The forearm consists of 2 long bones (the radius and the ulna), the interosseous membrane, and multiple arteries, nerves, and muscles. Forearm
    • Suprascapular nerve: arises from the upper trunk
    • Dorsal scapular nerve: arises from the C5 root
    • Long thoracic nerve: arises from the C5, C6, and C7 roots

Classification

  • Grade I injury:
    • Usually mild
    • Involves damage to the myelin sheath without the involvement of the axon of the nerve
    • Symptoms improve in a few days.
  • Grade II–IV injury:
    • Based on the extent of nerve tissue damage
    • Involves injury to the axon itself
    • Regeneration is possible, but may require months.
  • Grade V injury:
    • Most severe
    • Involves complete disruption of the axon of the nerve
    • Clinical recovery is not likely.

Pathophysiology

Peripheral nerve damage affecting the upper extremities is a common occupational injury that can also occur in individuals who participate in recreational sports. Several mechanisms are involved in nerve injury.

  • Overuse injury:
    • Caused by a combination of individual factors:
      • Genetics Genetics Genetics is the study of genes and their functions and behaviors. Basic Terms of Genetics
      • Previous trauma
      • Age-related musculoskeletal changes
      • Conditioning and lifestyle
    • Types:
      • Impingement syndrome/rotator cuff tendinitis
      • Carpal tunnel syndrome Carpal Tunnel Syndrome Carpal tunnel syndrome (CTS) is a complex of signs and symptoms caused by compression of the median nerve as it crosses the carpal tunnel. Presentation is with pain and paresthesia of the dermatomal target tissues innervated by the median nerve as well as weakness and atrophy of the nerve's myotomal targets. Carpal Tunnel Syndrome
  • Compression injury:
    • Common problem; occurs during contact sports
    • Related to nerve entrapment:
      • As the nerve courses through a ligamentous canal (e.g., carpal tunnel)
      • At the root level due to compression by a herniated cervical disc
    • Focal demyelination occurs at the site of compression without axonal damage.
    • Compression → nerve ischemia → demyelination → degeneration
  • Transection:
    • Occurs with severe trauma → complete disruption of the axon of the nerve
    • Complete loss of sensory and motor responses
    • Variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables levels of clinical recovery with regeneration
  • Nerve ischemia/infarct:
    • Ischemia occurs due to atherosclerosis Atherosclerosis Atherosclerosis is a common form of arterial disease in which lipid deposition forms a plaque in the blood vessel walls. Atherosclerosis is an incurable disease, for which there are clearly defined risk factors that often can be reduced through a change in lifestyle and behavior of the patient. Atherosclerosis → occlusion of small intraneural vessels due to:
      • 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
      • Radiation
      • Metabolic abnormalities (e.g., diabetes)
    • Nerve infarction can occur with vasculitis → axonal injury pattern → entire distal segment of the nerve degenerates within a few days
    • Nerve conduction velocity does not decrease.
    • Nerve repair:
      • After nerve injury, nerve growth factor promotes the proliferation of Schwann cells.
      • Production of neurotrophic factors by Schwann cells in the myelin sheath is crucial to axonal regeneration.
  • Infection due to various viral, microbial, and parasitic causes:
    • EBV
    • Herpes zoster Herpes Zoster Varicella-zoster virus (VZV) is a linear, double-stranded DNA virus in the Herpesviridae family. Shingles (also known as herpes zoster) is more common in adults and occurs due to the reactivation of VZV. Varicella-Zoster Virus/Chickenpox virus Virus Viruses are infectious, obligate intracellular parasites composed of a nucleic acid core surrounded by a protein capsid. Viruses can be either naked (non-enveloped) or enveloped. The classification of viruses is complex and based on many factors, including type and structure of the nucleoid and capsid, the presence of an envelope, the replication cycle, and the host range. Virology: Overview
    • Coxsackie B virus Virus Viruses are infectious, obligate intracellular parasites composed of a nucleic acid core surrounded by a protein capsid. Viruses can be either naked (non-enveloped) or enveloped. The classification of viruses is complex and based on many factors, including type and structure of the nucleoid and capsid, the presence of an envelope, the replication cycle, and the host range. Virology: Overview
    • Mumps Mumps Mumps is caused by a single-stranded, linear, negative-sense RNA virus of the family Paramyxoviridae. Mumps is typically a disease of childhood, which manifests initially with fever, muscle pain, headache, poor appetite, and a general feeling of malaise, and is classically followed by parotitis. Mumps Virus/Mumps
    • HIV
    • Human parvovirus B19 Parvovirus B19 Primate erythroparvovirus 1 (generally referred to as parvovirus B19, B19 virus, or sometimes erythrovirus B19) ranks among the smallest DNA viruses. Parvovirus B19 is of the family Parvoviridae and genus Erythrovirus. In immunocompetent humans, parvovirus B19 classically results in erythema infectiosum (5th disease) or "slapped cheek syndrome." Parvovirus B19
    • Lyme disease Lyme disease Lyme disease is a tick-borne infection caused by the gram-negative spirochete Borrelia burgdorferi. Lyme disease is transmitted by the black-legged Ixodes tick (known as a deer tick), which is only found in specific geographic regions. Patient presentation can vary depending on the stage of the disease and may include a characteristic erythema migrans rash. Lyme Disease
    • Leprosy Leprosy Leprosy, also known as Hansen's disease, is a chronic bacterial infection caused by Mycobacterium leprae complex bacteria. Symptoms primarily affect the skin and peripheral nerves, resulting in cutaneous manifestations (e.g., hypopigmented macules) and neurologic manifestations (e.g., loss of sensation). Leprosy
  • Metabolic disorders:
    • Hypothyroidism Hypothyroidism Hypothyroidism is a condition characterized by a deficiency of thyroid hormones. Iodine deficiency is the most common cause worldwide, but Hashimoto's disease (autoimmune thyroiditis) is the leading cause in non-iodine-deficient regions. Hypothyroidism: distal sensory 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 possibly due to demyelination or axonal degeneration
    • Vitamin B12 Vitamin B12 Folate and vitamin B12 are 2 of the most clinically important water-soluble vitamins. Deficiencies can present with megaloblastic anemia, GI symptoms, neuropsychiatric symptoms, and adverse pregnancy complications, including neural tube defects. Folate and Vitamin B12 deficiency causes demyelination.
    • Vitamin B6 deficiency causes decreased nerve fiber density and increased axon-to-myelin ratio.
    • Vitamin B6 toxicity causes loss of large myelinated fibers.
  • Medications:
    • Chemotherapy
    • Antibiotics
  • Malignancy: direct nerve invasion by cancer cells

Axillary Nerve Injury

The axillary nerve carries cutaneous sensory fibers to the area over the lateral shoulder and innervates the deltoid muscle for shoulder abduction and teres minor for external rotation.

  • Causes of injury:
    • Trauma:
      • Shoulder dislocation
      • Fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures of the surgical neck of the humerus
    • Compression:
      • Sleeping prone with arms raised above the head
      • Positioning of the individual while under general anesthesia Anesthesia Anesthesiology is the field of medicine that focuses on interventions that bring a state of anesthesia upon an individual. General anesthesia is characterized by a reversible loss of consciousness along with analgesia, amnesia, and muscle relaxation. Anesthesiology: History and Basic Concepts
      • Hypertrophy of the muscles of the quadrangular space (e.g., in weight lifters)
      • Compression in the axilla Axilla The axilla is a pyramid-shaped space located between the upper thorax and the arm. The axilla has a base, an apex, and 4 walls (anterior, medial, lateral, posterior). The base of the pyramid is made up of the axillary skin. The apex is the axillary inlet, located between the 1st rib, superior border of the scapula, and clavicle. Axilla and Brachial Plexus from the improper use of crutches
  • Clinical presentation:
    • Inspection: atrophy of the deltoid/loss of rounded shoulder contour
    • Sensory loss: lateral shoulder
    • Motor weakness:
      • Loss of abduction beyond 15 degrees
      • Variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables; seldom severe, as other muscles assist in shoulder abduction and external rotation
  • Diagnosis: electromyography (EMG) and nerve conduction studies (nerve conduction velocity)
  • Management:
    • Conservative:
      • PT and exercise to preserve range of motion
      • Recovery: usually within 3–4 months with incomplete nerve injury
    • Surgical intervention, if failure to improve with conservative management:
      • Nerve grafting
      • Neurolysis
      • Neurotization (direct implantation Implantation Endometrial implantation of embryo, mammalian at the blastocyst stage. Fertilization and First Week of a nerve graft into a denervated muscle)

Musculocutaneous Nerve Injury

The musculocutaneous nerve arises from the lateral cord of the brachial plexus and contains fibers from the C5, C6, and C7 nerve roots. The musculocutaneous nerve innervates the coracobrachialis, biceps, and brachialis muscles and provides sensation to the lateral forearm Forearm The forearm is the region of the upper limb between the elbow and the wrist. The term "forearm" is used in anatomy to distinguish this area from the arm, a term that is commonly used to describe the entire upper limb. The forearm consists of 2 long bones (the radius and the ulna), the interosseous membrane, and multiple arteries, nerves, and muscles. Forearm via the lateral cutaneous nerve.

  • Causes of injury:
    • Direct trauma
    • Shoulder dislocation
    • Strenuous exercise
    • Malposition of the arm Arm The arm, or "upper arm" in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). Arm during anesthesia Anesthesia Anesthesiology is the field of medicine that focuses on interventions that bring a state of anesthesia upon an individual. General anesthesia is characterized by a reversible loss of consciousness along with analgesia, amnesia, and muscle relaxation. Anesthesiology: History and Basic Concepts
  • Clinical presentation:
    • Weakness of elbow flexion
    • Weakness of forearm Forearm The forearm is the region of the upper limb between the elbow and the wrist. The term "forearm" is used in anatomy to distinguish this area from the arm, a term that is commonly used to describe the entire upper limb. The forearm consists of 2 long bones (the radius and the ulna), the interosseous membrane, and multiple arteries, nerves, and muscles. Forearm supination
    • Sensory loss over the lateral forearm Forearm The forearm is the region of the upper limb between the elbow and the wrist. The term "forearm" is used in anatomy to distinguish this area from the arm, a term that is commonly used to describe the entire upper limb. The forearm consists of 2 long bones (the radius and the ulna), the interosseous membrane, and multiple arteries, nerves, and muscles. Forearm via the lateral cutaneous nerve
  • Diagnosis:
    • Clinical motor and sensory examination
    • Electrodiagnostic tests:
      • Nerve conduction studies
      • EMG
    • MRI
  • Management:
    • Conservative:
      • Splinting
      • NSAIDs
      • PT
    • Surgical decompression if no improvement

Median Nerve Injury

The median nerve innervates the flexor muscles of the forearm Forearm The forearm is the region of the upper limb between the elbow and the wrist. The term "forearm" is used in anatomy to distinguish this area from the arm, a term that is commonly used to describe the entire upper limb. The forearm consists of 2 long bones (the radius and the ulna), the interosseous membrane, and multiple arteries, nerves, and muscles. Forearm (except the flexor carpi ulnaris and ulnar head of the flexor digitorum profundus (FDP)), the thenar muscles, and the 2 radial lumbricals in the hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand. The median nerve supplies sensation to the thumb, index, middle, and lateral half of the 4th fingers.

Causes of injury

  • Direct trauma at the wrist and elbow joints
  • Supracondylar humeral fracture
  • Entrapment at the elbow between the 2 heads of the pronator teres (pronator teres syndrome)
  • Entrapment below the flexor retinaculum (carpal tunnel syndrome)
  • Degenerating and demyelinating disorders
  • Surgical procedures
  • Chemotherapy

Carpal tunnel syndrome Carpal Tunnel Syndrome Carpal tunnel syndrome (CTS) is a complex of signs and symptoms caused by compression of the median nerve as it crosses the carpal tunnel. Presentation is with pain and paresthesia of the dermatomal target tissues innervated by the median nerve as well as weakness and atrophy of the nerve's myotomal targets. Carpal Tunnel Syndrome

  • Epidemiology:
    • Most common upper extremity mononeuropathy Mononeuropathy Neuropathy is a nerve pathology presenting with sensory, motor, or autonomic impairment secondary to dysfunction of the affected nerve. The peripheral nerves are derived from several plexuses, with the brachial and lumbosacral plexuses supplying the major innervation to the extremities. Mononeuropathies affect a single nerve. Mononeuropathy and Plexopathy due to compression
    • Prevalence: approximately 3% of the general population
    • Annual incidence: 1.1–3 and 2.2–5.4 per 1000 person-years in men and women, respectively
  • Risk factors:
    • Obesity Obesity Obesity is a condition associated with excess body weight, specifically with the deposition of excessive adipose tissue. Obesity is considered a global epidemic. Major influences come from the western diet and sedentary lifestyles, but the exact mechanisms likely include a mixture of genetic and environmental factors. Obesity
    • Female gender
    • Pregnancy
    • Diabetes
    • Hypothyroidism Hypothyroidism Hypothyroidism is a condition characterized by a deficiency of thyroid hormones. Iodine deficiency is the most common cause worldwide, but Hashimoto's disease (autoimmune thyroiditis) is the leading cause in non-iodine-deficient regions. Hypothyroidism
    • Repetitive use of hands at work
  • Clinical presentation:
    • Pain in the thumb, 2nd and 3rd digits, and the adjacent palm
    • Thenar weakness
    • Numbness and paresthesia in the 1st 3 and a ½ fingers
    • Burning pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain in the median nerve distribution
    • Symptoms worsen at night (awakens individuals).
  • Diagnosis:
    • Provocative maneuvers:
      • Tinel test: Tapping over the course of the median nerve on top of the carpal tunnel in the volar wrist causes pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain and paresthesias Paresthesias Subjective cutaneous sensations (e.g., cold, warmth, tingling, pressure, etc.) that are experienced spontaneously in the absence of stimulation. Respiratory Alkalosis.
      • Phalen test: Holding wrists fully flexed with the elbows bent for 30 seconds reproduces symptoms.
      • Compression test: applying pressure over the transverse carpal ligament
      • Hand elevation test: raising hands above the head for 1 minute
    • EMG/nerve conduction velocity testing
  • Management:
    • Conservative:
      • Wrist splinting
      • NSAIDs
      • Steroid injection into the “carpal tunnel”
    • Surgical release of the flexor retinaculum

Pronator teres syndrome

  • Clinical presentation:
    • Forearm pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain
    • Sensory loss over the entire lateral palm
    • Sensory loss over the thenar eminence
  • Diagnosis: EMG/nerve conduction velocity
  • Management:
    • NSAIDs
    • Corticosteroid injections
    • Local anesthetic injections
    • Surgical decompression

Anterior interosseous neuropathy

  • Branches off from the median nerve in the region of the elbow
  • Descends the anterior forearm Forearm The forearm is the region of the upper limb between the elbow and the wrist. The term "forearm" is used in anatomy to distinguish this area from the arm, a term that is commonly used to describe the entire upper limb. The forearm consists of 2 long bones (the radius and the ulna), the interosseous membrane, and multiple arteries, nerves, and muscles. Forearm to innervate:
    • Flexor pollicis longus (FPL) muscle
    • Deep flexors of digits 2 and 3
    • Pronator quadratus muscle
  • Does not provide sensory innervation to 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. Structure and Function of the Skin
  • Injury to the nerve is characterized by weakness of the above muscles.
  • The affected individual cannot make a standard “O” (as in “okay”) with the thumb and forefinger.
  • Isolated injury is very rare.

Recurrent branch of the median nerve injury

  • Innervates the thenar muscles
  • Injury/compression results in loss of thumb flexion, opposition, and abduction.
  • No sensory deficits
Sensory innervation of the hand

Sensory innervation of the hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand

Image by Lecturio.

Ulnar Nerve Injury

Ulnar neuropathy at the elbow is the 2nd-most diagnosed focal neuropathy. The incidence of ulnar neuropathy at the wrist is much lower than that at the elbow, but can be caused by injury at either location.

Ulnar nerve function

  • Motor innervation to:
    • Flexor carpi ulnaris
    • Medial ½ of the FDP
    • Intrinsic hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand muscles except for lateral 2 lumbricals, opponens pollicis, abductor pollicis brevis, and flexor pollicis brevis
  • Sensory innervation to:
    • Palmar aspect of the 5th finger and medial ½ of the 4th finger
    • Medial side of the dorsum of the hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand

Ulnar neuropathy at the elbow

  • Causes of injury:
    • Acute trauma (e.g., distal humerus fracture, perioperative injury)
    • Osteophytes/arthritis
    • Synovitis
    • Anomalous muscles or fibrous bands
    • Mass lesions
    • Subluxation of the ulnar nerve
  • Clinical presentation:
    • Sensory symptoms of numbness or paresthesias Paresthesias Subjective cutaneous sensations (e.g., cold, warmth, tingling, pressure, etc.) that are experienced spontaneously in the absence of stimulation. Respiratory Alkalosis in the ulnar nerve distribution:
      • Palmar aspect of the 4th and 5th digits
      • Dorsal and palmar medial (ulnar) aspects of the hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand
    • Motor deficits: intrinsic hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand muscles → loss of dexterity
    • Deficits → severe muscle wasting and claw hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand deformity

Ulnar neuropathy at the wrist

  • Causes of injury:
    • Extrinsic:
      • Bone fractures (e.g., hook of hamate fracture)
      • Lacerations
      • Direct repetitive trauma (e.g., work tools, propulsion of manual wheelchairs, cyclists)
    • Intrinsic:
      • Ganglion cysts
      • Tumors
  • Clinical presentation:
    • Hand weakness and atrophy
    • Loss of dexterity
    • Variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables sensory involvement in the ulnar distribution depending on the small branches that are affected

Diagnosis and management of ulnar neuropathy at both locations

  • Diagnosis:
    • Sensory assessment (pinprick, light touch) of territories innervated by:
      • Superficial terminal branch
      • Palmar cutaneous nerve
      • Dorsal cutaneous nerve
    • Provocative tests: positive if pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain/ paresthesias Paresthesias Subjective cutaneous sensations (e.g., cold, warmth, tingling, pressure, etc.) that are experienced spontaneously in the absence of stimulation. Respiratory Alkalosis is reproduced over the ulnar areas
      • Tinel test: percussion of the ulnar nerve over the ulnar groove or cubital tunnel
      • Elbow flexion: sustained maximal elbow flexion for 1 minute with the wrist in a neutral position
      • Pressure test: Apply sustained pressure over the ulnar nerve in the ulnar groove.
    • Palpation for local nerve tenderness and nerve thickening
  • Tests:
    • EMG/nerve conduction velocity
    • MRI shows nerve enlargement.
  • Management:
    • Activity modification:
      • Avoid leaning on the elbows.
      • Use the other hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand or headset for the phone.
      • Soft elbow pad to reduce compression
      • Splints/wrap to limit flexion at night
    • Surgery:
      • Ulnar nerve decompression
      • Ulnar nerve transposition
“claw hand” due to ulnar nerve damage

“Claw hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand” due to ulnar nerve damage, resulting in atrophy and contractions on the denervated intrinsic hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand muscles

Image: “Photograph of a healthy hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand imitating an ulnar claw” by Mcstrother. License: CC BY 3.0

Radial Nerve Injury

The radial nerve is particularly predisposed to compression in the spiral groove, where it runs adjacent to the humerus. The radial nerve provides motor innervation to the extensors of the forearm Forearm The forearm is the region of the upper limb between the elbow and the wrist. The term "forearm" is used in anatomy to distinguish this area from the arm, a term that is commonly used to describe the entire upper limb. The forearm consists of 2 long bones (the radius and the ulna), the interosseous membrane, and multiple arteries, nerves, and muscles. Forearm and extrinsic extensors of the wrists and hands, as well as sensation to the lateral half of the back of the hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand.

  • Causes of injury:
    • “Saturday night palsy”
    • Penetrating trauma (e.g., knife injury to the axilla Axilla The axilla is a pyramid-shaped space located between the upper thorax and the arm. The axilla has a base, an apex, and 4 walls (anterior, medial, lateral, posterior). The base of the pyramid is made up of the axillary skin. The apex is the axillary inlet, located between the 1st rib, superior border of the scapula, and clavicle. Axilla and Brachial Plexus)
    • Compression injuries at the humeral spiral groove
    • Humeral fracture
  • Clinical presentation:
    • Radial neuropathy at the spiral groove:
      • Normal strength in triceps
      • Weakness of wrist extensors (i.e., wrist drop)
      • Weakness of finger extension and thumb abduction
      • Sensory loss over the back of the hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand extending to the posterior forearm Forearm The forearm is the region of the upper limb between the elbow and the wrist. The term "forearm" is used in anatomy to distinguish this area from the arm, a term that is commonly used to describe the entire upper limb. The forearm consists of 2 long bones (the radius and the ulna), the interosseous membrane, and multiple arteries, nerves, and muscles. Forearm, except for the back of the little finger and adjacent ½ of the ring finger
    • Posterior interosseous neuropathy:
      • Brachioradialis reflex is intact.
      • Radial deviation with wrist extension, as the extensor carpi radialis is spared
      • Tenderness to palpation of the proximal forearm Forearm The forearm is the region of the upper limb between the elbow and the wrist. The term "forearm" is used in anatomy to distinguish this area from the arm, a term that is commonly used to describe the entire upper limb. The forearm consists of 2 long bones (the radius and the ulna), the interosseous membrane, and multiple arteries, nerves, and muscles. Forearm with forceful supination (e.g., turning a doorknob)
      • Weak forearm Forearm The forearm is the region of the upper limb between the elbow and the wrist. The term "forearm" is used in anatomy to distinguish this area from the arm, a term that is commonly used to describe the entire upper limb. The forearm consists of 2 long bones (the radius and the ulna), the interosseous membrane, and multiple arteries, nerves, and muscles. Forearm supination (due to the brachioradialis being affected)
  • Diagnosis:
    • Plain radiography to exclude fractures
    • MRI can precisely show pathological anatomical determinants.
    • EMG/nerve conduction velocity to differentiate between nerve and muscle injuries
    • Ultrasonography
  • Management: conservative treatment in individuals with a short-term injury (e.g., radial nerve compression due to “Saturday night palsy”)
    • PT
    • Wrist splinting
    • Pain management Pain Management Pain is defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage. Pain is a subjective experience. Acute pain lasts < 3 months and typically has a specific, identifiable cause. Pain Management

References

  1. Doherty, T.J. (2021). Ulnar neuropathy at the elbow and wrist. UpToDate. Retrieved August 20, 2021, from https://www.uptodate.com/contents/ulnar-neuropathy-at-the-elbow-and-wrist
  2. Dydyk, A.M., Negrete, G., Cascella, M. (2021). Median Nerve Injury. StatPearls. Retrieved August 20, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK553109/
  3. Gragossian, A., Varacallo, M. (2021). Radial Nerve Injury. StatPearls. Retrieved August 20, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK537304/
  4. Rutkove, S.B. (2019). Overview of upper extremity peripheral nerve syndromes. UpToDate. Retrieved August 20, 2021, from: https://www.uptodate.com/contents/overview-of-upper-extremity-peripheral-nerve-syndromes

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