Neuropathies Flashcards
What is a neuropathy?
Functional or pathological changes in the peripheral nervous system
What is compression neuropathy?
Process where a nerve becomes entrapped as it passes through a narrow tunnel or passage Can occur at any site along the nerve
Biomechanical causes
Space occupying lesion - Herniated disc or cyst
Degenerative causes - foraminal stenosis
Post-traumatic causes - Fracture and hematoma
Mechanical causes - Muscle spasm and pinching
Systemic causes
- Pregnancy
- Hypothyroidism
- Diabetes
Structure of an Axon
Pathogenic Changes to Axon
Ischemia
Thickening of epineurium
Myelin thinning distortion
Microtubule Closure
Axonal degeneration
Nerve Damage: 1st Degree
Neuropraxia
Focal damage of myelin fibers arounf axons
Connective tissue sheath remains intact
Recovery: Days to weeks - less severe
Nerve Damage: 2nd Degree
Axonotmesis
Some disruption/injury to the axon itself
Myelin sheath remains intact
Recovery: Is possible but takes months
Nerve Damage: 3rd Degree
Neurotmesis
Disruption of axon and endoneurium
Recovery: Cannot occur as intraneural fibrosis occurs
Nerve Damage: 4th Degree
Neurotmesis
Disruption og axon, endoneurium, and perineurium (nerve fasciculi)
Large area of intraneural scarring at the injury site - Stops any nerve regeneration distal to the injury
Surgery required to restore neural continuity
Nerve Damage: 5th Degree
Neurotmesis
Whole nerve from the axon to the epineurium is damaged
Perineural hemorrhage and scarring occurs
Surgery required to restore neural continuity
Sites of Radial Nerve Entrapment
High on the humerus
Radial Tunnel
At the wrist
Radial Nerve Entrapment - High on the humerus
Usually secondary to a humerus fracture or compression of nerve near spiral groove
Symptoms: Wrist drop, weakness in elbow flexion (brachioradialis), +/- tricep involvement, pain/numbness
Treatment: Function usually returns in 4-5 months
Radial Nerve Entrapment - Radial Tunnel
Repetitive rotatory movement - rowing, discus, racquet sports
Heavy manual labor
Symptoms: Pain and tenderness 5 cm distal to lateral epicondyle, wrist drop or pain w/ resisted pronation
Radial Nerve Entrapment - At the wrist
Superficial branch (sensory) pinched between brachialialis and extensor carpi radialis longus during forearm pronation
Sensation change over posterolateral hand
Pronator Syndrome
Median nerve
Travels between the humeral (superficial) and ulnar (deep) head of the pronator teres
Worsens when pronating against force and flexing elbow against force
Positive Provocation maneuver
Pain over proximal middle forearm and numbness over palmar surface of thumb and thirst 3 digits
Provocation maneuvers
Tests for pronator syndrome and compression of median nerve by pronator teres
Flexion of middle finger against resistance
Causes compression by the flexor digitorum superficialis
Anterior Interosseus Syndrome
Compression of median nerve
No sensory loss
Inability to make “OK” sign
Due to weak flexion ability of the index finger’s DIP and thumb’s IP
Treatment: General treatment and splinted elbow flexion at 90 for ~12 weeks
Ulnar Nerve Entrapment/Cubital Tunnel Syndrome
Symptoms: Parasthesia to 4th and 5th digits, medial elbow pain that radiates down arm
Decreased intrinsic strength (can’t turn key)
Symptoms reproduced when elbow and wrist are flexed
Treatment: LImit elbow flexion and provide cushion
Positive Tests for Ulnar Nerve Entrapment/Cubital Tunnel
+ Tinel Sign at Elbow
Froment sign - pinch paper between 1st and 2nd digit if thumb flexes (+)
Due to weak 1st dorsal interosseus and ADP muscle
Median Nerve Entrapment/Carpel Tunnel Syndrome
Most common compression syndrome
Compression as passes under flexor retinaculum
Symptoms: Nighttime numbness of lateral 3.5 digits, tingling, wrist pain, grip weakness, thenar atrophy
Caused by repetitive wrist flexion and pregnancy
Treatment: Gold Standard EMG
Thoracic Outlet Syndrome and Symptoms
Compresion of the brachial plexus and/or subclavian vessels
Symptoms: Weakness, paresthesia of medial arm, forearm, and hand exacerbation by overhead activities
Testing for Thoracic Outlet Syndrome
Points of Compression that cause Thoracic Outlet Syndrome
Sclene Triangle
Costclavicular passage
Attachment of the pectoralis minor attachment at the coracoid process
