Compressive Neuropathies

NERVE INJURY     [Back To Top] 

Pathological processes

Usually neuropraxia +/- axonotmesis with different fibres damaged by varying degrees

• Seddon 1942
• Reversible physiological nerve conduction block
• Segmental demyelination due to compression
• causes loss of some types of sensation and muscle power
• recovers within days or weeks

• Axonal disruption but endoneurium and nerve in continuity.
• Wallerian degeneration of axons occurs
• Axonal regeneration within hrs, 1-3mm/day
• Target organs atrophy, if not reinnervated within 2 yrs, don't recover

• Proximal entrapment makes nerve susceptible to effects of more distal entrapment

Median nerve Anatomy     [Back To Top] 

• From C5,C6,C7,C8,T1
• Condensation of lateral & medial cords of brachial plexus
• Travels lateral to brachial artery in arm, but crosses medial to artery in antecubital fossa
• No branches before elbow
• Between 2 heads of pronator teres at the elbow
• 5-6cm distal to elbow gives off anterior interosseous branch (motor to FPL, FDP index finger & pronator quadratus)
• Proceeds betw. FDS & FDP
• Palmar cutaneous branch (sensory to thenar skin) arises 5cm proximal to wrist joint & overlies flexor retinaculum
• Enters carpal tunnel betw. PL & FCR
• Recurrent motor branch to thenar muscles arises at distal end of carpal tunnel