Median nerve - carpal tunnel syndrome

Compression of median nerve within the tunnel formed by the carpal bones and the transverse carpal ligament.
Multiple diseases and environmental factors may predispose to the condition:
- Women are more commonly affected than men.
- Diabetes mellitus, rheumatoid arthritis, amyloidosis, acromegaly, renal dialysis and pregnancy predispose to the condition.
- Increased incidence is found in ocupations where repetitive wrist movements, awkward wrist positioning and great force to the wrist are frequent (eg. musicians, cyclists, electronic equipment assemblers, dental hyginists).

Pain and paresthesia may radiate to the forearm and show typical nocturnal exacerbation.
Sensory symptoms (often bilateral) may be reported by the patient in regions not innervated by median nerve but sensory signs are confined to median nerve distribution areas.
Sensory deficit on the radial palm, volar aspect of the three first fingers, most prominent at the fingertips.
Sensation at thenar eminence and proximal palm is spared otherwise the lesion lies proximal to the wrist in the forearm.
Abductor pollicis and opponens pollicis weakness and atrophy. Opponens pollicis may be spared because of ulnar nerve innervation.
Tinnel’s sign - percussion of over median nerve at volar wrist causes tingling sensation in the median nerve distribution in volar hand.
Phalen’s sign - maximal flexion of the wrist for 30-60 seconds aggravates pain and paresthesias.
Durkan carpal compression test - external pressure over wrist by the examiner induces symptoms.
“Flick sign” - when patient is asked what they do to alleviate the symptoms at night, they demonstrate a shaking/flicking wrist motion.
Cuff compression test - when a blood pressure cuff is inflated at the forearm, above systolic pressure level, paresthesias and pain may be aggravated.