carpal tunnel syndrome Flashcards
definition of carpal tunnel syndrome
the symptom complex brought on by compression of the median nerve in the carpal tunnel.
aetiology of carpal tunnel syndrome
compression of the median nerve in the carpal tunnel - formed by flexor retinaculum superiorly and the carpal bones inferiorly
median nerve and 9 tendons compete for space
usually idiopathic - 43%
may be secondary to:
- tenosynovitis: overuse, RA, other inflamm rheum disease, sarcoidosis
- infiltrative disease of teh canal/increased soft tissue: amyloidosis, myeloma, myxoedema, acromegaly
- bone involvement in the wrist: osteoarthritis, fracture, tumour
- tumour - lipoma, ganglia
- fluid retention state: pregnancy, nephrotic syndrome
- obesity
- menopause
- end-stage renal disease
- prolongued flexion eg in Colle’s splint
epidemiology of carpal tunnel syndrome
Overall prevalence 2.7%. Incidence in adults 0.1% per year. Lifetime risk 10%.
more in women - narrower wrist, same size tendons
sx of carpal tunnel syndrome
Tingling and aching pain in the hand and fingers (patients may be woken up at night - worse at night)
parasthesia in thumb, index and middle fingers - relieved by dangling the hadn over the bed adn shaking
Weakness and clumsiness of hand
signs of carpal tunnel syndrome
sensory impairment in the median nerve distribution - first 3.5 fingers
weakness and wasting of the thenar eminence - abductor pollicis brevis and opponens
tinel’s sign - tapping the carpal tunnel triggers symptoms
Phalen’s test - max flex of the wrist for 1min may cause symptoms
signs of underlying cause eg hypothyroidism or acromegaly
light touch, 2 point discrimination and sweating may be impaired
Ix for carpal tunnel syndrome
blood
- TFT
- ESR
nerve conduction study
- not always necessary
- shows impaired median nerve conduction across the carpal tunnel in context of normal conduction elsewhere
neurophysiology confirms the lesion’s site and severity and liklihood of improval with surgery
