Carpal Tunnel Syndrome

Trapped nerve at the wrist.

 

It results from entrapment of the median nerve at the wrist.

 

It is the commonest form of mononeuropathy (pathology in one nerve).

 

Carpal tunnel syndrome images
Nerve supply of handsThenar wasting in carpal tunnel syndrome

 

(In mononeuropathy, individual peripheral or cranial nerve is affected. If two or more nerves are affected, it is called Mononeuritis multiplex. Causes are – trauma, diabetes, leprosy, sarcoidosis, amyloidosis, polyarteritis nodosa, cancer etc)

 

9 tendons and the median nerve compete for space within the wrist. So, the median nerve is likely to be compressed by anything which reduces the space in the carpal tunnel at the wrist.

 

Women are most commonly affected – they have narrower wrist but have similar sized tendons to men. Middle aged obese females are more prone to develop it.

 

Associations – Pregnancy, Oral contraceptive pills, Hypothyroidism, Diabetes, Trauma, Dialysis, Acromegaly, Osteoarthritis of the wrist with old fracture, Amyloidosis, Tophaceous gout, Tenosynovitis at the wrist.

 

Features – Aching pain in the hand and arm especially at night, pain numbness paraesthesia in the thumb index and middle fingers, relieved by dangling the hand over the bed and/or by shaking it.

There may be sensory loss on the palmar aspect of three and a half fingers – thumb, index, middle finger and outer half of the ring finger. Thenar muscles may be weak and wasted – these are late features.

 

Tinel’s sign – tapping over the median nerve at the wrist induce tingling (non-specific).

 

Phalen’s test – maximal flexion of the wrist for 1 minute may elicit symptoms (unreliable).

 

Nerve conduction study – to find the level and assess axonal degeneration (and the likelihood of improvement after surgery).

 

Treatment :

 

Splint the wrist at night.

 

Local Hydrocortisone injection.

 

Surgical decompression of the carpal tunnel (Carpal tunnel release).

 

Symptoms may improve on treatment of the underlying cause.

 

Those adopting the ‘namaskar’(prayer position) in yoga may obviate the need for surgery: the forced wrist extension is beneficial (confirmed in a randomised study).