One of the commonest reasons for seeing a hand surgeon is altered sensation in the fingers. Whilst the commonest reason for this symptom is carpal tunnel syndrome (median nerve entrapment at the wrist), it may also be due to cubital tunnel syndrome (ulnar nerve entrapment at the elbow) or cervical (neck) nerve root entrapment. There are also much less common causes.
Carpal Tunnel Syndrome
Patients commonly present with numbness and tingling in the thumb, index and middle finger. There is sometimes a pain in the forearm which can radiate to the shoulder. The symptoms come on commonly at night, or when holding a book or telephone or steering wheel. The underlying cause is inflammation in the flexor tendons that share the same tunnel with the median nerve. This is another condition which is common in patients with busy hands. The diagnosis is proven by clinical examination, electrical tests, and occasionally ultrasound. Treatments include physiotherapy, steroid injections, and surgical decompression.
Cubital Tunnel Syndrome
This condition commonly presents with numbness in the little finger and weakness in the small muscles other hand. It is caused by entrapment of the ulnar nerve at the elbow, on the inner side, commonly referred to as the ‘funnybone’. The diagnosis is proven by nerve conduction studies. Treatment is usually by surgical decompression.
Cervical Nerve Root Entrapment
This is the commonest differential diagnosis for the two conditions above. If the symptoms do not quite fit with the diagnoses above or the nerve conduction studies are negative, it is usual to perform an MRI scan of the neck to exclude a protruding disc pressing one of the nerve roots to the hand. This can usually be treated by physiotherapy.