Focal Compression Neuropathies

Compression of a peripheral nerve of the extremities (“pinched nerve”) tends to cause pain, changes in sensation of skin areas innervated by the involved nerve (numbness, pins & needles, anaesthesia) and/or weakness and wasting of target muscles.

The focal neuropathies treated most frequently by surgery are carpal tunnel syndrome and cubital tunnel syndrome in the arm, and meralgia paraesthetica in the leg. Less common and somewhat controversial entities include supinator syndrome, thoracic outlet syndrome, tarsal tunnel syndrome, and peroneal nerve entrapment

Diagnosis is by clinical assessment plus electrophysiological studies and /or imaging.

Carpal tunnel syndrome is more common in women than men. The classic symptoms are nocturnal numbess of the fingers with associated pain in the forearm or even the arm. A variant presentation in older persons is painless loss of strength and bulk of thumb muscles and loss of sensation on the radial three digits. The diagnosis is usually confirmed by nerve conduction studies although MRI study of the wrist is being used increasingly frequently. The symptoms of median nerve compression in the carpal tunnel may be alleviated by wrist splints or disappear after birth if they come on during pregnancy. The median nerve at the wrist can be decompressed by conventional or endoscopic surgery. For carpal tunnel syndrome without persistent sensory change, symptoms are almost always relieved immediately with very low morbidity. When there is established sensory loss from median nerve compression at the wrist, recovery of sensation may be prolonged and incomplete although pain should be relieved promptly.

If an ulnar neuropathy is of sudden onset after suspected external compression, then surgery is probably not indicated. When the onset is progressive, surgery is usually indicated. The diagnosis is confirmed by nerve conduction studies and/or imaging by MRI scanning or sonography. Relief of symptoms from ulnar nerve decompression at the elbow is less predictable and more delayed than for carpal tunnel syndrome. Several randomised controlled studies have shown that simple decompression of the ulnar nerve at the elbow (which can be performed under local anaesthesia) has fewer complications and is as effective as more invasive procedures involving nerve transposition.

Meralgia paraestetica (burning pain of the anterolateral thigh) results from compression of the lateral femoral cutaneous nerve under the lateral portion of the inguinal ligament. It can be relieved by weight loss and is usually not debilitating enough to warrant surgery. If necessary, the nerve can be decompressed by conventional or endoscopic surgery.