Mononeuropathy

20th October 2006 at 22:56 BST by Dr.C.A.Jenner MB BS, FRCA. Permalink.

Mononeuropathy

Introduction

Mononeuropathy is a type of peripheral neuropathy that involves loss of movement or sensation to an area caused by damage to a single nerve or nerve group.

This disorder might occur due to entrapment, compression, stretch injury, ischemia, infection or inflammation of a nerve. It involves damage or destruction of an isolated nerve or nerve group.

The damage includes destruction of the myelin sheath or covering of the nerve or of part of the nerve cell (the axon). This eventually results in the slowing down or prevention of the conduction of impulses through the nerve.

Common Forms of mononeuropathy

Some of the most common forms of mononeuropathy include:

• Sciatic nerve dysfunction

• Radial nerve dysfunction

• Bells palsy

• Cranial mononeuropathy (VI, VII)

• Carpal tunnel syndrome

• Femoral nerve dysfunction

• Tibial nerve dysfunction

Symptoms of Mononeuropathy

The varied symptoms of mononeuropathy arise out of one of the two below factors:

i) Impairment of sensation in a body part supplied by a specific nerve

ii) Impairment of movement in one muscle supplied by a specific nerve

Each of these symptoms is isolated to one location. Here we list the few main amongst the signs of mononeuropathy:

• Numbness

• Decreased sensation

• Loss of sensation

• Weakness

• Paralysis

Causes of Mononeuropathy

Physical injury is perceived as the most common cause of mononeuropathy. The injury is normally caused by a prolonged pressure on a nerve that runs close to the surface of the body near a bony prominence, such as a nerve in the elbow, shoulder, wrist or knee.

In fact, factors such as pressure on a nerve during a long, sound sleep; especially when under the influence of alcohol might be enough to cause the damage. Such pressure might also result from:

• Misfitting cast

• Improper use of crutches

• Staying in a cramped position for long

• Anesthesia

• Paralysis

Other causative factors include

• Strenuous activities

• Accidents

• Prolonged exposure to heat or cold

• Radiation therapy for cancer

• Repeated injuries

• Infections such as leprosy, Lyme disease

Diagnostic Tools

The main aim of the diagnostic tools is to indicate the nerve involved. Neuromuscular examination of the affected area is normally helpful for this purpose. Besides, reflexes are also abnormal in the area.

The main diagnostic tests for mononeuropathy include:

• EMG (a recording of electrical activity in muscles)

• Nerve conduction tests

• Nerve biopsy

• Blood tests, x-rays and scans

Treatment Options

The treatment modalities of mononeuropathy are aimed at enhancing the ability to use the affected body part. In certain cases, no treatment is required and recovery is natural and spontaneous.

Conservative treatment is suggested in the cases where:

• No history of trauma to the area exists

• Sudden onset of symptoms

• Minimal sensation changes

• No difficulty in movement

• Negative diagnostic results

In some cases, corticosteroids are also injected in to the area to reduce swelling and pressure on the nerves. Surgical intervention is sought if the symptoms are caused by entrapment of the nerve. Surgical removal of such lesions that press on the nerve has often been found helpful.