Ulnar nerve dysfunction; Ulnar nerve palsy
Ulnar nerve dysfunction involves impaired movement or sensation in the wrist and hand caused by damage to the ulnar nerve.
Causes, incidence, and risk factors
Ulnar nerve dysfunction is a common form of peripheral neuropathy. It occurs when there is damage to the ulnar nerve, which travels down the arm, supplying flexion (bending movement) to the wrist and aiding movement and sensation of the wrist and hand.
Dysfunction of a single nerve group (such as the ulnar nerve) is classed as mononeuropathy. Mononeuropathy implies a local cause of the nerve damage, although systemic disorders may occasionally cause isolated nerve damage such as occurs with mononeuritis multiplex.
The usual causes are direct trauma, prolonged external pressure on the nerve, or compression of the nerve caused by swelling or injury of nearby body structures. Entrapment involves pressure on the nerve where it passes through a narrow structure.
The damage involves destruction of the myelin sheath of the nerve, or destruction of part of the nerve cell (the axon). This damage slows or prevents conduction of impulses through the nerve.
The ulnar nerve is commonly injured at the elbow because of elbow fracture or dislocation. The ulnar nerve is near the surface of the body where it crosses the elbow, so prolonged pressure on the elbow or entrapment of the nerve may cause damage.
Prolonged pressure on the base of the palm may also cause damage to part of the ulnar nerve, resulting in symptoms that are localized to the small hand muscles. In some cases, no detectable cause can be identified.
The mechanical factors may be complicated by ischemia (lack of oxygen related to decreased blood flow) in the area.
- Sensation changes o Of the 4th or 5th fingers o Of the hand below the 4th and 5th fingers o Numbness, decreased sensation o Tingling, burning sensation o Pain o Abnormal sensations
- Weakness of the hand
Pain or numbness may awaken the patient from sleep. The dysfunction is aggravated by activities such as tennis or golf.
Signs and tests
Neuromuscular examination of the hand and wrist indicates ulnar nerve dysfunction. There may be weakness of wrist and hand flexion and difficulty moving the fingers. Severe cases may display wasting of the hand muscles, or a characteristic “claw-like” deformity. A detailed history may be needed to determine the possible cause of the neuropathy.
Tests that reveal ulnar nerve dysfunction may include an EMG (a recording of electrical activity in muscles) and nerve conduction tests. Testing is guided by the suspected cause of the dysfunction, which in turn is suggested by the history, symptoms, and pattern of symptom development. Tests may include various blood tests, X-Rays, scans, or other tests and procedures.
Treatment is aimed at maximizing use of the hand and arm. The cause should be identified and treated as appropriate. In some cases, no treatment is required and recovery is spontaneous.
If there is no history of trauma to the area, conservative treatment is indicated by sudden onset, minimal sensation changes, and the lack of difficulty in movement, added to the absence of test results indicating degeneration of the nerve axon. In this case, the use of a supportive splint or elbow pads may be effective in preventing further injury.
Corticosteroids injected into the area may reduce swelling and pressure on the nerve.
Surgical intervention is indicated if the disorder is chronic, symptoms are worsening, movement is difficult, or if there is evidence that the nerve axon is degenerating. Surgical decompression may be recommended if the symptoms are from entrapment of the nerve. Surgical removal of lesions that press on the nerve may be of benefit.
CONTROL OF SYMPTOMS:
Over-the-counter analgesics or prescription pain medications may be needed to control pain (neuralgia). Other medications may reduce stabbing pains, including gabapentin, phenytoin, carbamazepine, or tricyclic antidepressants such as amitriptyline. Whenever possible, use of medications should be avoided or minimized to reduce the risk of medication side effects.
Physical therapy exercises may be appropriate to maintain muscle strength.
Vocational counseling, occupational therapy, occupational changes, job retraining, or similar interventions may be recommended as appropriate.
If the cause of the dysfunction can be identified and successfully treated, there is a possibility of full recovery. The extent of disability varies from none to partial or complete loss of movement or sensation. Nerve pain may be uncomfortable and persist for a prolonged period of time. If pain is severe and continuing, see a pain specialist to be sure you have access to all options for pain treatment.
- Partial or complete loss of wrist or hand movement
- Partial or complete loss of sensation in the hand or fingers
- Recurrent or unnoticed injury to the hand
- Deformity of the hand
Calling your health care provider
Call your health care provider if symptoms of ulnar nerve dysfunction occur. Early diagnosis and treatment increase the chance of controlling the symptoms.
Prevention varies depending on the cause. Avoid prolonged pressure on the elbow or palm. Casts, splints, and other appliances should always be examined for proper fit.
by Simon D. Mitin, M.D.