Anterior Interosseous Nerve Syndrome

ExitCare ImageAnterior interosseous nerve syndrome is a nerve disorder in the elbow and upper arm. Anterior interosseous nerve syndrome causes pain and weakness in the hand and forearm. The cause of the symptoms is the compression of a branch of the median nerve by muscles or ligament-type tissues. This compression causes the pain and weakness. Anterior interosseous nerve syndrome may negatively affect performance in sports that require pinching of the thumb and index fingers. Since the branch of the median nerve does not supply sensation to the skin, there is no numbness associated with the disorder.

SYMPTOMS

  • Vague pain in the upper forearm.

  • Pinching your thumb tip to index fingertip (the "OK" sign) becomes difficult.

  • Weakness in the thumb and index finger, particularly bending the thumb.

  • Difficulty writing.

  • Frequently dropping objects grasped by the hand.

  • Weakness when turning the palm down against resistance.

CAUSES

  • Pressure on the anterior interosseous nerve at the forearm caused by swollen, inflamed or scarred tissue, ligament-like tissue, or pressure between muscles of the forearm.

  • A virus may also be causing inflammation and dysfunction of the nerve.

RISK INCREASES WITH:

  • Repetitive and strenuous movements (especially wrist and hand rotation) of the forearm and wrist (rowing, weightlifting, body building, tennis, squash, racquetball, carpentry).

  • Poor strength and flexibility.

  • Inadequate warm-up prior to physical activity.

  • Diabetes mellitus.

  • Underactive thyroid gland (hypothyroidism).

PREVENTIVE MEASURES

  • Warm up and stretch before physical activity.

  • Maintain physical fitness

  • Flexibility (especially in the wrist, forearm, and elbow).

  • Muscle strength.

  • Muscular endurance.

  • Cardiovascular fitness.

  • Knowing and using proper technique and correcting improper technique.

PROGNOSIS

If treated properly, anterior interosseous nerve syndrome is usually curable. In some cases the condition may resolve spontaneously; however, on occasion surgery is required. Spontaneous recovery has been observed between 3 and 18 months after the onset of symptoms.

POSSIBLE COMPLICATIONS

  • Permanent weakness or paralysis of the thumb or index finger in the affected hand.

  • If usual activities are resumed too early, the healing process may be prolonged.

GENERAL TREATMENT CONSIDERATIONS

To treat anterior interosseous nerve syndrome initially, activities that cause pain should be discontinued and medications and ice should be used to reduce inflammation. It is important to begin stretching and strengthening exercises of the forearm and elbow. A caregiver may also give a referral for physical therapy if necessary. If these treatments are insufficient for healing, surgery may be necessary. The surgery is typically an outpatient procedure (allowing you to return home the same day) and provides almost complete pain relief. Surgery will typically be offered if pain and weakness subsist for 8 weeks to 1 year after the onset of symptoms.

MEDICATION

  • If pain medication is necessary, nonsteroidal anti-inflammatory medications, such as aspirin and ibuprofen, or other minor pain relievers, such as acetaminophen, are often recommended.

  • Do not take pain medication for 7 days before surgery.

  • Prescription pain relievers are usually prescribed only after surgery. Use only as directed and only as much as you need.

HEAT AND COLD:

  • Cold treatment (icing) relieves pain and reduces inflammation. Cold treatment should be applied for 10 to 15 minutes every 2 to 3 hours for inflammation and pain and immediately after any activity that aggravates your symptoms. Use ice packs or an ice massage.

  • Heat treatment may be used prior to performing the stretching and strengthening activities prescribed by your caregiver, physical therapist, or athletic trainer. Use a heat pack or a warm soak.

SEEK MEDICAL CARE IF:

  • Symptoms get worse or do not improve in 8 weeks despite treatment.

  • Pain, numbness, or coldness is felt in the hand.

SEEK IMMEDIATE MEDICAL CARE IF:

  • Fingernails appear blue, gray, or dark in color.

  • Any of the following occur after surgery.

  • Increased pain, swelling, redness, drainage, or bleeding in the surgical area.

  • Signs of infection (headache, muscle aches, dizziness, or a general ill feeling with fever).

  • New, unexplained symptoms develop (drugs used in treatment may produce side effects).