brachial plexus neck arm pain

by Nathan Wei, MD, FACP, FACR

Nathan Wei is a nationally known board-certified rheumatologist and author of the Second Opinion Arthritis Treatment Kit. It's available exclusively at this website... not available in stores.

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The syndrome of brachial plexus neuritis or neuropathy is an uncommon disorder with no clear cut cause that is easily confused with other neck and upper extremity disorders, such as cervical spondylosis (neck arthritis) and cervical radiculopathy (pinched nerve in neck).

Patients with acute brachial plexus neuritis present with a typical pattern of acute or subacute onset of pain followed by profound weakness of the upper arm and shoulder girdle. Patients with acute brachial plexus neuritis are often misdiagnosed as having cervical radiculopathy(pinched nerve in the neck).

Pain in the cervical and shoulder area is common and may reflect multiple conditions. However, when a patient develops neurologic deficits, the list of differential diagnoses becomes shorter. Cervical radiculopathy is the most common condition. Patients with cervical radiculopathy present with cervical pain and neurologic deficits resulting from a herniated nucleus pulposus or an osteophyte. Acute brachial plexus neuritis mimics cervical radiculopathy in several aspects, but the treatment is significantly different.

The time profile of pain preceding weakness is important in establishing a prompt diagnosis and differentiating acute brachial plexus neuritis from cervical radiculopathy. Patients with cervical radiculopathy present with simultaneous pain and neurologic deficits that fit a nerve root pattern. This differentiation is important to avoid unnecessary surgery for cervical spondylotic changes in a patient with a plexitis.

Brachial plexus dysfunction (brachial plexopathy) is a form of peripheral neuropathy. It occurs when there is damage to the brachial plexus, an area where a nerve bundle from the spinal cord splits into the individual arm nerves.

Damage to the brachial plexus is often related to direct trauma to the nerve, stretch injury (such as rapid jerking of the arm), pressure caused by tumors in the area of the brachial plexus and damage that results from radiation therapy (therapy for some forms of cancer, such as lung cancer).

A viral etiology has been proposed for some cases, while other studies have emphasized that various infections precede the onset of acute brachial plexus neuritis in as many as 25 percent of cases. Up to 15 percent of cases have been reported to occur following vaccinations, including hepatitis B vaccination. Some evidence suggests that acute brachial plexus neuritis may be an immunologic disease.

Most cases of acute brachial plexus neuritis occur between 20 and 60 years of age; however, cases have been reported in all age groups. A male predominance is reported, with a male-to-female ratio ranging from 2:1 to 11.5:1.3,4. The annual incidence has been estimated as 1.64 cases per 100,000 persons, but this figure is probably low because many cases may be misdiagnosed, or the symptoms are mild and clinically unrecognized. It is not uncommon for patients to present with bilateral acute brachial plexus with only one side being symptomatic.

This condition may be related to pressure caused by congenital abnormalities that affect the cervical ribs and can also sometimes be associated with exposure to toxins, chemicals, or drugs.

The hallmark clinical presentation of patients with acute brachial plexus neuritis is severe, acute, burning pain in the shoulder and upper arm with no apparent cause. On occasion, it may awaken the patient from sleep. In the majority of patients, the pain subsides over the ensuing days to weeks, resulting in a subsequent weakness in the upper arm--at times to the point of extreme weakness and muscle flaccidity. This temporal profile of initial arm and shoulder pain followed by muscle weakness as the pain subsides is an important characteristic of acute brachial plexus neuritis.

Among the common symptoms are:

• Shoulder pain.

• Numbness of the shoulder, arm, or hand.

• Tingling, burning, pain, abnormal sensations, with the location varying with the part of the plexus injured.

• Weakness (decreased muscle strength, independent of exercise) of the arm, hand, or wrist so that a patient is unable to extend or lift the wrist (wrist drop) and also has hand weakness.

• If caused by a lung tumor compressing the plexus, there may be associated Horner's syndrome (eye drooping and decreased sweating in the face and small pupil).

The usual abnormality evident on physical examination is one of a brachial plexus lesion, as indicated by involvement of two or more nerves. Weakness commonly occurs in the supraspinatus, infraspinatus, deltoid and/or the biceps muscles usually involving the upper plexus. However, isolated or single nerve involvement has been clinically reported. The course of the neuritis is usually one of gradual improvement and recovery of muscle strength in three to four months. Some patients, however, experience several years of muscle weakness or a slight permanent weakness. In general, a longer duration of pain will result in a longer delay in recovering strength.

Neuromuscular examination of the arm, hand, and wrist indicates brachial plexus dysfunction. Reflexes may be abnormal in the arm. Specific muscle loss may indicate the portion of the brachial plexus that has been damaged.

Variable deformities may develop in the arm or hand, and loss of muscle mass (atrophy) may be profound. Detailed history may be needed to determine the possible cause of the problem. Patients with cervical radiculopathy present with pain beginning in the neck area and radiating down the arm for variable distances. The pain may occur after a documented trauma but, not uncommonly, patients may awake in the morning with the pain and no obvious preceding etiology. The pain is associated with partial weakness in the muscles supplied by the involved nerve root and sensory loss in the appropriate dermatome.

Unlike acute brachial plexus neuritis, the pain, weakness and sensory loss associated with cervical radiculopathy tend to occur simultaneously. While acute brachial plexus neuritis involves multiple nerves of the brachial plexus, a radiculopathy by definition is restricted to one nerve root.

Tests that reveal brachial plexopathy may include:

• Nerve conduction test and electromyography (NCS/EMG), which is a recording of the electrical activity of nerves and muscles.

• Nerve biopsy -- indicating systemic diseases that may affect the brachial plexus.

Tests are guided by the suspected cause of the dysfunction, as suggested by the history, symptoms, and pattern of symptom development. They may include various blood tests, X-rays, scans, or other tests and procedures.

Magnetic resonance imaging of the shoulder and upper arm musculature may reveal denervation within days, allowing prompt diagnosis. Electromyography, conducted three to four weeks after the onset of symptoms, can localize the lesion and help confirm the diagnosis.

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 may be tried for patients who have experienced sudden onset of symptoms, minimal sensation changes, no movement difficulties, and no evidence of nerve fiber loss on NCVS/EMG.

Corticosteroids may be recommended for cases that are caused by inflammatory lesions (such as brachial amyotrophy and brachial neuritis).

Surgery may be necessary if the disorder is long lasting, symptoms worsen, difficulty with movement is profound, or if there is evidence of nerve fiber loss where there is a mechanical cause. Surgical "decompression" (surgical removal of lesions that press on the nerve) may help some patients.

Anti-inflammatory medications may be given a trial. If they are not enough to control pain (neuralgia), then other medications- including a course of glucocorticoids- may be necessary. Other medicines to consider include anti-seizure medications (such as phenytoin, carbamazepine, and gabapentin). Tricyclic antidepressants, such as amitriptyline, may also provide pain relief.

Whenever possible, medication use should be avoided or minimized to reduce the risk of side effects. If pain is severe, a pain specialist should be consulted in order to make sure all options for pain treatment are considered.

Physical therapy exercises to maintain muscle strength may be appropriate for some people. Orthopedic assistance with different aids (such as braces, splints, or other appliances) may maximize the ability to use the arm.

Vocational counseling, occupational therapy, occupational changes, job retraining, or similar interventions may be recommended in some cases.

The probable outcome is variable depending on the cause. Recovery may be incomplete or complete and takes several months. Nerve pain may be quite uncomfortable and may persist for a prolonged period of time.

Complications include:

• Partial or complete arm paralysis

• Partial or complete loss of sensation in the arm, hand, or fingers

• Recurrent or unnoticed injury to the hand or arm due to diminished sensation

• Deformity of the hand or arm, mild to severe, which can lead to contractures

Brachial plexus neck arm pain