Neuralgic amyotrophy: variable expression in 40 patients

Neuralgic amyotrophy

Neuralgic amyotrophy has a broad variety of clinical manifestations. Although it was initially thought to be a plexopathy, its diverse presentation can include isolated sensory nerves or even cranial nerves. Although neuralgic amyotrophy is usually a benign condition with a good recovery, pain can be a disabling feature. NSAIDs and short-term narcotics are appropriate treatments. There is lack of evidence whether the use of corticosteroids has an impact on the duration of the disease or the neuropathic pain. However, given the few adverse effects in a selective population and low cost, short-term steroids can be an option for the treatment of these patients.

Neuralgic amyotrophy

Neuralgic amyotrophy is an uncommon condition characterised by the acute onset of severe pain in the shoulder and arm, followed by weakness and atrophy of the affected muscles, and sensory loss as the pain subsides. The diversity of its clinical manifestations means that it may present to a variety of different specialties within medicine. This article describes the epidemiology, aetiopathogenesis, clinical features, differential diagnoses, investigations, treatment, course and prognosis of the condition.

Brachial plexopathies: etiology, frequency, and electrodiagnostic localization

OBJECTIVES

Brachial plexopathy is clinically, and electrodiagnostically, a well-recognized entity. However, the involvement pattern of different parts of the plexus with different etiologies has not been well-characterized.

METHODS

A retrospective analysis of clinical and electrophysiologic findings in 203 patients with brachial plexopathies was performed.

RESULTS

Of 203 patients with brachial plexopathy, 182 (90%) were supraclavicular and 21 (10%) were infraclavicular. The following localizations were noted: upper trunk (UT) 27%; lower trunk (LT) 11%; UT + MT (middle trunk) 11%; LT + MT 7%; UT + MT + LT 25%; and UT + LT 1. Among the patients with brachial neuritis, 47% patients did not have pain before the onset and only 28% had a definable antecedent illness.

CONCLUSION

We report the largest to date reported case series of well-characterized brachial plexopathy patients. Upper trunk was the most frequently affected site of injury. In brachial neuritis, absence of pain and antecedent viral illness is more common than described in the literature.

Neuralgic Amyotrophy, Diagnosed With Magnetic Resonance Neurography in Acute Stage

OBJECTIVE

We present a case of neuralgic amyotrophy (NA) diagnosed with magnetic resonance neurography (MRN) in the acute stage.

METHODS

NA is an uncommon neurologic syndrome that affects mainly the brachial plexus. MRN is considered to be more sensitive than magnetic resonance imaging (MRI) for peripheral nervous system disorders. A case of acute NA with the sudden onset of shoulder pain and weakness in the shoulder girdle is presented.

RESULTS

Electrodiagnostic testing revealed an upper trunk lesion. Plexitis that could not be demonstrated with conventional MRI was revealed with MRN. The left brachial plexus was thickened and hyperintense with MRN, consistent with plexitis.

CONCLUSIONS

MRN should be the preferred imaging modality for the diagnosis of acute NA. This might not only help early diagnosis and guide treatment but also prevent unnecessary testing.

Paraneoplastic syndromes of the peripheral nerves

PURPOSE OF REVIEW

To describe the paraneoplastic disorders of the motor and sensory nerves and neurons, and their immunologic associations.

RECENT FINDINGS

Recently proposed diagnostic criteria for paraneoplastic disorders may assist in determining the likelihood a given neuropathy or neuronopathy is related to an underlying malignancy. Of this group of disorders, paraneoplastic sensory neuronopathies are the most frequent; many of these patients have anti-Hu antibodies and small-cell lung cancer. There is often motor, autonomic, or central nervous system involvement, and electrophysiological studies may demonstrate not only sensory changes, but also motor abnormalities. While cancer has been found more frequently than expected in patients with Guillain-Barré syndrome, this association is extremely rare. A limited number of reports have described chronic inflammatory demyelinating polyradiculoneuropathy, multifocal motor neuropathy with conduction block, vasculitic neuropathies, and motor neuron disease as paraneoplastic disorders. Anti-CV2 antibodies are frequently associated with a paraneoplastic sensorimotor axonal neuropathy and small-cell lung cancer. Peripheral nerve hyperexcitability may occur with or without a cancer association, and in both instances patients often have antibodies to voltage-gated potassium channels; thymoma and small-cell lung cancer are the most common underlying tumors. Plasma cell proliferative disorders are frequently associated with neuropathies, particularly demyelinating ones.

SUMMARY

There is increasing recognition of an extensive variety of paraneoplastic disorders of the peripheral nerves. In many of these disorders onconeuronal antibodies are absent. Whole body fluorodeoxyglucose positron emission tomography scanning helps uncover the associated tumor, and recently proposed criteria may assist in the diagnosis. In many instances, prompt treatment of the tumor and immunotherapy result in symptom stabilization or neurologic improvement.

Idiopathic Neuralgic Amyotrophy: An Illustrative Case Report

OBJECTIVE

To describe the case of a patient diagnosed with neuralgic amyotrophy (NA) illustrating pertinent aspects of differential diagnosis, the use of clinical neurophysiological procedures to aid in establishing the diagnosis, and issues of management.

CLINICAL FEATURES

A 39-year-old male soldier presented with a rapid onset of marked loss of left shoulder movement. This started acutely early one morning as a sharp, severe lower neck pain progressing over the following 2 weeks to a less severe dull ache in the left shoulder and arm. Pain was rapidly replaced with weakness. Physical examination and electrodiagnostic investigation helped establish a diagnosis of NA.

INTERVENTION AND OUTCOME

The patient was reassured that this is normally a self-limiting condition. Range of motion exercises progressing to a strengthening program was prescribed. He was progressing well; however, we lost contact because of his commitments in the armed service.

CONCLUSION

When a patient presents with shoulder and arm pain of neurogenic origin, NA should be a consideration. Differentiating NA from radiculopathy is especially important in making management decisions. With a careful history and physical examination, the diagnosis may be made without the need for ancillary investigations. Neuralgic amyotrophy is a self-limiting condition requiring reassurance and monitoring.

The clinical spectrum of neuralgic amyotrophy in 246 cases

We investigated the symptoms, course and prognosis of neuralgic amyotrophy (NA) in a large group of patients with idiopathic neuralgic amyotrophy (INA, n = 199) and hereditary neuralgic amyotrophy (HNA, n = 47) to gain more insight into the broad clinical spectrum of the disorder. Several findings from earlier smaller-scale studies were tested, and for the first time the potential differences between the hereditary and idiopathic phenotypes and between males and females were explored. Generally, the course of the pain manifests itself in three consecutive phases with an initial severe, continuous pain lasting for approximately 4 weeks on average. Sensory involvement was quite common and found in 78.4% of patients but was clinically less impairing than the initial pain and subsequent paresis. As a typically patchy disorder NA can affect almost any nerve in the brachial plexus, although damage in the upper and middle trunk distribution with involvement of the long thoracic and/or suprascapular nerve occurred most frequently (71.1%). We found no correlation between the distribution of motor and sensory symptoms. In INA recurrent attacks were found in 26.1% of the patients during an average 6 year follow-up. HNA patients had an earlier onset (28.4 versus 41.3 years), more attacks (mean 3.5 versus 1.5) and more frequent involvement of nerves outside the brachial plexus (55.8 versus 17.3%) than INA patients, and a more severe maximum paresis, with a subsequent poorer functional outcome. In males the initial pain tended to last longer than it did in females (45 versus 23 days). In females the middle or lower parts of the brachial plexus were involved more frequently (23.1 versus 10.5% in males), and their functional outcome was worse. Overall recovery was less favourable than usually assumed, with persisting pain and paresis in approximately two-thirds of the patients who were followed for 3 years or more.

Pectoral Nerve Conduction Studies: Technique in Healthy Subjects and Evaluation of Brachial Plexopathy

OBJECTIVE

To define the optimal nerve conduction study (NCS) technique of the pectoral nerves and evaluate its clinical utility.

DESIGN

Prospective electrophysiologic study with healthy controls.

SETTING

Electrophysiologic laboratory in a large general hospital.

PARTICIPANTS

Thirty healthy controls and 10 patients with cervical root or brachial plexus pathologies.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

Correlation of pectoral NCS with electromyography and magnetic resonance imaging.

RESULTS

For pectoral NCS, the mean values +/- standard deviation of onset latency, amplitude, and interside amplitude ratio (ratio of smaller over larger amplitude) were 2.01+/-0.22 ms, 11.75+/-2.21 mV, and .95+/-.04 mV, respectively. Subject age correlated significantly with both onset latency (r=.46, P<.001) and amplitude (r=-.34, P<.008). All 5 patients with brachial plexopathy had amplitude ratios below the normal limit of controls (.87). However, this was not seen for all 5 patients with cervical spondylotic radiculopathy.

CONCLUSIONS

The pectoral NCS technique is feasible in healthy subjects. It is useful when differentiating brachial plexopathy from cervical root lesions.