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.