Clinical Features and Electrophysiological Findings of Acute Brachial Plexitis

급성상완신경총염의 임상 소견과 전기생리학적 소견

Background: Acute brachial plexitis is an acute idiopathic inflammatory disease affecting brachial plexus, which is characterized by initial severe pain in shoulder followed by profound weakness of affected arm. This is a retrospective study to evaluate the clinical and electrophysiological profile of acute brachial plexitis. Methods: Sixteen patients with acute brachial plexitis were sampled. The electrodiagnostic studies included motor and sensory nerve conduction studies (NCSs) of the median and ulnar, sensory NCSs of medial and lateral antebrachial cutaneous nerves, and needle electromyography (EMG) of selected muscles of upper extremities and cervical paraspinal muscles. The studies were performed on both sides irrespective of the clinical involvement. Results: In most of our patient, upper trunk was predominantly affected (14 patients, 87.50%). Only two patients showed either predominant lower trunk affection or diffuse affection of brachial plexus. All had an acute pain followed by the development of muscle weakness of shoulder girdle after a variable interval ($7{\pm}8.95$ days). Ten patients (62.50%) had severe disability. In NCSs, the most frequent abnormality was abnormal lateral antebrachial cutaneous sensory nerve action potentials (SNAPs). On needle EMG, all the patients showed abnormal EMG findings in affected muscles. Conclusions: In this study, pain was the presenting feature in all patients, and the territory innervated by upper trunk of the brachial plexus was most frequently involved. The most common NCS abnormality was abnormal SNAP in lateral antebrachial cutaneous nerve. Our findings support that the electrodiagnostic test is useful in localizing the trunk involvement in acute brachial plexitis.