<p>We present a challenging case that serves as a cautionary tale pertaining to the appropriate incorporation of electrophysiological assessment of the acute neuromuscular patient. This 64&#xa0;year-old man presented with acute arm pain and weakness, with electrophysiological assessment suggestive of a brachial plexopathy. Subsequent investigation, however, led to a diagnostic shift to one of a radiculoplexus neuropathy, leading to a revised diagnosis of Lyme Polyradiculoneuritis. This new diagnosis had implications for management. Knowledge of the limitations of electrophysiological assessment is important for both the neuromuscular specialist and general neurologist. The case also bears educational import for the modern practice of neurology in the Appalachian region of the United States, as Lyme disease has become endemic to Appalachia as well.</p>