Case report: a case review of Lambert-Eaton myasthenic syndrome and low back pain.

Abstract

The following is a case report which reviews the essential aspects of Lambert-Eaton myasthenic syndrome (LEMS) in a patient with long standing back pain and gait dysfunction. The patient was referred to our electrodiagnostics laboratory for a 9-month history of low back pain and difficulty walking following a charity breast cancer walk. A workup including magnetic resonance imaging of the brain, entire spine, and EMG/NCS at another institution were reportedly normal. A detailed history revealed symptoms of proximal weakness and autonomic dysfunction. Physical findings were consistent with proximal weakness, a bilateral gluteus medius gait, and diffusely absent reflexes obtainable in the biceps after 3s of contraction. Electrical testing revealed an initial low compound muscle action potential amplitude in the deep peroneal nerve recording from the extensor digitorum brevis. Repetitive stimulation at 2Hz revealed a decremental response of 42% from the 1st response to the 4th response. Following 3s of exercise, the amplitude increased by 300%. After 30s of exercise followed by 1min of rest, there was a return of the decremental response. The history, physical examination, and electrical findings were illustrative of a presynaptic neuromuscular junction disorder, specifically LEMS.