Shayna is a 25-year-old African American female. Shayna has been experiencing lower back pain that has become progressively worse over the last 3 months. After participating in a 3-day walk for charity, she discovered she had difficulty walking. She noticed that her legs would "give out", initially starting on the right side, then progressing to include both legs. She tried massage therapy, and when that did not work, she sought medical attention.
Her doctor ordered a full medical workup, including magnetic resonance imaging of the brain and entire spine. A detailed history revealed symptoms of proximal weakness and autonomic dysfunction. She showed no signs of muscle atrophy and had full range of motion and function in all major muscles and joints in her upper and lower extremities. However, the results of electrodiagnostic tests were consistent with presynaptic neuromuscular junction disorder, specifically Lambert-Eaton myasthenic syndrome (LEMS).
LEMS is an autoimmune disease in which the patient's antibodies attack presynaptic calcium channels at the neuromuscular junction, decreasing the ability of these calcium channels to open when stimulated.