Lambert–Eaton myasthenic syndrome associated with alemtuzumab administration

Abstract Background Alemtuzumab administration is known to cause secondary autoimmune disease but has not been associated with the development of neurologic autoimmune conditions. Lambert–Eaton myasthenic syndrome (LEMS) is caused by autoantibodies directed against calcium channels on the neuromuscular junction. Case report We report a case of a patient with relapsing-remitting multiple sclerosis (RRMS) treated with alemtuzumab who develop generalized weakness initially attributed to progression of MS but eventually determined to be due to LEMS. Conclusion Alemtuzumab treatment can result in the development of neurologic autoimmune conditions that could mimic MS progression.