Neuromuscular Case Vignettes

Case 15: Differential diagnosis and further electrophysiological studies

Exam is suggestive for a myopathy vs neuromuscular junction disease such as myasthenia gravis or Lambert Eaton myasthenic syndrome (LEMS). Other differential diagnosis include motor neuronopathy, specially Kennedy syndrome, who may also have distal sensory symptoms, and motor neuropathy. Motor neuropathy is uncharacteristic for neuropathies associated with diabetes or HCV infection. Low amplitude CMAPs and normal conduction velocities are specially suggestive for LEMS. See the  further nerve conduction studies (i.e. assessment of CMAP amplitude after 10 second of exercise, low frequency and high frequency repetitive nerve stimulations). Click here for diagnosis and discussion.