Serum positive botulism with neuropathic features.

A 32-year-old man presented with multiple cranial neuropathies and his serum was positive for botulism type B. However, serial electrodiagnostic studies were consistent with a primarily neuropathic process, such as Fisher syndrome, rather than a neuromuscular junction disorder. Electrodiagnostic study findings in patients with presumed neuromuscular junction disorders may mimic findings suggestive of a neuropathic process, or the bioassay for botulism may be falsely positive in patients with Fisher Syndrome.