Diagnostic Difficulties in Patients with Adult Botulism Type A

Although the electrodiagnostic abnormalities in botulism have been well characterized, the expected abnormalities, such as facilitation of compound muscle action potential amplitudes after sustained activation or with repetitive stimulation at fast rates, may not always be present, especially early in the disease. This may lead to electrodiagnostic difficulties and sometimes a delay in establishing a diagnosis. We describe four serologically proven cases of type A botulism in adults that illustrate the variability in electrodiagnostic findings in this disease.