Use of 3,4-Diaminopyridine in the Treatment of Lambert-Eaton Syndrome

Inclusion Criteria: * Age 18 years or older, * Diagnosed with LEMS, * If female, have a negative pregnancy test, and * If premenopausal, be willing to practice an effective form of birth control during the study, * Tested and found by ECG not to have a prolonged QT syndrome, * Agree to have a second ECG at the time of peak drug effect, * Has understood and signed the Informed Consent. Exclusion Criteria: * Is known to have a sensitivity to 3, 4-DAP, * Has a history of: 1. past or current seizures, 2. cardiac arrhythmia, 3. hepatic, renal or hematologic disease, or 4. severe asthma, * Is believed by the investigator to be unable to comply with the protocol.