Electromyography in Patients on Chronic Pyridostigmine Therapy

The investigators are intending to enroll Patients who are chronically treated with pyridostigmine for the treatment of any medical condition and presenting at the investigators' outpatient clinics for follow up appointment. Subjects taking pyridostigmine for the treatment of myasthenia gravis will be excluded. Both adults and children older than 12 years of age will be approached. Those subjects that agree to participate will be asked to sign an informed consent. For the participation of minors a parental (or guardian) consent and subject assent will be obtained. Those that participate will answer a few questions pertaining to their medical history and will then undergo electromyograph (CMAP) measurement with repetitive stimulation at 2 sites (ulnar nerve at the wrist and the accessory nerve in the neck). Evoked electromyogram will be recorded on a computer hard drive. Eight percent or greater decrement in the CMAP response on repetitive stimulation will be considered positive.

All subjects taking Pyridostigmine for at least 6mo, except for myasthenia gravis patients, will be considered for the study.Those that participate will answer a few questions pertaining to their medical history and will then undergo electromyography (CMAP) measurement with repetitive stimulation at 2 sites (ulnar nerve at the wrist and the accessory nerve in the neck). The first and fifth stimuli are delivered 2 seconds apart. Eight percent or greater decrement in the CMAP response on repetitive stimulation will be considered positive.

Subjects taking pyridostigmine bromide for more than 6 weeks for a condition other than myasthenia gravis were observed with Electromyography (EMG)

Percent Change in the Amplitude of Evoked Compound Muscle Action Potential by Electromyography Between the First to Fifth Response

Normally when a nerve is rapidly stimulated the successive Compound Muscle Action Potentials (CMAP) are of the same height. We are hoping to investigate if chronic pyridostigmine therapy reduces the margin of safety and hence the successive CMAPs may be smaller than the preceding ones.

Baseline measurement only. First and Fifth stimuli delivered 2 seconds apart on the same day. There are no additional days/times.

Inclusion Criteria: Subjects who have been taking pyridostigmine for the treatment of any condition other than myasthenia gravis Exclusion Criteria Subjects taking pyridostigmine for the treatment of myasthenia gravis will be excluded.