Myoclonus is a condition related to epilepsy of involuntary twitching or jerking of the limbs.

The purpose of this study is to determine if stimulation of the brain with magnetic pulses can decrease myoclonus. Researchers believe that this may be possible because in studies on normal volunteers, magnetic stimulation made areas of the brain difficult to activate for several minutes. In addition, early studies on patients with myoclonus have shown magnetic stimulation to be effective at decreasing involuntary movements.

Transcranial Magnetic Stimulation (TMS) is a non-invasive technique that can be used to stimulate brain activity and gather information about brain function. It is very useful when studying the areas of the brain and spinal cord related to motor activity (motor cortex and corticospinal tract). Repetitive transcranial magnetic stimulation (rTMS) involves the placement of coil of wire (electromagnet) on the patient's scalp and rapidly turning on and off the electrical current. The changing magnetic field produces weak electrical currents in the brain near the coil. This permits non-invasive, relatively localized stimulation of the surface of the brain (cerebral cortex). The effect of magnetic stimulation varies, depending upon the location, intensity and frequency of the magnetic pulses.

Researchers plan to use rTMS for 10 days on patients participating in the study. The 10 day period will be broken into 5 days of active repetitive magnetic stimulation and 5 days of placebo "ineffective" stimulation. At the end of the 10 day period, if the results show that rTMS was beneficial, patients may undergo an additional 5 days of active rTMS.

Repetitive transcranial magnetic stimulation (rTMS) at frequencies in the single Hz range causes a decrease in the excitability of the primary motor cortex and there is preliminary evidence that it can suppress abnormal excess cortical activity. We plan to test 1 Hz rTMS as treatment for cortical myoclonus.

Age 5 to 90 with severe cortical myoclonus.

No intracranial metal hardware (excluding dental fillings), pacemakers, indwelling medication pumps, cochlear implants, intracardiac lines, significant intracranial masses or increased intracranial pressure.

Subject must not be pregnant.