Transcranial Magnetic Stimulation in Parkinson's Disease

Paired pulse transcranial magnetic stimulation (TMS) provides a measure of the balance of inhibitory and facilitatory activity evokable in the motor cortex. Studies in several diverse disorders of basal ganglia outflow and cortical regulation show an alteration in the direction of decreased inhibition or increased facilitation. In general, these have been quite small, data from different interstimulus intervals have been pooled for analysis, and, therefore, disease and state-specific information may have been missed. A deeper understanding of what this technique can tell us about pathological and normal cortical regulation requires detailed studies within populations looking for correlations between physiological and clinical/behavioral variables and large, uniform, head-to-head comparisons between clinical populations. This proposal contains a project that combines the correlational and comparative approaches in Parkinson's disease and healthy individuals. Data from this project will then be comparable to future similar studies in other disorders.

Inclusion criteria

Patients:

Patients with established, dopa-responsive PD, Hoehn and Yahr stage I-III, age 21 and older will be included.

Patients will be recruited from the NINDS HMCS and ETB clinical programs and from the community.

Healthy Controls:

Healthy controls 21 and older will be recruited through the NIH Clinical Research Volunteer Program and from the community.

Exclusion criteria

Exclusionary criteria will be: any significant medical or psychiatric illness (other than PD), pregnancy, history of epilepsy, concurrent use of tricyclic antidepressants, neuroleptic agents, or any other licit or illicit drugs that could lower the seizure threshold or significantly affect cortical excitability.

Persons with surgically or traumatically implanted foreign bodies in the head (other than dental appliances of fillings) that may pose a physical hazard during magnetic stimulation will also be excluded.

Patients:

Patients with persistent "resting" tremor that precludes testing at rest may be excluded as well as any patient to whom the screening physician makes a judgment that withdrawal of medications poses a significant risk due to immobility or risk of falling.

Patients on long-acting dopamine agonists will also be excluded.

Patients in Hoehn and Yahr stage IV will also be excluded, since they are least likely to tolerate medication withdrawal and are also unlikely to be able to maintain muscle relaxation for TMS testing.

No significant medical or psychiatric illness (other than PD), pregnancy, history of epilepsy, concurrent use of tricyclic antidepressants, neuroleptic agents, or any other licit or illicit drugs that could lower the seizure threshold or significantly affect cortical excitability.

Must not have surgically or traumatically implanted foreign bodies in the head (other than dental appliances or fillings) that may pose a physical hazard during magnetic stimulation.

HEALTHY CONTROLS:

Ages 21 and older will be recruited through the NIH Clinical Research Volunteer Program (CRVP) and from the community.

All individuals will be processed through the CRVP before participating. Recruitment will be focused on optimizing age, sex, educational, and racial matching with patient group. Patients' spouses will be invited to participate.

No significant medical or psychiatric illness (other than PD), pregnancy, history of epilepsy, concurrent use of tricyclic antidepressants, neuroleptic agents, or any other licit or illicit drugs that could lower the seizure threshold or significantly affect cortical excitability.

Must not have surgically or traumatically implanted foreign bodies in the head (other than dental appliances or fillings) that may pose a physical hazard during magnetic stimulation.