Transcranial Magnetic Stimulation (TMS) for Individuals With Tourette's Syndrome

Transcranial Magnetic Stimulation for Individuals With Tourette's Syndrome

This study will evaluate the clinical efficacy of 1 Hz repetitive transcranial magnetic stimulation (rTMS) applied to the supplementary motor area (SMA) in Tourette's Syndrome (TS) patients who have not fully responded to conventional therapies. The investigators will collect TMS measures of motor cortex excitability to test whether rTMS restores normal levels of intracortical inhibition found to be deficient in TS. The investigators will administer neuropsychological tests to demonstrate that SMA targeted rTMS can be administered safely without significant impairments of cognitive or motor functioning. The investigators hypothesize that:

1. Compared to sham (placebo), active rTMS will improve symptoms of TS as assessed with the Yale Global Tic Severity Scale (Y-GTSS) and Clinical Global Impression (CGI).
2. Active (but not sham) rTMS will normalize levels of motor cortex excitability, as reflected by increased intracortical inhibition, motor threshold, and cortical silent period, and by decreased intracortical facilitation, relative to pre-treatment baseline.

This study tests the efficacy of repetitive Transcranial Magnetic Stimulation (rTMS) in the treatment of Tourette's Syndrome (TS). It also examines measures of brain function to study the brain basis underlying TS.

Despite major advances in the study and treatment of TS, patients often do not experience full remission from pharmacotherapy or behavioral therapy (Leckman 2002). rTMS is a non-invasive procedure that stimulates the brain using magnetic fields. This pilot study reported that rTMS may reduce TS symptoms (Mantovani et al., 2006). While promising, prior research has several limitations (e.g., relatively small sample sizes, and lack of sham [placebo] comparison).

This study addresses the drawbacks of prior work, and will provide data that will help to determine whether rTMS can be useful for TS patients resistant to conventional therapies. 25 outpatients with TS who have been only partially responsive to conventional therapies will be randomly assigned to either active low frequency (1 Hz) rTMS or sham (placebo) stimulation. The active or sham stimulation will be applied to the supplementary motor area (SMA) daily for three weeks. If rTMS will be added onto ongoing pharmacotherapy, the doses must have been stable for four weeks prior to study entry. The SMA was selected because of its connections with brain areas implicated in TS. Pilot work indicates that stimulation of SMA with low frequency rTMS is beneficial in TS patients. Low frequency rTMS has the added benefit of a better safety profile (i.e. no risk of seizure) than high frequency rTMS.

Rating scales for symptom change will be obtained at baseline, during the rTMS course, and at the end of three weeks of treatment. Patients will then be offered an open-label cross-over phase for an additional three weeks of daily active rTMS treatment. Patients who meet remission criteria in either phase or response criteria following the cross-over phase will continue routine clinical care under the supervision of their treating psychiatrist and will be invited back for assessment at 1, 3, and 6 months to determine the persistence of benefit.

Excitability of the motor cortex has been reported to be abnormal in TS, and may relate to dysfunction in motor pathways. We will collect measures of motor cortex excitability (with single and paired-pulse TMS) at baseline and after each phase to study whether changes in these measures may be correlated with clinical improvement.

Inclusion Criteria:

• Primary diagnosis of Tourette's Syndrome, as confirmed by the DSM-IV-TR criteria
• Residual TS symptoms, defined as a total Y-GTSS total motor tic or phonic tic score > 20, despite treatment with an adequate trial of medications (defined as a failure to respond to a trial of commonly used medications for TS such as clonidine, guanfacine, or neuroleptic medications, given at recommended dosage and duration based on the clinician's judgment)
• Persistent high level of tic severity for 4 months despite efforts to control the tics using medications, or the presence of self injurious tics
• Duration of the index episode of at least a year
• Individuals who cannot tolerate medications of class and dose at the specified duration as described above will also be included
• Patients currently on medication must be at the same stable dose(s) for one month prior to enrollment and be willing to continue at the same dose(s) through the duration of the study

Exclusion Criteria:

• Individuals diagnosed with major depressive disorder (current) of moderate or severe intensity (CGI ≥ 4), bipolar disorder (lifetime), any psychotic disorder (lifetime), or an Axis II personality disorder; with a history of substance abuse or dependence within the past year (except nicotine and caffeine); or at significant acute suicide risk will be excluded

Other exclusion criteria include those common to every TMS protocol:

• Individuals with a clinically defined neurological disorder, with an increased risk of seizure for any reason, with a history of treatment with TMS, deep brain stimulation for any disorder will be excluded
• Patients with cardiac pacemakers, implanted medication pumps, intracardiac lines, or acute, unstable cardiac disease, with intracranial implants (e.g. aneurysm clips, shunts, stimulators, cochlear implants, or electrodes) or any other metal object within or near the head, excluding the mouth, that cannot be safely removed will be excluded
• Current use of any investigational drug, any medications with proconvulsive action, such as bupropion, maprotiline, tricyclic antidepressant, clomipramine, classical antipsychotics, and daily use of any medications with a known inhibitory effect on cortical excitability measures (e.g., anticonvulsants, standing doses of benzodiazepines, sedative/hypnotics, and atypical antipsychotics) will not be permitted
• If participating in psychotherapy, patients must have been in stable treatment for at least three months prior to entry into the study, with no anticipation of change in frequency therapeutic sessions, or the therapeutic focus over the duration of the TMS trial
• Finally, current significant laboratory abnormality, known or suspected pregnancy, women who are breast-feeding or women of childbearing potential not using a medically accepted form of contraception when engaging in sexual intercourse will also be excluded.