Tourette syndrome (TS) is a chronic neuropsychiatric disorder occurring in early childhood or adolescence that’s characterized by multiple motor and vocal tics that are usually preceded by premonitory urges.1,2 Usually, the tics are repetitive, sudden, stereotypical, non-rhythmic movements and/or vocalizations.3,4 Individuals with TS and other tic disorders often experience impulsivity, aggression, obsessive-compulsive disorder (OCD), attention-deficit/hyperactivity disorder, and various mood and anxiety disorders.3 Psychosocial issues may include having low self-esteem, increased family conflict, and poor social skills. Males are affected 3 to 5 times more often than females.3 For most patients, the tics get less severe in late adolescence and early adulthood. However, approximately 10% to 15% of patients continue to experience chronic tics that are associated with significant disability.2,5-7
There is no definitive treatment for TS. Commonly used interventions are pharmacotherapy and/or behavioral therapy, which includes supportive psychotherapy, habit reversal training, exposure with response prevention, relaxation therapy, cognitive-behavioral therapy, and self-monitoring. Pharmacotherapy for TS and other tic disorders consists mainly of antipsychotics such as haloperidol, pimozide, and aripiprazole, and alpha-2 agonists (guanfacine and clonidine).4,8-10 Unfortunately, not all children respond to these medications, and these agents are associated with multiple adverse effects.11 Therefore, there is a need for additional treatment options for patients with TS and other tic disorders, especially those who are not helped by conventional treatments.
Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive therapeutic technique in which high-intensity magnetic impulses are delivered through an electromagnetic coil placed on the patient’s scalp to stimulate cortical neurons. The effect is determined by various parameters, including the intensity, frequency, pulse number, duration, coil location, and type of coil.3,8
rTMS is FDA-approved for treating depression, and has been used to treat anxiety disorders, Parkinson’s disease, chronic pain syndromes, and dystonia.12,13 Researchers have begun to evaluate the usefulness of rTMS for patients with TS or other tic disorders. In this article, we review the findings of 11 studies—9 clinical trials and 2 case studies—that evaluated rTMS as a treatment option for patients with tic disorders.
A proposed mechanism of action
TS is believed to be caused by multiple factors, including neurotransmitter imbalances and genetic, environmental, and psychosocial factors.14 Evidence strongly suggests the involvement of the motor cortex, basal ganglia, and reticular activating system in the expression of TS.2,15-17
Researchers have consistently identified networks of regions in the brain, including the supplementary motor area (SMA), that are active in the seconds before tics occur in patients with these disorders.6,18-22 The SMA modulates the way information is channeled between motor circuits, the limbic system, and the cognitive processes.3,23-26 The SMA can be used as a target for focal brain stimulation to modulate activity in those circuits and improve symptoms in resistant patients. Recent rTMS studies that targeted the SMA have found that stimulation to this area may be an effective way to treat TS.19,20,23,27
Continue to: rTMS for tics: Mixed evidence