Study: Transcranial magnetic stimulation may be given securely, swiftly

Washington [US], May 13 : According to a team of clinician-researchers and neuroscientists, individuals with treatment-resistant major depressive disorder (MDD) can benefit from accelerated regimens for repeated transcral magnetic stimulation (rTMS).

The association advises against suggesting such a course of action before having a thorough conversation with patients regarding acceleration as an alternative to rTMS scheduling and documenting their informed permission.

Harvard Review of Psychiatry (HRP) released the recommendations in a special edition titled "Interventional Neuropsychiatry and Neuromodulation: An Emerging Subspecialty in Brain Medicine." Wolters Kluwer is the publisher of HRP in the Lippincott line of products.

Repetitive TMS is a noninvasive therapy in which an electromagnet delivers repeated low-intensity pulses to stimulate the brain. It has been proven safe and effective in numerous clinical trials involving patients whose MDD does not respond to antidepressant medication. Conventionally, rTMS is given once daily 20 to 30 days over four to six weeks. That places great time demands on both patients and clinicians.

Theta burst stimulation treats MDD

The next step in the development of rTMS is accelerated schedules in which patients undergo two or more sessions per day, each approximately 30 minutes long, separated by one hour or more. Although this change was just as effective in treating depression as once-daily rTMS, it created a different kind of impracticality and clinical inefficiency, according to Leo Chen, MBBS, MPsych, PhD, FRANZCP, of Monash University/Alfred Health in Melbourne, Australia, and colleagues. "These schedules required patients to attend treatment settings for long periods on each treatment day, limiting patient capacity at treatment clinics," they note.

The time burden can be alleviated, at least in part, with a novel approach called theta-burst stimulation (TBS). The most commonly used conventional rTMS protocol delivers electromagnetic pulses at a frequency of 10 Hz, whereas TBS refers to three pulses applied at 50 Hz (gamma frequency), and repeated at 5 Hz (theta frequency) intervals. Two or more TBS sessions can be delivered within an hour.

Dr. Chen and his colleagues recently published results from a multicenter randomized, controlled trial in which 10 days of TBS was compared head-to-head with a four-week course of conventional rTMS. The two approaches were similar in antidepressant effect and safety. This was the largest study of accelerated TBS in depression to date.

Standardization needed

Accelerated delivery doesn't necessarily mean accelerated response, the authors caution. Some retrospective studies have shown that twice-daily rTMS induce antidepressant effects faster than once-daily administration, but the evidence is mixed. One barrier is that studies have varied widely in factors such as the stimulation target, frequency and intensity of stimulation, the duration of breaks between sessions, and the number of pulses applied per session and over a treatment course.

Importantly, though, "accelerated rTMS' antidepressant efficacy appears comparable to conventional, once-daily rTMS protocols," Dr Chen's group writes. In addition, "studies show that accelerated rTMS protocols are well-tolerated and not associated with serious adverse effects."

"As with all therapies, the efficacy, safety, and tolerability of protocols that deviate from those investigated in clinical trials are unknown and should be cautioned against," the researchers continue. "The durability and depression relapse patterns following accelerated rTMS remain a recognized knowledge gap."