While there are clear guidelines that doctors can follow when treating patients with depression, what works for one patient often does not work for another. And most of the time, it’s not clear why. That means that doctors and their patients often have to use ‘trial and error’ to determine the best therapies for individual cases. Usually this involves the use of different types of behavioral therapies and medications. But there’s another powerful intervention that can help many patients who do not get better with such traditional treatments: transcranial magnetic stimulation, or TMS.
Researchers at Beth Israel Deaconess Medical Center (BIDMC) helped develop the technology, which changes a patient’s brain activity without surgery. In addition to being used to treat depression, TMS has also been applied to other disorders including severe pain, epilepsy, stroke, and Parkinson's disease. TMS works by using magnetic fields to stimulate or block specific nerve cell activity in the brain. During sessions, which take about 40 minutes and are administered every day for several weeks, patients remain awake and recline in a comfortable chair. A current passes through a coil of copper wire that resembles a large spoon and is held over the patient's head. This pulse of current generates a magnetic field that penetrates the scalp and skull and in turn induces a current in the patient's brain without the need for surgery. “We can use each patient’s own brain scan to guide the precise placement of the stimulation coil and thus target specific parts of the brain.” says Dr. Alvaro Pascual-Leone, who is the Director of the Berenson-Allen Center at BIDMC. “Our Center has helped establish the utility of TMS and other similar noninvasive brain stimulation techniques in neurology, psychiatry, and neurorehabilitation. For over a decade now, the clinical program of the Berenson-Allen Center at BIDMC has helped hundreds of patients overcome and cope with the symptoms of otherwise highly debilitating disorders.”
Dr. Pascual-Leone and his colleagues conducted the first controlled clinical trial demonstrating the efficacy of TMS in depression. Since reporting the results of that trial in 1996, the therapy has continued to be offered to appropriate patients in both research trials and in the clinical setting.
In 2009, the US Food and Drug Administration approved the NeuroStar Transcranial Magnetic Stimulation Therapy System for use in some patients suffering from medication-resistant depression, and earlier this year another device manufactured by Brainsway was also cleared. In clinical trials, about two thirds of the patients treated with these systems experienced a very significant improvement in their symptoms. About a third of the treated patients experienced striking benefits with complete resolution of their depression while feeling practically no side effects. Because individual responses can vary, Dr. Pascual-Leone and his team continue to conduct research studies supported by the National Institutes of Health to design individualized treatment protocols to maximize patients’ chances of improvement.
Dr. Pascual-Leone notes that TMS is not for everyone. “We need better tests that can identify an individual’s likelihood of response to TMS and what the best TMS protocol might be,” he says. “Selection of the appropriate candidates for this treatment is important also to ensure safety and prevent complications,” he adds. Without proper precautions, some patients can experience side effects, including a slight risk of seizure and convulsions. Therefore, careful evaluation by capable clinicians is critical. In more than 10,000 treatments administered in clinical studies, the most common side effect was mild-to-moderate scalp pain or discomfort at the treatment area, which declined markedly after the first week.