Transcranial magnetic stimulation

What is transcranial magnetic stimulation (TMS)?

TMS is a procedure that uses an electromagnetic coil placed over the scalp to stimulate the nerve cells beneath it. In general, low frequency stimulation reduces nerve cell activity and high frequency stimulation increases nerve cell activity. Repetitive TMS (rTMS) has been tested as a possible treatment for schizophrenia. While most people with schizophrenia respond adequately to antipsychotic medication, some find it is not completely effective; rTMS may be of use in these circumstances.

What is the evidence for rTMS?

For positive symptoms, moderate to high quality evidence shows low frequency rTMS (1Hz) applied via continuous stimulation to the left temporo-parietal cortex can reduce the severity of auditory hallucinations in the short term (medium-sized effect). The evidence is uncertain of any benefit over the longer term (>1-month post-treatment), and there was no clear benefit for other positive symptoms.

For negative symptoms, moderate to high quality evidence shows small to medium-sized improvements with rTMS applied to the dorsolateral prefrontal cortex (mostly left side). Negative symptoms were most improved in studies with a pulse frequency of 20 to 50Hz, in those with motor threshold intensity of 110%, and in those with a trial duration over 3 weeks. However, positive symptoms were worsened in studies using these parameters.

Moderate to high quality evidence finds a small placebo effect of improved auditory hallucinations with sham rTMS; either non-active sham, or active sham with 45° or 90° tilt away from the stimulation site.

There was more headache reported with active rTMS than sham rTMS.

August 2019

Last updated at: 4:09 am, 29th August 2019
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