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rTMS and Vagus Nerve Stimulation

© John McManamy

"I am singing. I am humming. People do not recognize me ..."

You might say it was inevitable. After all, everyone else was into magnet therapy. It was only a matter of time before someone started aiming these things at a person's skull to see if it worked for depression. Significantly, it was the medical profession who got into the act rather than the alternative healers.

Welcome to rTMS, or repetitive transcranial magnetic stimulation, psychiatry's possible successor to ECT or shock therapy. Consider these cases, reported in NAMI California's The Journal:

Martha (not her real name) suffered from major depression for 19 years. "I'd rather end my life than continue on the way I am," she confided. She'd been through every new medication, only to be let down time and time again, but desperate as she was, she was unwilling to take a gamble on electro-convulsive therapy (ECT).

Janine (not her real name) had been receiving treatment for depression for nearly as long as Martha, 16 years. On three occasions she had undergone 10 to 12 sessions of ECT, only to discover the benefit lasted but a few months. Her last round of ECT resulted in her being so confused that she could not work.

As a last resort, both women signed on to an experimental course of rTMS at Boston's Beth Israel Deaconess Hospital, affiliated with Harvard.

Transcranial magnetic stimulation was first developed by Dr Anthony Barker and his colleagues at the University of Sheffield (UK) in the early 1980s. The technique is based on the principle that passing a current through a coil of wire generates a magnetic field, which passes through the skull and into the brain. The neurons in the brain are activated by a secondary current induced by the magnetic field.

Technological improvements led to repetitive transcranial magnetic stimulation (rTMS), and new coil design made it easier to target small areas of the brain. In the early 1990s, scientists began applying rTMS to mood disorders. Depression correlates with decreased levels in brain activity in the prefrontal cortex, particularly in the left side, and soon researchers were finding that their patients were responding to magnetic coils placed over that area.

In one study using sham rTMS as a control, researchers found that after five days of treatment, 11 of 17 patients had marked antidepressant effects, with no side effects. Another study found modest improvement for 12 medication-resistant patients after 10 days of treatment, but significantly greater than those receiving sham treatment. Another study found that four weeks of daily rTMS was equivalent in efficacy to ECT for depressed patients, but that ECT was superior for those who were psychotically depressed. Yet another study found no difference between the active and sham treatment, and a further study found rTMS to be effective for acute mania. A more recent study found that rTMS also worked when the coil was placed over the right prefrontal cortex.

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