Neurostimulation and Depression

When discussing Magnetic Seizure Therapy (MST) colleagues confused it with repetetive transcranial magnetic stimulation (rTMS). That’s not so strange, both use a magnetic field.

An important difference is that with MST the intensity of the stimulation with the magnetic field is much higher than the intensity of rTMS. The aim of MST is to induce a seizure with the magnetic field. For this patients have to be treated in a hospital and they must receive anaesthesia and muscle paralysis during seizure induction. More about MST in a recent post on this blog.

With rTMS anaesthesia is not needed although Engadget errounously mentioned otherwise. It is not intended to elicit a seizure.
rTMS is not approved in the USA nor Europe as far as Dr Shock knows. The TMS device induces a widespread current distribution due to the magnetic field. This magnetic field is elicited by pulsing high-intensity current through an electromagnetic coil placed near the scalp.
The magnetic field induces electricla currents in the cortex of the brain. Yes, only the cortex, that’s why Dr Shock has a hard time beliefing rTMS is an antidepressant. There is some evidence that rTMS causes indirect activation of deeper structures including hippocampus and thalamus.

rTMS has no cognitive side-effects, because of the noise the apparatus makes ear protection needed during therapy.

Drawbacks of rTMS are that coil placement, stimulus frequency and intensity have not yet been determined. A recent published meta-analyses found no diffference between sham rTMS and real rTMS. More large trials are needed to convince Dr Shock and others.

Besides MST and rTMS there are two other neurostimulation treatments for depression:

1. ECT, for information about ECT this blog delivers a lot of articles, one here and the other over here.

2. Vagus nerve stimulation

Have to write another post about VNS another time.