TMS for medication resistant depression

It’s been a while since my last post on this blog about transcranial magnetic stimulation (TMS).

Myself ‘m not impressed by it’s efficacy for treatment resistant depression. Especially in treatment resistant depression, whatever that may be, rTMS is probably best avoided for more evidence based form of treatments with proven efficacy.

The reason for this post about TMS is a recent publication in the Journal of Clinical Psychiatry. FDA approval for rTMS was based on a large, industry-sponsored, multicenter, double-blind, monotherapy study with 325 patients with “moderately treatment resistant depression” also discussed on this blog here. My opinion on this trial was

This is a trial very well done. Due to its design only the scores on time point of week 4 are truly double-blind. They introduced a new method for sham treatment: the sham coil had a embedded magnetic shield. This study also shows that longer treatment with rTMS is well tolerated. The use of pharmacotherapy treatment failure as an inclusion criterion every time amazes Dr Shock. There are far better treatment options e.g. plasma level controlled TCAs, lithium addition and ECT to name a few.

Considering the outcome on the time point at week 4, Dr Shock is not very impressed by the results. For significant difference with the primary outcome 6 patients had to be excluded from the analysis. The mean difference between active and sham on the severity scales is in the range of 2-3 points, significant but hardly clinical relevant. Absolute figures on response and remission at week 4 are not given in this article. Remission rate at 6 weeks on the HAMD-17 was 15.5% increasing to 22.6% at week 9 with open labeled therapy. Not very impressive.

Fortunately in this article the authors also state that rTMS was more effective in those with failure of just one antidepressant trial and minimal effective for those patients who failed 2-4 trials. Moreover, the efficacy of rTMS with a structural MRI-based neuro-avigational procedure can have the capacity to improve response to the rTMS treatment in TRD. Other such as altering stimulation frequency increasing dose, and the use of a neuro-navigationally guided rTMS based on pretreatment positron emission tomography (PET) scans did not improve efficacy.

The conclusion of this article sums it up nicely:

….questions remain about patient selection, how best to deliver the treatment, and it’s place in the treatment algorithm relative to existing treatments for depression

What is TMS?
rTMS is a non-invasive method to stimulate the brain. Weak electric currents are induced in the cortex of the brain by rapidly changing magnetic fields (electromagnetic induction). This way, brain activity can be triggered with minimal discomfort, no need for anesthesia, and no cognitive side-effects. Side effects of rTMS are: discomfort or pain from the stimulation of the scalp and associated nerves and muscles on the overlying skin and hearing from the loud click made by the TMS pulses. You can see a treatment with TMS in the video above.
Yip AG, & Carpenter LL (2010). Transcranial magnetic stimulation for medication-resistant depression. The Journal of clinical psychiatry, 71 (4), 502-3 PMID: 20409447