Positioning TMS

To the Editor

Malhi et al. (2021) have given reasons for transcranial magnetic stimulation (TMS) not being prominently positioned on the 2020 Royal Australian and New Zealand College of Psychiatrists (RANZCP) mood disorders guidelines algorithm. They state positioning is based on clinical effect, ‘(b)ut rTMS has been posited as a treatment for depression largely because of its mechanism of action and not because of its clinical effect’. It is not stated who or when this positing was performed.

We have been involved with TMS since the early 1990s and offer historical facts. For much of the 20th century, it was known that (1) ECT is effective in the treatment of MDD and (2) because the skull is a poor conductor, current electricity cannot be focused and spreads out across the brain causing the side-effects of memory loss and seizure. Psychiatrists around the world explored the application of focused electrical energy (electromagnetic technology) to the brain of people with MDD (with fingers crossed that depolarization would not spread). There was no extravagant expectation of replacing ECT – rather, it was hoped to harness some ECT magic with fewer side-effects.

The first study of TMS in MDD was conducted in Germany in 1993 – stimulation was applied over the vertex. In 1995, based on the pathophysiology of MDD, Mark George and colleagues conducted a trial with TMS applied to the left dorsolateral prefrontal cortex – this has remained a potent option for the last quarter century.

From the beginning, TMS has been offered to people who have not responded to psychotherapy and medication – treatments which are widely available, proven and relatively inexpensive. TMS involves set-up costs and professional clinical supervision. In the early years, in addition to expense, TMS was reserved for non-responders to other treatments because of the possibility (unrealized) of side-effects.

With each failed treatment, the chance of a subsequent treatment achieving a good outcome is greatly reduced. This is sometimes overlooked when the general outcome of TMS is being evaluated – because most of those who come to TMS have failed at least two other treatments, the achievement of >40% response (Fitzgerald et al., 2016) is remarkable and valuable. While ECT may be more efficacious, TMS has a better balance of efficacy and acceptability.

If TMS is to be positioned on an algorithm, for the last two decades, the general recommendation and specific requirement of insurers has been – after two failed treatment attempts and before ECT. This position could be reasonably retained.