Background: There is much interest in whether daily left prefrontal repetitive transcranial magnetic stimulation (rTMS) over several weeks may become a clinically useful antidepressant treatment. Although rTMS appears largely safe, many patients report that this procedure is somewhat painful, which may restrict its ultimate appeal and utility. We analyzed interim results from the open-label phase of a multi-site randomized trial of rTMS as a treatment for depression to investigate whether the procedural pain of left prefrontal rTMS changes over time.
Methods: Patients with unipolar depression who had failed to respond during at least three weeks of the sham-controlled double-masked rTMS were then offered three more weeks (15 sessions) of open-label rTMS. Retrospective pain ratings and state emotional factors from 20 subjects were assessed using visual analog scales (VAS) recorded on computers before and after each treatment (289 sessions).
Results: Over the 15 treatment sessions, subjective reports of the painfulness of rTMS decreased 48% from baseline. This reduction, although greatest in the first few days, continued steadily (average 2.11 points per session) over the 3 weeks of treatment. The analysis found a significant effect for rTMS-session (p<0.0001) on rTMS-procedural pain over and above changes in subjective emotional states.
Conclusion: The procedural pain of left, prefrontal rTMS decreases over time, apparently independently of other emotional changes. Since rTMS scalp pain may decline over time, physicians and patients may decide to continue treatment despite initial discomfort. These observational data can be better tested once the data from the blinded phase of the trial becomes available.