rTMS effects in patients with co-morbid somatic pain and depressive mood disorders

Pain is a common co-morbidity among clinically depressed individuals. We investigated a group of patients who were treated with repetitive transcranial magnetic stimulation (rTMS) for treatment resistant depression (TRD) and who were assessed for severity of both depression and pain at baseline and throughout treatment.

Records of 71 patients treated for TRD with rTMS from 2008 to 2017 were reviewed. Primary outcome measures including depression severity using the Quick Inventory of Depressive Symptomatology (QIDS) and a 0-10 numeric pain rating scale were assessed at baseline and after every 5 sessions throughout the course of 30 treatments.

In the total sample, pain improved significantly over the course of treatment. Changes within subjects in QIDS were associated with the changes in pain (p = 0.011). TRD patients with higher pain scores at baseline tended to be older, experienced a longer duration of illness, and showed significant differences in QIDS over treatment time as compared with the low baseline pain group. Patients who had failed a serotonin norepinephrine reuptake inhibitor (SNRI) (venlafaxine or duloxetine) trial in the past had less pain at baseline and showed a group difference in pain scores at all time points, which was significant at treatments 20, 25 and 30, compared to patient groups who had never taken these medications or were currently taking these medications.

Limitations include the potential impact of the discomfort over the treatment site on the scalp, as it is unclear whether patients' assessment of pain included this side effect, and the lack of a control group due to the naturalistic design of this study.

Our data show that pain and depression respond well to rTMS in a TRD population. Pain and depression severity in rTMS patients may be associated over the course of rTMS treatment time-points in individuals with higher levels of baseline pain.