The relation between the efficacy of repetitive transcranial magnetic stimulation in treatment-resistant major depression and the pain perception

Major depression and pain are conditions frequently seen together in clinical practice. Concomitant pain complaints are frequently found in patients who seek treatment for major depression and concomitant major depression is reported to be seen in patients who seek treatment for chronic pain. It has been suggested that neurochemical imbalance of monoamines in the brain may be effective in both the emergence of depression and changes in pain perception. While depression and pain increases each other's intensity, they also make one another difficult to treat. Repetitive transcranial magnetic stimulation (rTMS) is increasingly being used worldwide both in the treatment of treatment-resistant major depression and in the treatment of pain syndromes. The aim of this study is to examine the relationship between the effectiveness of rTMS treatment and pain perception in treatment-resistant major depression patients. The study was carried out with 20 patients who applied to Gazi University Faculty of Medicine Department of Mental Health and Diseases, who were diagnosed with major depression according to DSM-5 diagnostic criteria, and were found to be unresponsive to treatment despite antidepressant pharmacological treatment for sufficient dose and time. During the rTMS treatment of the patients, no new drugs were added to their existing pharmacological treatments and the doses of the drugs they were using were not changed. 20 sessions of rTMS were applied to the left dorsolateral prefrontal cortex in 20 days, with a frequency of 10 Hz (high frequency), 120% of the motor threshold, 3000 pulses per session. The disease severity of the patients before and after treatment was measured with the Hamilton Depression Rating Scale (HAM-D), the Hamilton Anxiety Rating Scale (HAM-A) and the Beck Depression Inventory (BDI); pain perceptions were evaluated before and after treatment using the Brief Pain Inventory (BPI) and Visual Analogue Scale (VAS). Due to ethical concerns, Transcutaneous Electrical Nerve Stimulation (TENS), a method that is also used for treatment, was used to give pain stimuli to patients. When the values before and after the treatment were compared, it was observed that there was a statistically significant decrease in BDI, HAM-D, HAM-A and BPI scales and statistically significant changes in pain perception. According to HAM-D, it was observed that %65 of the patients (13 patients) responded to the treatment and remission rates were %10 (2 patients). Compared to other studies in the literature, it was evaluated that rTMS treatment was more effective in the moderate depression group compared to the severe depression group and the treatment response increased as the frequency of treatment was increased. It has been evaluated that rTMS can have positive effects on pain perception, independent of its therapeutic effect on depression. This study has shown that rTMS is effective in treatment-resistant patients with major depression, and at the same time it makes a positive change in pain perception. However, it is thought that this relationship can be revealed more clearly with prospective studies with larger samples and long-term follow-up of patients.