Case Report: Repeated courses of low-frequency rTMS for refractory tinnitus: an N-of-1 study

Chronic tinnitus is a disabling condition with limited long-term treatments, especially in refractory cases. Although repetitive transcranial magnetic stimulation (rTMS) shows short-term benefits, its sustained effects are unclear. This study evaluated long-term outcomes of repeated courses of rTMS in treatment-resistant chronic tinnitus.

This retrospective single-subject case study followed a 30-year-old female with severe, treatment-resistant chronic tinnitus. Three identical courses of repetitive rTMS were administered over one year, each consisting of 10 sessions of 1 Hz stimulation applied to the left auditory cortex at 110% of the resting motor threshold. The patient remained medication-free throughout the study. Outcomes included tinnitus severity assessed by the Tinnitus Handicap Inventory (THI), Tinnitus Severity Index (TSI), and a tinnitus visual analog scale (VAS); psychiatric symptoms assessed by the Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7), Chronic Stress Scale (CSS), and Symptom Checklist-90-Revised (SCL-90-R); and audiometric evaluations. Effect sizes were quantified using standardized mean change (SMC) indices, calculated as the change in score relative to the instrument's normative standard deviation.

Across three rTMS courses, tinnitus severity progressively decreased: THI dropped from 98 to 50, TSI from 59 to 41, and VAS from 10 to 5. Although short-term responses varied, overall effects were large (SMC -2.00 to -2.34). Psychological symptoms also improved markedly, with the greatest changes after the first course followed by stabilization. Marked reductions were observed in depression (PHQ-9), anxiety (GAD-7), and stress measures. Global psychological distress (SCL-90-R) declined sustainably, including improvements in overall severity and symptom domains. Peripheral hearing thresholds remained stable throughout follow-up, indicating no adverse auditory effects.

This case study suggests repeated low-frequency rTMS may be associated with reductions in tinnitus severity and psychiatric symptoms without medication. Observed changes varied with affective and stress states, indicating improvement may reflect reduced attentional bias rather than elimination of tinnitus. Findings warrant larger controlled studies of repeated courses of rTMS in chronic tinnitus.