Sequential Prefrontal and Temporoparietal Repetitive Transcranial Magnetic Stimulation (rTMS) for Treatment of Tinnitus With and Without Comorbid Depression: A Case Series and Systematic Review

Sequential Multilocus Repetitive Transcranial Magnetic Stimulation for Treatment of Tinnitus With and Without Comorbid Major Depressive Disorder

OBJECTIVE

Repetitive transcranial magnetic stimulation (rTMS) is a promising treatment for tinnitus, although outcomes are highly variable. We previously described a multilocus sequential rTMS treatment protocol for tinnitus involving stimulation of both prefrontal and auditory targets. In this study, we report results using this approach in an open-label treatment study of tinnitus with and without comorbid major depressive disorder (MDD).

MATERIALS AND METHODS

Forty patients with chronic tinnitus (mean age 56 years, ten female) and with (n = 17) or without (n = 23) MDD received multilocus rTMS administered sequentially to 1) left dorsolateral prefrontal cortex, followed by 2) auditory cortex (Heschel's gyrus). Patients completed weekly self-report ratings using the Tinnitus Functional Index (TFI) and Tinnitus Handicap Inventory, and patients with MDD completed the Inventory of Depressive Symptomatology Self-Report 30-item.

RESULTS

Patients showed significant mean improvement in tinnitus at sessions 5 (mean TFI improvement 6.8 points ± 12.2, p = 0.002) and 10 (mean improvement 9.2 points ± 14.1, p = 0.002), with 48% of patients responding within ten treatment sessions. Responders were significantly older than nonresponders (61.5 ± 15 years vs 51.3 ± 16 years), and there was a trend toward decreased likelihood of response in subjects with comorbid MDD compared with subjects without comorbidity (odds ratio = 0.28, p = 0.06). Patients with comorbid MDD reported significantly less improvement after ten sessions than did those with tinnitus alone (4.3 ± 10.3 vs 14.7 ± 15.0 points, p = 0.04). Post hoc analyses suggested that the comorbid group achieved improvement comparable to that of the tinnitus-only group after 30 treatments.

CONCLUSIONS

Patients showed significant improvement in tinnitus from multilocus sequential rTMS treatment, and those with tinnitus alone improved more quickly. Those with depression who continued rTMS through a full 30-session course further improved, indicating that tinnitus with comorbid MDD may respond with extended treatment.

Left prefrontal intermittent theta burst stimulation ameliorates tinnitus distress and symptoms of depression - A feasibility study

Tinnitus remains a notoriously difficult to treat clinical entity. 1-2% of the entire population report relevant emotional distress due to tinnitus, and causal treatments are lacking. Repetitive transcranial magnetic stimulation (rTMS), most commonly of auditory cortical areas, has shown mixed results in the past. Prefrontal rTMS, including intermittent theta burst stimulation (iTBS) has shown more promising results in the treatment of depression, and clinical data suggests a meaningful overlap between tinnitus and depression. Therefore, we performed a feasibility study of 28 consecutive patients with tinnitus treated with an iTBS protocol over the left dorsolateral prefrontal cortex for three weeks. After treatment, we observed significant ameliorations of tinnitus distress as measured by the Tinnitus Handicap Inventory Questionnaire (THI), the Tinnitus Functional Index (TFI), the Mini-Tinnitus Questionnaire (Mini-TQ) and also of depression as measured by the Major Depression Inventory (MDI). Effect sizes were small to moderate and short-lived. Treatment response rates, defined as improvement of the THI of at least 7 points, were 35.7%. At follow-up twelve weeks after end of treatment, severity of tinnitus and depression returned to approximately baseline level on a descriptive level. Amelioration of depressive symptoms correlated only with TFI change, but not that of other measures of tinnitus distress. The data suggest that a prefrontal iTBS protocol might be applied in the treatment of tinnitus and open avenues for future neurostimulatory treatments other than those of auditory regions.

Unresolved Issues Associated with Transcranial Magnetic Stimulation (TMS) Treatment of Chronic Tinnitus

Transcranial magnetic stimulation (TMS) has been investigated as a potential treatment for chronic tinnitus for 20 years. Numerous studies have reported that repetitive TMS (rTMS) has demonstrated efficacy for reducing the severity of tinnitus and its associated co-conditions such as depression, anxiety, and insomnia. However, some researchers have reported that active rTMS is no more effective than sham (placebo) rTMS as a tinnitus treatment method. There are numerous unresolved issues in this field that need to be addressed before rTMS can become a viable treatment for tinnitus. These issues include the type or brand of TMS system and its configuration; coil type, orientation, and placement method; scalp or neural target; laterality of rTMS application; dual site vs. single site stimulation; stimulation frequency and intensity; number of sessions; number of pulses per session; determination of the resting motor threshold (rMT); characteristics of the study population and their tinnitus; and outcome measures and follow-up assessments. To address and resolve these issues, large-scale, multi-site clinical trials of rTMS for tinnitus need to be conducted to determine which rTMS protocols are the most effective. In the absence of such investigations, the issues that need to be studied and addressed remain unresolved and continue to impede the clinical application of this treatment method.