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

Abstract

BackgroundTinnitus distress is related to both the loudness and intrusiveness of the tinnitus percept. Treatment approaches targeting both attentional/limbic and auditory systems may better alleviate tinnitus distress than approaches targeting the auditory system alone.Materials and MethodsTen subjects with chronic tinnitus received sequential rTMS treatment involving: 1) excitatory stimulation administered to the left dorsolateral prefrontal cortex (DLPFC) or inhibitory stimulation administered to the right DLPFC, followed by 2) inhibitory stimulation administered to primary auditory cortex (Heschel's gyrus or HG). A systematic literature review was performed to evaluate the existing literature on sequential repetitive Transcranial Magnetic Stimulation (rTMS) treatment approaches for tinnitus. Results of the case series are interpreted in the context of tinnitus neurobiology and the extant literature.ResultsSubjects experienced a significant decrease (average 21.7%) in symptoms on the Tinnitus Functional Index (TFI). Those with tinnitus alone experienced a greater mean symptom reduction than those with comorbid MDD (27.7 vs. 17.0%, respectively). Adverse effects were transient and minor. Literature review confirmed that sequential approaches had some advantages compared to single site rTMS; in general, the addition of 1 Hz treatment at DLPFC was superior to single site rTMS in the short term (1–12 weeks), while the addition of 20 Hz treatment at DLPFC appeared superior in the long term (90–180 days).ConclusionsSequential rTMS approaches for the treatment of tinnitus—particularly those administering low-frequency treatment at left DLPFC—merit further investigation.

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

“…However, Formanek et al [41] observed "no significant effect of bilateral low-frequency rTMS of the primary auditory cortex and high-frequency stimulation of the left dorsolateral prefrontal cortex" in a group of 20 tinnitus patients. More recently, Noh et al [42], Poeppl et al [43], and Marder et al [44] all reported that dual site rTMS demonstrated efficacy for tinnitus. Noh et al [42] and Marder et al [44] concluded that dual site stimulation was superior to single site rTMS for tinnitus.…”

“…More recently, Noh et al [42], Poeppl et al [43], and Marder et al [44] all reported that dual site rTMS demonstrated efficacy for tinnitus. Noh et al [42] and Marder et al [44] concluded that dual site stimulation was superior to single site rTMS for tinnitus.…”

“…Right-side rTMS might benefit some tinnitus patients who do not respond to left-side stimulation. Marder et al [44] delivered rTMS to 10 tinnitus patients in a sequential protocol: (1) excitatory stimulation administered to the left dorsolateral prefrontal cortex (DLPFC) or inhibitory stimulation administered to the right DLPFC, followed by (2) inhibitory stimulation administered to Heschel's gyrus. The results indicated that the addition of 1Hz rTMS at the right DLPFC was superior to single site rTMS in the short term (1-12 weeks), while the addition of 20 Hz rTMS at the left DLPFC appeared superior in the long term (90-180 days).…”