Effect of gabapentin on the sensation and impact of tinnitus

OBJECTIVES/HYPOTHESIS: This study evaluated the effectiveness of gabapentin in treating chronic tinnitus in two populations: participants with tinnitus with associated acoustic trauma and participants with tinnitus without associated acoustic trauma. The hypothesis was that gabapentin would decrease both subjective and objective features of tinnitus in the trauma group but would be less effective in the nontrauma group. STUDY DESIGN: Prospective, placebo-controlled, single-blind clinical trial. METHODS: Pure-tone audiograms and personal histories were used to categorize tinnitus etiology as either secondary to acoustic trauma or not associated with acoustic trauma. Participants were restricted to those with moderate to severe tinnitus for at least 1 year. All participants received gabapentin in a graduated ascending-descending dose series extending over 20 weeks (peak dose of 2,400 mg/d). RESULTS: There was a significant improvement in tinnitus annoyance for the trauma group (P = .05). Other subjective aspects of tinnitus were not significantly affected in either group. Between-subject variability of therapeutic response was considerable. Nevertheless, in consideration of subjective loudness ratings, 4 of 19 nontrauma participants and 6 of 20 trauma participants showed an improvement of 20% or better. In consideration of psychoacoustic loudness estimates, 3 of 19 nontrauma and 6 of 20 trauma participants showed an improvement of 20 dB HL or greater. Evenly dividing each group into high and low responders revealed significant improvement in loudness at 1,800 and 2,400 mg/day for the trauma high-response subgroup (P = .007). No significant improvement was obtained for other subgroups. CONCLUSION: Gabapentin is effective in reducing subjective and objective aspects of tinnitus in some individuals, with the best therapeutic response obtained in individuals with associated acoustic trauma.