Transcranial Magnetic Stimulation for the Treatment of Tinnitus
Transcranial Magnetic Stimulation for the Treatment of Tinnitus
Abstract & commentary
By Douglas Labar, MD, PhD, Director of the Comprehensive Epilepsy Center, Professor of Neurology and Neuroscience, Weill Cornell Medical College; Attending Neurologist, NewYork-Presbyterian Hospital. Dr. Labar reports no financial relationship relevant to this field of study.
Synopsis: Repetitive transcranial magnetic stimulation appears to be a safe and effective method to treat chronic tinnitus.
Source: Khedr E, Rothwell J, El-Atar A. One-year follow up of patients with chronic tinnitus treated with left temporoparietal rTMS. Eur J Neurol 2009;16:404-408.
Few therapies are available for chronic tinnitus. Following up on imaging research that previously demonstrated over-activity of auditory cortex in patients with tinnitus, pilot short-term clinical trials of temporoparietal repetitive transcranial magnetic stimulation (rTMS) treatment have led to reduced symptoms in this illness. Khedr et al now report persistent symptomatic improvement in tinnitus for a year after just two weeks of rTMS therapy.
The authors randomized 66 patients to two weeks of 1,500/day left temporoparietal rTMS pulses at 1 Hz, 10 Hz, or 25 Hz, or comparable sham stimulation over the occipital cortex. There was a significant improvement on a standardized inventory measuring the degree of tinnitus handicap, and on a self-rating scale of tinnitus annoyance in the rTMS-treated group (but not in the sham-treated group). This response remained present at both the four-month and one-year follow-up visits, and was present with all three stimulation frequencies. Of the 66 studied patients, 10 became tinnitus free, while 36% of patients showed no response. Patients with the longest duration of tinnitus were the least likely to respond.1
The clinical response to rTMS promises to be beneficial for those afflicted with chronic tinnitus. Furthermore, the time course of the response is intriguing with regards to mechanistic considerations. A temporary (two-week) physiological alteration of temporoparietal cortical function by the stimulation produces a modification of symptoms that lasts up to 52 weeks! The authors speculate that plastic reversal of abnormal cortical functional changes that contribute to tinnitus in the first place may account for their findings. The worse response to rTMS among patients with the longest pre-existing duration of tinnitus raises the possibility that the involved cortex may be less amenable to plastic reversal once more longstanding abnormal neuronal connections are established and strengthened over time.
Commentary
Persistent anti-epileptic effects after cessation of neurostimulation therapy have been reported with vagus nerve stimulation2 and deep brain stimulation.3 On the other hand, one study found cortical rTMS had only a mild anti-seizure effect, which did not persist.4 The temporal aspects of neural stimulation therapies differ substantially from medical therapies, and require further elucidation.
Khedr et al did not report any side effects from the rTMS they employed. If in fact, as speculated by the authors, plastic functional cortical reorganization takes place due to rTMS, screening for subtle untoward effects may be advisable. Future research might include testing of items such as language comprehension, in addition to the efficacy measures employed.
References
1. Khedr E, Rothwell J, Ahmed M, et al. Effect of daily rTMW for treatment of tinnitus: comparison of different stimulus frequencies. J Neurol Neurosurg Psych 2008; 79:212-215
2. Labar D, Ponticello L. Persistent antiepileptic effects after vagus nerve stimulation ends? Neurology 2003; 61:1818
3. Hodaie M, Wennberg R, Dostrovsky J, et al. Chronic anterior thalamus stimulation for intractable epilepsy. Epilepsia 2002; 43:603-608
4. Theodore W, Hunter K, Chen R, et al. TMS for the treatment of seizures: A controlled study. Neurology 2002; 59:560-562.
Repetitive transcranial magnetic stimulation appears to be a safe and effective method to treat chronic tinnitus.Subscribe Now for Access
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