Improvement in smell and taste dysfunction after repetitive transcranial magnetic stimulation

Olfactory and gustatory distortions in the absence of odors or tastants (phantosmia and phantageusia, respectively) with accompanying loss of smell and taste acuity are relatively common symptoms that can occur without other otolaryngologic symptoms. Although treatment of these symptoms has been elusive, repetitive transcranial magnetic stimulation (rTMS) has been suggested as an effective corrective therapy.

The objective of the study was to assess the efficacy of rTMS treatment in patients with phantosmia and phantageusia.

Seventeen patients with symptoms of persistent phantosmia and phantageusia with accompanying loss of smell and taste acuity were studied. Before and after treatment, patients were monitored by subjective responses and with psychophysical tests of smell function (olfactometry) and taste function (gustometry). Each patient was treated with rTMS that consisted of 2 sham procedures followed by a real rTMS procedure.

After sham rTMS, no change in measurements of distortions or acuity occurred in any patient; after initial real rTMS, 2 patients received no benefit; but in the other 15, distortions decreased and acuity increased. Two of these 15 exhibited total inhibition of distortions and return of normal sensory acuity that persisted for over 5 years of follow-up. In the other 13, inhibition of distortions and improvement in sensory acuity gradually decreased; but repeated rTMS again inhibited their distortions and improved their acuity. Eighty-eight percent of patients responded to this therapeutic method, although repeated rTMS was necessary to induce these positive changes.

These results suggest that rTMS is a potential future therapeutic option to treat patients with the relatively common problems of persistent phantosmia and phantageusia with accompanying loss of taste and smell acuity. Additional systematic studies are necessary to confirm these results.