Abstract

Background: Phantageusia is an unpleasant, commonly persistent oral taste occurring without any oral stimulus. It is commonly experienced by patients subsequent to loss of taste acuity (hypogeusia). There is currently no defined treatment. We wished to describe phantageusia and efficacy of its treatment with repetitive transcranial magnetic stimulation (rTMS).
Methods: An open label controlled clinical trial of 30 patients with phantageusia of two months to six years duration. Phantageusia was judged subjectively on a 0-100% scale with 100 indicating greatest phantageusia intensity before treatment and changes measured on the same scale after treatment. Patients were initially treated with rTMS and followed after treatment initially for periods of 2-4 months and subsequently for 1-10 years.
Results: rTMS inhibited phantageusia from a mean 58% before treatment to a mean 30% after treatment. Twentyfour of these 30 patients responded with significant phantageusia inhibition with six with total inhibition. Inhibition persisted for months-years without recurrence. These patients were labeled responders. Six of these 30 patients did not respond with significant phantageusia inhibition and were labeled non-responders. Repeated rTMS two or three additional times in some non-responders inhibited phantageusia similar to initial inhibition in responders.
Conclusions: rTMS is an effective method to inhibit phantageusia. Inhibition in 80% of patients persisted for months to years after rTMS suggesting that placebo responses did not contribute significantly to this inhibition. Activation of brain gamma-aminobutyric acid (GABA) and synaptic and cortical plasticity by rTMS may play roles in this inhibition.

Keywords: Phantageusia; Repetitive transcranial magnetic stimulation; Taste distortion; Sensory hallucinations; Hypogeusia