Dysgeusia in deep brain stimulation for essential tremor.

Dysgeusia, or foul taste, is a rarely reported side effect in patients who have undergone deep brain stimulation (DBS) in the thalamus for essential tremor. This retrospective study evaluated the incidence, nature, neurophysiological and anatomical location of dysgeusia following DBS. Of 52 patients who had undergone DBS for essential tremor, eight (15%) reported dysgeusia, which was described as a "metallic," "sour," "foul," or "cold" taste in the mouth. Dysgeusia was separate and distinguishable from paresthesia. Dysgeusia was more frequently reported with bilateral than unilateral DBS implants (6 of 27 (22%) vs. 2 of 25 (8%) patients, respectively). The anatomical locations of the contacts causing dysgeusia were measured on postoperative MRI, and compared to those from seven control patients who did not experience dysgeusia after receiving bilateral DBS implants. Leads causing dysgeusia were more posterior than non-dysgeusia-associated leads (4.5 ± 1.2 vs. 5.7 ± 1.8 mm anterior to the posterior commissure, respectively, P < .001). Intraoperative microelectrode recording indicated that these contacts were in the sensory region of the thalamus. Intraoperative testing found that low sensory threshold for paresthesia predicted the development of dysgeusia postoperatively (1.5 ± 0.5 V vs. 3.3 ± 1.9 V; P < .05). These data indicate that taste perception can be altered in the human through DBS, with posterior leads likely within the sensory region of the thalamus. Dysgeusia can be reduced by changing stimulation parameters, or surgical revision of the lead.