Tactile dysgeusia : a new clinical observation of middle ear and skull base surgery

OBJECTIVE: To describe a new clinical observation of "tactile dysgeusia," a phenomenon associated with otologic and skull base surgery likely caused by injury to the chorda tympani nerve (CTN) or the nervus intermedius (NI) with subsequent aberrant cross-innervation with somatosensory fibers in the surgical field. STUDY DESIGN: Descriptive case series. SETTING: Tertiary university referral center. METHOD: Eight patients described a sensation of touch-evoked dysgeusia after surgery. Seven patients underwent a variety of middle ear procedures including stapedotomies and mastoidectomies. One patient had a large cerebellopontine angle meningioma excised through a translabyrinthine approach. There were no preoperatively sensory symptoms of any kind. RESULTS: In five of seven patients who had an otologic procedure, the CTN nerve was transected, whereas in the remaining two, the nerve was preserved but stretched. In the meningioma patient, the facial nerve was preserved without clear identification of the NI; the facial nerve function was normal postoperatively. All of the otologic patients experienced symptoms of dysgeusia and sensory alteration triggered by touching various parts of the outer ear. One also has a secondary trigger in the V2 dermatome. In the meningioma patient, taste and sensory alteration was induced by stimulating the ipsilateral V2 and V3 dermatome. In all patients, the symptom was located in the lateral aspect of the ipsilateral hemitongue. CONCLUSION: Tactile dysgeusia is an unusual complication after otologic and neurotologic procedures. It is likely related to aberrant re-innervation of the special sensory fibers within the CTN nerve or the NI with somatosensory fibers. Postoperative "tactile dysgeusia" may not be so rare; its true incidence could only be ascertained through a more rigorous postoperative assessment.