Keiko Onoda

Gustatory Disturbance Due to Cerebrovascular Disorder

Objectives: Review three cases of unilateral gustatory disturbance due to central lesions caused by cerebrovascular disorders, describe clinical findings and the results of taste examinations, and discuss the central gustatory pathways in humans. Study Design: Retrospective review of three gustatory disturbance cases due to cerebrovascular disorders. Additional review of 12 cases with central gustatory disturbance that have been reported. Methods: Central lesions of three cases were examined by magnetic resonance imaging or computed tomography scan. Electrogustometry and a filter‐paper disk assay using taste solutions were performed in these cases for each of the bilateral gustatory nerves. Results: In one case of pontine infarct, gustatory disturbance ipsilateral to the lesion was found, and in one case of thalamic infarct and one case of internal capsular infarct, gustatory disturbance contralateral to the lesion was observed. Conclusions: Fifteen cases of unilateral gustatory disturbance due to central lesions, including the present cases, have been reported to our knowledge. Examination of these cases strongly suggested that the central gustatory pathways in humans ascend ipsilaterally from the solitary nucleus of medulla oblongata to the pons, and from the pons, cross to a higher position in midbrain and reach the thalamus contralaterally.

Facial nerve paralysis caused by middle ear cholesteatoma and effects of surgical intervention

Conclusions. The clinical and surgical findings of this study indicated advanced cholesteatoma in many patients with facial paralysis. The outcome of facial paralysis was good. Poor outcomes were observed in cases with petrosal cholesteatoma and in those who underwent surgery ≥2 months after the onset of paralysis. Objective. To investigate clinical features of cholesteatoma associated with facial paralysis. Material and methods. Sixteen patients with facial paralysis due to middle ear cholesteatoma were reviewed. After removal of the cholesteatoma lesion, a limited area of the fallopian canal, that in which facial nerve edema or redness was evident, was opened. Incision of the epineural sheath for nerve decompression was not performed. Results. Initial paralysis was incomplete in 11 patients (69%). The onset of paralysis was sudden in 12 patients (75%). Labyrinthine fistulae (n=9; 56%) and bone destruction in the cranial fossa (n=10; 63%) were frequently observed. Six patients (38%) were totally deaf due to labyrinthitis. The outcome of facial paralysis was good in 13 patients (81%). Patients who underwent surgery ≥2 months after the onset of paralysis frequently had a poor outcome. Paralysis was not improved in two cases with petrosal cholesteatoma.

Impaired specific cellular immunity to the varicella-zoster virus in patients with herpes zoster oticus

The possible involvement of depression on cellular immunity in reactivation of varicella-zoster virus (VZV) in herpes zoster oticus was investigated. The subjects comprised 59 cases of herpes zoster oticus, 33 cases of herpes zoster sine herpete (ZSH) with facial paralysis, and 205 cases of Bells palsy. The transformation rate of lymphocytes to phytohaemagglutinin in herpes zoster oticus tended to be lower than that in Bells palsy. In skin tests with purified protein derivatives of tuberculin, the positivity rate in herpes zoster oticus was significantly lower than that in Bells palsy (p < 0.015). In skin tests using VZV antigen the positivity rate in herpes zoster oticus and ZSH were significantly lower than that of Bells palsy (p < 0.001 and p < 0.015, respectively). Thus, it was noted that cellular immunity, especially specific cellular immunity against VZV, was significantly depressed in herpes zoster oticus and ZSH. We consider that depression of specific cellular immunity plays an important role in triggering reactivation of VZV and onset of these diseases.

Patients with phantogeusia show increased expression of T2R taste receptor genes in their tongues.

Objectives: The taste receptor gene family T2R has been implicated in the sensation of bitter taste. Phantogeusia is a spontaneous abnormal taste with no external stimulus. We analyzed the expression of T2R taste receptor genes in the tongues of patients with phantogeusia to assess their role in the pathogenesis of phantogeusia. Methods: We obtained specimens from 43 patients with phantogeusia and 24 normal volunteers by scraping the foliate papillae and examined these specimens for the expression of 10 T2R taste receptor genes using reverse transcription–polymerase chain reaction and electrophoresis. Results: The expression rate (subjects with detectable expression) of the 10 taste receptor genes in the healthy subjects ranged from 16.7% to 100%; 3 receptor genes were found in 50% or fewer of these subjects. In the patients with phantogeusia, the expression rate was increased significantly compared to that in the healthy control subjects for 3 of the 10 receptor genes examined. Conclusions: Our results show that the expression rate of some of the T2R taste receptor genes was increased significantly in patients with phantogeusia. These results suggest that increased expression of taste receptor genes is involved in the pathogenesis of phantogeusia; this finding may contribute to elucidation of the mechanism of this disorder.

Patients with hypogeusia show changes in expression of T2R taste receptor genes in their tongues

Taste receptor genes associated with bitterness belong to the T2R gene family. In this study, we compared the expression of genes of the T2R family in the tongues of patients with hypogeusia to those in healthy subjects and examined the possibility that T2R genes are involved in the pathogenesis of hypogeusia.