Takeshi Kanaya

Discharges of neurons in the midpontine dorsal tegmentum of mesencephalic cat during locomotion.

Discharges of neurons in the midpontine dorsal tegmental field (DTF neurons) were recorded and analyzed during locomotion and were compared with those of reticulospinal neurons (RS neurons) located lateral to the DTF area. The conduction velocity of the descending axon of the DTF neurons was significantly smaller than that of the RS neurons. During locomotion, the DTF neurons showed a tonic increase in the discharge rate. In contrast, the discharge rate of the RS neurons showed cyclic modulation in step with locomotion.

Primary position upbeat nystagmus localizing value.

Primary position upbeat nystagmus has been associated predominantly with lesions of the midbrain, midline cerebellum, and lower brainstem. However, the precise localization still remains unclear. We report one case of primary position upbeat nystagmus in which magnetic resonance imaging showed probable bilateral lesions of the prepositus hypoglossi nuclei. Morphological and physiological studies have shown that this nucleus plays important roles in vertical eye movements. We conclude that the dysfunction of bilateral prepositus hypoglossi nuclei causes the upbeat nystagmus in our patient.

A Case of Pharyngeal Syphilis

We report a 25-year-old woman who complained of an increasing throat pain. Physical examination revealed that the mucosa of her oropharynx exhibited butterfly appearance and serological testing showed high RPR and TPHA titers. According to these findings, we diagnosed it as pharyngeal syphilis. After treatment with oral penicillin, the pharyngeal lesion was improved. Because of the increase in the commercial sexual activities, consultations for sexually transmitted diseases of the oropharynx are increasingly common.

Correlation between nystagmus and body sway induced by caloric stimulation.

To clarify the difference between the vestibulo-ocular system and the vestibulospinal system, we analyzed the relationship between nystagmus and body sway induced by caloric stimulation. The subjects were 8 healthy males who were asked to maintain an upright standing position with eyes closed on the platform. Caloric stimulation was applied to the right ear with cold water (20°C). Eye movement was recorded by electronystagmography. Body sway was analyzed from the output of the X and Y axis components from the platform.1) Increase in the amplitude of body sway corresponded closely with nystagmus intensity during caloric stimulation.2) The parameters of left-right body sway were significantly positively correlated with the parameters of nystagmus.3) No difference was observed in the velocity of body sway in either axis.4) The directionality of body sway still remained after the caloric nystagmus had disappeared.These results indicate that unilateral caloric stimulation has two effects on body equilibrium. One is a direct stimulus of the labyrinth which induces postural deviation during caloric stimulation. The other is a disturbance of the postural control system which induces body oscillation. The latter effect persists even after caloric nystagmus has disappeared.

Postural Deviation Evoked by Caloric Stimulation During Upright Standing in Man

To understand a disequilibrium of the peripheral vestibular disorders, we tried to analyze the body sway evoked by unilateral or bilateral caloric stimulation with warm and cold water systematically. As for postural deviation, the results of our study are summarized as follows. Unilateral warm stimulation evokes heterolateral and anterior postural deviation. Unilateral cold stimulation evokes homolateral and anterior postural deviation. Bilateral warm stimulation evokes posterior postural deviation. Bilateral cold stimulation evokes anterior postural deviation. Therefore we consider that there are several patterns of static disequilibrium of upright posture in the peripheral vestibular disorders.