Haruka Nakahara

Vibration-induced nystagmus in patients with vestibular disorders.

OBJECTIVE: Our goal was to clarify the clinical significance of vibration-induced nystagmus (VIN). METHODS: One hundred patients with unilateral vestibulocochlear disorders were enrolled into this study. However, patients with spontaneous nystagmus were excluded. Vibratory stimuli (approximately 100 Hz) were presented to the mastoids and the forehead. Patients also underwent caloric testing and vestibular evoked myogenic potential testing. RESULTS: Of the 100 patients, 60 (60%) showed VIN. The nystagmus was mainly horizontal. VIN was more frequently evoked on the mastoids than the forehead. In the majority of patients, the direction of VIN was toward the healthy side, whereas some patients, especially patients with Menieres disease, showed nystagmus toward the affected side. VIN was frequently evoked in patients with severe unilateral vestibular damages (canal paresis >50%) (39 of 43, or 90%). CONCLUSION: VIN testing is a simple and sensitive clinical test that indicates unilateral vestibular dysfunction.

Identification of the primary auditory field in archival human brain tissue via immunocytochemistry of parvalbumin.

Using parvalbumin (PV)-immunocytochemistry, we identified the human primary auditory field (PAF) for the first time. The first gyrus of the right Heschl was identified, and a serial perpendicular cut to the gyrus was made. PV-immunoreactive neuropils delineated four zones, as have been described in monkeys. Unlike with conventional staining, zone 1, characterized by intense immunostaining, corresponded to the koniocortex (PAF), while zone 2, characterized by moderate immunostaining around zone 1, to the parakoniocortex. PV-immunocytochemistry was a useful way to identify PAF in formaline-fixed archival human brain tissue.

Hearing changes and questionnaire responses in patients with paramedian suboccipital vestibular neurectomy

In order to determine the effectiveness of paramedian suboccipital transmeatal vestibular neurectomy, pre- and postoperative neurotological studies were conducted and questionnaire responses of 30 patients who underwent surgery were evaluated. Hearing was maintained within 10 dB of the preoperative level or improved in 54% of patients 2 years after surgery. Questionnaire responses indicated that all patients suffering from intractable vertigo experienced no vertiginous symptoms after surgery. Based on this study, we conclude that paramedian suboccipital transmeatal vestibular neurectomy is a useful method for relieving ear-related vertigo.In order to determine the effectiveness of paramedian suboccipital transmeatal vestibular neurectomy, pre- and postoperative neurotological studies were conducted and questionnaire responses of 30 patients who underwent surgery were evaluated. Hearing was maintained within 10 dB of the preoperative level or improved in 54% of patients 2 years after surgery. Questionnaire responses indicated that all patients suffering from intractable vertigo experienced no vertiginous symptoms after surgery. Based on this study, we conclude that paramedian suboccipital transmeatal vestibular neurectomy is a sueful method for relieving ear-related vertigo.