Kazunori Matsuda

Light cupula: the pathophysiological basis of persistent geotropic positional nystagmus

Objective To clarify the pathophysiological basis of persistent geotropic positional nystagmus (PGN) in patients with the horizontal canal type of benign paroxysmal positional vertigo (H-BPPV), the time constant (TC) of nystagmus and the relationship between its slow phase eye velocity (SPV) and the angle of head rotation in supine were defined. Methods Geotropic or apogeotropic positional nystagmus was recorded by video-oculography and analysed three-dimensionally. Results Geotropic positional nystagmuses in patients with H-BPPV were classified as transient geotropic positional nystagmus with a TC of ≤35 s or PGN with a TC of >35 s. Alternatively, the TC of persistent apogeotropic positional nystagmus (AN) in patients with H-BPPV was >35 s. The direction of the SPV of patients with PGN was opposite to that of patients with AN at each head position across the range of neutral head positions. The relationship between the SPV of patients with PGN and the angle of head rotation was linearly symmetrical against that of patients with AN with respect to a line drawn on the neutral head position. Conclusions Since its TC was >35 s, it is suggested that PGN is induced by cupula deviation in response to gravity at each head position. It is also suggested that the direction of cupula deviation in patients with PGN is opposite to that of patients with AN across the neutral head positional range with no nystagmus where the long axis of cupula is in alignment with the axis of gravity. Since the pathophysiological basis of AN is considered a heavy cupula, it is suggested that PGN is conversely induced by a light cupula.

Effects of sleep position on time course in remission of positional vertigo in patients with benign paroxysmal positional vertigo

Abstract Conclusion: The findings suggest that it is easy for otoconial debris dislodged from the utricle to fall into the posterior semicircular canal (PSCC) or the horizontal semicircular canal (HSCC) of the undermost ear during sleep, but not to exit from the uppermost ear in patients with benign paroxysmal positional vertigo (BPPV). Objective: The aims of the present study were two-fold. (1) To examine the association between the preferred side of head-lying during sleep and the side of the affected ear in patients with both posterior canal BPPV (P-BPPV) and horizontal canal BPPV (H-BPPV). (2) To see whether that position affects the time course in remission of their positional vertigo. Methods: One hundred and sixteen patients with P-BPPV and 40 patients with H-BPPV who showed a habitual preference for right or left side sleeping position were included in this study. Results: The side of the affected ear was significantly associated with the head-lying side during sleep in patients with P-BPPV and was closely but not significantly associated with it in patients with H-BPPV. However, the head-lying side during sleep did not affect the remission rate of their positional vertigo.

Risk factors for poor outcome of a single Epley maneuver and residual positional vertigo in patients with benign paroxysmal positional vertigo

Abstract Conclusion: The findings suggest that in patients with posterior semicircular canal (PSCC) benign paroxysmal positional vertigo (P-BPPV), head trauma and prolonged bedrest, but not inner ear disease, are risk factors for poor outcome of a single Epley maneuver and persistent residual positional vertigo. Objectives: We first examined the efficacy of a single Epley maneuver and then assessed the time course in remission of residual positional vertigo in patients with idiopathic P-BPPV and secondary P-BPPV. Methods: A total of 157 patients with idiopathic P-BPPV and 40 patients with secondary P-BPPV (secondary to head trauma in 8 patients, to prolonged bedrest in 14 patients, and to inner ear disease in 18 patients) were treated with a single Epley maneuver. Results: The negative rates of the Dix-Hallpike test on day 7 after a single Epley maneuver in both patients with P-BPPV secondary to head trauma (25%) and those with prolonged bedrest (36%) were significantly lower than that (73%) in patients with idiopathic P-BPPV. Additionally, the remission of residual positional vertigo in the former groups of patients was significantly delayed in comparison with that of the latter group. However, there were no significant differences in the efficacy of a single Epley maneuver and persistent residual positional vertigo between idiopathic P-BPPV and P-BPPV secondary to inner ear disease.

Long-term prognosis of hearing loss in patients with unilateral Meniere's disease

Abstract Conclusion: The finding of deteriorated hearing loss at the initial visit at middle to high frequencies is a factor of poor hearing prognosis in Ménière’s disease. Early intervention with instructions for lifestyle changes may lead to good outcomes in hearing. Objective: An attempt was made to examine long-term changes in hearing loss in unilateral Ménière’s disease and factors associated with prognosis of hearing loss retrospectively. Methods: Based on their last hearing level of the affected ear, 36 patients were subdivided into two groups: the poor prognosis of hearing (PPH) group and the good prognosis of hearing (GPH) group. Results: In the PPH group, the hearing levels at the initial visit at middle and high frequencies were significantly worse than those in the GPH group. Moreover, the hearing loss progressed during the first 2 years of the disease, and stayed flat to approximately 50 dB at the later stage. Conversely, the hearing loss at the onset in the GPH group showed no further progression over the first 2 years, and remained constant to approximately 35 dB at the later stage. In addition, the mean intervals from the onset to the initial visit in the PPH group were significantly longer than those in the GPH group.

Combination of Bernouilli effect producing maneuver-induced pharyngeal narrowing rate with body mass index as predictive tool for obstructive sleep apnea syndrome

Conclusions. It is suggested that the combination of the pharyngeal narrowing rate during the Bernouilli effect producing maneuver (BEPM) with the body mass index (BMI) might be a promising predictive method for obstructive sleep apnea syndrome (OSAS). Objectives. An attempt was made to clarify the possibility that the dynamic narrowing of the pharynx evaluated by nasopharyngoscopy with BEPM, a forced inspiration through the nose with the mouth closed, might be a reliable clinical daytime predictor for identifying patients at risk of developing OSAS. Subjects and methods. Subjects were 57 patients complaining of snoring and sleepiness during daytime. Endoscopic images of the retropalatal pharynx were obtained and their area was measured by NIH imaging. The pharyngeal narrowing rate during quiet nasal breathing and that during BEPM were compared to assess pharyngeal dynamics. To increase the sensitivity of this method, BMI was added to the pharyngeal narrowing rate during BEPM. Results. The criterion of BEPM at a cut-off value of 50% with BMI at a cut-off value of 25 kg/m2 achieved a sensitivity of 93%, while the specificity was 67% in differentiating simple snorers from OSAS patients (apnea index >5). In addition, the likelihood ratio of the method was found to be 2.81.

Office-based differential diagnosis of transient and persistent geotropic positional nystagmus in patients with horizontal canal type of benign paroxysmal positional vertigo.

Abstract Conclusion: A 30 s observation of geotropic positional nystagmus is sufficient to distinguish persistent geotropic positional nystagmus (PGPN) from transient geotropic positional nystagmus (TGPN) in patients with horizontal canal type of benign paroxysmal positional vertigo (H-BPPV) in ENT office. Objective: As a canalith repositioning procedure effectively treats H-BPPV with TGPN, but not PGPN, the differentiation between patients with PGPN and with TGPN is essential. The purpose of this study is to determine the observation period enough to distinguish TGPN from PGPN. Methods: This study first analyzed positional nystagmus images recorded with an infrared CCD camera three-dimensionally in 47 patients with H-BPPV. PGPN is distinguished from TGPN in patients with H-BPPV precisely by means of time constant calculated form analysis of positional nystagmus. Ten-second and 30-s movies were made of positional nystagmus of the all 47 patients. Ten independent otolaryngologists were then asked to distinguish TGPN from PGPN after a 10 s or 30 s observation of the geotropic positional nystagmus images in 47 patients with H-BPPV. Results: The sensitivity and specificity to distinguish TGPN from PGPN was 100% and 97% after 30 s observation, but 100% and 40% after 10 s observation, respectively.

Effects of repeated snowboard exercise in virtual reality with time lags of visual scene behind body rotation on head stability and subjective slalom run performance in healthy young subjects

Abstract Conclusion: After repeated snowboard exercises in the virtual reality (VR) world with increasing time lags in trials 3–8, it is suggested that the adaptation to repeated visual-vestibulosomatosensory conflict in the VR world improved dynamic posture control and motor performance in the real world without the development of motion sickness.Objectives: The VR technology was used and the effects of repeated snowboard exercise examined in the VR world with time lags between visual scene and body rotation on the head stability and slalom run performance during exercise in healthy subjects.Methods: Forty-two healthy young subjects participated in the study. After trials 1 and 2 of snowboard exercise in the VR world without time lag, trials 3–8 were conducted with 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6 s time lags of the visual scene that the computer creates behind board rotation, respectively. Finally, trial 9 was conducted without time lag. Head linear accelerations and subjective slalom run performance were evaluated.Results: The standard deviations of head linear accelerations in inter-aural direction were significantly increased in trial 8, with a time lag of 0.6 s, but significantly decreased in trial 9 without a time lag, compared with those in trial 2 without a time lag. The subjective scores of slalom run performance were significantly decreased in trial 8, with a time lag of 0.6 s, but significantly increased in trial 9 without a time lag, compared with those in trial 2 without a time lag. Motion sickness was not induced in any subjects.