Biomedical subjects

Kazutaka Higashino

Publications and source records attributed to Kazutaka Higashino.

4 recordsLinked to original sources

PubMed2003

Compensatory changes in static and dynamic subjective visual vertical in patients following vestibular schwanoma surgery.

OBJECTIVE: Among patients with vestibular schwanoma (VS), vestibular function is nonhomogeneous, both before and after surgical removal of the VS. This paper reports investigations of neural changes, especially changes in the contribution of visual input to vestibular system integration, after VS surgery. METHODS: We examined 33 patients who underwent VS surgery via a middle fossa approach. Static and dynamic subjective visual vertical (SVV) was measured once after surgery and compared to those measured in control subjects. SVVs were assessed using a paradigm requiring the subject to manually adjust an image of a bar to the perceived vertical alignment. SVVs were measured when the background was stationary or rotating. RESULTS: In almost all patients, static SVV deviated toward the operated side. In VS subjects, the mean static SVV was 1.8+/-2.2 degrees; the amount of deviation in the dynamic SVV toward the operated side (11.7+/-8.3 degrees ) was significantly larger than that to the intact side (8.8+/-5.5 degrees ). In VS subjects, static SVV was correlated with dynamic SVV only in cases of bar adjustments toward the operated side (R=0.67, P<0.001), but not in cases of adjustments toward the intact, unoperated side. The axis of rotation was defined as the mean value of dynamic SVV for adjustments toward either side. There was only a weak correlation between the static SVV and the axis of rotation (R=0.31; P<0.05) in the control subjects. On the other hand, a more robust correlation between static SVV and axis of rotation was found (R=0.67, P<0.001) in VS subjects. There was no correlation between the static SVV and the deviation of dynamic SVV from static SVV for CCW and CW in control subjects. In contrast, there were significant correlations between static SVV and deviation of dynamic SVV from static SVV for adjustments made toward both operated (r=0.48, P<0.001) and intact sides (r=038, P<0.05). CONCLUSION: It is assumed that the amount of deviation in static SVV reflects the individual level of compensation. In addition, increased visual dependency evoked a symmetrical bias of the dynamic SVV from the measures at initial SVV assessment (i.e. static SVV or the center of tilt). As a result, we conclude that the contribution of visual inputs had changed after surgery, while at the same time, each patient used their static SVV as their reference point for orientation.

Adaptation, Physiological↗

PubMed2002

Three-dimensional analysis of nystagmus in benign paroxysmal positional vertigo. New insights into its pathophysiology.

Nystagmus is a rhythmical rotation of the eyeball. Its characteristics can be defined mathematically by the axis of rotation and the angular velocity around this axis. We analysed the axis of rotation for the nystagmus in benign paroxysmal positional vertigo (BPPV) to elucidate its pathophysiology. Thirteen patients with typical unilateral BPPV participated in the present study. The axis of rotation for the nystagmus was calculated from images recorded on digital videotape with an infrared CCD camera, using an algorithm that we developed. The patients' responsiveness to Semont's liberatory maneuver was also assessed.The results showed that patients could be assigned to one of two groups based on the rotation axis of the nystagmus. In one group of patients (n = 7; Group A), the axis of rotation was almost vertical to the plane containing the posterior semicircular canal (PSC) on the presumed affected side. In the other group of patients (n = 6; Group B), it was clustered around the naso-occipital axis. These results suggest that in the patients in Group A the responsible lesion is confined to the PSC, whereas the pathogenesis underlying the conditions in those in Group B is considered to be more complicated. This speculation was reinforced by the difference in responsiveness to Semont's liveratory maneuver. All of the patients in Group A showed remission of vertigo within 10 days (mean, 2.4 days) after onset of treatment using Semont's liberatory maneuver, whereas the patients in Group B required much longer periods of time for remission to occur (mean, 25.7 days). Our findings lead to the conclusion that by considering the spatial orientation of individual semicircular canals, in the patients in Group B the pathophysiology is not confined to the PSC, but most probably all three semicircular canals are involved.

Adult↗

PubMed2002

Dynamic and static subjective visual vertical with aging.

OBJECTIVE: Our vestibular function is gradually deteriorating during aging, although, its behavioral consequences are not easily recognized due to a substitution process by other sensory modalities as visual or proprioceptive inputs. METHODS: To reveal such a hidden substitution process by visual signals, the measurement of the static as well as the dynamic subjective visual vertical (SVV) was performed among 63 healthy subjects of different age. RESULTS: The static SVV was found to be stable among all subjects, whereas the shift of the dynamic SVV during rotation of a background scene gradually increased with age. CONCLUSION: This result indicates that the substitution process identified as a function of age in a perceptual test may have its counterpart in postural stabilizing reflex.

Adult↗

PubMedDate not supplied

Classic hypoglossal-facial nerve anastomosis after acoustic neuroma resection. A review of 46 cases.

To clarify the factors contributing to patient satisfaction with facial movement after the classic hypoglossal-facial nerve anastomosis, we examined 46 such patients who consented to an interview and video-recording. No correlation was seen between the physician's evaluation of returned function (according to Yanagihara's 40-point scale and the grading system of House-Brackmann) and the scores (full marks: 100 points) the patients assigned to their own facial movements. Instead the scores that the patients assigned were closely related to subjective oral dysfunction, such as difficulty in masticating, articulating, and swallowing. Those scores did not correlate with eye-related functional deficits. These findings indicate that modified techniques to minimize the hypoglossal nerve deficit may enhance patient satisfaction without sacrificing recovery of facial movements.

Adult↗