Keiko Sugasawa

Assessment of diagnostic accuracy of foam posturography for peripheral vestibular disorders: analysis of parameters related to visual and somatosensory dependence.

OBJECTIVES Simple tests to detect peripheral vestibulopathy might be practically useful before conducting elaborate examinations. The purpose of this study was to assess the diagnostic accuracy of foam posturography for peripheral vestibulopathy, with emphasis on visual and somatosensory dependence. METHODS Two-legged stance tasks were conducted in patients with unilateral (n=68) and bilateral (n=16) vestibulopathy and healthy controls (n=66), under four conditions; eyes open with and without the foam rubber, and eyes closed with and without the foam rubber. RESULTS The values of six parameters; the velocity of movement of the center of pressure (COP) and envelopment area tracing by the movement of the COP in eyes closed/foam rubber, the Rombergs ratios of velocity and area with foam rubber, and the foam ratios (ratios of a measured parameter with to without the foam rubber), of velocity and area in eyes closed, were significantly higher in unilateral and bilateral vestibulopathy compared with the control (p<0.001). The area under the receiver operating characteristic curve for the Rombergs ratio of velocity with the foam rubber was the largest. CONCLUSIONS Foam posturography detected high levels of visual and somatosensory dependence in patients with vestibulopathy. SIGNIFICANCE Foam posturography is useful for preliminary assessment of possible peripheral vestibulopathy.

Analyses of neuro-otological complications after radiosurgery for acoustic neurinomas

PURPOSE To find out the optimum treatment parameters and the proper indications for treatment of acoustic neurinomas, univariate and multivariate actuarial analyses of neuro-otological complications after stereotactic radiosurgery for acoustic neurinomas were performed. METHODS AND MATERIALS The subjects were 46 patients with acoustic neurinomas who underwent unilateral radiosurgery between June 1990 and June 1994 and were followed up at the University of Tokyo. Age ranged from 13 to 77 years (median, 54 years). Tumor diameter ranged from 0 to 25 mm (mean, 12 mm) at the cerebellopontine angle and from 2 to 15 mm (mean, 8.3 mm) in the internal auditory meatus. Maximum tumor doses ranged from 20 to 40 Gy (mean, 31.4 Gy), and peripheral doses from 12 to 25 Gy (mean, 16.8 Gy). One to eight isocenters were used (mean, 3.2). Median follow-up was 39 months. Eight events concerning neuro-otological complications were chosen, and the potential risk factors for them were analyzed by the actuarial analyses (univariate and multivariate). The events examined include hearing loss, vestibular function loss, facial palsy, and trigeminal nerve dysfunction. In order to point out potential risk factors for neuro-otological complications, univariate analyses were performed using both the Wilcoxon test and the log rank test, and multivariate analyses were performed with the Cox proportional hazards model. Variables nominated as potential risk factors were 1) demographic variables such as patient age and sex, 2) tumor dimensions, 3) treatment variables such as tumor doses and number of isocenters, and 4) pretreatment hearing levels. A variable with significant p-values (p < 0.05) in two or more of the three actuarial analyses (two univariate and one multivariate) was considered a possible risk factor. RESULTS The possible variables that increase the risk for each event analyzed were: neurofibromatosis type II (NF2) and the number of isocenters for total hearing loss; experience of prior operation, the tumor diameter in the internal auditory meatus, and NF2 for hearing threshold elevation; peripheral tumor dose for vestibular function loss; patient age or midporus transverse tumor diameter (the two variables were correlated), and the number of isocenters for facial palsy; and the number of isocenters for trigeminal neuropathy. CONCLUSION NF2 and the tumor diameter were the common risk factors for hearing loss in previous studies and ours. For the 5th/7th nerve dysfunction, the tumor diameter was the common risk factor. The risk of using more isocenters remains controversial. The difference in risk factors for hearing impairment and vestibular function loss suggests different mechanisms for the two. Further studies with larger populations and longer follow-up periods are required in order to draw conclusions on the risk factors in radiosurgery.

Risk factors for neurological complications after acoustic neurinoma radiosurgery: refinement from further experiences

PURPOSE Further actuarial analyses of neurological complications were performed on a larger population treated by stereotactic radiosurgery at our institution, to establish the optimal treatment parameters. METHODS AND MATERIALS Between June 1990 and September 1998, 138 patients with acoustic neurinomas underwent stereotactic radiosurgery at Tokyo University Hospital. Of these, 125 patients who received medical follow-up for 6 months or more entered the present study. Patient ages ranged from 13 to 77 years (median, 53 years). Average tumor diameter ranged from 6.7 to 25.4 mm (mean, 13. 9 mm). Maximum tumor doses ranged from 20 to 40 Gy (mean, 29.8 Gy) and peripheral doses from 12 to 25 Gy (mean, 15.4 Gy). One to 12 isocenters were used (median, 4). Follow-up period ranged from 6 to 104 months (median, 37 months). The potential risk factors for neurological complications were analyzed by two univariate and one multivariate actuarial analyses. Neurological complications examined include hearing loss, facial palsy, and trigeminal nerve dysfunction. Variables included in the analyses were four demographic variables, two variables concerning tumor dimensions, and four variables concerning treatment parameters. A variable with significant p values (p < 0.05) on all three actuarial analyses was considered a risk factor. RESULTS The variables that had significant correlation to increasing the risk for each neurological complication were: Neurofibromatosis Type 2 (NF2) for both total hearing loss and pure tone threshold (PTA) elevation; history of prior surgical resection, tumor size, and the peripheral tumor dose for facial palsy; and the peripheral tumor dose and gender (being female) for trigeminal neuropathy. In facial palsies caused by radiosurgery, discrepancy between the course of palsy and electrophysiological responses was noted. CONCLUSION Risk factors for neurological complications seem to have been almost established, without large differences between institutions treating a large number of patients by radiosurgery. Radiosurgical doses and tumor dimensions were considered the two important risk factors for the 7th and 5th nerve injuries. Neurofibromatosis Type 2 was an important factor for hearing loss.

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.

The diagnostic value of vestibular-evoked myogenic potential in patients with vestibular schwannoma

OBJECTIVE This study examined the diagnostic value of the vestibular-evoked myogenic potential (VEMP) in comparison with the caloric test in patients with vestibular schwannoma (VS). METHODS Data were retrospectively collected from 803 consecutive patients who visited our vertigo clinic and underwent vestibular tests. Amongst them, 78 patients were diagnosed as having untreated unilateral VS. VEMP was performed using click and short-tone burst stimulation. The caloric test was performed using ice water. The sensitivity and specificity of each test were evaluated. RESULTS Of the 78 patients with VS, 63 had abnormal VEMPs as well as abnormal caloric responses. Of the 725 patients without VS, 382 had normal VEMPs and 416 had normal caloric responses. The sensitivity and specificity of VEMP were 80.8% (95% CI: 72.0-89.5%) and 52.7% (95% CI: 49.1-56.3%), respectively; those of the caloric test were 80.8% (95% CI: 72.0-89.5%) and 57.4% (95% CI: 53.8-61.0%), respectively. CONCLUSIONS The sensitivity and specificity of VEMP and the caloric test showed no significant differences. SIGNIFICANCE In patients with VS, although the specificity of VEMP was not very high, its sensitivity was high and comparable to that of the caloric test.

Vestibular Evoked Myogenic Potentials in Ipsilateral Delayed Endolymphatic Hydrops

We recorded vestibular evoked myogenic potentials (VEMPs) in 12 patients diagnosed as having ipsilateral delayed endolymphatic hydrops (DEH). Seventy-five percent (9/12) of the patients showed decreased or absent VEMPs in the affected ears. Almost all patients had normal VEMPs in the unaffected ears. In addition, in 4 patients, VEMPs were recorded before and 3 h after oral glycerol administration (1.3 g/kg body weight). VEMPs improved after glycerol administration in 2 of the 3 patients whose VEMPs had been abnormal in the affected ears before glycerol administration. None of the 4 patients presented significant changes in VEMPs in the unaffected ears after glycerol administration. Improvement of VEMPs after glycerol administration confirmed the existence of endolymphatic hydrops in patients with ipsilateral DEH. In conclusion, VEMPs are useful to evaluate the function of otolith organs in patients with ipsilateral DEH, and the glycerol test using VEMPs may be useful to detect endolymphatic hydrops in ipsilateral DEH.

Vestibular evoked myogenic potentials in patients with contralateral delayed endolymphatic hydrops.

Abstract We studied vestibular evoked myogenic potentials (VEMPs) in nine patients with unilateral profound hearing loss followed by contralateral delayed hearing fluctuation and episodic vertigo. This condition has been called contralateral delayed endolymphatic hydrops. Five of nine ears with profound hearing loss (56%) showed an absence of VEMPs. One ear (11%) showed decreased responses, and three ears (33%) had normal responses. Of the ears with fluctuation of hearing, six (67%) showed an absence of responses, and three ears (33%) showed normal responses. In four patients we recorded VEMPs before and after oral administration of glycerol. Three hours after glycerol administration, two of four ears with fluctuating hearing loss showed the appearance of VEMPs although there was an absence of VEMPs before glycerol administration. These results suggested that saccular dysfunction could exist not only in the ears with profound hearing loss but also in ears with fluctuating hearing loss and that saccular endolymphatic hydrops could exist in the ears with fluctuating hearing loss. “Contralateral delayed endolymphatic hydrops” might be an appropriate term.

Clinical characteristics of inferior vestibular neuritis

Abstract Conclusions: Inferior vestibular neuritis (IVN) is a relatively minor subtype of vestibular neuritis (VN) and its clinical characteristics are unique. Objectives: To clarify clinical characteristics of IVN in comparison with conventional VN. Methods: This was a retrospective case series review. Caloric responses and cervical vestibular evoked myogenic potential (cVEMP) responses were measured in 71 patients with VN. The patients were classified into three groups: (1) IVN group, who showed only asymmetrical cVEMP responses; (2) superior VN (SVN) group, who showed only asymmetrical caloric responses; (3) total VN (TVN) group, who showed asymmetrical responses in both tests. The clinical records of time course of subjective symptoms (duration of attack, duration of hospitalization, and time to remission) were reviewed and other profiles (age, sex, affected side, acute symptoms, and sequelae) were evaluated. Results: Of the 71 patients with VN, 13 (18%) were classified as having IVN. The mean age and time to remission of patients with IVN (44.2 ± 4.8 years, 0.9 ± 0.5 months) were significantly lower and shorter, respectively, than those of patients with TVN (57.3 ± 2.5 years, 4.9 ± 4.7 months). There were no significant differences in other symptoms and profiles among the three groups. No patients with IVN showed benign paroxysmal positional vertigo as a sequela.

The outcome of the canalith repositioning procedure for benign paroxysmal positional vertigo: are there any characteristic features of treatment failure cases?

To demonstrate the success rate of the canalith repositioning procedure (CRP) in our clinic and to establish any characteristic features of cases of treatment failure, we reviewed clinical records of 62 patients who were diagnosed with posterior semicircular canal-benign paroxysmal positional vertigo (BPPV) and treated with the CRP. The basic strategy of the CRP was to rotate the involved canal slowly in the plane of gravity so that free-floating materials could migrate into the utricle only once. After the procedure we instructed patients to keep their heads upright for 10 h and not to sleep on the affected ear for 2 weeks. After the initial treatment, successful results were obtained in 51 of the 62 patients (82.2%). After the second treatment, 56 patients (90.3%) experienced success. Six patients (9.7%) did not obtain resolution even after the second treatment. While 46 patients were diagnosed with idiopathic BPPV, in 16 patients a different diagnosis was determined (head injury in 7 patients, Ménières disease in 2, vestibular neuritis in 2 and unilateral sensorineural hearing loss in 5). We categorized these 16 patients as having secondary BPPV. Patients with idiopathic BPPV showed a significantly higher success rate with CRP than those with secondary BPPV. Patients with secondary BPPV may have quantitatively or qualitatively different lesions than those with idiopathic BPPV.To demonstrate the success rate of the canalith repositioning procedure (CRP) in our clinic and to establish any characteristic features of cases of treatment failure, we reviewed clinical records of 62 patients who were diagnosed with posterior semicircular canal-benign paroxysmal positional vertigo (BPPV) and treated with the CRP. The basic strategy of the CRP was to rotate the involved canal slowly in the plane of gravity so that free-floating materials could migrate into the utricle only once. After the procedure we instructed patients to keep their heads upright for 10 h and not to sleep on the affected ear for 2 weeks. After the initial treatment, successful results were obtained in 51 of the 62 patients (82.2%). After the second treatment, 56 patients (90.3%) experienced success. Six patients (9.7%) did not obtain resolution even after the second treatment. While 46 patients were diagnosed with idiopathic BPPV, in 16 patients a different diagnosis was determined (head injury in 7 patients, Ménières disease in 2, vestibular neuritis in 2 and unilateral sensorineural hearing loss in 5). We categorized these 16 patients as having secondary BPPV. Patients with idiopathic BPPV showed a significantly higher success rate with CRP than those with secondary BPPV. Patients with secondary BPPV may have quantitatively or qualitatively different lesions than those with idiopathic BPPV.

Migraine-associated vertigo: clinical characteristics of Japanese patients and effect of lomerizine, a calcium channel antagonist

Conclusion. Lomerizine, a calcium channel blocker, may be effective as a treatment for migraine-associated vertigo (MAV). Objective. To determine the clinical characteristics of patients with MAV in Japan and the effectiveness of lomerizine. Patients and methods. This was a retrospective chart review carried out in a university hospital of 33 patients who fulfilled the diagnostic criteria for MAV. All patients were initially treated with dietary manipulation. If this therapy was unsuccessful, oral medications, mainly lomerizine, were administered. Medical records were reviewed to find clinical characteristics of patients with MAV and to evaluate the effects of the therapy on vertigo/dizziness symptoms. Results. A marked female predominance was found (23 women, 10 men). The frequency and the duration of vertigo varied across patients. About 60% of the patients had cochlear symptoms during an attack, among which bilateral aural fullness was most frequent. Oto-neurological examination showed abnormalities in 33% of the patients. Overall, 27 of the 33 patients (82%) responded to our therapy. Among the 22 patients who were prescribed lomerizine, 19 patients (87%) showed resolution or significant improvement of the symptoms.