Evidence for the utricular origin of the vestibular short-latency-evoked potential (VsEP) to bone-conducted vibration in guinea pig.

Previous studies have shown that the vestibular short-latency-evoked potential (VsEP) in response to the brief head acceleration stimulus is a compound action potential of neurons innervating the otolith organs. However, due to the lack of direct evidence, it is currently unclear whether the VsEP is primarily generated by the activity of utricular or saccular afferent neurons, or some mixture of the two. Here, we investigated the origin of the VsEP evoked by brief bone-conducted vibration pulses in guinea pigs, using selective destruction of the cochlea, semicircular canals (SCCs), saccule, or utricle, along with neural blockade with tetrodotoxin (TTX) application, and mechanical displacements of the surgically exposed utricular macula. To access each end organ, either a dorsal or a ventral surgical approach was used. TTX application abolished the VsEP, supporting the neurogenic origin of the response. Selective cochlear, SCCs, or saccular destruction had no significant effect on VsEP amplitude, whereas utricular destruction abolished the VsEP completely. Displacement of the utricular membrane changed the VsEP amplitude in a non-monotonic fashion. These results suggest that the VsEP evoked by BCV in guinea pigs represents almost entirely a utricular response. Furthermore, it suggests that displacements of the utricular macula may alter its response to bone-conduction stimuli.

The effect of a first-generation H1-antihistamine on postural control: a preliminary study in healthy volunteers.

First-generation H1-antihistamines are known to cause fatigue and drowsiness, due to their poor receptor selectivity and their high penetration rate of the blood-brain barrier. However, little is known about the effects of first-generation H1-antihistamines on postural stability. The purpose of this study was to evaluate the effects of d-chlorpheniramine on postural stability using posturography with and without foam rubber. A double-blind study with three parallel groups was conducted. Twenty-seven healthy young volunteers (mean age 21.9 years) were recruited and orally administered d-chlorpheniramine, 2 or 4 mg, or placebo. Postural sway was measured every hour up to 8 h after administration. Two-legged stance tasks were performed by each subject in four conditions: eyes open or eyes closed and with or without foam rubber. Inter-group comparisons showed that the group receiving 4-mg d-chlorpheniramine showed significantly larger sway in the eyes open with foam rubber condition (visual and vestibular information available, somatosensory information reduced). Inter-subject analysis in the 4-mg d-chlorpheniramine group showed that the effect of d-chlorpheniramine on postural control was variable. Our results suggest that among the three main sensory systems responsible for postural control (visual, vestibular, and somatosensory), d-chlorpheniramine may have a larger effect on the visual and/or vestibular systems in susceptible individuals.

Effect of vestibular dysfunction on the development of gross motor function in children with profound hearing loss.

OBJECTIVE: To evaluate the function of the superior and inferior vestibular nerve systems in children with profound sensorineural hearing loss, and to assess the influence of dysfunction of each vestibular nerve system on the development of gross motor function. STUDY DESIGN: Retrospective study. SETTING: A tertiary referral center. METHODS: Eighty-nine children (age range: 20-97 months) with profound sensorineural hearing loss who were due to undergo cochlear implant surgery were recruited. Function of the superior vestibular nerve system was evaluated by the damped rotation test and the caloric test, whereas functions of the inferior vestibular nerve systems were evaluated by the vestibular evoked myogenic potential (VEMP) test. Gross motor development was assessed using the age of acquisition of head control and independent walking. RESULTS: Among the children able to complete the vestibular function tests, abnormalities were found in 20% (16 of 84 children) in the damped rotation test, 41% (31 of 75 children) in the caloric test and 42% (26 of 62 children) in the VEMP test. Children who showed abnormal responses in the vestibular function tests showed significantly delayed acquisition of head control (p < 0.05) and independent walking (p < 0.05) in comparison with children with normal responses. The children who showed abnormal responses in all 3 vestibular tests showed the greatest delay in acquisition of gross motor function in comparison with the other groups. CONCLUSIONS: Children with profound hearing loss tend to have dysfunction in the superior as well as the inferior vestibular nerve systems. Both the superior and inferior vestibular nerve systems are important for the development of gross motor function in children.

Diagnostic usefulness of multifrequency tympanometry for Ménière's disease.

Multifrequency tympanometry (MFT) is the measurement of the impedance of the middle ear transmission system at a wide range of frequencies from 200 Hz to 2 kHz. A potential use of MFT as a new diagnostic tool for detecting endolymphatic hydrops has recently been reported. However, its clinical usefulness for diagnosing Ménière's disease (MD) remains unclear. To evaluate the clinical usefulness of MFT as a new qualitative and diagnostic test for MD, we performed MFT in 70 patients with unilateral or bilateral MD and in 29 normal control subjects. The width of double peaks in the admittance tympanograms (Y width) at 2 kHz and the resonance frequency (RF) were analyzed, and receiver operating characteristic (ROC) curves were constructed. The Y width in MD-affected ears was significantly greater than that in control ears (p < 0.001). The RF in MD-affected ears was significantly lower than that in control ears (p < 0.01). Neither the Y width nor RF had a significant relationship with hearing levels or the results of caloric and vestibular myogenic potential testings. The area under the ROC curve was 0.71 for the Y width and 0.66 for the RF. At the optimal cutoff points, the sensitivity and specificity of the Y width were 47.3 and 86.8%, respectively, and those of the RF were 41.3 and 84.2%, respectively. These results indicated that MFT is significantly associated with the presence of MD, but its diagnostic accuracy is only modest. MFT is a simple, noninvasive test, which should be considered as a complementary test in the diagnosis of MD.

Different effects of head tilt on ocular vestibular-evoked myogenic potentials in response to bone-conducted vibration and air-conducted sound.

The ocular vestibular-evoked myogenic potentials (oVEMPs) in response to air-conducted sound (ACS) and bone-conducted vibration (BCV) have recently been used to assess otolith-ocular pathways in humans. Although the oVEMPs to BCV are considered to reflect the function of the utricle and superior vestibular pathway, the pathway of the oVEMPs to ACS remains controversial. In this study, we compared the effect of different head positions in the roll plane on oVEMPs in response to BCV and ACS in 20 normal subjects. Head tilt in the roll plane significantly increased the asymmetry ratio of oVEMPs to BCV (p < 0.01) but did not affect the asymmetry ratio of oVEMPs to ACS. Head tilt did not affect the latencies of oVEMPs to either BCV or ACS. Rotation of the body in the yaw plane while keeping the head straight ahead did not affect the asymmetry of oVEMPs to BCV (p > 0.6). These results suggest that oVEMPs to BCV reflect the activity of a different population of vestibular afferents to those which are active during oVEMPs to ACS.

Bilateral vestibulopathy with dissociated deficits in the superior and inferior vestibular systems.

OBJECTIVES: The aim of this study was to reveal the clinical characteristics of dissociated bilateral vestibulopathy (BV) affecting the superior vestibular nerve system on one side and the inferior vestibular nerve system on the other side. It is probable that BV does not always show bilateral deficits of the same vestibular nerve system. METHODS: In a retrospective study of 2,752 consecutive new patients, 1,560 patients had undergone both caloric testing and cervical vestibular evoked myogenic potential testing. All 1,560 patients had also undergone a battery of tests including standardized neurologic, neuro-otologic, neuro-ophthalmologic, and audiological examinations. RESULTS: Forty-three patients (2.8% of 1,560 patients) were given a diagnosis of dissociated BV. Among them, 10 patients (23%) had Meniere's disease and 6 patients (14%) had vestibular neuritis. Eighteen patients (42%) did not have any identifiable disease involving the peripheral vestibule, and 9 patients (21%) could be regarded as having a novel subtype of idiopathic BV. CONCLUSIONS: Although dissociated BV might be induced by some of the same causes that provoke bilateral vestibular dysfunction, a definite proportion of the patients did not have any identifiable causes of dissociated vestibular dysfunction. Idiopathic cases could be categorized into a novel subtype of idiopathic BV.

Fusiform aneurysm of the basilar artery presenting as a cerebellopontine angle mass.

It is extremely rare that nonsaccular intracranial aneurysms are located at the cerebellopontine angle. A 60-year-old woman presented with dizziness and left-sided sensorineural hearing loss that had developed gradually for 6 months. Magnetic resonance imaging scan and magnetic resonance angiography revealed that the basilar artery was ectatic and markedly displaced to the cerebellopontine angle. The association between otoneurological findings and radiological findings is discussed.

Testing of vibratory thresholds as a clinical examination for patients with unsteadiness due to somatosensory disorders.

The somatosensory system is an important component for balance control. Disorders of this system are characterized by postural unsteadiness and could be assessed by vibratory sensation. However, the measurement of vibratory thresholds (VTs) has been rarely employed as a clinical test for patients with unsteadiness. This study aimed to evaluate the difference in vibratory thresholds between patients with somatosensory disorders and healthy volunteers, and to provide a means for evaluating somatosensory disorders in patients with balance problems. Using a vibrometer and a force-measuring platform, VTs and postural balance in 108 healthy volunteers (age, 17-79) and 19 patients with somatosensory disorders (age, 60-79) were examined. VTs of the plantar surface, as well as total length of the path and envelope area (ENV) of posturograms, in patients with somatosensory disorders were significantly larger than those in healthy volunteers. Regression analyses showed that VTs> or =28dB (peak-to-peak amplitude, 24 microm) of the plantar surface at 125Hz and ENV> or =10 cm(2) were significant indices for unsteadiness due to somatosensory disorders. VT testing of the plantar surface as well as posturography appears to be useful as a clinical examination for patients with unsteadiness.

Wall-eyed bilateral internuclear ophthalmoplegia in a patient with progressive supranuclear palsy.

Wall-eyed bilateral internuclear ophthalmoplegia (WEBINO) is a rare disorder consisting of a bilateral adduction deficit and primary gaze position exotropia. Associated with bilateral medial longitudinal fasciculus lesions, it has been mostly reported in patients with multiple sclerosis and brainstem stroke. A 72-year-old man with characteristic clinical features of progressive supranuclear palsy (PSP) later developed WEBINO. Brain MRI revealed atrophy of the midbrain tegmentum. Caloric irrigation revealed intact horizontal eye movements in both eyes. We believe this to be the first report of WEBINO in PSP. The preservation of vestibulo-ocular horizontal eye movements supports the notion that the WEBINO in this condition was caused by a supranuclear rather than a nuclear lesion and suggests the possibility that even in other causes of WEBINO, the lesion is supranuclear and not in the medial rectus subnucleus as is often suggested.

Abnormal deviation of subjective visual horizontal in patients with vestibular schwannoma.

OBJECTIVES: This study was aimed to examine the correlation between the results of subjective visual horizontal (SVH) and other vestibular function tests in patients with untreated unilateral vestibular schwannoma (VS). METHODS: The subjects comprised 40 consecutive patients (17 men, 23 women) with VS who underwent vestibular function tests before surgery and had surgically and histopathologically confirmed unilateral VS. The vestibular function tests included SVH, caloric, and vestibular evoked myogenic potential (VEMP) tests. RESULTS: Of the 40 patients, 31 (77.5%) showed deviation of the SVH toward the affected side down. Especially in 8 patients (20.0%), abnormal deviation (more than 2.2 degrees) toward the affected side down was seen. None of the patients showed abnormal deviation toward the unaffected side down. On the caloric test, the proportion of absent caloric responses and the percent canal paresis in patients with an abnormal SVH was significantly higher than those in patients with a normal SVH. The proportion of abnormal VEMP responses was higher and the percent VEMP asymmetry was smaller in patients with an abnormal SVH than in patients with a normal SVH; however, the differences were not significant. CONCLUSIONS: Abnormal results on the caloric test and/or VEMP test were more frequently seen in VS patients with abnormal deviation of the SVH.

Periodic alternating nystagmus in Meniere's disease: the peripheral type?

Periodic alternating nystagmus (PAN) is a spontaneous horizontal nystagmus that reverses direction periodically. PAN has been reported in acquired and congenital forms. The lesion site of the acquired form of PAN has been attributed to the caudal brainstem or cerebellum. We report an extremely rare case (a 59-year-old woman) with bilateral Meniere's disease, who presented PAN. PAN in this patient was suppressed in the light. This patient had smooth pursuit and normal optokinetic nystagmus, although patients with PAN usually show saccadic pursuit and impaired optokinetic nystagmus. These findings were different features from those of the central or congenital form of PAN. It should be kept in mind that peripheral vestibular disorders such as Meniere's disease could produce PAN.

Vestibular-evoked extraocular potentials by air-conducted sound: another clinical test for vestibular function.

OBJECTIVE: The purpose of this study was to identify an appropriate way to detect vestibular-evoked extraocular potentials (oVEMPs) produced by air-conducted sound stimulation in healthy subjects and to apply this test clinically in patients with various vestibular disorders. METHODS: Ten healthy subjects were included in this study. Surface electromyographic (EMG) activity was recorded from active electrodes placed on the face just inferior to each eye. Stimulation with 0.1 ms clicks and 500 Hz short tone bursts was used to activate the vestibular end-organs in healthy subjects. We also tested 12 patients with unilateral vestibular disorders using 500 Hz short tone bursts. RESULTS: In healthy subjects, negative-positive biphasic responses with short latency by air-conducted click (the first negative peak latency=8.8 ms and the following positive peak latency=14.5 ms on the average) (oVEMP) were only identified beneath the eye contralateral to the stimulating ear. On the other hand, stimulation with 500 Hz short tone bursts evoked negative-positive biphasic responses (the first negative peak latency=10.5 ms and the following positive peak latency=15.9 ms on the average) on both ipsilateral and contralateral eyes, while responses were contralateral eye-dominant. Contralateral eye responses by 500 Hz short tone bursts had higher response prevalence and larger amplitudes than clicks. In patients, oVEMPs evoked by the affected side stimulation tended to decrease or lacked a response. The presence of oVEMPs and cVEMPs coincided well in patients when 500 Hz short tone bursts were presented. CONCLUSIONS: oVEMPs can be evoked using air-conducted 500 Hz tone burst and are best recorded contralaterally on upgaze. SIGNIFICANCE: oVEMPs by air-conducted sounds could be a useful alternative clinical test for patients with vestibular lesions.

Tone burst-galvanic ratio of vestibular evoked myogenic potential amplitudes: a new parameter of vestibular evoked myogenic potential?

OBJECTIVE: To clarify whether the ratio of tone burst vestibular evoked myogenic potential (VEMP) amplitude to galvanic (electric) VEMP amplitude can be a useful indicator of peripheral vestibular disorders, especially labyrinthine disorders. METHODS: Twelve healthy volunteers and 12 patients with endolymphatic hydrops (EH) were enrolled in this study. VEMP was recorded using 500 Hz short tone bursts (135dBSPL, rise/fall time 1 ms, plateau time 2 ms) and galvanic stimulation (3 mA, 1 ms). Amplitudes of p13-n23 (tone burst) and p13g-n23g (galvanic) were corrected using background muscle activity. We defined the ratio of the corrected amplitude of p13-n23 to the corrected amplitude of p13g-n23g as TGratio. RESULTS: The mean+/-SD of logarithmic value of TGratio (LTGratio) of healthy volunteers was 0.34+/-0.12. LTGratios in patients were 0.002+/-0.24 on the affected side and 0.34+/-0.14 on the unaffected side. LTGratio on the affected side of patients was significantly smaller than the ratio on the unaffected side and the ratio of healthy volunteers. Among the 12 patients with EH, 8 patients (66%) had significantly decreased LTGratio (smaller than mean-2SD of healthy volunteers). CONCLUSIONS: Patients with EH had decreased ratio of tone burst VEMP amplitude to galvanic VEMP amplitude. SIGNIFICANCE: TGratio (or LTGratio) could be a new promising parameter of VEMP as it can be calculated from results of one side.

Facial canal anatomy in patients with mandibulofacial dysostosis: comparison with respect to the severities of microtia and middle ear deformity.

OBJECTIVE: To study the difference in the facial canal anatomy in terms of the severity of microtia and deformity of the middle ear in patients with mandibulofacial dysostosis using high-resolution computed tomography. STUDY DESIGN: Retrospective analyses. SETTING: The study was carried out at the Department of Otorhinolaryngology, University of Tokyo, Tokyo, Japan. PATIENTS: Thirty-six ears of 18 patients with mandibulofacial dysostosis were examined by high-resolution computed tomography. These ears were graded based on the Marx classification and Jahrsdoerfer scoring systems. MAIN OUTCOME MEASURES: The high-resolution computed tomography findings and age distribution of each group were compared with those of other groups by multiple comparison using Tukey's honestly significant difference test. RESULTS: The course of the facial nerve was not significantly different in terms of the severity of microtia and deformity of the middle ear. The bony cochlea in the patients with mandibulofacial dysostosis was displaced by a mean value of 2 mm more anteriorly and a mean value of 0.7 mm shallower than that in the cases with normal auricles. CONCLUSION: The facial nerve of patients with mandibulofacial dysostosis is displaced more anterolaterally than that of the cases with normal auricles; however, the auricle anomaly is not severe.

Fibromatosis of the infratemporal fossa extending to the parapharyngeal space accompanied by trismus.

Fibromatosis is a tumor of fibroblastic origin that may arise in any musculoaponeurotic structure. Although fibromatosis is histologically benign, it has a tendency to invade surrounding tissues and often recur locally after treatment. A 34-year-old female patient was presented with pain in the left buccal region, left loss of visual acuity, and trismus. Computed tomographic scans revealed a large mass in the infratemporal fossa and parapharyngeal space. An open biopsy was performed and the pathological diagnosis was a fibromatosis. Surgical treatment for her trismus was performed simultaneously.

[A case of pulmonary metastases from laryngeal cancer showing a complete response to chemotherapy with docetaxel].

Docetaxel (TXT) is a new cytotoxic agent against head and neck, (H and N) cancer since the emergence of cisplatin. We herein describe the efficacy of TXT in treating distant metastases from H and N cancer. The patient was a 61-year-old man who had undergone laryngectomy and irradiation for laryngeal cancer (glottic type: T3N0M0). More than 2 years later after the first course of therapy, pulmonary metastases involved in the left lower area were revealed by lung CT. The divided TXT therapy (20 mg, 3 times, and 40 mg, 3 times) was carried out without any sequelae. This consecutive therapy resulted in complete disappearance of the metastases on follow-up CT. It is suggested that divided TXT therapy has potential as a new treatment modality for distant metastases of H and N cancer.

[Surgical treatment of patients with severe obstructive sleep apnea syndrome].

No standard indications currently exist for surgical treatment of severe obstructive sleep apnea syndrome (OSAS). We treated 15 patients with severe OSAS surgically, evaluated surgical indications, and evaluated surgical success. We retrospectively reviewed 15 cases of surgery for OSAS in which polysomnography met 2 or more criteria for the following surgical indications: (1) apnea hypopnea index (AHI) > or = 50, (2) minimum SpO2 below 80%, and (3) enlarged tonsils (grade III, Mackenzie's classification). Among the 15, mean AHI was 85.1. Surgery was done under general anesthesia, with uvulopalatopharyngoplasty (UPPP) in 13 and tonsillectomy alone in 2. Postoperative AHI was measured in 9 patients. According to Nishimura's criteria for assessing surgical success, improvement was "excellent" in 5, "good" in 1, "fair" in 1, and "poor" in 2. When we compared preoperative and postoperative use of continuous positive airway pressure (CPAP) in 7, we found that surgery decreased CPAP requirements. Surgical success was assessed in patients requiring CPAP and improvement was "excellent" in 5, "good" in 1, and "fair" in 1. In conclusion, surgical indications for severe OSAS, including the criterion of enlarged tonsils, were useful. Surgery decreased CPAP requirements and the degree of improvement in this requirement and AHI was valuable in assessing surgical success.

The effect of systemic administration of desmopressin on cochlear function in guinea pigs.

CONCLUSIONS: Systemic desmopressin (dDAVP) administration in guinea pigs for up to 2 weeks induced only minor or no significant changes in cochlear sensitivity, suggesting that other factors may be required to induce the cochlear dysfunction that is usually associated with endolymphatic hydrops. OBJECTIVES: To investigate the effects of chronic systemic administration of dDAVP, a synthetic analog of vasopressin, on cochlear sensitivity in guinea pigs. METHODS: dDAVP was administered subcutaneously via a mini-osmotic pump, at a rate of 0.2 ng/kg/min (low-dose group) or 2.0 ng/kg/min (high-dose group) for up to 2 weeks. Cochlear responses (compound action potentials) and distortion product otoacoustic emissions (DPOAEs) were measured. Example specimens were scanned using X-ray micro-tomography (micro-CT). RESULTS: Compared with the control group, the low-dose dDAVP group showed a significant threshold increase in response to a 2 kHz tone-burst after 2 weeks of treatment, and also a decrease in the amplitude of the DPOAE after 1 week of treatment. However, individual results were variable and the high-dose dDAVP group showed no significant change compared to the control group. In the micro-CT images, two of four ears in the low-dose group showed mild hydrops, but no hydrops was found in the three ears sampled from the high-dose group.