Tomoko Okumura

Sensorineural hearing loss in patients with large vestibular aqueduct

In examining 181 patients (327 ears) with sensorineural hearing loss of unknown etiology and 25 people (50 ears) with normal hearing by high‐resolution computed tomography (CT), the image of the large vestibular aqueduct (VA) was defined as being a visible large aperture (≥4 mm), and small distance between vestibule and traceable part of the VA nearest to the vestibule (≥1 mm). The large VA was found in 13 patients (23 ears, 7.0%); it was relatively frequent following hypoplastic cochlea (33 ears, 10.1%) in all the inner ear anomalies detected. In patients with large VA, high‐frequency hearing was affected more than low frequency, and history of sudden hearing loss was observed frequently (61% of ears with large VA), which was found to be triggered by characteristic episodes such as minor head trauma, etc. Those clinical features were observed more in those without cochlear anomaly than in those accompanying cochlear anomaly. Pathogenesis of sensorineural hearing loss and characteristic fluctuation of hearing in those patients are discussed.

Vestibular Function in Patients with a Large Vestibular Aqueduct

Four patients (7 ears) with a large vestibular aqueduct (VA) were examined for history of vertigo and vestibular function. Vertigo was observed in all the 4 patients. The caloric responses were significantly poorer in ears with a large VA than in the controls. On a patient with a large VA who had several attacks of sudden hearing loss and vertigo following minor head trauma, long-time exposure to sunshine, common cold, and exercise, vestibular function tests were performed several times; the caloric responses were found to fluctuate and direction changing apogeotropic positional nystagmus was observed. These findings suggest that in patients with a large VA, not only hearing but also the vestibular function are generally impaired. We believe than direct transmission of intracranial pressure changes to the inner ear or subsequent inner ear fluid movement through the large endolymphatic sac and duct have an influence on the cochlea and vestibule.

Magnetic resonance imaging of patients with large vestibular aqueducts

The vestibular aqueduct (VA) and endolymphatic sac (ES) were examined by magnetic resonance imaging in eight patients (14 ears) with large VAs, and the results were compared with those obtained in five normal volunteers (10 ears). It was not possible to identify either the VA or ES in any of the control ears. However, in all the 14 ears with a large VA, the VA was detected as a fluid-filled structure. In 12 ears the ES was seen to be markedly enlarged and also filled with fluid. In one ear, the volume of the fluid-filled space within the VA and ES was measured as 912 mm3 on serial images. Five patients (ten ears) were observed to have a fluid-filled VA and enlarged ES without cochlear anomalies and reported frequent episodes of sudden hearing loss and vertigo following exercise, long exposure to sunshine, minor trauma and the like. Two other patients (three ears) also had enlarged VA and ES as well as cochlear anomalies, but did not have episodes of sudden hearing loss and vertigo. These findings suggest that direct transmission of intracranial pressure changes to the inner ear or subsequent movement of endolymph in patients with a large VA may adversely influence a seemingly normal cochlea and vestibule.

Three-dimensional analysis of otolith-ocular reflex during eccentric rotation in humans.

When a participant is rotated while displaced from the axis of rotation (eccentric rotation, ER), both rotational stimulation and linear acceleration are applied to the participant. As linear acceleration stimulates the otolith, the vestibulo-ocular reflex (VOR) caused by the otolith (linear VOR; lVOR) would be induced during ER. Ten participants were rotated sinusoidally at a maximum angular velocity of 50°/s and at frequencies of 0.1, 0.3, 0.5, and 0.7Hz. The radius of rotation during ER was 90cm. The participants sat on a chair at three different positions: on the axis (center rotation, CR), at 90cm backward from the axis (nose-in ER, NI-ER) and at 90cm forward from the axis (nose-out ER, NO-ER). Their eye movements during rotation were recorded and analyzed three-dimensionally. The VOR gain during NI-ER was lower at 0.5 and 0.7Hz, and that during NO-ER was higher at 0.3, 0.5, and 0.7Hz than during CR. These results indicate that lVOR actually worked at 0.5 and 0.7Hz during ER and that the enhancement and decline of the VOR gain relative to the VOR gain during CR was seen in humans. Thus, we suggest that otolith function can be assessed via rotational testing of NI-ER and NO-ER.

Assessment of endolymphatic hydrops and otolith function in patients with Ménière’s disease

Ménière’s disease is associated with hydrops of the inner ear endolymphatic space, and histopathologically, the cochlea and vestibule are usually involved. We used gadolinium-enhanced magnetic resonance imaging and measured cervical and ocular vestibular evoked myogenic potentials and the gain in the utricular induced linear vestibulo-ocular reflex to test the hypothesis that vestibular hydrops in Ménière’s disease patients is associated with otolith organ dysfunction. We evaluated 21 patients diagnosed with unilateral definitive Ménière’s disease using gadolinium magnetic resonance imaging to detect endolymphatic hydrops in the cochlea and vestibule. Cervical and ocular vestibular evoked myogenic potentials and the gain in utricular induced linear vestibulo-ocular reflex during eccentric rotation were measured to assess otolith organ function. For eccentric rotation, patients were rotated while displaced from the axis of rotation, while linear acceleration stimulated the utricle and induced the vestibulo-ocular reflex. Magnetic resonance imaging revealed vestibular hydrops in 14 of 20 patients (70%). Among the 14 patients, ten (71%) had abnormal cervical and three (21%) had abnormal ocular vestibular evoked myogenic potentials. Four patients (4/21, 19%) had abnormal linear vestibulo-ocular reflexes, three of whom also had abnormal ocular vestibular evoked myogenic potentials. Overall, 16 of 17 patients had normal linear vestibulo-ocular reflexes and normal ocular vestibular evoked myogenic potentials. Vestibular endolymphatic hydrops in Ménière’s disease patients caused otolith organ dysfunction, mainly in the saccule. The number of Ménière’s disease patients with abnormal ocular vestibular evoked myogenic potentials was low (19%), and they also had abnormal utricular induced linear vestibulo-ocular reflexes.

Somatosensory shift of postural control in dizzy patients

Abstract Conclusions: Postural control is dependent on the visual system in normal conditions. Shift from visual to somatosensory dependence in dizzy patients suggests that utilizing the stable visual references is recommended for the rehabilitation of dizzy patients. Objectives: To investigate which of the visual or somatosensory system is mainly used for substitution of the impaired spatial orientation in dizzy patients. Methods: We recruited 189 consecutive patients with or without dizziness and vestibular dysfunction. Dizzy patients were divided into three groups: acute, episodic, and chronic dizziness. Vestibular function was assessed by caloric test, traditional head impulse test, and head shaking nystagmus. Visual or somatosensory dependence of spatial orientation was assessed by posturography on a solid surface or on foam in eyes open or closed condition. The foam ratio (posturography with/without foam) when eyes were closed was indicative of somatosensory dependence of postural control, whereas the Romberg ratio on foam showed visual dependence. (Romberg ratio on foam)/(foam ratio with eyes closed) was calculated and used as an index of the visual/somatosensory dependence of postural control. Results: The visual/somatosensory ratio of postural control was significantly lower in dizzy patients as well as patients with vestibular dysfunction, however, no differences were found between acute, episodic, and chronic dizziness.

Unilateral posterior canal-plugging surgery for intractable bilateral posterior canal-type benign paroxysmal positional vertigo

OBJECTIVE To investigate the effectiveness of unilateral posterior semicircular canal (PSCC)-plugging surgery for patients with intractable bilateral PSCC-type benign paroxysmal positional vertigo (P-BPPV). METHODS From July 2011 to December 2015, we diagnosed 136 patients with P-BPPV. Of these, 3 patients had bilateral P-BPPV, and in 2 of the 3, the condition had been refractory to conservative treatment for more than 1 year. We planned a staged PSCC-plugging surgery for these 2 patients; initially one side was treated, and the contralateral side was treated 6 months later. RESULTS After the first surgery, both patients experienced improvement in symptoms of vertigo and nystagmus on the operated side and no change on the non-operated side. Patients underwent the Epley maneuver for the non-operated side. In one case, the non-operated side was cured. In the other case, although the P-BPPV was not completely resolved, the patient was satisfied with the result of unilateral surgery because he was now able to turn in bed to the operated side without vertigo. Before surgery, he had experienced vertigo when turning even slightly in bed. CONCLUSION We propose that even unilateral PSCC-plugging surgery is effective for some patients with intractable bilateral P-BPPV.

Gadolinium contrast-enhanced MRI reveals cystic lateral semicircular canal contents

Abstract Conclusion: Contrast-enhanced magnetic resonance imaging (MRI) reveals variations in the endolymphatic morphology of the cystic lateral semicircular canal (CLSC) that correlate with inner ear function. This report is the first to suggest a relationship between the morphology and function of this common inner ear malformation in clinical cases. Objectives: This study investigated the radiological and functional findings of a common inner ear malformation using computed tomography (CT), gadolinium contrast-enhanced magnetic resonance imaging (MRI), caloric testing, and cervical and ocular vestibular evoked myogenic potential (VEMP) testing. Method: Four ears in three patients who were radiologically diagnosed with a CLSC and a normal cochlea on high-resolution CT and contrast-enhanced MRI were included. Semicircular canal and vestibular functions were analyzed using the caloric test and cervical and ocular VEMP testing. Results: Unilateral and bilateral cystic canals were found in two and one patients, respectively. In the first patient, the malformed vestibule and cystic space were separate on imaging, and perilymph filled the cystic space. The functional test results were normal. In the second patient, endolymph filled both cystic spaces, and the functional responses were poor. In the third patient, endolymph filled the cystic space, and the ear did not respond during functional testing.

Visual Target Strategies in Infantile Nystagmus Patients With Horizontal Jerk Waveform

The aim of this study was to propose a new pathophysiological hypothesis for involuntary eye oscillation in infantile nystagmus (IN): patients with IN exhibit impaired gaze fixation, horizontal smooth pursuit and optokinetic nystagmus (OKN) and use saccadic eye movements for these underlying impairments. In order to induce saccades, they make enough angle between gaze and target by precedent exponential slow eye movements. IN consists of the alternate appearance of the saccade and the slow eye movements. Unlike most previous theories, IN is therefore considered a necessary strategy allowing for better vision and not an obstacle to clear vision. In five patients with IN, eye movements were analyzed during the smooth pursuit test, saccadic eye movement test, OKN test and vestibulo-ocular reflex (VOR) test. Their gaze fixation, horizontal smooth pursuit, OKN and the last half of the slow phase of VOR were impaired. The lines obtained by connection of the end eye positions of fast phase of nystagmus coincided with the trajectories of targets. The findings indicate that patients followed the target by the fast but not the slow phase of nystagmus, which supports our hypothesis. By setting the direction of slow phase of nystagmus opposite to the direction of the OKN stimulation, enough angle can be effectively made between the gaze and target for the induction of saccade. This is the mechanism of reversed OKN response. In darkness and when eyes are closed, IN weakens because there is no visual target and neither the saccade for catching up the target or slow phase for induction of the saccade is needed.

A Case of a True Malignant Mixed Tumor of the Parotid Gland.

True malignant mixed tumor (carcinosarcoma) of salivary glands, with carcinomatous and sarcomatous components, is aggressive and extremely rare. We report a case of a true malignant mixed tumor in a parotid lesion.A 58-year-old man had a painless right inf raauricular mass that had been present for about 30 years. A 6×4cm elastic hard nodule existed from the tragus to the angle of the mandible. The patient underwent total parotidectomy with facial nerve preservation. The entire tumor was resected with the surrounding tissues except along the main trunk of the facial nerve. Histologically, the tumor showed a biphasic pattern composed of both carcinomatous and sarcomatous elements. The carcinomatous component was adenocarcinoma with ductal structure and the sarcomatous components varied from unclassified sarcoma to unequivocal chondrosarcoma. Two months later, the patient suddenly complained of right facial paralysis. Magnetic resonance imaging revealed a irregular mass extending to the parapharyngeal space. A radical operation, combined with chemotherapy and radiotherapy, was performed with neck dissection, partial mandibulectomy and facial nerve sacrifice. Despite these intensive therapies, an X ray study showed multiple pulmonary coin lesions three months after the second operation.We emphasize the necessity for radicality in initial operations when dealing with this type of tumor.