Neurofibromatosis 2 (NF2) and von Hippel-Lindau disease (VHL) are both autosomal dominantly inherited tumor syndromes. In these diseases, there is a high probability of tumors developing in the central nervous system, which cause vertigo and equilibrium disturbance in affected patients. An outline of these two tumor syndromes is presented in this review. In addition, the importance of genetic counseling especially for presymptomatic diagnosis is discussed.

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　In this review, the authors introduce the international guidelines on the clinical application of cervical vestibular evoked myogenic potential (cVEMP) published in 2014, with an added commentary. Protocols recommended in these guidelines are basically the same as those of cVEMP recording conducted in Japan. The guidelines stated that both air conducted sound (ACS) and bone conducted vibration (BCV) can be used as stimulation but that BCV can be used in addition to ACS, and not to replace it. For ACS the most effective frequencies are between 400 and 800 Hz below safe peak intensity levels (e.g., 140 dB SPL). The number of sweeps averaged should be between 100 and 250 per run. Raw amplitude corrected by the level of background muscle activities narrows the range of normal values. The authors suggested that these guidelines should be taken into consideration when performing any VEMP study.

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　The positional and positioning tests are essential when we see patients with vertigo. Recently we examined cases of nystagmus using glasses with CCD infra-red cameras which enabled us to detect even the slightest nystagmus, and to record it. However, one of the problems is that we cannot record the head position, so when we review the record afterwards, we do not know the head position at the moment when the nystagmus was released. In order to solve this problem we developed a device which enabled us to see both the eye movement and concurrent head position at once on the remote display terminal such as an iPad or iPhone. We applied the “Air Micro Frenzel” glasses (Scala Company) with which the pictures of the eye movement detected by a C-MOS sensor are sent via high fidelity wireless to the remote receiver such as an iPad or iPhone, and so on, to be shown and/or recorded. We improved the device, and equipped the glasses with a gravity sensor positioned near the CCD camera so that the information of the head position is also shown on the same remote display. As a result, our newly developed device enabled us to observe nystagmus and concurrent head position at the same time on the same display. Some technical problems remain, however, such as stabilization of the glasses on the patient's head, so we are now developing an improved device.

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　This study was performed to determine the frequency and degree of sleep disturbance in patients with dizziness using the Pittsburgh Sleep Quality Index, Japanese Version (PSQI-J), and investigate the relationship between dizziness and sleep disturbance. Fifty-two patients (20 male, 32 female) with a chief complaint of dizziness visited the dizziness clinic of the Department of Otolaryngology, Tokyo Medical University, for 3 months in 2013. The patients' age (average ± standard deviation) was 54.4±17.0 years (range, 10-88 years). The average PSQI global score was 7.6±4.2 points, which exceeds the 5.5-point cut-off for insomnia. In total, 67.3% of patients scored >6 points, and 35.8% scored >9 points, indicating definite sleep disturbance. With respect to the demography of disease groups, patients with Meniere's disease scored an average of 7.9 points, those with autonomic imbalance scored 8.8 points, and those with psychogenic dizziness scored 9.7 points; all of these diseases were associated with high PSQI scores. Patients with benign paroxysmal positional vertigo and patients with no abnormal findings showed relatively low scores (6.7 and 5.3 points, respectively). Patients with suspected sleep apnea syndrome, restless leg syndrome, and parasomnias tended to show high scores (>10 points). A high rate and high grade of sleep disturbance were confirmed in patients with dizziness, indicating that sleep quality affects several types of dizziness and vertigo. Understanding sleep disorders is helpful for the diagnosis and treatment of dizziness and provides a new perspective on the etiology of dizziness.

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　In recent years, a definitive diagnosis of spinocerebellar ataxia type 3, also known as Machado-Joseph disease (SCA3/MJD), has become possible at an early stage with the development of a gene analysis method. We retrospectively investigated the otoneurological findings of 56 patients (male, 23 patients; female, 33 patients) who had been definitively diagnosed as having SCA3/MJD by gene information retrieval at Tokyo Metropolitan Neurological Hospital. In SCA3/MJD patients, the incidence of abnormal oto-neurological findings, e.g., upgaze palsy, gaze nystagmus, impaired optokinetic nystagmus (OKN), smooth pursuit, and saccade, reduced bilateral vestibulo-ocular reflex (VOR), and impaired visual suppression of VOR, was high. 12 of 56 patients had horizontal gaze palsy, so that those 12 cases were excluded from the later investigation. The reduced bilateral VOR performed by caloric response with cold and/or iced water was observed in 31 of 56 ears within six years of the disease; however, it was observed in all 32 ears of patients who had developed SCA3/MJD more than six years previously. Therefore, reduced bilateral VOR is considered to be a very useful biomarker of SCA3/MJD in clinical diagnosis, especially at six years or more since the onset of the disease. Moreover, the otoneurological findings in the markedly reduced VOR group (six patients) and normal VOR group (six patients) within six years after onset of the disease was investigated. In the markedly reduced VOR group, the incidence of upgaze palsy was higher, the impaired visual suppression of VOR was more advanced, and the mean maximum slow phase velocity of OKN was lower in comparison with the normal VOR group. It could indicate that the brainstem dysfunctions were more severe in the markedly reduced VOR group than in the normal VOR group. This may account for the fact that the bilateral VOR dysfunction in patients with SCA3/MJD may be due to a disorder in the central vestibular system originating from the VOR pathways.

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　A number of studies have demonstrated that vestibular rehabilitation improves the function such as postural stability and gaze stability and reduces the dizziness in patients with vestibular disorders. However, there are few reports about the effectiveness of vestibular rehabilitation for those patients in Japan. The aim of this study was to investigate the efficacy of an individualized vestibular rehabilitation program for patients with refractory dizziness. Twelve patients who suffered from refractory dizziness participated in this study. The rehabilitation sessions were performed once a week by a physical therapist and patients executed a customized rehabilitation program at home. The Modified Clinical Test for Sensory Interaction and Balance (standing on a firm surface with eyes open, firm surface with eyes closed, foam surface with eyes open and foam surface with eyes closed) and dizziness handicap inventory were evaluated pretreatment at baseline and at one month and three months after treatment. The results showed that postural stability on a foam surface with eyes closed and dizziness handicap inventory had significantly improved at 3 months after treatment compared with the pretreatment findings. There were no significant differences for all parameters between the pre- and one month posttreatment groups. These findings support the importance of an individualized rehabilitation program for patients with refractory dizziness.

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　We hereby report on our experience regarding a case of rotatory vertigo exhibiting vestibular disorder-like findings accompanying normal pressure hydrocephalus (NPH).
　The case pertains to a 60-year-old man. Gait disturbance, dysuria, and so on, appeared from around 2007, and he was diagnosed as having NPH by the Department of Neurology of our hospital?. Rotatory vertigo suddenly appeared in October 2011, and he was admitted to the Department of Neurology and subsequently referred to our department on the 2nd sick day. Third degree of horizontal rotatory nystagmus to the left was observed, with no difference between the left and right observed upon a hearing test, and although he was observed with an increased threshold in the high sound area appropriate to his age, no other neurologic symptoms were observed. An equilibrium test was carried out at a later date under the suspicion of right vestibular neuronitis, however, no decline in semicircular canal function was observed upon caloric testing, with no difference between the left and right observed as well upon vestibule-ocular reflex (VOR), and so a follow-up was carried out with a diagnosis of vertebrobasilar insufficiency. The symptoms subsequently rapidly improved, however, nystagmus to the left at III° appeared again one week later, with the same nystagmus appearing again two months later. Lightheadedness was prolonged when rotatory vertigo attacks were not observed and so the patient consulted the Department of Neurology and underwent a tap test taking into consideration his dizziness caused by NPH, as a result of which his dizziness rapidly disappeared compared to the day prior, along with the other symptoms including improved gait disturbance and dysuria, which all continued to improve further. Subsequently, all dizziness disappeared after undergoing an endoscopic third ventriculostomy.

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　We report herein on the clinical features in ten patients with positional down-beat nystagmus (p-DBN) without any sign and symptom of central nervous system (CNS) disorder. Brain MRI was normal in all subjects, except in one patient who refused the examination. Gaze nystagmus was not present in any patient. Down-beat nystagmus was observed only in the supine or head-hanging position: it was never observed upon returning to a sitting position. The patients' p-DBN had no torsional component, but had some latency. All patients felt dizziness when p-DBN was observed. In 8 patients (80%), benign paroxysmal positional vertigo (BPPV) preceded the incidence of p-DBN. Three patients (30%) were diagnosed as having posterior semicircular canal BPPV before the occurrence of p-DBN. Dizziness disappeared in 8 patients (80%) within 6 months, while p-DBN remained in 4 patients (40%). Although p-DBN without any CNS disorder was suspected to be a symptom of BPPV associated with the anterior semicircular canal, we question the strength of this hypothesis mainly because no upward-beat nystagmus is seen by reversing the position.

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