Orthostatic tests, which include an active orthostatic test and a passive orthostatic test, are effective tests for differentiating among causes of orthostatic intolerance, such as orthostatic hypotension (OH), postural orthostatic tachycardia syndrome (POTS), and vasovagal syncope (VVS). OH is diagnosed when the systolic blood pressure (SBP) decreases by more than 20mmHg and/or the diastolic blood pressure (DBP) decreases by more than 10mmHg as soon as the patient stands, based on the criteria of the International Autonomic Nervous Society. The passive orthostatic test has a higher sensitivity for the diagnosis of OH as compared to the active orthostatic test. On the other hand, in cases where the blood pressure decreases are seen at 3 minutes or after, the diagnosis of VVS should be considered. POTS is diagnosed if the heart rate increases by more than 30 bpm when the patient stands, in the absence of OH. Orthostatic tests are useful to understand the underlying condition in patients suffering from orthostatic dizziness and chronic dizziness.

　In order to set a draft reference value for clinical stabilometry by 100Hz sampling, we collected and reported the data of 365 healthy subjects. The subjects were divided into 7 ten-year age groups, from the 20s to the 70s, and a group of over 80. As a draft reference value, we thought that it might be reasonable to use the mean ±2×standard deviation and the 95th percentile/5th percentile together. In this analysis, mixed gender data were used, as, based on the results of statistical analysis, we considered that the reference value could be used as a standard value for both men and women.

　A-60-year-old woman presented with a 6-month history of progressive coordination imbalance with gait disturbance, until she became obliged to use a cane for walking. Neurological examination revealed a cerebellar syndrome with limb, trunk and gait ataxia and downbeat nystagmus (DBN). MRI showed cerebellar atrophy, especially of the cerebellar vermis. CSF examination was negative for both oligoclonal bands and myelin basic protein. Serology for anti-YO antibodies was positive, which led us to make the diagnosis of paraneoplastic cerebellar degeneration (PCD). Eventually, abdominal ultrasonography revealed left ovarian cancer. After total hysterectomy, bilateral oophorectomy, partial omentectomy, and periaortic lymphadenectomy, the patient became able to walk again without assistance. The characteristic ENG findings were as follows: (1) In the light/dark, DBN was observed mainly during rightward gaze, and less prominently at the primary position and during leftward gaze. (2) However, when the patient lay in the supine posture, the DBN totally disappeared, even during rightward gaze. (3) Both horizontal and vertical pursuits revealed saccadic pursuit. (4) The peak slow-phase velocities and frequency of horizontal OKN were markedly reduced. (5) The horizontal OKAN disappeared bilaterally. (6) Hypermetric saccades, overshoot, were observed in both the horizontal and vertical directions. (7) Caloric nystagmus was well-induced bilaterally, although the visual suppression (VS) ratio was markedly reduced bilaterally. The above ENG findings suggest mainly impairment of the cerebellar systems, but also some dysfunction of the velocity storage systems. Presumably, impairment of smooth pursuit was derived from a lesion of the flocculus/paraflocculus, vermis and cerebellar hemispheres. As for dysfunction of the velocity storage systems, it is considered that the velocity storage integrators themselves in the brainstem were still intact. Rather, conceivably, the visual-vestibular interaction could not function well in the velocity storage systems because of insufficient supply of visual inputs from the impaired vestibular cerebellum.

　Objective: Onset of psychogenic vertigo/dizziness is affected by psychosocial factors. Somatosensory amplification is one of the psychological factors associated with functional physical symptoms, but its relationship to psychogenic vertigo remains unclear. We investigated the relationship between the frequency of vertigo episodes and somatosensory amplification in patients with psychogenic vertigo.

　Methods: Participants were individuals aged 20 to 79 years complaining of psychogenic vertigo. They were referred by otolaryngologists to the department of psychosomatic medicine of a university hospital in Japan. The participants' physical and mental conditions were evaluated using the Vertigo Symptom Scale-Short Form (VSS-sf), Somatosensory Amplification Scale (SSAS), and Hospital Anxiety and Depression Scale (HADS). Multiple linear regression analysis, with VSS-sf as the independent variable, was used to assess the associations.

　Results: Of the 41 participants, 35 (12 males and 23 females) were included in the analysis. The VSS-sf scores showed positive correlations with the scores for the anxiety scale of the HADS and SSAS. Linear multiple regression analysis identified the VSS-sf scores as being positively associated with the scores on the SSAS (p<0.01) and negatively associated with age (p<0.05).

　Conclusion: Our findings suggest that in patients with psychogenic vertigo, the vertigo episodes occur more frequently as somatosensory amplification increases, however, the frequency might decrease with age.

　To clarify the dynamic changes in the membranous lesions of Meniere's disease, the effects of aerobic exercise on different symptoms were analyzed. Out of a total of 351 patients with Meniere's disease who performed aerobic exercises for 6 months or longer who were enrolled, 338 showed improvement of one or more symptoms: disappearance of vertigo in 97.6% of cases; complete resolution of ear fullness in 60.1% of cases; improvement of hearing impairment in 38.5% of cases; complete resolution or marked decrease of tinnitus in 29.6% of cases. On the other hand, complete recovery of hearing was noted in 29.5% of the 78 patients with low-tone loss, 12.5% of the 96 patients with high-tone loss, and only 4.1% of the 170 patients with hearing loss across all frequencies. More than half of the patients with high-tone hearing loss and hearing loss across all frequencies failed to show any change in the degree of hearing loss. Considering the findings of temporal bone pathology, it seems probable that the Reissner's membrane, being ballooned and highly distended by endolymphatic hydrops, disturbs conduction of low-frequency waves by the perilymph, and the membrane, once it loses tension, is not resonant with either high-frequency waves or indeed waves of any frequency. Although aerobic exercise is effective to cure hydrops and improve membranous tension by activating homeostasis, its effect worsens with decreasing membranous tension.

　Purpose: To discuss the mechanism of development of eight-a-half syndrome in a case with a pontine lesion.

　Case: A 60-year-old man presented with left facial palsy and abnormal eye movements. Neuro-ophthalmologic examination showed conjugate leftward gaze palsy, impaired left eye adduction, rightward gaze-evoked nystagmus of the right eye on looking rightward, and upward gaze-evoked nystagmus. Vergence movements of the eyes were preserved. Contrast-enhanced MRI revealed an approximately 3-cm lesion in the dorsal paramedial pons. Histopathology revealed diffuse large-cell malignant lymphoma. He was diagnosed as having eight-a-half syndrome due to malignant lymphoma of the pons. Eight-a-half syndrome is one-and-a-half syndrome, characterized by impairment of both the medial longitudinal fasciculus (MLF) and paramedian pontinereticular formation (PPRF), accompanied by facial palsy. Ipsilateral facial palsy can be associated with one-and-a-half syndrome, because the facial nuclei and nerve are adjacent to the MLF, PPRF, and the abducens nucleus.

　Conclusion: In a patient with the eight-and-a-half syndrome, neurophysiologic information would be useful to speculate the extent of the lesion.

　Bilateral vestibulopathy (BVP) is a chronic vestibular syndrome characterized by persistent unsteadiness when walking or standing, particularly in the dark and/or on uneven ground. In BVP, the function of the peripheral vestibular system is bilaterally impaired or absent. For patients with BVP who do not show much improvement in postural stability after vestibular rehabilitation, development of novel treatments is expected. Noisy galvanic vestibular stimulation (nGVS) is a procedure in which an electrical current is applied as a zero-mean current noise to the vestibular system through electrodes placed over the bilateral mastoid processes. In healthy subjects and patients with BVP, the application of imperceptible optimal-level nGVS improved the stability of the standing posture and gait performance. On the other hand, further increase of the nGVS intensity degraded the stability of the standing posture. The proposed mechanism behind these effects is stochastic resonance, in which the existence of an optimal amount of noise can enhance subthreshold signals in a non-linear system. It has also been reported that nGVS has a post-stimulation ameliorating effect on postural stability in healthy adults and BVP patients, even after cessation of the stimulus. The ameliorating effect of nGVS on the posture varies among subjects. We reported that the ameliorating effect of nGVS on postural stability was greater in subjects who had greater instability to begin with, both during application of the stimulus and after cessation of the stimulus. Subjects with a lower dependence on vestibular inputs show greater ameliorating effects of nGVS. nGVS is considered to be one of the promising candidates for novel treatment of refractory postural instability in patients with vestibulopathy, and further clinical studies are needed to increase the evidence level of its therapeutic effects. In addition, the development of basic research on the mechanism underlying the effect of nGVS on the postural control system is also desired.

　Bilateral vestibulopathy is characterized by bilateral functional impairment of the peripheral vestibular system. The usual symptoms are persistent unsteadiness and oscillopsia during head and body movements. It has been reported that sensory substitution therapy, that is, vestibular rehabilitation using a sensory substitution device, which transmits other sensory information to a stimulator as a substitute for defective vestibular information, might be effective in patients with bilateral and unilateral vestibulopathy. Recently, we developed a new wearable device, TPAD (tilt perception adjustment device), that transmits vibratory input containing head-tilt information to the mandible as a substitute for defective vestibular information.

　We assessed the patient using the dizziness handicaps inventory (DHI), gait analysis, and visual/somatosensory dependence of postural control in the patients with unilateral vestibulopathy. Three months after therapy in patients with unilateral vestibulopathy, the DHI and walking speed improved even when the subjects were not wearing the TPAD. Moreover, the index of the visual dependence of posture control that was evaluated by posturography with/without foam rubber in the eyes open or closed condition decreased. The findings suggested that the sensory vibratory substitution with a TPAD for defective vestibular information induced brain plasticity related to sensory re-weighting to reduce the visual dependence of posture control, resulting in the improvement of dizziness and imbalance even while not wearing the TPAD in vestibulopathy patients.

　We then investigated the effects of sensory substitution therapy using a TPAD in patients with bilateral vestibulopathy and normal subjects. Three months after sensory substitution therapy in patients with bilateral vestibulopathy, the DHI and area with eyes closed measured by posturography improved even when the subjects did not wear a TPAD. However, the gait parameters improved only under the condition of wearing a TPAD. These findings suggest that sensory vibratory substitution with a TPAD might serve as temporary replacement for defective vestibular information in patients with bilateral vestibulopathy. Moreover, wearing of the TPAD improved posture control under the eyes-closed condition with foam rubber measured by posturography in normal subjects. TPAD might be applicable as a wearable device for improving posture control, not only in patients with bilateral vestibulopathy, but also in those with presbyvestibulopathy.

　In our aging society, maintaining one's equilibrium is very important. However, the risk of falling gradually increases with age, because of various hypofunctions, including vestibular disorders. Until date, no curative therapy for vestibular disorders has been established. So, the development of new treatments for vestibular disorders is one of the most urgent needs for our aging society. Vestibular hair cells and vestibular ganglion cells are the main sites of peripheral vestibular damage. Both are related to age-related equilibrium disorders, as the number of these cells decrease with aging. Recently, cell transplantation therapy has become a major focus of clinical research in various fields, such as ophthalmology, neuronal research and so on. Cell transplantation therapy might be a promising tool for severe damage of the peripheral vestibular system. We demonstrated that induced pluripotent stem cells (iPSCs) and human neural stem cells (hNSCs) can morphologically differentiate into hair cell- and vestibular ganglion cell-like cells, respectively, in vitro. These cells have potential as donor cells for transplantation therapy of vestibular disorders. We established animal models of bilateral vestibular disorders using 2 kinds of ototoxic drugs to produce target-specific damage. We used an aminoglycoside to produce hair cell damage and an inhibitor of sodium-potassium ATPase to produce vestibular ganglion cell damage. For evaluation of the vestibular functions, we also examined the vestibulo-ocular reflex (VOR) and performed vestibular function tests such as circling behavior, trunk curling, and swimming ability. Both VOR gain and vestibular disorders decreased after bilateral application of ototoxic drugs. At present, we are investigating the effectiveness of cell transplantation using animal model in vivo. Morphologically, we could observe survival of the transplanted cells, but no differentiation into the desired cells. However, partial improvement of the vestibular function was observed in the transplanted animals. Although extensive investigations are required, cell transplantation might offer promise as a new regenerative therapy for bilateral vestibular disorders.

　Postural control is coordinated by the vestibular, somatosensory, and visual systems. Maintenance of equilibrium requires proper functioning of these systems. Vestibular rehabilitation is a form of physical therapy for disorders of the vestibular system. A practice guideline on vestibular rehabilitation for peripheral vestibular hypofunction was published by the American Physical Therapy Association in 2016. The rate of improvement is lower in cases of bilateral vestibulopathy as compared to those of unilateral vestibulopathy. There have been no reports of adequate functional recovery in cases of bilateral vestibulopathy. Vestibular rehabilitation includes gaze stability exercises, habituation exercises, substitution exercises, and balance training. Exercises tailored to the individual and performed under supervision are more effective than those performed alone at home. Vestibular rehabilitation tends to be monotonous in its approach, and it often takes long before improvement begins to be noted. This usually results in patients dropping out of the protocol. In recent years, there has been an increasing number of reports on vestibular rehabilitation using virtual reality. Virtual reality involves the use of screens and head-mounted displays. It has been found to lead to improvement of the vestibulo-ocular reflex, postural control, dizziness handicap inventory, and quality of life. Using virtual reality games for vestibular rehabilitation may lead to patients enjoying and immersing themselves more in the rehabilitation process. It may improve their motivation, and ultimately lead them to continue and help them persevere with vestibular rehabilitation. In this paper, we discuss vestibular rehabilitation, especially for patients with bilateral vestibulopathy, and vestibular rehabilitation using virtual reality.

　Patients with chronic dizziness often complain of headache; conversely, patients with headache complain of dizziness. Patients with migraine complain of dizziness more often than patients with tension-type headache. Diagnostic criteria for both Meniere disease and vestibular migraine have been reported recently. However, in some cases, it is difficult to clearly distinguish between Meniere's disease and vestibular migraine. In the patients complains symptom, which is described in the diagnostic criteria of Meniere disease and vestibular migraine at the same time may define as Patients complaining of symptoms described in both the diagnostic criteria for Meniere's disease and vestibular migraine may be defined as having vestibular migraine and Meniere's disease overlap syndrome. Here, I would like to describe the etiology of migraine and Meniere's disease. In Japan, migraine is reported to occur at a prevalence of 3.6% in men and 12.9% in women, while Meniere's disease is reported to occur at a prevalence of approximately 2-30 cases per 1,000,000 inhabitants. In otorhinolaryngologic? outpatient practice, Meniere's disease and vestibular migraine are reported to account for about 8%-10% of patients. There are no objective tools yet to clearly diagnose either vestibular migraine or Meniere's disease. Recently, the habituation of middle latency response was reported as a potential objective evaluation tool for the diagnosis of vestibular migraine. Further study is required to identify objective tools for the diagnosis of vestibular migraine and Meniere's disease.

　We report a nystagmus recording system using the iPhone. The greatest advantage of this system is that nystagmus can be recorded anytime and anywhere using the iPhone. In addition, the system can synthesize the head position information as an animation over the nystagmus image. We previously reported a nystagmus and head position capture software for windows PC. We ported this software for Windows PC to this iPhone system. The software for Windows PC that we reported earlier needs medical infrared Frenzel goggles and a self-made motion sensor device. The system that we report herein needs only an iPhone. The iPhone camera is used to record the nystagmus, the head position information is obtained from the motion sensor built into the iPhone, and the head position information is synthesized as an animation over the nystagmus image using the iOS app. The iPhone camera has an infrared filter, which has the disadvantage of not being able to shoot nystagmus in the dark with infrared lighting, but it is considered to be sufficiently useful as a method for recording nystagmus during dizziness attacks.

　Personal experience of computer system development in the field of vestibular science was reviewed, and suggestions are made for wide distribution of developed systems in the future.

　The 4 computer systems developed by the author were introduced: 1) ABR data processing software; 2) Eye-head coordination analysis software; 3) Universal ENG data analysis software; 4) Web software for drawing nystagmograms. The former 3 systems could not be distributed widely, while the latter web software can be accessed by anyone via the internet. However, for this system to be used as a tool for a large-scale study of the relationships between nystagmus findings and diseases, “standardization” of the drawing convention is mandatory.

　Although the field of vestibular science is appropriate for personal system development, supports of certain organizations are necessary for wide distribution of the developed systems.