The relationship between postural disturbance and vertical perception after cerebrovascular disease remains unclear and studies have only recently begun to be conducted. On the other hand, the symptomatic aspect is evident: body lateropulsion is ipsilateral in the case of caudal brainstem lesions and contralateral in the case of rostral brainstem and cerebral hemispheric lesions. In addition, patients with cerebral hemispheric lesions sometimes show“pusher behavior” in which they resist any attempt to correct their posture and push the body back to the paralyzed side using the healthy limbs, as they have a fear of deviation to the healthy side. The pusher behavior is always accompanied by hemiplegia and is detected in about 10% of cases of hemispheric vascular lesions.

　The pathogenesis of lateropulsion associated with the Wallenberg syndrome has traditionally been suggested to involve a high-level central deficit due to a subjective visual vertical (SVV) tilt of vestibular origin, but more recently it has been interpreted as being the result of neurological deficits at lower levels in the spinocerebellar and vestibulospinal tracts. On the other hand, pusher behavior is a result of a disturbance in the higher central mechanisms involved in the perception of verticality as indicated by the subjective postural vertical (SPV) tilts. However, studies on the direction of the SPV tilts have yielded conflicting results. The first pioneering report of SPV in patients with pusher behavior showed that the SPV is tilted toward the lesion side, and pusher behavior occurs on the paralyzed side to correct it. On the contrary, a subsequent study indicated that pusher behavior is an attempt to adjust oneself from a true vertical to a falsely perceived vertical that is tilted toward the paralyzed side. The SPV is derived from the somatosensory system of the trunk. The main lesion site is thought to be the posterior lateral thalamus and the parietal insula, more common in right hemispheric lesions.

　In recent years, neuroscience of body graviception has been discussed in terms of the internal model, which is thought to play a role in clarifying ambiguous sensory information, integrating information among visual, vestibular, and somatosensory modalities, and summarizing efferent and afferent information. As research tools for evaluation, SVV, SPV, and subjective haptic vertical have been used.

　We report two patients with Persistent Postural- Perceptual Dizziness (PPPD) who were successfully treated by Cognitive Behavioral Therapy (CBT) after initially showing limited responses to vestibular rehabilitation and pharmacotherapy. The vestibular symptoms and psychiatric status were evaluated by the Dizziness Handicap Inventory (DHI) and Hospital Anxiety and Depression Scale (HADS), respectively, before and after six sessions of biweekly CBT intervention. The difficulties and abilities in handling activities of daily living as assessed by medical interviews improved in both patients, suggesting the effectiveness of CBT for PPPD. However, the results of assessment by the DHI/HADS differed between the two patients. Patient 1 showed improvement in the score on the DHI, but not in that on the HADS, whereas Patient 2 showed improvement in the score on the HADS, but not on that in the DHI. Given that both the patients reported improvements in the difficulties and abilities in handling the activities of daily living, we consider that the different results of assessment by the DHI may suggest the need for use of more appropriate measures to evaluate the quality of life after CBT than the DHI. These results might also suggest that CBT may not always exert equal effects on the psychiatric status and vestibular symptom status.

　We report the case of a 33-year-old man who presented with disequilibrium and downbeat nystagmus. Balance testing showed failure of visual suppression of caloric nystagmus with insufficient optokinetic nystagmus responses, suggesting central vestibular dysfunction. However, MRI showed no lesions in the brain, including in the cerebellum. The patient had been diagnosed previously as having epilepsy, and the convulsions had remained under control for more than 10 years with a maintenance dose of carbamazepine (900mg/day). Blood tests revealed a serum level of carbamazepine of 10.7mEq/l, which was over the therapeutic range (4.0-10.0mEq/l). Therefore, his carbamazepine dose was reduced, and with a reduction of the dose to 600mg/day, his disequilibrium and downbeat nystagmus gradually disappeared, along with a decrease in return of the serum level of carbamazepine to the therapeutic range. Therefore, we diagnosed the disequilibrium with downbeat nystagmus in this patient as having been caused by carbamazepine intoxication. Although carbamazepine is metabolized by CYP3A4 in the liver, elevated levels of the drug have been reported in cases of renal failure. As he also suffered from polycystic kidneys, we consider that the progressive renal dysfunction in our patient could have precipitated the carbamazepine intoxication.

　Recording eye movement at a patient's first visit to primary care is critical, because abnormal eye movement findings can disappear, accompanied by a lessening of symptoms. In addition, sharing such data with an expert institution can support a precise diagnosis. However, recording devices such as ENG and VOG are relatively expensive to introduce to private clinics. In addition, the series of eye movement examinations can take a relatively long time, potentially delaying other medical care. Recent advances in virtual reality (VR) technology have led to the development of VR goggles, which can project 3D images and also record eye movements. This kind of device can be a useful tool for the development of a novel and affordable instrument for private clinics. We have been participating in the development of a VR goggle-based VOG. This device can record ordinary sequential examinations automatically, to save time. At the same time, we are also developing an advanced model for specialists. In this manuscript, we introduce our novel VOG equipment. In addition, we discuss the possibility of future applications.

　A statistical analysis examining 206 patients (61 males, 145 females) who had visited the neurotological clinic in the Department of Otorhinolaryngology, Ikeda City Hospital, complaining of vertigo and dizziness between August 2020 and January 2022 was conducted. The age distribution peaked for patients in their seventies. Vertigo and dizziness of peripheral origin accounted for 65.5%, while that of central origin accounted for 0.5% and that of unknown origin accounted for 8.7%. Most patients with vertigo and dizziness of peripheral vestibular origin had BPPV [Please define] (26.7%) or Meniere's disease (26.2%), followed by cardio-circulatory disease (13.6%), vestibular neuritis (9.2%), persistent postural perceptual dizziness (PPPD, 5.8%), psychogenic vertigo (2.9%), or delayed endolymphatic hydrops (2.4%).

　Sensory inputs used by the central nervous system to generate commands for postural control mainly come from three sources: the vestibular system, the somatosensory system, and the visual system. Spatial orientation, or the ability to recognize one's own position, direction, and posture in space accurately, is formed based on information obtained from the above three sources combined with auditory and other information. In postural control, the somatosensory system provides the central nervous system with information about the position and motion of the body with respect to the support surface. Foam posturography is a clinical application of the phenomenon in which a decrease in somatosensory input exacerbates postural sway. The lower limb somatosensory input is disturbed by standing on foam rubber. Foam posturography can thus be used to suggest a diagnosis of vestibulopathy and to assess the dependence of postural control on somatosensory input. The dependence of postural control on somatosensory input in patients with persistent postural-perceptual dizziness (PPPD) remains controversial, and further research on changes in the weighting of various sensory inputs and their mechanisms in PPPD are expected.