Various eye movements can be recorded using Electronystagmography (ENG) or Video-oculography (VOG). Recently, VOG which allows three-dimensional eye movement recording, has become the mainstream choice for eye movement testing. However, VOG has several practical shortcomings, such as poor recording ability in patients with narrow palpebral fissures, inaccurate recording in the lateral eye position, and the time-consuming three-dimensional analysis. In contrast, ENG is capable of stable recording, accurate two-dimensional analysis, and prolonged recordings, still making it one of the most important means for evaluating equilibrium functions in patients with for dizziness and other balance problems. Nevertheless, ENG testing will also need to be adapted to the digital transformation age in the near future. Next, we discuss the clinical significance of various oculomotor assessments using ENG and VOG. The vestibulo-ocular reflex and visuo-ocular reflex (optokinetic nystagmus: OKN) are both sensed through the central nervous system. The circuit shared between these two reflexes is the velocity storage integrator (VSI), assumed to reside in the vestibular nuclei. The VSI is further controlled by positive cerebellar feedback. Understanding these control mechanisms is one of the most important aspects when interpreting the results of oculomotor evaluation on the ENG and VOG systems. Other eye movements that reflect the functions of the VSI include various types of after-nystagmus (AN). Finally, we discuss the mechanisms of the different types of AN that can be recorded with ENG or VOG.

　We have reviewed previously reported procedures for diagnosing vertigo, dizziness and imbalance. Most experts recommend first distinguishing between pre-syncope and other symptoms. The symptoms are then classified into 4 or 5 categories according to the clinical history (acute or chronic, triggered or spontaneous, continuous or episodic). Further differential diagnosis is then needed in each category. A recent trend in the classification is not to focus on rotational vertigo or non-rotational dizziness as a symptom.

　The most important consideration in diagnosing the cause of acute vertigo is stroke detection, which is often difficult to distinguish from peripheral vestibular disorders. There are three possible strategies: (1) use of an algorithm, such as a flowchart, (2) defining symptoms/findings suggestive of a stroke, and (3) scoring and evaluation of the symptoms/findings. The sensitivity and specificity are increased by defining multiple symptoms and findings suggestive of stroke. However, if many specialized findings are required, it lacks versatility as a diagnostic procedure. The optimal strategy differs depending on the situation, the target patient, and the doctor. The strategies are expected to continue to be evaluated and improved.

　(Objective) To investigate the relationship between sleep disorder and autonomic imbalance (AI) in dizziness cases diagnosed as having AI by clinical symptoms and inspections centered on the active standing test (Schellong test). (Method) A total of 27 who had clinical symptoms suggestive of AI and were diagnosed as having AI by the active standing test, and/or the responses to a questionnaire on AI of 237 patients who visited the specialized dizziness outpatient department and answered items for determination of the Pittsburgh sleep quality index (PSQI) were analyzed. The dizziness severity associated with AI was evaluated by the dizziness frequency and Dizziness handicap index (DHI). (Results) The average PSQI in the patients with AI was 8.2±3.5 (cutoff value of PSQI, 5.5), and 70.4% (19/27) in patients with AI with dizziness who were suspected as having some sleep disorder. The PSQI was not correlated with the age or severity of AI. The pulse rate increase in the standing test (r=0.45, p=0.019) and absolute value of SBP change after standing (r=0.45, p=0.018) were correlated with the PSQI (Conclusion) High-grade sleep disorder, similar to that in depression or primary insomnia was found in patients with AI, suggesting the possibility some sort of sleep disorder being associated with the onset and severity of orthostatic hypotension (OH) and postural tachycardia syndrome (POTS).

　A-76-year-old woman presented with abrupt onset of imbalance during standing and walking. Neurological examination revealed slight truncal ataxia and downbeat nystagmus on lateral gaze while wearing Frenzel goggles. MRI showed pons infarction (right paramedian perforating artery territory), which led to the diagnosis of branch atheromatous disease (BAD). ENG revealed downbeat nystagmus (DBN) occurring at the primary eye position and lateral gaze in the dark, but not during vertical gaze. Abnormal eye movements, such as square wave jerks and saccadic intrusions were also observed in the dark. While the horizontal pursuit was almost normal, saccadic pursuit was noted during vertical pursuit. Horizontal OKN and OKAN were well induced. The rightward saccade was relatively hypometric, while the upward saccade was slightly hypermetric (overshoot). In contrast to reports of DBN being generally caused by cerebellar flocculus/paraflocculus lesions, there are scarce reports of DBN resulting from discrete brainstem lesions. According to the aforementioned reports, DBN is conceivably induced by interruption of the neural pathways between the brainstem and the cerebellar flocculus/paraflocculus. There are three main neural pathways conveying important signals about eye movements from the brainstem to the flocculus/paraflocculus, namely, the pathways via the nucleus reticularis tegmenti pontis (NRTP), via the central tegmental tract to the inferior olive, and via the paramedian tract (PMT) neurons. In our case, we speculated that the DBN was most likely caused by damage to the PMT neurons induced by the pons infarction, as follows. PMT neurons, which represent several cell groups of neurons associated with both horizontal and vertical eye movements which project to the flocculus/paraflocculus and vermis, are present in the paramedian region of the lower brainstem; these neurons transmit vestibular information from the anterior semicircular canals to the cerebellum, forming a cerebellum-brainstem feedback loop. Therefore, damage to PMT neurons could cause disruption of this feedback loop, resulting in DBN.

　Motion sickness (MS) is a familiar complaint among scuba divers. We examined the long-term prognoses of scuba divers suffering from MS. We report the case of a 42-year-old woman with repetitive MS. For 2 years, we tested her otolith organ function every month. The otolith organ function of each ear was tested separately via ocular counter rolling (OCR) testing, which was performed under a 30° head tilt. The R-L side asymmetry ratio for OCR values (%OCRA) was compared with the divers' static OCR. In addition, we studied the relationship between the %OCRA and climatic factors, such as sunshine exposure duration, global solar radiation, and the UV index. %OCRA scores differed significantly (p<0.01) between our subject and the volunteer diver without MS. There were sharp fluctuations in the %OCRA of our subject diver with MS. MS was more likely to occur in the summer season, especially when the %OCRA exceeded the cutoff value (45.9). There was a significant correlation between the %OCRA and the UV index. Physiological differences in R-L otolith organ function could be involved in the onset of MS. The amount of UV light exposure and female hormone levels may affect the metabolism of the otolith organ. As MS is caused by multiple factors, otolaryngologists need to consider various causative factors beyond those related to the otolith organ function in scuba divers with MS.

　The purpose of this study was to determine the relationship between the results of the dual-task Timed Up and Go test and the clinical outcomes in patients with chronic dizziness/vertigo.

　A total of 18 patients with dizziness/vertigo were included in the study. The patients were evaluated by the Timed Up and Go test (TUG), dual-task Timed Up and Go test (TUGdt), Dizziness Handicap Inventory (DHI), Activities-Specific Balance Confidence Scale (ABC scale), Dynamic Gait Index (DGI), and Functional Gait Assessment (FGA). The difference between the results of TUG and TUGdt was defined as ΔTUG. We analyzed the correlation between the results of each evaluation using Pearson product-moment correlation and Spearman's rank correlation coefficient.

　Significant correlations were found between the results of TUG-TUGdt, TUG-FGA, TUGdt-ΔTUG, ΔTUG-ABC scale, and DGI-FGA.

　Dual task during gait was found to be related to the self-efficacy in activities of daily living. Dual task during gait could be influenced by psychological factors. TUGdt may be useful to assess the gait performance reflecting psychological aspects.

　Vestibular migraine is a disease characterized by vertigo attacks associated with migraine symptoms such as headache, photosensitivity, and hyperacusis; it has come to be recognized as an important disease in recent years. On the other hand, Meniere's disease is a disease characterized by recurrent vertigo, the dizziness accompanied by cochlear symptoms such as hearing loss or tinnitus. It is often difficult to distinguish between the two conditions, and moreover, some patients suffer from both diseases. Recently, magnetic resonance imaging with intravenous gadolinium injection has been shown to be useful to detect endolymphatic hydrops, the salient pathological feature of Meniere's disease. In the present study, we performed magnetic resonance imaging in patients with Meniere's disease and vestibular migraine, including a total of 128 patients with a definitive diagnosis of Meniere's disease, 9 patients with vestibular-type Meniere's disease, and 19 patients with vestibular migraine. Among the affected ears of patients with a definitive diagnosis of Meniere's disease, 78.1% showed endolymphatic hydrops, while only 5.6% of the ears of patients with the vestibular migraine revealed endolymphatic hydrops. The incidence of endolymphatic hydrops among patients with a definitive diagnosis of Meniere's disease was significantly higher than that in the patients with vestibular migraine (p<0.05, chi-square test). This difference could be helpful in the differential diagnoses of Meniere's disease from vestibular migraine, and therefore, in the selection of the appropriate treatment for patients with the two diseases.

　Evaluation of human postural stability and gait performance is important to prevent falls. We examined postural and gait function to determine the prevalence of fall risk in patients with unilateral vestibular disorder (UVD). Patients with persistent chronic dizziness and postural imbalance/gait disturbance due to UVD, as determined by significant unilateral caloric canal paresis, received tests of standing balance and gait function, including 4-directional (anterior, posterior, left and right) weight-shifting stabilometry for evaluation of postural stability and Functional Gait Assessment (FGA), and the Timed up and go (TUG) and Gait Speed (GS) test for assessment of dynamic gait function.

　The index of postural stability (IPS), the ratio of the range of body movement to the area of body sway as calculated by 4-directional weight-shift stabilometry was used to evaluate the instability of posture and fall risk. The IPS was significantly lower in patients with UVD than in healthy subjects. Increased fall risk, as indicated by an FGA score of less than 22, TUG result of over 11.1 sec or GS of less than 0.85m/sec was detected in 22 (61.1%) of the 36 patients with UVD. Increased fall risk was seen significantly more frequently in patients over 65 years of age than in those under 65 years of age.

　These results suggest that it is essential to conduct a precise evaluation of the postural/gait function and fall risk using balance and gait function tests including the weight shifting stabilometry, FGA, TUG and GS, in elderly patients with UVD, to improve balance performances and prevent falls.