Since more than a century ago, rotational testing has been used as a quantitative test for the estimation of canal-oriented vestibulo-ocular-reflex (VOR). Originally, rotational stimuli were induced by manual rotation of a chair, and the eye movements after sudden cessation of rotation were observed and recorded by counting the number of nystagmus and measuring the duration of the rotational sensation. With the development of devices for recording eye movements (including ENG and VOG), VOR and its visual modulation (suppression and enhancement) has been studied more intensively in both the clinical and basic science fields. The frequency range applicable to rotational testing is between 0.01 to 1.5Hz. In this range, both vestibular and visual sensations can be used as signal sources for sensing head movements. Wide frequency rotational testing, in which the subject is rotated sinusoidally at several frequencies using a high torque motor is advantageous in that the VOR dynamics can be quantitatively assessed and even fitted by a numerical model. However, it is time- and space-consuming and also expensive, and has, therefore, failed to become popular in clinical practice. However, measuring VOR and its visual modulation at a single frequency still provides useful information regarding vestibular function and imbalance, and about the lesion site (peripheral or central). Also, recording and analyzing VOR and its visual modulation against manual rotation can be performed within a few minutes in routine vestibular clinical practice. In this paper, the history of rotational testing is reviewed and its future application is discussed.

　A 48-year-old man visited our emergency outpatient on day X with the chief complaint of dizziness from an hour ago. He was sent back home, because examination revealed no neurological deficits, and no abnormalities were detected on head CT or head MRI. The following day, he experienced vertigo and returned to the emergency outpatient again. Head positional testing revealed direction-fixed right beating horizontal nystagmus. He was hospitalized on the same day with suspected peripheral vertigo, and initiated on conservative treatment. Although the vertigo resolved, on day X+5, the patient was found to show left Horner's syndrome, decreased pain (and temperature) sensation on the left side of the face and decreased pain (and temperature) sensation in the right trunk and limbs. Two-point alternating gaze test confirmed undershoot toward the right side, and OKP (optokinetic nystagmus pattern) confirmed poor resolution on the right side. In the caloric test, visual suppression of right beating nystagmus had almost disappeared. We suspected central disease, and repeated the head MRI. MRA revealed left vertebral artery dissection and the patient was transferred to the Stroke Department. Cerebral angiography was performed on day X+10. The pearl and string sign was observed, and the patient was diagnosed as having lateral medullary syndrome due to left vertebral artery dissection. In a patient presenting with vertigo associated with head and neck pain, the possibility of central disease should be borne in mind, even if the patient is young.

　Superior canal dehiscence syndrome (SCDS) was first described by Minor et al. in 1998. Symptoms associated with SCDS include conductive hearing loss and vertiginous symptoms in the setting of loud noises (Tullio phenomenon) or during the Valsalva maneuver. The condition is caused by a bony defect in the roof of the superior semicircular canal. We encountered the case of a 46-year-old male patient with SCDS who presented with pressure- and loud sound-induced vertigo. The patient was diagnosed as having SCDS based on pressure- and sound-induced occurrence of nystagmus confirmed by video-oculography (VOG). We also investigated the prevalence of superior semicircular canal dehiscence at our hospital using our CT scan database. The roof of the superior semicircular canal was classified into three types, normal, thin bony roof, and bony defect. Out of 1003 ears, 897 ears (89.4%) were normal, 77 ears (7.7%) had a thin bony roof, and 29 ears (2.9%) showed a bony defect in the roof of the superior semicircular canal. Out of 25 patients (29 ears) with a bony defect, only one patient was diagnosed as having SCDS.

　Objective: The purpose of this study was to investigate the incidence of endolymphatic hydrops (EH) and the clinical features in patients with atypical Ménière's disease (aMD), by 3-T gadolinium-enhanced magnetic resonance imaging (MRI).

　Methods: Thirty-three patients who were diagnosed as having aMD participated in this study. Out of the 33 patients, 23 were classified as having cochlear MD (CMD) and the remaining 10 as having vestibular MD (VMD). 3-T MRI was performed 24 hours after intratympanic injection of gadolinium in 24 patients, and 4 hours after intravenous injection of gadolinium in the remaining 9 patients. We investigated the prevalence rate of EH, the relationship between detection of EH and the duration of illness, and the transition rate to classical MD in the study participants. In addition, in the CMD group, the degree of hearing fluctuation was also evaluated.

　Results and Conclusions: The incidence of EH was 78.3% (18/23) in the CMD group and 40% (4/10) in the VMD group. There was no significant difference in the prevalence of EH in relation to the duration of illness between the two groups. The degree of hearing fluctuation in the patient group with CMD was slightly greater in the patients with EH than in those without EH. It was assumed that patients with other diseases causing episodic vertigo were diagnosed could be misdiagnosed as having VMD, and that 3-T MRI with gadolinium injection could be a good diagnostic tool for confirming the presence of EH.

　Dizziness can arise from diverse causes. According to reports, 20%-80% of patients presenting with vertigo have psychogenic vertigo. Diagnosis of psychogenic vertigo is not always easy. Until date, there is no objective examination tool for the diagnosis of psychogenic vertigo. Therefore, it is important for physicians to evaluate patients presenting with vertigo both physically and psychologically in order to make a definitive diagnosis of psychogenic vertigo. Posturography is the conventional method for evaluating the postural perturbation in patients with vertigo or dizziness, and there are many ways of analyzing the results of posturography. One such method is with the use of the “gravichart,” and a characteristic finding in patients with psychogenic vertigo is a teardrop-shaped “gravichart.” However, the detailed characteristics of patients showing the teardrop-type “gravichart” are still unknown. In this study, we attempted to identify the clinical importance of the teardrop-shaped “gravichart” in patients with psychogenic vertigo. While many patients with a teardrop-shaped “gravichart” are diagnosed as having psychogenic vertigo, not all patients with psychogenic vertigo show a teardrop-shaped “gravichart”. Thus, while a teardrop-shaped “gravichart” may be useful for the diagnosis of psychogenic vertigo, it is necessary to clarify what types of patients with psychogenic vertigo show a teardrop-shaped “gravichart” in a future study.

　Vertigo and headache are both common symptoms and could coexist. Vestibular migraine (VM) is characterized by recurrent attacks of vertigo with concomitant headache fulfilling the diagnostic criteria for migraine. It is important to distinguish VM from Meniere's disease (MD), because the symptoms are similar, but MD often also coexists with VM. The term “VM/MD overlap syndrome” has been suggested for cases in which different types of vertigo attributable to VM and MD coexist. Delayed endolymphatic hydrops (DEH) is a clinical entity characterized by recurrent vertigo developing years to decades after the onset of severe sensorineural hearing loss; the pathology is similar to that of MD. We encountered a case suspected overlap of VM and DEH.

　A 65-year-old male patient with a history of onset of sudden hearing loss in the right ear 15 years earlier visited us with complaints of recurrent vertigo and headache. He was diagnosed as having VM; his “dizziness and headache diary” revealed simultaneous onset of migraine-like headache and vertigo. He was also diagnosed as having ipsilateral DEH, because both the vertigo and headache resolved with isosorbide; lomerizine hydrochloride, used previously, improved, but did not resolve the symptoms.

　We diagnosed this patient as a case of suspected overlap of VM and DEH, based on the coexistence of the signs and symptoms of VM and DEH. This is the first report of a case of overlap of VM and DEH; a relationship appears to exist between VM and not only MD, but also DEH.

　Background: Recent advances in the techniques of MRI have enabled us to visualize and measure the endolymphatic spaces in the inner ear, leading to a new paradigm for the diagnosis of Meniere's disease and other inner ear disorders. For proper interpretation of inner-ear MRI, otolaryngologists and radiologists need to have a precise understanding of the three-dimensional (3D) configuration of each compartment in the membranous labyrinth. However, resources for learning the complex anatomy of the bony and membranous labyrinth have been remained limited to histological sections. The aim of the present study was to provide serial images as reference information for a more precise interpretation of inner-ear MRI.

　Methods: We used 3D model data, that are freely available, of a healthy human inner ear, including the cochlear duct, the saccule, the utricle, the three semicircular canals, and the bony labyrinth, generated by micro-computed tomographic scanning. The 3D model was converted into serial images on the axial plane using a computational approach. The endolymphatic and perilymphatic spaces are shown in black and gray, respectively. The area ratio of the endolymphatic space to the sum of the endolymphatic and perilymphatic spaces in the vestibule was calculated for each section.

　Results: Serial cross-sectional images similar to delayed intravenous contrast-enhanced MRI in the normal ear were obtained. The images clearly illustrate the anatomical orientation of the cochlear duct, the saccule, the utricle, and the ampullae and duct of the semicircular canals. The calculated area ratio of the endolymphatic space in the vestibule was up to 61%.

　Conclusion: These serial images can be a powerful educational resource for understanding the relationship of the 3D anatomy of the endolymphatic spaces and the 2D morphology seen in inner-ear MRI.