We classified psychogenic dizziness into 3 types, such as the narrow type, the wide type and psychiatric comorbidity. Among these, 69.1% (362/524) of our patients with dizziness were diagnosed as having psychiatric comorbidity, and independently in a German facility, similar number of 68.3% (129/189) of patients with dizziness were diagnosed as having psychiatric comorbidity. Therefore, in our hospital, psychological tests are routinely performed on our patients with dizziness. Patients with dizziness of unknown cause (DUC), otogenic vertigo (OV) and Meniere's disease (MD) exhibited a higher prevalence of psychiatric comorbidity (DUC=73.6%, OV=69.5%, MD=70.1%). Of patients with dizziness and psychiatric comorbidity, various types of psychiatric disorders were found, such as anxiety or panic disorders (F41), mood disorders (F3), adjustment disorders or post-traumatic stress disorders (F43), dissociative disorders (F44), other neurotic disorders, organic mental disorders (F0) and schizophrenia (F2). These patients suffering from dizziness were not only treated by otolaryngologists, but also received psychiatric therapy, and 72.9% of these patients were prescribed psychotropic drugs in our hospital. We believe that psychotropic drugs should be prescribed according to the advice given from psychiatrists or the doctors who are familiar with these drugs. Patients with depression often complain of somatic symptoms. In clinical practice 90% of these patients with depression are in general examined by physicians (non-expert psychiatrists) for their primary medical examination. However, it is not easy to distinguish patients with depression from those with bipolar disorder. Recently, serotonin selective re-uptake inhibitors (SSRI) have been prescribed more frequently by physicians, but caution should be exercised in the treatment of patients with depression when physicians prescribe SSRI because these patients may have bipolarity or mild manic symptoms. To reduce the risk of these incidents of misdiagnosis, physicians are strongly encouraged to consider referring these patients with psychiatric disorders to psychiatrists. We believe that collaboration between psychiatrists and physicians in the hospital and/or local doctors can improve the mental condition and the quality of life (QOL) of patients who are suffering from dizziness with psychiatric comorbidity.
The superior colliculus serves to orient an animal to a target in the opposite visual hemifield. Commissural connections between the bilateral superior colliculi (SCs) are known to help maintain visual fixation and suppress saccades. Sprague (1966) showed that after transection of the commissure between the SCs, cats that had been made blind by prior ablation of the occipitotemporal cortex once again visually oriented to objects in a hemifield. This outcome, called the Sprague effect, suggests that the commissural connection of the SC may play an important role in visual-orienting behavior, and may mediate mutual suppression between the two SCs to prevent competing responses in the opposite direction. Later electrophysiological studies confirmed the inhibitory nature of the commissural tectotectal projection. Our recent study, using intracellular recording combined with electrical stimulation of the SC, showed that tectoreticular neurons (TRNs) in the caudal ‘saccade zone’ mainly received monosynaptic inhibition from the contralateral rostral SC and mono- or disynaptic inhibition from its caudal part, whereas TRNs in the rostral SC received monosynaptic excitation from the contralateral rostral SC, and mono- or disynaptic inhibition from all rostrocaudal levels of the contralateral SC. This review summarizes the characteristic features of commissural inhibition and excitation between the two SCs on various output TRNs terminating on different kinds of interneurons in the horizontal saccade generator in the brainstem of the cat.
With vertigo patients, it is important that we pay attention to vertigo caused by central lesions as there are different diagnoses. Vertigo caused by central lesions such as brain tumors and cerebellar infarction sometimes appear as if the lesions were peripheral ones. The patient in the present study was a 50 y.o. female, with cerebellar metastasis caused by breast cancer and whose chief complaint was positional vertigo at a glance. However, detailed interview, past history, and careful neuro-otological findings based on nystagmus and the results of electric nystagmography led us to diagnose vertigo caused by a central lesion. Subsequent MRI findings revealed a cerebello-pontine angle lesion as a metastatic tumor. The ratio of brain tumors, especially metastatic tumors, among vertigo patients is low. However, this case indicated that MRI might be useful for patients who have a past history of cancer.
The illusion of environmental tilt (tilt illusion) is a rare disorder of visuospatial perception, which suddenly turns through a variable arc, most frequently 90-180°, in either three dimensional planes such as yaw, pitch, and roll planes. This rare phenomenon has been reported to occur with pathologic lesions involving the lateral medullary syndrome (Wallenberg's syndrome) or the transient vertebrobasilar ischemia, less commonly cerebral or cerebellar lesions. To our knowledge, as for the case of such visual illusion with a megadolichovertebrobasilar anomaly (MDVBA), there has been only one case report by Slavin & LoPinto (1987) before. However, the pathophysiology of this rare visual illusion is still unclear. We report herein on three cases of tilt illusion with a MDVBA, who experienced transiently (within a few minutes) visual inversion of 90°in the pitch plane (patient 1), 30° counter-clockwise rotation in the roll plane (patient 2), and 90°clockwise inversion in the roll plane (patient 3), accompanied with vertigo and nausea. In our outpatient clinic, no abnormal findings could be found out in neurological and neuro-otological studies in the present three cases. MRI findings in each case disclosed compression of the lateral medulla by dolichoectatic vessels. Consequently, it was assumed that compression of the lateral medulla by dolichoectatic vessels the transient ischemia resulting in the inactivation of vestibulo-otolith pathways running from the medulla to the supratentorial structures. In our present cases, it was hypothesized that the tilt illusion might result from the sudden and transient spatial misperception in the cortex such as the posterior parietal cortex between the inappropriate vestibulo-otolith input caused by a transient otolithic dysfunction and other intact visual and somatosensory inputs. In conclusion, the tilt illusion appears to be related to mismatch among vestibular, visual and somatosensory inputs. In order to investigate the pathophysiological mechanism of the tilt illusion, further studies are necessary to systematically examine the vestibular, visual and proprioceptive functions in patients who have experienced the tilt illusion.
We have recently encountered five patients with a perilymphatic fistula (PLF) judging from typical episodes at the onset. At the first visit, vestibular symptom and positional nystagmus were observed in two cases. Progressive sensorineural hearing loss was observed in all five patients, in whom expiratory tympanotomy was performed. In only two patients could the fistula be identified with perilymphatic leakage during surgery. We covered both the oval and round windows with temporal fascia and fixed them with fibrin glue in all patients. Hearing was improved by more than 30 dB in four patients (80%) and by more than 20 dB in one patient (20%) according to the criteria of sudden deafness. All the five patients showed good control of vertigo and dizziness after surgery. We should be willing to perform exploratory tympanotomy for patients suspected as having a perilymphatic fistula at the early stage around the onset to improve hearing.
Enlargement of the vestibular aqueduct (EVA) is the most common malformation of the inner ear. EVA can be observed in various disorders including DFNB4/Pendred syndrome, branchio-oto-renal/branchio-oto (BOR/BO) syndrome, and distal renal tubular acidosis (dRTA). Characteristic phenotypes of EVA include progressive, fluctuating hearing loss (HL), and repetitive vertigo. In this study, we compared the audiovestibular findings in patients with mutations of SLC26A4, ATP6V1B1 or SIX1 to clarify whether the anatomical enlargement itself was related to the characteristic phenotypes. We enrolled five Pendred syndrome patients with SLC26A4 mutations, one dRTA patient with ATP6V1B1 mutations and two BO syndrome patients with a SIX1 mutation. One patient with a SIX1 mutation showed unilateral EVA, and the others had bilateral EVA. All five patients with SLC26A4 mutations had progressive HL, fluctuating HL and/or repetitive vertigo. A patient with ATP6V1B1 mutations also showed repetitive progression HL, fluctuating HL and repetitive vertigo. Fluctuating HL and repetitive vertigo were not recognized in two patients with SIX1 mutation, although one patient showed slight progression of HL. There were no significant positive associations in patients with SLC26A4 mutations between EVA widths and pure tone averages, and the widths and maximum slow phase velocities. These findings suggested that EVA itself had no relationship with either progressive, fluctuating HL, nor repetitive vertigo. The product of SLC26A4, the Cl-/HCO3- exchanger pendrin, and the product of the ATP6V1B1, B1-subunit of H+-ATPase, can play a role in the maintainance of endolymph pH homeostasis. Therefore, a disruption of endolymph pH homeostasis can be associated with the characteristic phenotypes.
Perilymphatic fistula are difficult to diagnose, and the associated hearing loss is not easy to treat. In 18 patients with perilymphatic fistula, who visited our department from April 2008 to December 2010 with a confirmed diagnosis by exploratory tympanotomy, 19 ears were retrospectively analyzed from chart review. The purpose of this study was to investigate the clinical findings, treatment efficacies, and the clinical usefulness of the CTP (Cochlin-tomoprotein) detection test for this disease. The primary symptoms were hearing loss, and dizziness or vertigo, which were both observed in over 70% of the patients. Nystagmus was observed in 50% of the patients with vertigo or dizziness, the direction of which varied and exhibited no consistent correlation with the side on which the fistula had occured. The hearing loss recovered in 33%, especially when the operation was performed early after the onset.