The sensation of rotation derived from the semicircular canal system during a Coriolis stimulus, or cross-coupled rotation, was estimated by an mechanical approach by giving some hypotheses and simplifications on the semicircular canal system. By solving an equation of motion of the endolymph during a Coriolis stimulus with a moderate time course, the rotating angle of the endolymph was obtained, and the sensation of rotation derived from each semicircular canal was estimated. Then, the sensation was integrated in the whole semicircular canal system, which was considered to be composed of three orthogonal semicircular canals. The sensation of rotation derived from the semicircular canal system comes into conflict with those from the otolithic and somatosensory system. The conflict causes an illusion such that the head rotates vertically while keeping inclination at a constant tilt angle. The nauseogenic severity of motion sickness caused by a Coriolis stimulus is enhanced in accordance with the integrated angle of rotation perceived by the illusion.
We reported a case of Paget's disease presenting fluctuating hearing loss together with repeated dizziness and vertigo attacks. Pure tone audiometry in this patient was performed successively during follow-up periods. She visited our hospital 13 years ago with slight low tone sensorineural hearing loss in her left ear. Sensorineural hearing loss in her right ear and sensorineural and conductive hearing loss in left side deterio-rated. Results of her latest examinations were as follows. Glycerol test was positive and inverted reflex was recorded in her right ear. CT showed severe calcification in skull bone and stenos of bilateral internal auditory canal. Endolymphatic hydrops, compres-sion of VIII nerve in internal auditory canal, damage of cochlear hair cell and changes in middle ear conductive system were possible etiology of hearing loss and vertigo. Oral bisphosphonate is used to prevent deterioration of these symptoms. Evaluation of auditory and vestibular function should be continued.
Patients with low tone hearing impairment with repeated vertigo are often diagnosed and treated as Meniere's disease. We reported cases with arterial lesions presenting positional veritcal nystagmus. Case 1 was a 33-year-old woman treated as Meniere's disease because of bilateral low tone hearing impairments and repeating vertigo. She had dysphonia from childhood and a right central retinal artery occlusion. The level of anti-nucleus antibody was significantly elevated. It showed a relation to some autoimmuno vasculitis and vasculitis probably caused the low tone hearing impairment and vertigo. Case 2 was a 50-year-old women who had right deafness and repeated vertigo. However, upbeat nystagmus was presented. Delayed endolymphatic hydrops cannot explain the reason why vertical nystagmus was presented. MRI revealed multiple ischemic lesions for her age. It was related to microangiopathy and she probably suffered from incomplete Susac syndrome. Microangiopathy was probably the pathophysiology in both cases and somewhere occluded the neural pathway of vertical eye movement. It was thought that unsymmetrical stimulation of anterior and posterior semicircular canals decollated the semicircular canal reflex and caused vertical nystagmus.
It has been known that psychological factors are one cause of dizziness. We report a patient with dizziness with specific psychological causes. The patient was a 26-year-old woman who had previously been examined at several hospitals for a complaint of dizziness. A detailed examination at our hospital revealed no organic or functional abnormalities. She participated in group psychotherapy on the supposition that her dizziness had strong psychological causes, but communication with the doctor and other patients was difficult and psychotherapy had no effect. We then introduced a clinical psychotherapist, who said the patient had a borderline personality disorder. The patient become hostile to treatment when administration of drugs either by drip infusion or orally was also ineffective, making further treatment virtually impossible. Mistakes in the care of patients with borderline personality disorders can aggravate the symptoms or even lead to self-mutilation or suicidal behavior. Moreover, commonly used simple psychological tests do not always detect this disorder. Consequently, accurate diagnosis and treatment of borderline personality disorder is difficult for the otorhinolaryngologist. If this disorder is suspected, the best course for the otorhinolar-yngologist is to introduce a specialist in psychiatric diagnosis at an early stage.
The aim of this study is to examine a method to evaluate the center of foot pressure (CFP) during a static upright posture using the following 4 body-sway factors: unit time sway, front-back sway, left-right sway and high frequency band power. Four body-sway factors were interpreted in a previous study by applying factor analysis to a correlation matrix consisting of 32 parameters representing 6 domains of distance, distribution of amplitude, area, velocity, power spectrum, and body sway vector. Data was gathered from 220 healthy young males and females. The CFP measurement for 1 min was carried out twice with 1 min rest. The measurement device was an Anima's stabilometer G5500. The data sampling frequency was 20 Hz. It was confirmed that 4 body-sway factors follow a normal distribution and their reliability is very high (ICC=0.89-0.95). After the distribution of each body-sway factor was divided into 4 domains (0-25% (A), 25-50% (B1), 50-75% (B2), and 75-100% (C)), each domain was subdivided into 4 categories. Boundary domains were made up between A and B (1), B (1) and B (2), and B (2) and C (AB, BB and BC). In analyzing trial-to-trial change for each factor, it was confirmed that 74% of the subjects (F3)-97% (Fl) belonged to the same domain. As a result of expanding the range of AB, BB and BC domains to determine each individual's pattern, 95% or more of the subjects could be placed by their positions on 2 trials. Based on the above-stated domain decision method, as a result of examining the change of body-sway for 20 subjects before and after alcohol intake, 65-75% of the subjects showed a domain change in each factor, and all had a body-sway pattern change. From the above, the convenient evaluation method of body-sway developed in this study was considered to have high reliability and validity, and can synthetically and simply evaluate individual body-sway.
In previous study reports, we conducted a questionnaire-based study of patients with Meniere's disease and workers in the industrial company and found several behavioral characteristics specific to the patient group. To confirm our findings, we used the questionnaire in control groups from two other areas, that is, individuals from a farming district (n=161) and individuals from an office workers' district (n=663), and we compared the results from those with Meniere's disease to the results from the three control groups. As a group, patients showed a significantly strong propensity to immerse themselves in whatever they do, to be perfectionists, to worry before doing something, and to strive to meet superiors' expectations (p<0.005). Between the three control groups, we did not find any significant difference in behavioral characteristics. It seems likely that patients with Meniere's disease possess specific behavioral characteristics that are not influenced by daily environmental factors. We think that stress-re-lated behavioral characteristics may be an important underlying cause of Meniere's disease.
Interferon-a (IFNa) has been recognized to be effective for the treatment of chronic hepatitis B or C. At the same time, it has been reported that IFNa can cause various side effects such as hearing loss, sensory neuropathy, retinopathy, behavioral changes, and so on. Acute vestibular dysfunction without cochlear symptoms has rarely been reported. We encountered two patients who had acute vestibular dysfunction without cochlear symptoms associated with IFNa therapy for chronic hepatitis. A 53-year-old woman was treated daily with 6 million U of IFNa for hepatitis C. On the second day of IFNa treatment she experienced dizziness. She did not have any cochlear symptoms or other neurological symptoms. On examination, she showed bilateral decreased caloric responses. A 32-year-old man was treated daily with 6 milion U of IFNa for hepatitis B. In the third week of IFNa treatment, he experienced spontaneous vertigo without cochlear or any other neurological symptoms. On examination he showed right-beating spontaneous nystagmus and decreased caloric responses on left ear stimulation. After discontinuation of IFNa therapy, caloric responses were recovered in both patients. Although the mechanism of acute vestibular dysfunction associated with IFNa therapy is still unclear, IFNa associated acute vestibular dysfunction might be caused by microvascular problems. We need to be mindful of IFNa associated acute vestibular dysfunction without cochlear symptoms.
We treated 7 cases of Meniere's disease with an oral osmotic diuretic, isosorbide, at a dose of 90 ml per day for more than one year (mean: 31.7 months). One case suffered from bilateral Meniere's disease. The long-term administration of constant daily amounts of isosorbide attained good long-term results in vertigo but poor in hearing according to the criteria of the Japan Society for Equilibrium Research for Meniere's disease. The results were as follows: the administration of isosorbide completely controlled vertigo in 29% and improved it in 42%, however, hearing was unchanged in 71% and worsened in 29%. To see if long-term follow-up of Meniere's patients using electro-cochleogram (ECoG) is useful for determination of therapeutic effects of isosorbide and establishment of its effective medication protocol, we examined relation-ships between long-term results of oral medication of isosorbide and the medication-induced changes in dominant -SP of ECoG. All eight affected ears of seven cases showed dominant -SP at their first visit and half of them didn't show it anymore after the long-term medication. There was no significant relationship between normalization of ECoG findings and improvement of vertigo. These findings indicate that normalization of ECoG findings cannot be a good marker for determination of therapeutic effects of isosorbide or establishment of its effective medication protocol.
Spinocerebellar ataxia (SCA) indicates a group of heterogeneous disorders. In Japan, approximately 60% of SCA cases consist of sporadic disorders, and the rest consist of a variety of dominant disorders. A major disorder of sporadic SCA is multiple system atrophy (MSA). MSA is a progressive neurodegenerative disease, showing parkinsonism and cerebellar, autonomic, urinary, and pyramidal dysfunction in many combinations. A 63-year-old man with short-lived bouts of positional vertigo was pre-sented. He showed no cochlear symptom or abnormal neurological symptoms. And when he was underwent Dix-Hallpike maneuver, direction-changing torsional nystagmus was observed. Initially he was diagnosed as having benign paroxysmal positioning vertigo (BPPV). Canalith repositioning procedure (CRP) improved the patient's condition for a time, but positional vertigo and torsional nystagmus recurred soon after the CRP. An eye-tracking test and an optokinetic pattern test, undergone after 1 month from the onset, showed impaired pursuit eye movement. Drug therapy and CRP was not effective anymore. 13 months after the onset, he complained of dysarthria and rapidly showed autonomic, cerebellar ataxia, pyramidal and urinary dysfunction. Finally, he was diagnosed as having multiple system atrophy. This case indicated that the eye-tracking test and optokinetic pattern test can be useful for the primary symptoms of the initial stage of SCA.