Abstract: “Foulage test”. Subjects step on the center of a stabilometer, keeping both toes constantly in contact with the plate, and lifting up only the heels alternately. Subjects had to accurately keep up a tempo of 120 beats per minute (BPM 120) as set by an electric metronome. The examination time was 60 seconds, 120 steps, with eyes open and closed. Sixteen healthy volunteers (8 men, 8 women, 24 to 55 years old, mean 36 years old) were tested with their eyes in the open and closed condition, changing the height of heels, from lower than 1 cm to almost 12 cm. 12 subjects were tested 5 times, 3 subjects were tested 6 times and also one volunteer, a 45-year-old healthy man, performed the test 16 times to get fine data. As the heels rose up, the locus was enlarged side to side and bent at the center like an inverted ‘V’ shape (Λ). The locus length was enlarged as the heels were raised higher, believed to reflect the activity of the subject. On the other hand the width of the locus band, front to back, was almost the same under conditions of stepping stably. However, if the subject swayed, this distance might increase. The total locus length (L) and the environed area (A) were investigated. The long length of the locus “Λ” shaped band was nearly the distance of one step. The subjects were stepping 120 times, therefore 原 著

Abstract: Cochlear implants (CIs) are associated with a potential risk for vestibular system insult or stimulation with resultant dysfunction. Twenty-six patients underwent equilibrium tests before undergoing CI surgery at our institute. As part of the equilibrium tests, a caloric test, static posturography, observation of nystagmus using an infrared CCD camera, and measurement of the vestibular-evoked myogenic potential (VEMP) were performed. Half of the patients (13 out of 26 patients) complained of vertigo or dizziness after the operation. In most patients (12 out of 13 patients), these symptoms occurred immediately after the operation and disappeared within one week. Patients who did not complain of vertigo or dizziness after the CI surgery had a statistically significant lower response for the caloric testing than the patients who experienced these symptoms. No significant differences in the static posturography, nystagmus and VEMP test results were seen between the group of patients who did not complain of vertigo or dizziness after the CI surgery and the group of patients who experienced these symptoms. This result suggests that the patients with normal peripheral vestibular functions preoperatively had a greater tendency to complain of vertigo or dizziness after the operation. The cause of postoperative vertigo or dizziness was judged to be due to the peripheral vestibular function before surgery. It is important for CI candidates to undergo equilibrium tests preoperatively as means of predicting postoperative vertigo or dizziness.

Abstract: 「めまい」は日常診療においてどの診療科でも 経験されるありふれた症状であるが,患者ごとに その意味する内容はさまざまである。ここではそ の詳細に立ち入らないがおおまかに区別すると, 1回転性めまい(vertigo),2ふらつき,浮動感 と表現される非回転性めまい(dizziness,disequilibrium),3失神様発作(presyncopal lightheadedness)となる。脳血管障害ないし循環不全によ り生じるめまいは主に前二者であるが,3は全般 性の脳循環障害による可能性の高い症状である。 すなわち,起立性低血圧や過呼吸症候群,種々の 不整脈などによることが多く,心血管系や自律神 経疾患などの精査が必要である。なお,中高年以 上でみられる原因の特定困難な慢性めまいも日常 臨床ではよく遭遇するが,われわれの検討によれ ば脳磁図によっててんかん様の異常の得られる症 例がその中に存在することが明らかとなった。た だし本稿の主旨とは異なるため詳細は別紙に 譲る。 一般に1は末梢から中枢まで含めた前庭機能障 害による症状であり,2はその他に四肢の位置覚 などの感覚系,自律神経系,さらには運動障害に よる立位時や歩行時に不安定感を含む症状であ る。これらには循環障害,炎症や腫瘍など種々の 病態による内耳前庭系疾患から小脳脳幹を主とす る中枢神経系疾患が関与すると考えられる。前者 は末梢性めまい,後者は中枢性めまいと呼称され るが,存外臨床的な鑑別は困難なことが多い。し かも緊急時には十分な診察ができないこともあり シリーズ教育講座「めまいに対する学際的アプローチ」

Abstract: This study was designed to investigate bone mineral density in patients with idiopathic BPPV to determine whether there is a clinical association between etiologically unknown (idiopathic) BPPV and osteoporosis. Dual energy X-ray absorptiometry was used to measure the bone mineral density (BMD) at lumbar vertebrae L2L4 in menopausal women over the age of 50 years who had been diagnosed as having idiopathic BPPV. A BMD value of less than 70% of the young adult mean (YAM) was regarded as indicating the presence of osteoporosis. The overall prevalence of osteoporosis in patients with BPPV was 27.5%, which was almost the same as that in a previously reported national survey. However, the rate of concurrent osteoporosis was higher among patients with recurrent BPPV (38.9%) than among those with non-recurrent BPPV (21.2%). Subjects with recurrent BPPV had a lower BMD (72.4% of the YAM) than those with non-recurrent BPPV. Subjects with multiple occurrences had an even lower BMD (69.4% of the YAM) and were classified as having osteoporosis. Thus, BPPV and osteoporosis may have similar pathogenetic mechanisms associated with calcium metabolism in both otoconia and bone. These results suggest that idiopathic BPPV with osteoporosis may be capable of recurring.

Abstract: There is little definitive evidence of the clinical significance of the vestibularcardiovascular reflex in humans, despite the fact that the vestibular system is known to contribute to cardiovascular control in animals. Our first finding in this paper was that about 10% of 1479 dizzy patients in our hospital met the criteria for orthostatic hypotension (OH) set by the American Autonomic Society (2011). Second, a positive rate of the criteria for the OH was significantly higher in patients with abnormal subjective visual vertical (SVV) than patients with normal SVV, however abnormality of canal function did not affect the positive rate of the OH. Third, we classified 248 dizzy patients aged<65 into three groups based on their vestibular evoked myogenic potential (VEMP) responses; absent VEMP, asymmetry VEMP and normal VEMP. In order to investigate the effect of the otolith disorder, which was estimated by the VEMP, on the orthostatic blood pressure responses, the subjects’ systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate were monitored during the orthostatic test after standing up. The male patients in the absent VEMP group presented a significant drop in their DBP at 1 min. after standing up (p<0.05) without any change in SBP. In the entire group of participants, a total of 19.6% of the patients in the absent VEMP group fulfilled the criteria for orthostatic hypotension (OH), which was significantly larger than the 8.6% of patients in the normal VEMP group and the 7.2% in the asymmetry VEMP group (P<0.05). Our results suggest that vestibular disorders due to the dysfunction of otolith organs provoke OH.

Abstract: 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 (F 41), mood disorders (F 3), adjustment disorders or posttraumatic stress disorders (F 43), dissociative disorders (F 44), other neurotic disorders, organic mental disorders (F 0) and schizophrenia (F 2). 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. シリーズ教育講座「難治性めまいへのアプローチ」

Abstract: There have been several reports about the relation between acid-base imbalance or arterial blood gas abnormalities and the occurrence of vertigo, including Meniere’ disease. In animal experiments, respiratory acidosis induced by CO2 inhalation or metabolic acidosis induced by injection of NH4Cl has been shown to cause attacks of vertigo in rabbits with hemilabyrinthectomy. In clinical studies, approximately half of the patients with dizziness have arterial blood gas abnormalities when their dizziness occurs. An increase of HCO3is found in many patients with dizziness, and the frequency of attacks is higher in patients who have arterial blood gas abnormalities during the remission period. These patients are thought to have unilateral vestibular dysfunction, and it is suggested that arterial blood gas abnormalities cause temporary vestibular dehabituation that increases the frequency of dizziness. It has also been reported from a study that the middle ear pressure difference between both ears, which is larger during periods of dizziness or recurrent dizziness than at the time of remission, might be related to blood gas abnormalities in Meniere’s disease. In the same study, a difference of more than 50 decapascals was significantly more common in the patient group with blood gas abnormalities. In addition, metabolic acidosis has been reported in patients with Meniere’s disease, and the base excess and bicarbonate levels were also found to be beyond the normal range in Meniere’s disease. Arterial blood gas abnormalities might develop for various reasons, including underlying diseases and middle ear pressure differences. The endolymph in the endolymphatic sac is acidic (pH 6.6―7). It has been reported that carbonic anhydrase, vacuolar H-ATPase, pendrin and aquaporin may participate in the acidification process or homeostasis. The role of acid-base disturbance or arterial blood gas abnormalities in dizziness, and the relation in acid-base balance between inner ear and arterial blood gas need to be investigated further.

Abstract: メニエール病に対しては薬物療法を中心に,理 学療法,心理療法,生活指導などの治療が通常な されるが,このような保存的治療に抵抗を示し, めまい発作が頻発して日常および社会生活の活動 に支障をきたす場合には手術療法が考慮される。 手術療法には内リンパ嚢開放術が内耳機能を温存 できることから第1選択として行われることが多 い。また,近年ではゲンタマイシン鼓室内注入 法も普及してきている。しかし,それでも再発を きたし,患者の QOLが著しく低下する場合に は,迷路破壊術,前庭神経切断術などが最終手段 として検討される。これら破壊的な手術は,め まい発作をほぼ確実に消失させることができる が,前庭機能の伝達を廃絶させることから,代償 されるまでの期間,ふらつきや体平衡障害に悩ま されることも多い。さらに前者では聴力を損失さ せ,後者は手術侵襲のため頭蓋内合併症の問題も 有する。最近,回転性めまいを改善させる目的で 半規管を遮断する治療がメニエール病に対して試 みられている。従来,半規管遮断術は,難治 性の BPPVや上半規管裂隙症候群において,当 該半規管のリンパ流動に起因するめまいの抑止に 有効な手術法として知られている。本稿では, メニエール病に対する本治療の概念や方法,有効 性などについての最近の知見を述べる。 2.概念と適応 半規管遮断術は,半規管内のリンパ流動を阻害 してクプラを不動化させることにより,半規管由 来のめまいを防止する概念に基づいて行われる。 BPPVや上半規管裂隙症候群において有効性が確 かめられており,低破壊的な対症治療法として位 置づけられている。同手法をメニエール病に適 用する場合には,半規管に起因する回転性めまい 発作を抑制することが主な目的となり,蝸牛機能 の改善や聴力悪化の防止には期待できない。 難聴が進行し,水平・回旋成分の強い眼振に回転 性めまいを強く訴え,日常・社会生活に大きな支 障をきたしている症例に対してよい適応と考えら れる。破壊的な手術を行う前の段階で考慮するの に有用なオプションと思われる。 3.治療効果の機序 メニエール病めまい発作の発症機序については 完全には明らかになっていないが,内リンパ圧上 昇説と膜迷路・ライスネル膜破裂説が現在の ところ有力である。前者では内リンパ水腫による 内リンパ圧の上昇に伴って膨大部クプラの変位が 生じて,めまいが発生すると考えられている。一 方,後者では膜迷路やライスネル膜の破裂で,ナ トリウム濃度の高い外リンパとカリウムイオン濃 度の高い内リンパが混ざり合うことにより,感覚 細胞や前庭神経の活動性が亢進して発作が生じる とされている。メニエール病において半規管を遮 断すると,圧上昇によるリンパ流動や膜破裂で混 トピックス

Abstract: We examined the cerebral blood flow in 6 patients with acute stage vestibular neuritis using single photon emission computed tomography (SPECT). SPECT images of cerebral blood flow were analyzed using an easy Z-score imaging system (eZIS), a method for statistical image analysis. The analysis results showed cerebral blood flow to be increased in the parieto-insular vestibular cortex (PIVC) contralateral to the affected side, whereas blood flow was decreased bilaterally in the visual cortex and Brodmann area 40 (BA 40). These results were identical to those obtained in patients with acute stage vestibular neuritis using PET by Bense et al. However, in our present analysis, increased cerebral blood flow was occasionally not detected in PIVC, rendering some cases unevaluable. Blood flow lowering in BA 40 tended to be predominantly left hemispheric, regardless of the diseased side. Although SPECT is considered to be inferior to PET in spatial resolution and quantifiability, we found that cerebral blood flow in patients with acute stage vestibular neuritis can be sufficiently evaluated using eZIS analysis.

Abstract: Background: The relationship of visual vestibular interaction with congenitally visual and hearing impairment in children has been discussed. The cochlear and vestibular organs are closely related anatomically and phylogenetically. Many studies have revealed the abnormal vestibular function and delayed motor development in the cases of severely hearing impaired children. Bilateral vestibular dysfunction may be manifested as the loss of postural control and the delay of development in gross motor function. In addition, congenitally blind children manifest delayed motor development due to the difficulties in space perception. Methods: The vestibular functions and gross motor development were assessed in 4 congenitally deafblind children. Of the 4 cases, one patient had congenital rubella syndrome and one had CHARGE syndrome. In all patients there was severe hearing loss with severe visual impairment. Results: Motor development in all cases was significantly delayed. None of the patients could stand up and walk by themselves until they were at least 2 years and 4 months old. The results of the rotational chair test in two patients showed no response. Conclusions: Because of loss of visual vestibular interaction, the gross motor development in all severe congenital deafblind cases was found to be delayed further than that in the cases with only congenital hearing impairment. Careful treatment and planning for rehabilitation or placement of a cochlear implant in deafblind children is needed to improve their quality of life.

Abstract: This study evaluated the effect of thyrotropin-releasing hormone (TRH) therapy on standing disabilities in 6 patients with spinocellular degeneration (SCD). Each patient was examined using a stabilometer before and after TRH treatment consisting of daily intravenous TRH injections for 2 weeks. The stabilography was performed while the patient's eyes were open and closed and while the patient stood with both feet together for 60 seconds. The total length, envelope area, length/area, length/time, area of root mean square (RMS) and area of rectangle were measured. A decrease in the area of the RMS after TRH treatment, compared with the baseline value, was statistically confirmed in all 6 patients. A stabilographical examination was also performed twice at an interval of 2 weeks in 6 normal subjects, but no significant differences in any of the parameters were detected between the first and second examinations. TRH therapy was assumed to be effective for the treatment of standing disabilities in patients with SCD, since the decrease in the value of the area after treatment appeared to result not from habituation, but from the effect of the therapy.

Abstract: The control of extraocular and neck movements relies on the information from the vestibular organs. The brainstem and cerebellum are in charge of these processes. Further, the higher-order processing of vestibular information is mediated by the posterolateral part of the thalamus (“vestibular thalamus”), which in turn projects to multiple cortical areas including the parieto-insular vestibular cortex and thus constitutes the “thalamocortical vestibular system”. Recent advances in neuroimaging techniques have enabled researchers to visualize brain activity changes in the thalamo-cortical vestibular system in response to unilateral vestibular perturbation by means of electric or caloric stimulation. Clinically, neuroimging studies on peripheral vestibular disorders have shown abnormal responses of the thalamo-cortical vestibular system to vestibular perturbation. Studies have also revealed anatomo-functional reorganization of non-vestibular cortical areas (such as visual or somatosensory cortices) in peripheral vestibular disorders. Moreover, such reorganization may be correlated with functional recovery after peripheral vestibular disorders. Studies on cerebrovascular disorders involving the vestibular thalamus support the importance of this area for controlling posture. These imaging studies have begun to cast light on the otherwise unknown pathophysiology and compensatory mechanisms of vestibular disorders, although many issues still remain to be answered.