Diagnostic advantages of the torok monothermal differential caloric test

In the Torok monothermal differential caloric test, each ear is irrigated with 10 ml and 100 ml of water at 20$$ C in 5 and 20 sec, respectively. The intensity of the induced nystagmus is expressed in terms of frequency at culmination. The ratio between the weak and strong caloric responses may be normal or disproportionately large or small. When large, the ratio exceeds 3.5 and is called vestibular recruitment, a sign of labyrinthine disease. A ratio of 1.1 or less is called vestibular decruitment, a sign indicative of posterior fossa abnormality. Of 54 patients showing decruitment, a central lesion was confirmed in 51, an identification rate of 94%. The test is thus valuable in differentiating labyrinthine from retrolabyrinthine lesions.     

Monothermal differential caloric testing in patients with Meniere's disease

The monothermal differential caloric test allows determination of vestibular recruitment and de-cruitment, variables which may help discriminate peripheral from central vestibular lesions. Previous reports indicated a strong association between vestibular recruitment and Meniere's disease. This study examined patients having unilateral Meniere's disease. Nystagmus beat frequency (NBF) and slow-component velocity (SCV) responses were recorded by electronystagmography (ENG). Electronystagmo-graphic findings showing unilateral dysfunction were present in 54% of patients by slow-component velocity and in 31% by nystagmus beat frequency. Unilateral hypofunction was the most frequent lat-eralizing ENG finding. Absolute vestibular recruitment occurred in less than 10% of patients but relative recruitment was found in nearly 20% of patients. Slow-component velocity had higher sensitivity than nystagmus beat frequency, with excellent clinical concordance. Monothermal caloric testing as described in this study best detects peripheral vestibular disease in Meniere's patients using slow-component velocity to determine unilateral hypofunction and relative vestibular recruitment.     

Pitfalls in detecting vestibular decruitment with air calorics.

Vestibular decruitment is a pathological finding which indicates retrolabyrinthine disease. In the overwhelming majority of cases, it is consistent with posterior fossa pathology. Weak and strong caloric stimulations must be applied with precision for detecting decruitment. Air-caloric stimulation has inherent limitation in regards to reproducing the strength of the stimulus. Thus, it is inadequate for decruitment detection. It is, therefore, advisable to use water-caloric testing to assess vestibular decruitment or recruitment as one of the most revealing diagnostic clues in our neurotologic armamentarium.     

Preoperative vestibular diagnosis in therapy of Menière's disease]

Surgical treatment of Meniere's disease is indicated in patients with severe attacks who have failed drug therapy. A decision between a conservative or destructive procedure demands firstly exclusion of patients with non-otogenic diseases, bilateral disease or complete unilateral loss of function, and secondly assessment of the laterality of the disease, of residual labyrinthic function and of vestibular compensation. A total of 185 patients with Meniere's disease were investigated. All of them had a history and clinical signs that indicated surgery. Canal function, otolith responses and vestibular compensation were examined, in addition to routine preoperative tests as recommended by the Committee on Hearing and Equilibrium of the American Academy of Ophthalmology and Otolaryngology. Of the 185 patients 22% had findings that contraindicated surgery, 4% suffered from Meniere's disease in the opposite ear, 6% showed no signs of vestibular compensation and 12% had dead labyrinths on the side of the cochlear disease. No caloric response was elicited from the labyrinth by thermal bilateral testing in 25% of the 185 patients. In patients who were thought to have dead labyrinths based on routine caloric tests, residual canal function was detected by means of 20 degrees C stimulation in the prone and supine position. Without extensive vestibular testing the indications for surgical treatment of Meniere's disease will be incorrect in 47% of patients.     

Vestibular decruitment. A study of the phenomenon in a normal population.

Vestibular decruitment is a phenomenon characterized by the presence of less intense responses following stronger vestibular stimulation, and its presence has been considered as indicative of central vestibular pathology. In this study conducted in 24 normal individuals, with normal caloric responses, decruitment was observed in 58.3% of the cases. These decruitments were of types I and II as defined by Torok. Type III decruitment was not seen in these patients. In view of the present findings the actual meaning of the phenomenon must be investigated in larger numbers of patients with peripheral or central vestibular disorders.     

Role of electrocochleography in identification of labyrinthine hydrops

We studied potentialities of extratympanic electrocochleography (ETECG) in detection of labyrinthine hydrops (LH) in 50 patients who had an audiological picture of unilateral neurosensory hypoacusis. The patients were divided into two groups: group 1 patients suffered from attacks of systemic vertigo typical for Meniere's disease; group 2 patients had no vestibular complaints. ETECG results were compared to the dynamic range, results of otoacoustic emission and brain stem response, vestibulometry with electronystagmography (data of bithermal caloric test as most informative). The comparison indicated advantages of ETECG used alone and in combination with other tests.     

Retrolabyrinthine vestibular nerve section: efficacy in disorders other than Menière's disease

The retrolabyrinthine vestibular nerve section has evolved as an effective treatment for intractable vertigo of peripheral vestibular origin when hearing preservation is desired. This report studies the efficacy of retrolabyrinthine vestibular nerve section for control of vertigo due to causes other than Meniere's disease. This report details our experience with 42 patients with a wide variety of diagnoses. The reduced success rate of retrolabyrinthine vestibular nerve section in these patients is difficult to evaluate, as very few patients have been analyzed with respect to their specific diagnoses. Of patients who underwent retrolabyrinthine vestibular nerve section for control of vertigo, 23 patients had uncompensated vestibular neuritis and 19 others had a wide range of other diagnoses. For patients with uncompensated vestibular neuritis (n = 23), the physician record noted that 39% of patients were cured and 30% improved. This compares to our series of patients with Meniere's disease (n = 48), where 94% were cured and 2% improved. The true vestibular abnormality may be less reliably identified in patients with uncompensated vestibular neuritis, contributing to the less effective results. Since the development of a vestibular rehabilitation program, retrolabyrinthine vestibular nerve section for uncompensated vestibular neuritis has been all but abandoned. Retrolabyrinthine vestibular nerve section appears to achieve a high cure rate in patients with sensorineural hearing loss associated with their vestibular abnormalities. While retrolabyrinthine vestibular nerve section is helpful for control of vertigo in some diagnoses, a substantial incidence of persistent postoperative dysequilibrium was noted.     

Intentional ablation of vestibular function using commercially available topical gentamicin-betamethasone eardrops in patients with Meniere's disease: further evidence for topical eardrop ototoxicity

OBJECTIVE: To determine whether the controversial findings of suspected ototoxicity from commercially available gentamicin sulfate and betamethasone sodium phosphate eardrops can be used in a therapeutic fashion to ablate (or attenuate) vestibular function in patients with unilateral Meniere's disease. STUDY DESIGN: Prospective case review. METHODS: At a tertiary care dizziness unit at the University Health Network, Toronto General Hospital, University of Toronto (Toronto, Ontario, Canada), adults with unilateral Meniere's disease undergoing intratympanic ablation therapy were studied. After insertion of a tympanostomy tube with the patient under local anesthesia, patients instilled gentamicin containing eardrops three times daily until they became vertiginous for longer than 24 hours and then for an additional 2 days longer or for 1 month, whichever came first. Electronystagmographic caloric test responses were measured before treatment using bithermal water caloric and after treatment using air caloric tests. Main outcome measures included clinical titration of drops to the onset of prolonged vertigo. As well, post-treatment findings on electronystagmography and audiometry were compared with pretreatment testing. RESULTS: Twenty patients were available for review. Fifteen patients had a significant reduction in caloric test responses compared with pretreatment values; among them, 10 patients had absent air caloric test responses on the treated side. In 10 patients hearing worsened according to the 1995 American Academy of Otolaryngology-Head and Neck Surgery Committee on Hearing and Equilibrium Guidelines for reporting in Meniere's disease. CONCLUSIONS: Topical gentamicin-betamethasone eardrops can pass through a tube into the middle ear, where they may prove primarily vestibulo-ototoxic patients with Meniere's disease. The study further confirms clinical observations that gentamicin-containing eardrops might prove ototoxic, especially in noninflamed ears with a tympanic membrane defect.     

Retrolabyrinthine vestibular nerve section: analysis of results

The retrolabyrinthine section of the vestibular nerve is an effective procedure for the ablation of unilateral vestibular function while preserving hearing. Although this procedure has been most frequently used for the control of unilateral Meniere's disease, it may also be effective in the control of unilateral vestibular dysfunction of other etiologies. A 2-year experience with the indications for and the surgical results in a series of patients who underwent this procedure is presented. Brief case histories of a variety of etiologies of unilateral vestibular dysfunction are discussed.     

Retrolabyrinthine vestibular neurectomy: a reevaluation

Selective vestibular neurectomy is considered an effective means of relieving intractable vertigo while preserving hearing. In order to determine the effectiveness of the retrolabyrinthine approach to selective vestibular neurectomy, we evaluated 161 patients who underwent vestibular neurectomy between April 1981 and September 1985. Questionnaire responses indicated that 97% of the Meniere's disease patients and 68% of the non-Meniere's disease patients experienced a substantial improvement or resolution of their vertiginous symptoms. Hearing was maintained within 10 dB of the preoperative level in the majority of the patients. Neurological complications were limited to 2 cases of meningitis which resolved with medical therapy, 7 cases of cerebral spinal fluid leaks, and 3 cases of complete sensorineural hearing loss. Based on this review, we concluded that retrolabyrinthine vestibular neurectomy continues to be a safe and effective approach to relieve ear-related vertigo.     

Monothermal air caloric test in children.

We compared the efficacy of bithermal (BAT) and monothermal cold (MCAT) and warm (MWAT) air caloric tests in identifying labyrinthine function anomalies in the child. At first, we established confidence intervals of normality for both monothermal tests in 40 children (22 males, 18 females) aged 6-14 years, clinically healthy and normal as previously shown by BAT. Subsequently, we compared the results of BAT with those of MCAT and MWAT performed in 46 children (22 males, 24 females) aged 6-14 years, affected by multiple labyrinthine diseases. These results confirmed that, as in the adult, MCAT alone should not be used in the evaluation of labyrinthine function in vertiginous patients. As to MWAT, we obtained good sensitivity and specificity with respect to BAT (83% and 90% for 90% probability; 78% and 92.5% for 95% probability). Sensitivity values increased or decreased depending on the disease causing vertiginous symptoms, with decreased or increased number of false negatives. In our opinion, MWAT cannot replace BAT for the study of labyrinthine function in children. MWAT alone can be used when vertigo is ascribable to vestibular neuritis or to endogenous disease (dysmetabolic, dyscrasic, dysendocrine).     

Does intratympanic gentamicin treatment for Meniere's disease cause complete vestibular ablation?

OBJECTIVE: To determine changes in vestibular function following intratympanic gentamicin (ITG) treatment for Meniere's disease and to correlate changes with the need for further treatment. STUDY DESIGN: Prospective case series. PATIENTS: One hundred and three patients with disabling unilateral Meniere's disease who had failed a minimum of 6 months medical treatment. MAIN OUTCOME MEASURES: Vestibular function was measured by electronystagmography (ENG) caloric testing before and serially following treatment. Caloric responses were classified as normal (excitability difference [ED] < 25%), bithermal response (ED > or = 25%), positive response to ice water only, and absent ice water response. RESULTS: Twenty-one percent of patients had a bithermal caloric response, 62% had an absent ice water response, and 17% had an ice water response only 1 month following treatment. Mean follow-up was 27.3 months (range = 1-106 months). Eighty-four patients had one treatment course only. Fourteen patients required a further course of treatment due to recurrence of vertigo; 38% of these had recovery of caloric function. Significantly more patients with normal caloric function prior to initial treatment required further treatment compared to those with initial reduced caloric function (p < .05). Patients rendered absent ice water responsive were significantly less likely to require further treatment than those with a persistent caloric response (p < .0001). CONCLUSION: An absent ice water response is highly predictive of adequate vertigo control. Regimens of ITG that aim to completely ablate vestibular function are recommended.     

Insights on different analysis techniques in the monothermal and bithermal caloric test – which parameter should we use to quantify vestibular function?

Objective: To investigate the use of maximum slow component velocity (MSCV) and time-constant duration (TC_d) of elicited nystagmus in quantifying the caloric response and to assess the efficacy of these parameters in the monothermal screening test. Design: Retrospective analysis of caloric results obtained from 150 patients. Bithermal unilateral weakness (UW), directional preponderance (DP), monothermal caloric asymmetry (MCA) based on warm or cool irrigations only, were calculated using both MSCV and TC_d. Study sample: 66 males and 84 females, aged 16–88 years (μ?=?50, σ?=?17), who underwent vestibular assessment. Results: The correlation-coefficient between bithermal caloric unilateral weaknesses calculated using either MSCV or TC_d is 0.155 (p?d and setting significant MCA at 5%, the sensitivity and specificity were respectively 90% and 77% for monothermal warm and 100% and 74% for monothermal cool tests. Conclusions: In the monothermal warm caloric test, MSCV can be used more reliably than monothermal cool to predict normal bithermal caloric response. The reverse is true if using TC_d. Unilateral-weakness calculated using TC_d and MSCV were poorly correlated and therefore likely to be demonstrating different aspects of vestibular function.     

前庭单温试验的筛选价值分析

目的:探讨单温试验筛选价值及评估前庭功能的可靠性.方法:1406例眩晕患者分2组进行冷热试验.先冷后热组705例.先热后冷组701例.2组的先冷和先热刺激分别作为单冷、单热试验,计算单温试验单侧前庭反应减退及冷热试验、眼震优势偏向(DP),以冷热试验结果为对照标准.计箅单温试验的灵敏度、特异度、止确诊断指数和Kappa值等.结果:先冷后热组:冷热和单冷试验均阳性428例.均阴性145例,单独阳性分别为85例、47例,单冷试验灵敏度为83.4%,特异度为75.5%.正确诊断指数为0.589,Kappa值为0.555(P<0.01).先热后冷组:冷热和单热试验均阳性429例,均阴性130例,单独阳性分别为82例、60例,单热试验灵敏度为84.0%.特异度为68.4%,上E确诊断指数为0.524,Kappa值为0.505(P<0.01).排除伴有自发性眼震(SN)患者,单冷和单热试验的灵敏度分别为86.9%、86.9%;排除含有DP患者,单冷和单热试验的灵敏度分别为89.3%、88.1%.结论:DP、SN等多种因素影响单温试验结果,单温试验的假阳性率、假阴性率均较高.不宜常规作为冷热试验的筛选试验.     

Extent of lesions in idiopathic sudden hearing loss with vertigo: study using click and galvanic vestibular evoked myogenic potentials

OBJECTIVE: To clarify the extent of the vestibular lesions in idiopathic sudden hearing loss with vertigo using vestibular evoked myogenic potentials (VEMPs) in response to click (click-VEMP) and galvanic (galvanic-VEMP) stimulation, as well as caloric tests. DESIGN: Retrospective study. SETTING: University hospital. PATIENTS: We enrolled 22 patients with idiopathic sudden hearing loss with vertigo in this study. All patients underwent audiometry and click-VEMP and caloric tests. Eight patients underwent a galvanic-VEMP test. RESULTS: Among the 22 patients, 17 (77%) showed an absence of click-VEMPs on the affected side. In response to caloric testing, 10 patients (45%) showed a decreased response on the affected side. All 8 patients who underwent galvanic-VEMP testing showed normal responses. Most patients with decreased caloric responses (9 [90%] of 10 patients) showed an absence of click-VEMPs, whereas 9 (53%) of the 17 patients who showed abnormal click-VEMPs showed decreased caloric responses. Initial hearing level and hearing outcome significantly correlated with abnormalities on the vestibular test results. CONCLUSIONS: The lesion site of vestibular disorders in idiopathic sudden hearing loss with vertigo appeared to be within the labyrinth on the basis of galvanic-VEMP findings. Results of the click-VEMP and caloric tests suggested that the saccule could be involved more frequently than the semicircular canals. The combined use of click-VEMP and caloric tests is useful for evaluating vestibular functions in idiopathic sudden hearing loss with vertigo because the extent of vestibular abnormalities correlated well with hearing outcome.     

梅尼埃病与偏头痛性眩晕的听-前庭功能比较

目的探讨梅尼埃病与偏头痛性眩晕的听功能及前庭功能状态的不同特点,进行比较分析,为二者的鉴别诊断提供帮助。方法回顾性分析2007年5月至2008年9月山东省立医院眩晕门诊52例梅尼埃病患者与36例偏头痛性眩晕患者的临床资料,全部患者均在急性期或亚急性期行纯音测听、视频眼震电图、冷热试验、前庭诱发的肌源性电位检查,部分梅尼埃病及全部偏头痛性眩晕患者行高刺激率听性脑干反应检查,对二者的听力与前庭功能检查结果进行比较分析。结果梅尼埃病患者共52例,男24例,女28例,年龄14-70岁,平均45.8岁。纯音测听异常52例,均为单侧感音神经性聋。视频眼震电图检查示中枢性异常眼动10例。冷热试验异常37例,均为单侧半规管反应低下。前庭诱发的肌源性电位检查异常31例。行高刺激率听性脑干反应检查共32例,5例异常。偏头痛性眩晕患者共36例,男8例,女28例,年龄16-62岁,平均43.6岁。纯音测听异常9例,均为单侧轻至中度感音神经性聋。视频眼震电图检查示中枢性异常眼动17例。冷热试验异常8例,均为单侧半规管反应低下。前庭诱发的肌源性电位检查异常18例,高刺激率听性脑干反应检查异常22例。经统计学分析,二者纯音测听、中枢性眼动检查、冷热试验及高刺激率听性脑干反应的检查结果差异有显著性。结论与梅尼埃病相比,偏头痛性眩晕患者纯音测听及冷热试验异常较少见,中枢性服动检查及高刺激率听性脑干反应异常率较高。在结合患者病史及临床表现的基础上.以上检查可为二者的鉴别提供辅助参考。     

Retrolabyrinthine vestibular neurectomy with simultaneous monitoring of eighth nerve action potentials and electrocochleography

Since November 1978, we have used retrolabyrinthine vestibular neurectomy in 29 of 42 cases as the primary procedure to relieve vertigo in Meniere's disease. The results indicate that 67% of patients had no vertigo postoperatively, while 21% were much improved. Hearing was maintained within 20 dB of the preoperative level in 78%. Simultaneous intraoperative electrocochleography and eighth nerve action potentials were used to monitor auditory function in the last fourteen cases using an Amplaid Mark V evoked potential signal processor. It appears that the intraoperative electrocochleography after vestibular neurectomy can be used as an indicator of postoperative auditory function. The retrolabyrinthine vestibular neurectomy has replaced the middle fossa vestibular neurectomy and the endolymphatic subarachnoid shunt in our practice.     

Vestibular pathophysiologic changes in experimental perilymphatic fistula.

An animal model of experimental perilymphatic fistula (EPLF) was developed in the guinea pig in order to study vestibular pathophysiology. In experimental animals, 4 microL of perilymph was suctioned from one cochlea via the round window membrane. Changes in vestibular function were as follows. 1) During the acute stage (5 hours postoperatively), spontaneous nystagmus directed toward the normal side was noted in 57.4% of the EPLF animals. This lasted less than 24 hours. 2) One week postoperatively, direction-fixed positional nystagmus toward the lesioned ear was present in 22.7% of the EPLF animals, especially when the lesioned ear was positioned inferiorly. 3) With the ice water caloric test, no response was present in 58.1% of the EPLF animals and an irregular response was found in 22.6% of them, 1 week postoperatively. These results tend to indicate that tests of vestibular function may differentiate between patients with Meniere's disease and those with perilymphatic fistula. Histologic findings indicate that a floating labyrinth is the cause of positional nystagmus and caloric irregularity. The absence of caloric responses was associated with collapse of the vestibular labyrinth.     

Subjective Visual Horizontal Determination During Otolith Stimulation by Eccentric Rotation in Conservatively Treated Meniere's Disease

Peripheral vestibular equilibrium disorders may originate in various parts of the labyrinth or of the vestibular nerve. Traditionally, the function of the lateral semicircular canals has been assessed by caloric irrigation and has been interpreted (sometimes falsely) as demonstrating a vestibular nerve lesion. The vertical semicircular canals are not assessed easily. Caloric testing with the head in various positions is not very helpful, but the canals may be tested in pairs using specific rotational techniques. Often, the otolith organs, detecting linear acceleration forces, are forgotten as a source of vertigo and dizziness. The extent of otolith involvement in Meniere's disease is not well understood. The tested subject is seated eccentrically in a rotatory chair and faces the direction of rotation. Thus, the otolith organs are stimulated in steady-state rotation. The subject experiences a lateral tilt and, in darkness, is instructed to point a short light bar in the position that he or she thinks a water surface would have (identical to the perceived tilt). Patients with conservatively treated unilateral Meniere's disease were tested. In the eccentric rotation test, the patients with unilateral Meniere's disease showed highly variable, sometimes even paradoxical, responses. No correlation was noted between the eccentric otolith test and pure-tone audiometry or the side difference of the caloric responses. Otolith and lateral semicircular canal functions may differ in patients with Meniere's disease, the nature of which remains to be elucidated in further studies.     

Abnormal vestibular evoked myogenic potentials in the presence of normal caloric responses.

OBJECTIVE: Combined use of vestibular evoked myogenic potential (VEMP) and caloric response testing has enabled us to examine the function of the inferior and superior vestibular nerves separately. Although results of VEMP testing and caloric response testing have been reported for many diseases, a clinical entity showing abnormal VEMP responses but normal caloric test responses has rarely been reported. The aim of the study was to investigate clinical features of diseases showing abnormal VEMP responses with normal caloric test responses. STUDY DESIGN: Retrospective. SETTING: University hospital. PATIENTS: Eight hundred eleven patients with balance problems who had undergone both caloric response and VEMP testing were included in the study. MAIN OUTCOME MEASURES: The amplitudes and latencies of the first positive-negative peak of the VEMP (p13-n23) were measured. RESULTS: Forty of the 811 patients (5%) were found to have abnormal VEMP responses with normal caloric test responses. Clinical diagnoses of these patients were Ménière's disease (n = 12), acoustic neuroma (n = 8), sudden deafness with vertigo (n = 6), and other diseases (n = 6). Eight patients could not be diagnosed as having a disease already recognized. Clinical manifestations of these eight patients were rotatory vertigo in six patients and non-rotatory dizziness in two. None of these patients showed abnormalities other than VEMP responses on neurologic or neurotologic examinations. CONCLUSION: Apart from Ménière's disease, acoustic neuroma, and sudden deafness with vertigo, which are already known as diseases with abnormal VEMP responses but normal caloric test responses, some patients might be diagnosed as having a disease that involves only the inferior vestibular nerve region.