Which is the best method to estimate the vestibular function?

Perioperative vestibular assessment and testing

Partial or total unilateral vestibular loss is the third most common cause of peripheral vestibular dysfunction. Dysfunction of one or both of the vestibular mechanisms can manifest physically as abnormalities of posture, balance, and/or visual acuity. This case report describes physical therapy examination and individualized intervention with vestibular rehabilitation for a patient with unilateral vestibular hypofunction. The patient was an 80-year-old male with electronystamographically confirmed unilateral vestibular loss of 98.3%. He demonstrated altered balance and gaze stability classifying him as having an increased risk for falling. After 5 weeks of individualized vestibular rehabilitation, the patient significantly decreased his fall risk from 11 to 20 of 24 on the Dynamic Gait Index. His gaze stability also improved from a 4 to 1 line disparity with dynamic visual acuity testing. The patient also had a decrease in perceived disability on the Dizziness Handicap Inventory from 30/100 at evaluation to 12/100 at discharge. Individualized vestibular rehabilitation decreased fall risk and improved gaze stability for a patient with significant unilateral vestibular hypofunction.

To evaluate the effect of endolymphatic sac surgery on vestibular functions using caloric testing on electronystagmography (ENG). Retrospective chart review. The medical records of 21 adult patients with unilateral Ménière's disease who underwent endolymphatic sac surgery between 1998 and 2004 were reviewed. With use of ENG, the absolute value of the caloric response of the operated ear (i.e., the cool + warm irrigation response) and the degree of reduced vestibular response (RVR) rates as indicators of caloric functions were compared before and after surgery. Average follow-up was 17 (6-52) months. The mean change in RVR after surgery was found to be 2.9%. In total, there were six (28.5%) patients who had an RVR increase more than 10%. Of those, there were three (14.2%) patients who demonstrated an RVR increase more than 20%. Only one (4.8%) patient had an RVR increase more than 30%. Total loss of vestibular function was not observed in any of the patients. There were three (14.2%) patients who exhibited a decrease of more than 10% in their RVR. In two (9%) patients, the contralateral ear was shown to have less vestibular function than the operated side on ENG postoperatively (in one case, the absolute caloric nystagmus response remained the same in the operated ear, and in the other case, the response increased on the surgical side). When we evaluated the absolute caloric responses of the operated ear only, we found no statistical difference between the pre- and postoperative values (P = .219). Early results of vertigo control and hearing outcomes were comparable with those in the literature. Endolymphatic sac surgery does not appear to be a vestibular destructive procedure, and it is a therapeutic alternative for patients with Ménière's disease who have failed medical treatment. This is important given the possibility of bilateral disease in some patients.

Background and Purpose: Radiologic abnormalities on computed tomography (CT), including narrowing or sclerosis of the semicircular canals (SCCs), and T2-weighted magnetic resonance imaging (MRI), including signal loss in the SCC, have been reported as potential biomarkers in patients with P51S mutations in the COCH gene (i.e., DFNA9). The aim of our study was to correlate caloric responses through electronystagmography (ENG) data with imaging results in DFNA9 patients.Materials and Methods: A retrospective study was performed in 45 patients; therefore, 90 ears with P51S mutations in the COCH gene were tested. Caloric responses and CT and MRI data were analyzed from June 2003 until May 2014. More than half of patients (54%) were candidates for cochlear implantation.Results: In our population, 91% of tested ears had sclerotic lesions and/or narrowing in one or more SCCs on CT scan. All tested ears had narrowing or signal loss in at least one SCC on T2-weighted MRI. The lateral SCC was affected in 87% on CT scan and 92% on MRI. However, in 83% of tested ears, all three SCCs were affected on MRI. Furthermore, in 77% of tested ears, caloric responses were reduced bilaterally, while 11.5% showed unilateral hypofunction and the other 11.5% had normal caloric responses. CT abnormalities correlated with hypofunction of caloric responses. This statistically significant difference was present if abnormalities were observed in at least one of the SCCs as well as in ipsilateral lateral SCC function loss. MRI abnormalities in at least one of the SCCs correlated with ENG hypofunction, but there was no direct correlation between lateral SCC abnormalities on MRI and caloric responses of the investigated lateral canal.Conclusion: Our retrospective analysis confirms the presence of CT and MRI abnormalities in DFNA9 patients with the P51S mutation in the COCH gene. A correlation between these radiologic features and vestibular function (tested by means of caloric response) was found in this population.

When investigating patients with suspicion of a posterior fossa lesion, case history and clinical examination are important. Additional information is obtained by using an otoneurological test battery consisting of electronystagmography and audiology, primarily brain stem audiometry. In the electronystagmography one should look for spontaneous, positional and gaze nystagmus and asymmetry in the caloric test. In our material of 78 patients with acoustic neuromas, spontaneous nystagmus was present in 58%, positional nystagmus in 43% gaze nystagmus in 5% and caloric asymmetry in 88%. To reveal CNS disturbances in the posterior fossa, whether due to pressure from a pontine angle tumour or a vascular loop, or caused by cerebellobrainstem infarction, bleeding or tumour, certain special tests have proved valuable: computerized sinusoidal vs. randomized rotatory and smooth pursuit tests and ocular saccade test. A visual suppression test performed in the rotatory chair makes it possible to compare suppression and pursuit at identical stimulation patterns, which adds a new diagnostic tool.

The observation that the caloric nystagmus response is dependent on body position has been repeated in several studies during the course of this century. For many, this position-dependent modulation of the caloric response has been interpreted as evidence in favour of the thermoconvection theory as originally proposed by Bárány. However, the adequacy of this theory has been put into question by recent observations of caloric nystagmus during weightlessness in orbital flight. These zero-g findings clearly demonstrate that any hypothesis based on thermoconvection alone must prove insufficient as a description of the caloric nystagmus response. In the light of these recent findings, it has also become necessary to reconsider the influence of body position on caloric nystagmus intensity and the physiological mechanisms involved. Caloric testing was performed with a group of 30 healthy test subjects. Each person was tested in eight different body positions in the sagittal plane. Caloric nystagmus response was registered by means of horizontal and vertical EOG. The observed modification of the caloric response (SPV) by assumed body position is discussed with reference to associated reports in the literature.

Age-related anatomical and morphologic vestibular deterioration has already been elaborated. Demonstrating a corresponding degradation in physiologic function, however, entails a much higher challenge. The objective of this study was to investigate age-related changes using rotational tests, caloric tests, and the vestibular-evoked myogenic potentials (VEMP) test. Eighty healthy human subjects (38 men and 42 women) ranging in age from 18 to 80 yrs participated in this study and were subjected to an extensive vestibular test battery. Function tests included sinusoidal harmonic acceleration tests, a pseudorandom rotation test, velocity step tests, a caloric test, and a VEMP test. No significant age trends were noted for the sinusoidal harmonic acceleration test and velocity step tests response parameters, in contrast to subtle decreasing gain values with advancing age for the pseudorandom rotation test. Increasing slow-component velocity values were measured with the caloric test, whereas the frequency parameter showed no relevant age changes. The largest age trends were detected with the VEMP, with decreasing amplitudes, increasing thresholds, and decreasing N1 latencies. All asymmetry parameters remained stable across the different age categories. Only subtle age changes could be demonstrated with the rotational and caloric tests, in contrast to more pronounced age trends with the VEMP.

Changes in caloric responses after temporal bone surgery with posterior tympanotomy

The treatment of active tuberculosis during pregnancy is complicated by the problem of the safety of the drugs employed. In order to prevent the emergence of drug-resistant organisms it is customary during the initial stages to give streptomycin as well as isoniazid and p-aminosalicylic acid, and, while the mother is of course subject to the risk of ototoxic damage due to streptomycin, it is not entirely clear how far this risk extends to the foetus. Certainly streptomycin does cross the placenta : this was established in 1945 by Woltz and Wiley and indepen dently by Heilman et al. (1945). Subsequent work (Bernhard et al, 1950 ; Riskaer et al., 1952 ; Charles, 1954) confirmed that, although the effectiveness of the placental barrier varies, streptomycin and dihydrostreptomycin (Jacobsen, 1953) are present in foetal blood in up to 50% of maternal concentrations. The effect of these drugs on the foetus was studied experiment ally by Riskser et al., using guinea-pigs ; no disturbance of auditory or vestibular function was apparent. Watson and Stow (1948) were the first to examine this ques tion clinically ; they found no obvious abnormality in two children born after high maternal doses of streptomycin during pregnancy. Later reports agreed, and Kreibich (1954) was able to collect from the literature 35 cases in which children at risk seemed to be unaffected. Since 1950, however, several case reports have appeared of deaf children born to mothers treated with streptomycin for tuberculosis. Leroux (1950) described the case of a child aged 2 with deafness (and normal caloric responses) whose mother had received 30 g. of streptomycin in the last month of pregnancy. Bolletti and Croatto (1958) reported the case of a girl of 5 with severe deafness and impaired vestibular function, the maternal dose of streptomycin having been 1 g. daily for 85 days prior to delivery. Kern (1962) described the case of a 6-year-old girl with severe deafness in the left ear and total deafness in the right. A caloric test evoked very little response. In this case the mother had been treated with 20 g. of dihydrostreptomycin in the first four months of pregnancy. Finally, in a study of the causes of deafness in 300 children, Robinson and Cambon (1964) dis covered two further children with severe deafness and absent caloric responses. The first mother fiad been given 1 g. of streptomycin twice weekly for eight weeks in the first trimester, and the second a similar dosage for the last four months of pregnancy. Apart from these isolated cases there have been three papers describing the otological findings in small groups of children at risk. Rebattu et al. (1960) found two cases of high tone loss among six children they examined, and in one the caloric tests were abnormal. Lenzi and Ancona (1962) studied 10 children aged 7-10 years and their mothers. Audiograms showed that three of the children were deaf ; all the mothers were normal. Grande and Vespa (1963) examined nine mothers and their 14 children, then aged 7-11 years. In this instance all the mothers had received dihydrostreptomycin, the dose ranging from 5 to 80 g. Four mothers and three children had perceptive deaf ness ; five more children had mixed deafness. Vestibular function was studied with galvanic and caloric tests, of which no details were given ; all the children were stated to be normal. These three series suggest a relatively high incidence of deaf ness (possibly related in the last one to the use of dihydro streptomycin, which is more apt than streptomycin itself to damage cochlear function), and it is therefore surprising that so few children with deafness caused in this way have been reported. The present investigation was undertaken in an attempt to reassess the incidence of deafness in children at risk. Furthermore, in theory one would expect labyrinthine rather than cQchlear damage to be the commoner finding after the use of streptomycin, and accordingly vestibular function was examined in detail.

To determine the utility of the hyperventilation test (HVT) in the diagnosis of vestibular schwannoma (VS). A retrospective analysis of hyperventilation-induced nystagmus (HVIN) in 45 patients with unilateral VS. A tertiary referral center. Forty-five patients with VS; 30 patients with chronic vestibular neuritis; 20 healthy subjects with normal hearing and without symptoms or a history of vertigo, migraine, or neurological diseases (control group). Audiological and vestibular examination; "side-stream" measurement of end-tidal CO2 pressure (P(EtCO2)) to standardize the procedure; magnetic resonance imaging (MRI) centered on the cerebellopontine angle. An analysis of HVIN, its patterns, and its appearance threshold via the measurement of P(EtCO2) correlations with the tumor size. HVIN was observed in 40 of 45 cases (88.9%) in the schwannoma group and in 12 of 30 cases (40%) in the chronic vestibular neuritis group; HVIN was not observed in the control group (0/20 cases) (p < 0.001). In the schwannoma group, HVIN was evoked at a mean P(EtCO2) value of 16.5 ± 1.15 mm Hg. The hypofunctional labyrinth was identified with high sensibility and specificity through caloric test, head shaking test, and head thrust test. The excitatory pattern, which included HVIN with slow phases that beat toward the hypofunctional side, and the paretic pattern, which included HVIN with slow phases that beat toward the hypofunctional side, were not significantly associated with VS size (19.04 ± 10.56 mm for the excitatory pattern and 19.06 ± 11.01 mm for the paretic pattern). The difference in the VS size in HVIN+ (19.05 ± 10.60 mm) and HVIN- (8.40 ± 2.19 mm) cases was significant (p = 0.009). A 60-second hyperventilation event causes metabolic changes in the vestibular system and reveals a latent vestibular asymmetry. The presence of an excitatory pattern is the major criterion that suggests VS in patients with signs of unilateral vestibular deficit.

Three cases of acute ataxia in children were reported and reviewed from the otoneurological point of view.Case t: A 6-year-old boy, several days after the development of skin eruption of chicken pox, complained of an occipital headache with a low-grade fever, followed by a staggering gait and incoordination of the arms. Otoneurological examination showed him to have an ataxic gait, an intention tremor, a bradylalia, dysmetric eye movement, an ataxic pursuit pattern for the eye tracking test (ETT). However, the results of the optokinetic nystagmus pattern (OKP) and rotation tests were within normal limits. These data suggest that the lesion dispersed diffusely within the cerebellum.Case 2: A 10-year-old boy, several days after an upper respiratory infection, complained of epigastralgia, an occipital headache and a staggering gait. Otoneurological examination showed him to have an ataxic gait, a dysdiadochokinesia of his left hand and upward vertical positional and positioning nystagmus and backward stepping. However, the results of OKP, rotational and ET tests were within normal limits. These data suggest that the lesion was localized in the vermis of the cerebellum.Case 3: A 3-year-old girl, 6 days after the development of skin eruptin of chicken pox, complained of a staggering gait and incoordination of the arms. Otoneurological examination showed her to have an intention tremor, wide-based back- and forward-stepping and an ataxic gait. However, neither nystagmus nor abnormal eye movement were observed and the results of optokinetic nystagmus and rotational tests were within normal limits. These data suggest that the lesion was within the cerebellum.The clinical courses of the three cases were very good, and they recovered completely within a few weeks.In conclusion we stress that the responsible lesion of acute cerebellar ataxia was just within the cerebellum, and the participation of the brain stem could be excluded.

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1. Three patients with multiple sclerosis presented with vertigo or dysequilibrium as an early symptom.2. Neurootological examination showed abnormal findings in all three cases.3. Gaze nystagmus, direction-changing positional nystagmus, rebound positional nystagmus and vertical positioning nystagmus were observed in these patients, indicating a disturbance of the central vestibular system.4. MLF (medial longitudinal fasciculus) syndrome, indicating a brainstem lesion, was present in two patients.5. Caloric testing was performed in two patients. The duration and the slow phase velocity of the caloric-induced nystagmus were within normal limits, while visual suppression of the caloric-induced nystagmus was impaired in both patients.6. The optokinetic nystagmus pattern test was performed in two patients. The optokinetic nystagmus was markedly depressed when the patients first visited the vestibular clinic shortly after the onset of the vertiginous attack. It gradually improved towards normal during the course of the disease in close correlation with recovery from other neurological signs and symptoms.

We compared the results of analysis of vestibulo-ocular reflex (VOR) obtained by manual rotation in routine vestibular clinical practice with that of caloric testing, and examined the validity and limitations of VOR analysis as a test for the estimation of peripheral vestibular function and imbalance. VOR response was recorded in daily vestibular clinical examinations by manually rotating the standard clinical chair for , 30 s. VOR gain was slightly, but significantly, correlated with the peak slow phase velocity of caloric response ( r = 0.50, p < 0.001). However, 8 out of 12 patients with no caloric response failed to exceed the range of two standard deviations of the mean value of age-matched normal subjects, indicating that it is clinically difficult to use VOR gain alone as a estimate of unilateral vestibular function. VOR directional preponderance (VOR DP%) correlated well with caloric canal paresis (CP) (CP%; r = 0.89, p < 0.001). VOR DP% was within the normal range in patients with caloric CP% < 40 and exceeded the normal range in most cases with caloric CP% > 80. VOR DP% varied widely when caloric CP% ranged between 40 and 80. The effect of vestibular compensation on VOR DP% was examined by plotting VOR DP% divided by caloric CP% (DP CP) against the number of days since the onset of vertigo in patients with vestibular neuritis or sudden deafness with vertigo. DP CP was large within 50 days of the onset of vestibular damage, especially when caloric CP% was < 80, and gradually decreased with time. These results indicate that determination of VOR DP% should contribute to the early diagnosis of fresh vestibular imbalance, especially in daily clinical practice, because this type of VOR recording can be performed in < 1 min in routine vestibular clinics. The decay time constant of DP CP was larger when caloric CP% exceeded 80, indicating that vestibular compensation proceeds more slowly when the vestibular damage is severe.

To evaluate the utility of positional testing in peripheral and central acute vestibular syndrome (pAVS, cAVS, respectively). Prospective; observational. Tertiary referral center. Consecutive AVS patients. Video-oculography in upright, supine and head hanging positions at presentation, 3-month and 1-year follow-up. Positional modulation of spontaneous nystagmus; co-occurrence of central paroxysmal positional nystagmus (CPPN). Fifteen pAVS [mean age (SD), 53.3 (16.6) (11 males)] and 15 cAVS [mean age (SD), 56.5 (17.8) (11 males)] patients were included (p=0.49). Acutely, in supine, in patients whose nystagmus was present in both head rotation sides, 12 of 13 (93%) pAVS and only 4 of 12 (33%) cAVS patients showed direction-fixed positional nystagmus which was stronger when turning the head to the slow phase side. The remaining cAVS patients showed either direction-fixed positional nystagmus which was stronger when turning the head to the fast phase side (5), or direction-changing positional geotropic nystagmus (2). One patient in each group showed direction-changing positional apogeotropic nystagmus. During follow-up, direction-changing positional apogeotropic and geotropic nystagmus became common in both groups. Acutely, in head hanging, 5 (33%) cAVS patients showed vertical CPPN and 2 showed positional saccadic intrusions. Positional downbeat nystagmus and saccadic intrusions became chronic. The presence of acute direction-changing positional geotropic nystagmus, stronger direction-fixed positional nystagmus when turning the head to the fast phase side, and acute or chronic head hanging vertical CPPN should raise the suspicion for central AVS. Chronic geotropic and apogeotropic nystagmus following AVS constitute an underrecognized manifestation of vestibular compensation.