Caloric Function After Endolymphatic Sac Surgery

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.

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.

In spite of many investigations in the form such as the duration, frequency, number of beats, total amplitude or eye-speed in the slow phase of nystagmus for estimation of the vestibular function, no decisive conclusion has not been obtained up to the present day as to the best diagnostic method for this function.This problem was investigated by the author with a number of statistical studies of the postrotatory and caloric responses in 50 normal subjects and 300 patients. In all tests the recording of nystagmus was performed by electronystagmography (ENG). Nystagmus was always recorded with the subjects' eyes shut. The technique of calorization was the same as that of Fitzgerald & Hallpike. The rotatory test was carried out with accelerations of 1.2°/sec2., up to a rate of 60°/sec, and followed by a period of rotation at a constant rate lasting 30sec. and suddenly brought to rest.From the recorded curves, the duration frequency, number of beats and maximum eye-speed in the slow phase were calculated and the normal limits of these characteristics were discussed by statistical analysis. Results obtained are summarized as follows;1) Duration is the most reliable factor for estimation of the vestibular function, and the reliable factor following this is the number of beats. The majority of pathological difference can be inspected from both observations. Pathological difference is rarely seen in maximum eye-speed in the slow phase.2) The frequency pattern of caloric nystagmus is convenint in observing the whole period of the reaction, however, quantitative determination should be investigated by the duration, number of beats and eye-speed in the slow phase.3) The rotatory test rarely gives any information of importance that cannot be obtained by caloric test, and selective asscsment of the function of the labyrinths is impossible. Therefore, the rotatory test is not always a vital examination of the vestibular function test.4) Spontaneous- and positional nystagmus do not appear in normal persons, whereas these ware observed in more than 50% of patients with vestibular or neural diseases. Therefore, this observation is one of the most important test of the vestibular examination.

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.

Trends in the diagnosis and the management of meniere’s disease: Results of a survey

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.

Three of the present authors described a trial in 1981 which showed that cortical mastoidectomy was as effective as an endolymphatic sac shunt in controlling vertigo in patients with Ménière's disease both on a short-term as well as a long-term basis. The hearing was not influenced by the treatment and any change was considered to be the result of time, rather than the effect of the surgery. Upon perusal of the literature only two other studies exist resembling our study, and they both reached the same conclusion, that sac surgery is at best non-specific and at worst of no value. None of the numerous other studies published have convinced the authors that sac decompression is specific in nature. We have also looked at ECoG as a means of proving the specificity of sac operations and come to the same conclusion that the existing information is conflicting and confusing, and cannot be used to prove anything about sac surgery. The present conclusion is therefore that in treating patients with Ménière's disease anything goes, even sac surgery.

Changes in caloric responses after temporal bone surgery with posterior tympanotomy

To evaluate the function of vestibular ocular reflex (VOR) in patients with unilateral peripheral vestibular disorder (uPVD) by the head impulse test (HIT). The HIT and caloric test were carried out in 135 cases of patients with uPVD. The results of HIT were considered as normal (negative reaction) and abnormal (positive reaction). The results of vestibular function evaluated by caloric test were divided into three kinds, including normal, decreased and deficit according to the degree of canal paresis as less than 30 percent, from 30 to 99 percent, and equal to 100 percent, respectively. The sensitivity, specificity, positive and negative predictive value of HIT in assessing the vestibular function was analyzed. For the 135 patients with uPVD, the HIT was normal in 90 (66.7%) cases and abnormal in 45 (33.3%) cases. When the caloric test was normal, the HIT was normal or abnormal in 58 cases and 6 cases, respectively. And when the canal paresis was from 30 to 99 percent, the HIT was normal or abnormal in 28 and 24 cases, respectively. When the vestibular function was deficit (CP was 100%), the HIT was normal or abnormal in 4 cases and 15 cases, respectively. When the results of caloric test were considered as the standard method to evaluate the VOR, the sensitivity, specificity, positive and negative predictive value of HIT were 54.9%, 90.6%, 86.7%, and 64.4%, respectively. When assessing the function of VOR in patients with uPVD, the HIT could not replace the caloric test, but it can be a supplementary method. The information from both the HIT and caloric test can be combined to evaluate the patients with vestibular hypofunction comprehensively.

The caloric test response from the unaffected ear in a case of acoustic neuroma may be normal, hypoactive or hyperactive; each has a different pathophysiological connotation: a normal response is the anticipated finding; a hyperactive contralateral response is due to the presence of a large neuroma with brainstem compression; and a hypoactive response may result from several factors, such as lack of mental alertness during the test, drugs like barbiturates, raised intracranial tension, or the presence of bilateral neuromas.

This study investigated the relationship among the severity of hearing impairment, vestibular function and balance function in patients with idiopathic sudden sensorineural hearing loss (ISSNHL). A total of 35 ISSNHL patients (including 21 patients with vertigo) were enrolled. All of the patients underwent audiometry, sensory organization test (SOT), caloric test, cervical vestibular-evoked myogenic potential (cVEMP) test and ocular vestibular-evoked myogenic potential (oVEMP) test. Significant relationship was found between vertigo and hearing loss grade (P=0.009), and between SOT VEST grade and hearing loss grade (P=0.001). The abnormal rate of oVEMP test was the highest, followed by the abnormal rates of caloric and cVEMP tests, not only in patients with vertigo but also in those without vertigo. The vestibular end organs were more susceptible to damage in patients with vertigo (compared with patients without vertigo). Significant relationship was found between presence of vertigo and SOT VEST grade (P=0.010). We demonstrated that vestibular end organs may be impaired not only in patients with vertigo but also in patients without vertigo. The cochlear and vestibular impairment could be more serious in patients with vertigo than in those without vertigo. Vertigo does not necessarily bear a causal relationship with the impairment of the vestibular end organs. SOT VEST grade could be used to reflect the presence of vertigo state in the ISSNHL patients. Apart from audiometry, the function of peripheral vestibular end organs and balance function should be evaluated to comprehensively understand ISSNHL. Better assessment of the condition will help us in clinical diagnosis, treatment and prognosis evaluation of ISSNHL.

In vestibular examinations anomalies in the saccade and smooth pursuit tests as well as the fixation suppression after caloric stimulation might indicate central lesions in the vestibular system. Additionally, a high gain in the torsion test is suspicious of cerebellar dysfunction. In this study, 141 patients out of 973 had at least one of these anomalies. For 125 patients we were able to compare the initial findings in the vestibular examination with the final diagnosis by otologists, neurologists and general practitioners. The complaints of 37.6% of the patients with these electronystagmographic (ENG) anomalies appeared to be of central origin. Abnormal saccades, an abnormal smooth pursuit, and an elevated gain in the torsion test were not independently diagnostic for central vestibular disease. The fixation suppression index appeared to be lower for subjects with peripheral vestibular disease. Otologists more often referred their patients to a neurologist if the fixation index was elevated.

The cervical vestibular evoked myogenic potential (cVEMP) is recorded from the sternocleidomastoid muscle (SCM) and represents a stimulus-evoked attenuation of electromyographic (EMG) activity following activation of the saccule and inferior vestibular nerve. In addition to the cVEMP, it is possible to record a biphasic response from the infraorbital region following stimulation that is identical to that used to record the cVEMP. This response is known as the ocular VEMP (oVEMP). The peripheral vestibular origins of the oVEMP elicited with air conduction remain controversial as some investigators argue the response originates from the saccule and others argue that the response emanates from the utricle. We review several lines of evidence and present several case studies supporting the contention that the oVEMP to air conduction stimulation derives its peripheral origins predominantly from the utricle and superior vestibular nerve. To review the current evidence regarding the peripheral origins of the oVEMP. Further, a purpose of this report is to present case studies illustrating that the cVEMP and oVEMP to air conduction stimulation may vary independently of one another in patients with peripheral vestibular system impairments. A collection of case studies illustrating three common patterns of abnormality observed in patients complaining of vertigo seen in a tertiary care referral center. Retrospective analysis of data from three patients complaining of dizziness and/or vertigo who have undergone vestibular function tests. Each case report illustrates a different pattern of abnormality of caloric, cVEMP, and oVEMP tests results from three patients with a vestibular nerve section, superior vestibular neuritis, and Ménière's disease, respectively. We have shown that the cVEMP and oVEMP can vary independent of one another, and in that way, provide topological information about the sites of impairment. We feel that, with caloric, oVEMP, and cVEMP tests, it is possible to augment the diagnostic information we are able to provide regarding the location, or locations, of vestibular system impairment. These findings suggest that air conduction oVEMPs measure a part of the peripheral vestibular system different from that measured by cVEMPs, perhaps the utricle, and similar to that measured by caloric testing, the superior portion of the vestibular nerve.

Conclusions: Although there was a statistically significant relationship between the results of the vHIT and the caloric test, the limited strength of this relationship suggests that, for unilateral vestibular schwannoma (UVS), caloric testing and vHIT may provide complementary information on vestibular function.Objective: There is limited information that can be used to determine which of the video head impulse test (vHIT) and caloric test might be better used in the diagnosis and management of UVS. In this study, a group of participants with un-operated UVS was studied using both methods.Methods: The subjects’ vestibular function was assessed using the vHIT and caloric testing. Tumour size was quantified using MRI and their balance disturbance assessed using the Jacobsen Dizziness Handicap Inventory (DHI).Results: Twenty of 30 subjects had an abnormal canal paresis according to the Jongkees’ criterion (> 0.25); however, only 10/30 had an ipsilesional vHIT gain of <0.79. Canal paresis could be predicted from the ipsilesional and contralesional vHIT gains. Tumour size could also be predicted from the ipsilesional vHIT gain and canal paresis. However, DHI scores could not be predicted from the degree of canal paresis, vHIT gain, or the MRI measures.