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PubMedDate not supplied

Sources of error in interpretation of caloric tests.

Caloric testing plays a prominent role in evaluating the vestibular system. A unilateral reduced vestibular response (RVR) is a common abnormality and is consistent with peripheral vestibular pathology. An erroneous interpretation of RVR may be made due to the following circumstances: laboratory technique, the influence of directional preponderance (DP) on monothermal tests (MT), unilateral hyperactivity, or pseudocaloric (PC) nystagmus. These errors in interpretation may be avoided by (1) repeating any single irrigation that is significantly different from the other three, to rule out laboratory technical error; (2) performing bithermal (BT) testing exists, to eliminate the effects of directional preponderance; (3) observing that a right/left (R/L) difference is not due to unilateral hyperactivity, by noting absolute slow phase (SP) velocity; and (4) by demonstrating bidirectional sensitivity of the cupula before concluding that residual caloric function exists instead of no function.

Caloric Tests↗

PubMed1979

[Air caloric test: as useful as the water caloric test (author's transl)].

Twenty normal probands were examined by us with air (60 sec, 121/min, 45 degrees/29 degrees C) and 25 with water (30 sec, 30 cm3, 44 degrees/30 degrees C) caloric test. Additionally we evaluated the influence of flow rate and tip position on the temperature near the tympanic membrane during the irrigation, using a polyacryl copy of the external auditory canal. A high flow rate and a reproducible tip position very near to the tympanic membrane during the irrigation appeared to be essential to achieve reliable results in air caloric test. Measurements of the actual temperatur should be done therefore at the irrigation tip delivery in every caloric test with air. Lower heat capacity of air, air jamming near the tympanic membrane and heat losses through the meatus wall are the main reasons of more distinct temperature drops and a higher variability in air caloric test, than in the common caloric test with water. Therefore, the air caloric test as a reliable instrument should be reserved for those cases, were water is contradicted.

Air↗

PubMed1979

A protocol for the air caloric test and a comparison with a standard water caloric test.

This communication describes the development of a protocol for the air caloric stimulus for vestibular testing. The protocol is based on matching the peak responses of air and water caloric stimuli and minimizing subject discomfort. Air stimulus temperatures of 30 and 44 degrees C are used, and these appear to minimize subject complaints of pain with the test. Composite data are presented from 16 normal subjects who were tested with the protocol. A comparison is made with their responses to a standard water protocol. Test-retest data for both air and water protocols are also presented, and these data indicate similar day-to-day variation in the two methods. On the basis of the work presented, it is concluded that the air protocol produces responses equivalent to that of standard water calorics in a group of normal subjects. Neither test was found, in the present experiments, to be particularly sensitive.

Air↗

PubMedDate not supplied

Influence of age on results of vestibular function tests. Review of literature and presentation of caloric test results.

Following a bibliographic review of currently known, age-dependent morphological and functional changes of the vestibular and auditory system, results are presented of our investigations concerning the influence of age on the outcome of the caloric test on 102 healthy subjects from six age groups ranging between the ages of 11 and 70 years. They prove, without any doubt, that the absolute values of nystagmic parameters in the caloric test are dependent upon age; but not in such a way that the intensity of reaction decreases with advancing age. On the contrary, they indicate that in awake, healthy subjects of middle and late middle-age, the most intensive reactions occur (maximum slow phase velocity, maximum amplitude, maximum frequency, total number of beats). In addition, based on the statistical analysis, it seems probable that the extent of the side difference of excitability depends upon age. Individuals in their middle years show side differences to a considerably lesser degree than children and elderly subjects. These represent findings which, to our knowledge, are reported here for the first time. Provided our results gain further substantiation, standard values for a true quantitative evaluation of the caloric test could only be determined as in the audiometric functional tests on the basis of larger test series of healthy subjects belonging to different age groups.

Adolescent↗

PubMed1979

The screening value of monothermal caloric tests.

A valid screening caloric test should decrease examination time, increase patient comfort and maintain a high degree of sensitivity in predicting bithermal (BT) caloric results. This prospective study of 362 consecutive electronystagmograms (ENG) compared right/left (R/L) difference results obtained using monothermal (MT) warm and cold irrigations alone with that of the (combined) BT tests. Comparing MT warm and cold irrigations, false negative (normal MT but abnormal BT test) results were obtained in 14% and 25% of irrigations, while false positive (abnormal MT but normal BT test) information was obtained in 22% and 15% of irrigations, respectively. False negative MT tests preclude detection of the abnormal BT test, while false positive tests require unnecessary completion of the BT caloric irrigations. This lack of diagnostic sensitivity limits the usefulness of the MT irrigation as a screening test.

Air↗

PubMedDate not supplied

Results of new air caloric testing method among normal subjects. I. Biphasic testing.

A new air caloric testing method is described in which the temperature of a continuous aural irrigation is switched hot and cold values at times calculated to control the intensity of the resulting vestibular stimulation. Applications of low or high caloric stimulus intensities to normal subjects were well tolerated and reliably produced appropriate low or high intensity nystagmic responses. Nystagmus intensity values obtained from this study were compared with predicted intensity values from a computerized simulation of the actual test conditions, and also with values obtained when using biphasic water irrigations. As a result, further improvements in our methodology have been effected.

Air↗

PubMed1992

An evaluation of commercial water irrigation systems used for caloric testing.

The post-1982 Grant Caloric Test Apparatus, and the Atmos Variotherm were evaluated and compared to BS5724 Part 1 (1989). Quality of construction is satisfactory, but design features may result in failure of tests for which this type of equipment should conform; namely splash, liquid leakage and spillage. For the Variotherm the proximity of the water piping to the electrical parts could result in wetting of the electrical units in the event of a leakage. The large vents in the Grant tanks allow easy access of water to electrical parts in the event of splashing. Both sets of equipment fail BS5724 Part 1 (1989) with respect to labelling. The Grant irrigation nozzle is well designed, but the Variotherm nozzles are not so, as they can accidentally pass down the external auditory meatus causing meatal wall or tympanic membrane damage. Both sets of equipment passed on electrical safety test for Class I Type B equipment. Cut-outs are fitted to prevent heating in the absence of water or over-heating of the water. The 44 degrees C Grant tank cut out after 20 s in the absence of water and at 49 degrees C as the water temperature rose above the operating temperature. The Variotherm heater did not operate in the absence of a water supply. The Variotherm thermal cut-out was not assessed. The force of the water at recommended flow rates using the Variotherm 'standard' metal nozzle was considered to pose a potential hazard of tympanic membrane perforation, and has subsequently been withdrawn by the supplier. The plastic nozzle minimized any such risk. The Variotherm is easier to use due to the well-designed trigger handle for controlling water delivery. Both sets of equipment performed at the correct temperature to within +/- 0.5 degrees C and achieved a flow rate of 250 ml in 30 s.

Caloric Tests↗

PubMed1977

Caloric test with oculogyral illusion as response.

It has been demonstrated that the caloric test can be simplified further by making use of the oculogyral illusion. Since the test is conducted under conditions of optic fixation, this method probably also enhances the sensitivity of the caloric test. The reproducibility of the tests also appears high, at least in respect of measures of "canal paresis". When used in conjunction with other tests for detecting vestibular imbalance, e.g. examination for spontaneous and provocation nystagmus using Frenzel glasses, this OGI caloric test should provide a convenient procedure for the clinical examination of vestibular function.

Adult↗

PubMedDate not supplied

Results of new air caloric testing method among normal subjects. II. Monophasic testing.

A new caloric irrigation method is described. In the new method, the temperature of a continuous aural irrigation is switched between hot and cold values at precisely specified times. The durations of hot and cold pulses have been calculated to produce specific caloric stimulation intensities based on known heat transmission characteristics of the labyrinth area. A brief "washout" irrigation is used to eliminate promptly all caloric stimulation effects at the conclusion of each test. The present study concentrated upon the question of how long the "washout" pulse should be in order to obtain optimum results. Repetitive application of a uniform stimulus intensity to 6 normal subjects indicated that short inter-test intervals can be used without causing vestibular habituation. Prompt removal of the caloric stimulus can be accomplished by proper timing the "washout" phase of the new technique.

Caloric Tests↗

PubMed1978

[Normal values of the caloric test (author's transl)].

Normal values of the caloric test are reported in 202 healthy subjects; besides the absolute values, these comprise the degree of side-difference of excitability and of directional preponderence in percent of the total reaction. In addition to mean values with standard deviations, the median values and the interquantile areas 80, 90, 94 and 100% have been reproduced in tabular form, because, according to statistical calculations, there is no normal distribution of the values in the strict sense. The problematic nature of borderline values for the separation of physiological from pathological responses is discussed in detail. In vieu of the considerable scattering, a knowledge of normal distribution areas appears to be absolutely necessary for an accurate evaluation of the caloric test in patients.

Adult↗

PubMed1979

Impulsive and sinusoidal rotatory testing: a comparison with results of caloric testing.

The usefulness of rotatory testing (impulsive and sinusoidal) as an indicator of impaired horizontal semicircular canal function was evaluated in 63 patients with unilateral and bilateral decreased caloric responses. The rotatory stimuli were precisely controlled over a large magnitude range and EOG recorded nystagmus responses were quantified using digital analysis techniques. Rotatory testing was consistently abnormal in patients with complete unilateral caloric paralyses but was normal in over one-half of the patients with significant but less than complete unilateral caloric paralyses. The difference in maximum slow component velocity (SVMX) of induced nystagmus after the largest rotatory stimuli was the best indicator of unilateral impaired function. The patients with bilateral decreased caloric responses demonstrated three categories of rotatory response: 1. normal at all magnitudes of stimulation, 2. decreased but present after large magnitude stimuli, and 3. absent responses. It is concluded that although rotatory testing cannot replace caloric testing it can provide useful clinical information particularly in patients suspected of having bilateral vestibular disease.

Caloric Tests↗

PubMed1975

Evaluation of a screening-procedure by hot-water caloric tests.

In order to introduce a screening-procedure for vestibular caloric testing, we tried to evaluate the hot and cold caloric tests separately. We made a review of a series of cases having been tested by the classical 4 tests (cold and hot bilateral). In supposing that we should have stopped the investigation when the hot calorics showed a side-difference of 20% or more for the slow-phase velocity at the culminationpoint, we verified how many cases would have been missed, presenting by global examination a significant difference either for the reflexivity or for the DP. This study showed us that an important number of cases would have been missed equally well by the hot calorics as by the cold ones. The comparison shows no difference between them. By narrowing the criteria we would allow a screening-technique either by the cold or by the hotwater test, but in this way more than 3/4 of the cases were indicated for complete examination.

Caloric Tests↗

PubMedDate not supplied

Caloric testing. 1. Effect of different conditions of ocular fixation.

Twelve normal subjects received standard caloric testing under the following conditions: 1) fixation, 2) Frenzel glasses in a dimly lit room, 3) eyes open in total darkness, and 4) eyes closed. Multiple nystagmus response parameters were evaluated and statistically compared for each condition. Fixation markedly diminished induced nystagmus and produced the largest coefficient of variation for each response parameter. Caloric testing with eyes closed resulted in periodic nystagmus suppression and a less distinct saw-toothed pattern. As with fixation, the coefficient of variation was consistently higher with eyes closed compared to eyes open in darkness or Frenzel glasses. It is concluded that caloric testing of the vestibulo-ocular reflex arc should be performed with eyes open in darkness or with Frenzel glasses.

Central Nervous System Diseases↗

PubMedDate not supplied

Caloric testing. 3. Patients with peripheral and central vestibular lesions.

Results of bithermal caloric testing in 83 patients with unilateral peripheral vestibular disease, cerebellopontine angle tumors and vertebrobasilar insufficiency were compared in order to find which response measurements identified the most abnormal responses in each disease category. A laboratory digital computer was used to quantitatively assess each caloric response and a large digital computer was used to statistically compare 110 measurements generated from each caloric test. Of the commonly used response parameters maximum slow component velocity (SVMx) and sum of slow amplitudes (SSA) were most sensitive in each category and duration of response (TDUR) was least sensitive. This order was maintained for the vestibular paresis (VP), directional preponderance (DP) and temperature effect (TE) formulas. The magnitude of DP was significantly correlated with the magnitude of spontaneous vestibular nystagmus and both occurred with approximately the same frequency in peripheral and central disorders. There was no reliable way of separating end-organ from VIII nerve or peripheral from central disorders on the basis of the caloric responses.

Adolescent↗

PubMed1979

The stimulus controlled caloric tests: a reliability study.

Preliminary studies have shown that a new caloric testing method described by Proctor and Dix offers several advantages over conventional methods. However, it had not been established that the Proctor-Dix method would prove reliable and practical when routinely applied in a clinical setting. Therefore, we administered the test to 60 patients referred for evaluation of vestibular function and compared the test scores with results from the conventional Fitzgerald-Hallpike test applied during the same test session. The analysis was based on the average slow phase eye speed of nystagmus during the most intense 20 seconds of individual responses. A close agreement was found between "right-left difference" and "directional preponderance" scores when results of the Proctor-Dix and Fitzgerald-Hallpike tests were compared in the 54 patients who completed all steps in the experiment. Larger differences between the results of the two tests were confined to subjects who were "normal" or only slightly abnormal. Order effects and additional analysis of correlations are discussed. The present study demonstrates that reliable results, comparable to those obtained from conventional methods, can be obtained when the new Proctor-Dix test is applied in a clinical setting.

Caloric Tests↗

PubMed1979

Air caloric testing in otitis media. (preliminary studies).

On certain occasions it becomes important to evaluate vestibular function in a patient with otitis media. The potential application of the air caloric test in evaluating such patients was examined. Patients with unilateral otitis media before and after surgery were studied to answer certain clinical questions. More questions were raised than answers provided. The preliminary conclusions from this study are: 1. Patients with tympanostomy tubes or small perforation of one ear may show a caloric response in the perforated ear equal to that of the intact ear. 2. Patients with a large tympanic membrane perforation on one side may show hyperactive caloric responses on the perforated side. 3. Patients with a moist ear may show inverted horizontal nystagmus to warm air caloric testing. This applies to patients with a large perforation or mastoidectomy cavity. 4. Patients with a dry open mastoid or fenestration cavity are likely to show a hyperactive caloric response on the side of previous surgery, accompanied by vegetative symptoms. This size of the cavity appears to be less important than the presence of the cavity per se. 5. Patients may be safely tested in the early postoperative period.

Air↗

PubMedDate not supplied

[Comparative evaluation of the Fitzgerald-Hallpike caloric test and the monothermal Torok test in lesions of the cerebellar hemispheres].

The Fitzgerald-Hallpike caloric test and the monothermal Torok test were done in 58 patients with damage to the cerebellar hemispheres. In the Fitzgerald-Hallpike test symmetric vestibular reactions were obtained in 79.3% of cases. In the monothermal test vestibular decruitment of only type I and II according to Torok was demonstrated in 68.9% of all cases. This suggests that Torok test may be of great value in the diagnosis of damage to the cerebellar hemispheres. In the light of these results the author concludes that cerebellar hemispheres are responsible for stabilization of vestibulo-ocular reflexes and regulate the adequacy of the vestibulo-ocular responses in relation to the stimulus.

Adolescent↗

PubMed1977

Air caloric test: irrigation technique.

The technique of using air to perform the caloric test is discussed. Greater temperature differences and larger volumes of air are needed to achieve stimulations equal to those caused by water irrigations. Special consideration must be given to the design and operation of air irrigation equipment. The effects of irrigating a wet canal and of misdirecting the air jet are discussed. A new air irrigation apparatus is described.

Air↗