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The caloric test procedure as suggested by Fitzgerald & Hallpike is still widely used. With a carefully standardized procedure it is well suited to identify the affected side in patients with unilateral vestibular impairments. By repeated testing it is also possible to follow the course of a vestibular affection.
Sinusoidal harmonic acceleration test (SHA) was performed on 89 patients with peripheral vestibular disorders. The results of SHA were compared with that of the alternate bilateral caloric test. The patients were classified into 3 groups according to the degree of asymmetry of the caloric response (CP). In the lowest frequency rotation (0.01 Hz), the phase lags for all 3 groups were smaller than the normals. The phase lags tended to approach the normal value as the frequency of rotation increased, resulting in a phase lag curve of typical peripheral type. Even subjects without CP revealed a decreased phase lag. This indicates that the SHA at low frequencies is more sensitive than the caloric test for diagnosing a vestibular lesion. In the 0.02 Hz range, the phase lag of the patient without CP were close to the normals, however, the phase lags of the patients with severe CP were smaller than the normals. This suggests that SHA to 0.02 Hz should be given more credence, since it appears to be critical for diagnosing more extensive lesions.
OBJECTIVE: To test the performance of the head-impulse and caloric tests in terms of sensitivity, specificity, and predictive efficiency. STUDY DESIGN: This was an open and prospective study conducted at a tertiary care center in which 265 patients were subjected to the head-impulse test and caloric test on the same day. The results of the head-impulse test were considered as normal or pathologic. In a similar way, the caloric test was rated as normal when the difference in canal paresis was less than 22 percent and directional preponderance less than 28 percent, and abnormal if canal paresis was more than 22 percent and/or directional preponderance was more than 28 percent. MAIN OUTCOME MEASURES: The results of each test were compared with obtain the specificity, sensitivity, and positive and negative predictive values. A receiver operating characteristics (ROC) curve was obtained from the false-alarm rate and the hit rate value of the head impulse test. RESULTS: The specificity of the head impulse test was 0.91 and the sensitivity was 0.45. The positive predictive value was 0.92, the negative predictive value was 0.41, and the area under the ROC curve was 0.866. A canal paresis value of 42.5 percent was considered to be the limit of the normal response, as seen when the head impulse test was used to predict a normal or abnormal result in a given patient. CONCLUSION: The head impulse test, when used as a bedside test, and the caloric test are by no means redundant methods. The information obtained form both can be used in combination to obtain a better insight into the degree of vestibular dysfunction of patients.
A simple and time-saving office procedure is presented. The test consists of placing a small piece of cotton-wool soaked in ice water against the tympanic membrane. We term this test the Cold mini caloric test. Our method has been compared quantitatively with the Bithermal caloric test in 20 normal controls, 50 unspecific dizzy patients with no vestibular or obvious neurological disorder, 22 Menière ears, 12 acoustic neuromas and 20 cases of vestibular neuronitis. The comparison between the two methods has shown the Cold mini caloric test to present consistently similar, though somewhat shorter, nystagmic reactions. There was no difference in the clinical information obtained by the two methods.
A new technique was designed for vestibular testing with an air caloric stimulator. With this technique, the temperature threshold necessary to induce caloric nystagmus was measured as air temperature decreased at a constant rate (from 37 degrees C). As a pilot study, an air caloric test with continuous thermal change was done at 6 different rates of decrease: 0.01, 0.03, 0.05, 0.1, 0.15 and 0.2 degrees C/s. The rate of 0.05 degrees C/s gave the smallest standard deviation for temperature threshold in normal subjects. This deviation had the narrowest normal limits of all ordinary caloric tests when the coefficient of variation was compared (standard deviation/mean x 100). No discomfort was observed during or after the air caloric test with continuous thermal change at this rate.
The use of caloric testing is widespread in hospital audiology departments. This paper describes contamination of the caloric water tanks with the organism Acinetobacter anitratus and the changes in practice instituted to eliminate this risk to patients.
The cold-warm caloric test is performed with water irrigation, using a hot temperature of 44 degrees C and a cold temperature of 30 degrees C, which are thermally equidistant from the body temperature 37 degrees C. However, the 30 degrees C irrigation nearly always produces a stronger nystagmic response than that of the 44 degrees C stimulation. The purpose of this study is to investigate the difference in nystagmic response between cold and hot stimulation. The achieved hot (44 degrees C) and cold (30 degrees C) water samples were prepared, and irrigation was with a disposable plastic syringe. Temperature changes in the external auditory canal were monitored by tympanic thermometry during the cold-warm caloric test. Maximal slow phase velocity and the duration of induced nystagmus were recorded on an electro-nystagmograph. The following conclusions were drawn; 1) The average normal external auditory canal temperature was 36.8 degrees C, and there was no side difference between the right and left ears. External canal temperature was higher than that of the axilla. 2) When 20 ml of 30 degrees C water was instilled the temperature change in the external canal was larger than that in response to the 44 degrees C water and the maximal slow phase velocity of nystagmus for cold stimulation was stronger than that for hot. However, the duration of nystagmus for the cold was not significantly longer than that of the hot stimulation.
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.
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.
This study considered whether the monothermal (MT) caloric test could predict the normality of the full conventional bithermal (BT) caloric test, and therefore be an alternative to full caloric investigation. This would have the advantages of reducing test time and patient discomfort as only two caloric tests would be needed instead of four. 744 BT caloric investigations were examined, and the unilateral weakness and directional preponderance calculated for the BT and the MT stimuli. By defining the BT results as the standard, the false-positive and false-negative results of the MT test were derived. Overall using very strict MT difference criteria of less than 5% and no spontaneous nystagmus, false-negative rates for the cool MT were very low (< 1%) and better than the warm MT (< 7.1%) suggesting that the cool MT was a reliable screen test. However, unacceptably high false-positive rates were produced reflecting more than 3/4 of normal BT results failing the MT criterion. This unacceptable false-positive rate decided against implementing the MT test at our facility. The results of this study however have guided the use of the cool air-stimulus first during BT testing and, when completion of the BT is not possible or inadvisable, satisfying the stringent MT criterion confidently indicates with a probability of > 99% the absence of an abnormal BT result.
Hot (44) and cold (30) caloric test are the most common tool to investigate canal activity. Many authors, otherwise, have pointed out that this method is very long needing about five minutes of interval among the irrigations and that it is often troublesome for the patient that is exposed four times to a vertigo. To investigate vestibular function some of these authors tried to use the hot monothermal test alone but results were poor. The aim of this study was to propose a shorter and a less troublesome method of investigation and to introduce a new diagnostic possibility not pointed out with traditional caloric test. We have tried to determine some new reliable diagnostic criteria modifying confidential value of the hot monothermal test and considering the eventual presence of the nystagmus and its direction during the cold simultaneous test; on the basis of this results we are able to distinguish a normal vestibular function from a labyrinthine preponderance or a directional preponderance or an aspecific disfunction. When the vestibular function is normal or when there is a labyrinthine preponderance our results are in total accord with those achieved with the traditional bithermal test. Therefore we suggest to use always the hot monothermal test associated with the cold simultaneous test, performing the two cold irrigations in additions, only in the case of a directional preponderance or an aspecific disfunction.
Vertical nystagmus may occur in caloric testing when only horizontal is expected. We examined this occurrence in 112 normal subjects and in 339 patients with dizziness. Vertical nystagmus was found in 29 percent of normals and in 12 percent of patients with dizziness, more often with hot than cool caloric stimuli and it is always accompanied by horizontal nystagmus. The finding occurred with peripheral and central nervous system diagnoses as well as with patients whose dizziness was considered psychogenic or was undiagnosed. Maximum slow component velocity (SCV) of vertical nystagmus was usually half or less than that of the nystagmus in the horizontal lead. The SCV time profiles of the nystagmus in horizontal and vertical leads differed considerably. Possible origins of vertical nystagmus are discussed. Whatever the origin, it is clear that the finding of vertical nystagmus in routine caloric testing does not automatically denote disease of the central nervous system.
OBJECTIVE: To investigate the complementary relation between head shaking nystagmus (HSN) and bithermal caloric test. METHOD: All of the 60 patients with vertigo were tested with bithermal caloric test, HSN and audiological tests. RESULT: There were 19 patients with normal CP and HSN, in which 8 had shared the same direction (towards the uninjured side) and 11 indicated opposite direction(HSN towards the lesioned side). Ten patients had normal CP with no HSN. Eight patients had abnormal CP and no HSN. In 23 patients with abnormal CP and HSN, HSN in 19 patients had opposite direction against that of CP and HSN in 4 patients had the same direction with that of CP (towards the lesioned side). CONCLUSION: HSN and bithermal caloric test had the complementary effects and it is helpful to interpret the vestibular function more accurately if they are applied together.
The caloric test was conducted on pigeons in two different ways: 'external calorization', stimulation by irrigation of the external ear canal, and 'internal calorization', stimulation through a coil winded around one horizontal semicircular canal. Different temperatures and amounts of irrigation water were tried out to obtain caloric responses. Internal calorization proved to be more effective than external calorization in a wide range of temperature levels. The experiments proved that a kind of modifying effect of the external ear canal sensory innervation exists on the vestibular caloric test.
Caloric nystagmus was investigated in 50 normal subjects with stimulation of the temperatures 30, 33, 35, 39, 41, and 44 degrees C. Mean values of the duration and the eye speed of the slow phase of adjacent temperatures were significantly different. No difference could be demonstrated between the equidistant temperatures 30/44 and 35/41 degrees C, but the response was significantly stronger with 35 than with 39 degrees C. This indicates that the caloric zero, i.e., the theoretical neutral temperature, is higher than 37 degrees C. The caloric zero was determined by extrapolation of the regression lines of the mean values for the six temperatures investigated. Determination by means of maximum eye speed of the slow phase values showed to be more accurate than with the duration, probably due to smaller interindividual variations of the responses.
The most commonly used method of testing the responses of the labyrinths is Water Stimulated Bithermal-Caloric Test of Fitzgerald-Hallpike. Before planning an otiatric surgery it is necessary to support by documentary evidence the responses of the vestibular organ in the ear planned to be operated on, however, irrigation with water may cause damage to structures of the ear and may intensify symptoms of the diseases and eventually make the treatment more difficult. In some centers where Water Stimulated Bithermal-Caloric Test were used alone, or a combination of air and water stimulated caloric test were performed, it seemed to be difficult to compare the results of both tests. In this study I tried to establish parameters of stimuli obtained in the Air Stimulated Bithermal-Calorics test that evoked nystagmus, similar to those obtained in the Fitzgerald-Hallpike water stimulated test. It was determined that the duration of nystagmus in both water and air stimulated bithermal-caloric tests were identical when the temperature of "cold" air wave was 26 degrees C, whereas "warm" air wave had the temperature of 48 degrees C and the time of stimulation for both tests was 80 seconds.
In a previous report (1) the author described a new air caloric test with continuous thermal change. In this study, 19 patients with vestibular disorders were examined with this technique, and the results were compared with the results of the water caloric test (30 degrees C, 50 ml, 20 s) in the same subjects. A difference in interaural response to the air caloric test was noted in 9 of the 19 patients (47.4%), greater than with the water caloric test, 5 of 19 (26.3%). The detectability of vestibular disorders with the air caloric test (28 of 38 ears; 73.7%) was significantly higher than that with the water caloric test (8 of 38 ears; 21.1%) (p < 0.01). The air test appeared to estimate vestibular function more precisely, as stimulation by this method is too weak to cause vestibular recruitment.
Vertical nystagmus elicited by caloric testing does not necessarily mean there is central pathology. In a patient with confirmed peripheral vestibular disease, caloric stimulation produced an intense vertical nystagmus, which showed all the features of a caloric nystagmus. The patient had bilateral mastoid cavities, allowing easy stimulation of the posterior semicircular canal, using air. At the same time, a unilateral horizontal semicircular canal functional loss was observed, raising the possibility of dissociated canal dysfunction.