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At least 1,405 records · Page 78Linked to original sources
PubMed1979

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.

Air↗
PubMed1991

Determining side of vestibular dysfunction with rotatory chair testing.

Determining side of vestibular lesion remains a challenging task during neurotologic investigations, particularly if auditory lateralizing signs are absent. Traditionally, absent or decreased caloric response has been regarded as evidence of unilateral vestibular deficit. But, the inability of the chair test to detect side of lesion has been generally accepted because rotation stimulates both end organs. A retrospective study postulated and tested a hypothesis that low-frequency asymmetry of sinusoidal harmonic acceleration (SHA) testing can determine side of lesion when phase is abnormal. The present prospective, double-blind study was designed to further test the retrospective study hypothesis. Results showed that SHA asymmetry detects side of unilateral vestibular deficit when phase is abnormal in 97% of cases.

Caloric Tests↗
PubMed1986

Unilateral sensorineural hearing loss: analysis of 200 consecutive cases.

The spectrum of diseases diagnosed and the protocol used in the investigation of 200 consecutive patients with unilateral sensorineural hearing loss (SNHL) is presented. The diagnostic tests found most useful in defining the site of the lesion were a combination of a well-masked pure tone audiogram, speech discrimination score (SDS), acoustic reflex test (ART), and a vestibular evaluation using photoelectric nystagmography (PENG) and the Torok Monothermal Differential Caloric Test. With this protocol, the site of the lesion was correctly defined in 94% of patients with unilateral progressive SNHL. Laboratory and radiological studies confirmed a variety of lesions other than acoustic tumors. It is, therefore, felt that the primary objective of investigations should be to define the site of the lesion rather than aim to diagnose a specific disease entity.

Adolescent↗
PubMedDate not supplied

Visual suppression of caloric nystagmus in normal individuals.

The effects of opening of the eyes and of ocular fixation upon caloric nystagmus were investigated during the period of maximum intensity of caloric nystagmus in a series of 32 normal individuals. The percentage reduction in slow-phase velocity induced depended upon the test conditions, but, on the other hand, did not depend upon the temperature of the water applied as caloric stimulus. This latter fact favors the theory of visual suppression of the caloric test. Another striking finding was that a clear correlation definitely existed between the percentage reduction of suppression in slow-phase velocity and that in the multiplication product of amplitude by nystagmus frequency (P.A.F.) during the period of eye opening and ocular fixation. The percentage of suppression in slow-phase velocity is interchangeable with that in P.A.F., which broadens the practical scope of the routine test.

Adolescent↗
PubMed1986

Otoneurological findings in Friedreich's ataxia and other inherited neuropathies.

Fifteen cases of Friedreich's ataxia (FA) were examined using an otoneurological test battery that included tone and speech audiometry, the synthetic sentence identification (SSI) test, impedance audiometry, cortical auditory-evoked response (CAER), brainstem auditory-evoked response (ABR) and electronystagmography. We also obtained ABR and CAER findings in 2 cases of familial spastic paraplegia, in 5 cases of Charcot-Marie-Tooth disease and 6 in cases of atypical FA of uncertain classification. The results of puretone and impedance audiometry were normal in all cases. ABR could not be elicited in 11 FA patients and were abnormal at higher intensity levels in the remaining 4 patients. In these 4 cases, however, the latencies were normal. ABR did not show any marked abnormalities in patients with familial spastic paraplegia or Charcot-Marie-Tooth disease. CAERs were normal in all 28 patients. ABRs tended to be absent with the progression of FA. ABR thresholds were correlated with the Inherited Ataxias Clinical Rating Scale score, which is an index of the severity of the illness. ABRs contributed to the diagnosis or to excluding FA in patients with an atypical clinical picture. The absence of ABRs and the normal latencies of the waves, when evoked, agree with the pathological finding of a reduction of fibers in the spinal root ganglion. SSI abnormalities and vestibular findings agree with this hypothesis.

Adolescent↗
PubMed1989

The caloric test in electronystagmography.

A wealth of information concerning the caloric test has accumulated since the test was introduced more than eight decades ago. Both convective and nongravity-dependent forces on endolymph are believed to underlie the response at the end-organ level. Higher-order influences are equally important and make the test findings highly dependent on specific test conditions. Slow-component eye velocity is the most widely accepted index of vestibular response, although success using nystagmus beat frequency has also been reported. Both bithermal and monothermal calorization sequences have been studied. Standardization of technique and a consensus on methods of interpretation will be necessary for the determination of the optimal clinical caloric test.

Caloric Tests↗
PubMed1988

[The significance of slow flows for the caloric excitability of the vestibular organs in weightlessness].

Bárány's theory of caloric nystagmus is based on the assumption of fluid convection in the perilymph. It was a great surprise that caloric nystagmus could be demonstrated in weightlessness as well, i.e. under conditions in which thermoconvection cannot occur because of loss of gravity. This phenomenon was explained by different theories, each of which is bound to certain assumptions. Experimental investigations and mathematical approaches concerning fluid mechanics of the endolymph under calorisation, indicate that creeping flow must be an important factor. This flow--not taken into consideration so far--may explain caloric nystagmus in weightlessness as well as some difficult problems in caloric excitability on farth.

Caloric Tests↗
PubMed1988

[Effect of the stimulus medium--water or air--in thermal evaluation of the vestibular apparatus].

The influence of the stimulus medium in thermal vestibular tests has been investigated by many authors, comparing nystagmus reactions after air and water irrigations. We first measured temperature changes in the ear canal and in the horizontal semicircular canal after both kinds of stimuli, using human temporal bone preparations, which were placed in a water bath of 37 degrees C. Irrigations were done with air of 45 and 27 degrees C with a flow of 5 l/min during 45 s and with 100 ml water of 44 and 30 degrees C during 30 s. The maximum temperature changes in the ear canal are almost equal after both kinds of irrigation (see Figs. 2 and 3). The change of temperature, however, lasts longer after water irrigation. The time constants are 20 and 57 s for the decay after warm and cold water irrigation and 9 and 20 s after air irrigation, respectively. The maximum temperature change in the lateral part of the horizontal semicircular canal is 0.4 and -0.3 degree after warm and cold irrigation with water. The corresponding values after irrigation with air are 0.1 and -0.15 degree. In addition, we investigated the effect of irrigating temporal bone preparations with perforated tympanic membranes (Fig. 4). After irrigation with air of 45 degrees C, the temperature in the horizontal semicircular canal decreased due to evaporation of humidity in the tympanic cavity. The equipment of choice for the irrigation of such ears is a stimulator reported by Scherer, where water flows through a silicon bubble which coats the ear canal.(ABSTRACT TRUNCATED AT 250 WORDS)

Air↗
PubMed1985

[Comparative studies of the results of caloric vestibular tests and classical torsion swing tests].

Vestibular Paresis (PL) and Directional Preponderance (PD) are the measurements found on caloric testing described by Fitzgerald and Hallpike (1942); frequency nystagmogram is the typical result of the torsion swing test of the French school. The differences between the two methods stimulated us to make a comparison of the results. Seventy-eight patients affected by unilateral peripheral vestibulopathy in various degree of compensation were submitted to both tests. Frequency nystagmogram was transformed, for calculation purposes, into normalized percentual difference (SSP). SSP and PD were found highly significantly correlated and were considered as equivalent from the statistical point of view. SSP and PL were completely independent at slow velocity stimulation. Using high velocities of stimulation a correlation was demonstrated between SSP and PL; unfortunately to the elevation of SSP corresponds a so minimal increasing of PL that the correlation is scarcely useful from the clinical point of view.

Caloric Tests↗