Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0028738 (nystagmus)
 7,431 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Air is a safer and more convenient caloric-irrigating medium than water, but many otologists are reluctant to use it because they suspect that it yields less reliable nystagmus responses. To compare reliabilities of air and water caloric responses, we subjected eight normal persons to 12 irrigations each of 50 degrees C air, 44 degrees C water, 24 degrees C air, and 30 degrees C water. Standard caloric-testing conditions were used, and nystagmus responses were recorded by the method of electronystagmography. We found that the reliabilities of air and water caloric responses were not significantly different. A single observation permitted estimation of response strength within approximalely +/- 5 degrees/sec (95% confidence level), regardless of whether air or water was used as the irrigating medium.
 ...
PMID:Reliabilities of air and water caloric responses. 66 43

The use of air as the caloric medium was investigated and compared to that of water. The ability of air and water to generate surface temperatures close to the fluid outlet temperature was studied by irrigation onto a thermocouple. Results of caloric tests performed with air and water are compared by calculating the average nystagmus response for the hot and cold stimuli for two groups of sixty patients. Also, the number of canal paresis, directional preponderance, mixed, bi-lateral canal paresis and normal responses are compared for each group. Finally, the effect of performing a bi-thermal air caloric on a patient having a unilateral drum perforation is discussed.
 ...
PMID:Air as the caloric stimulus. 66 96

The visual suppression test is one of the visual fixation tests. It is performed by recording caloric nystagmus by ENG, and the maximum slow phase velocity of caloric nystagmus in darkness is compared with the slow phase velocity in light with eyes open. Visual suppression of slow phase velocity of caloric nystagmus is 54 +/- 12% in 52 normal adults ageing from 21 to 40. Visual suppression in normal subjects is not influenced by water temperature used for the caloric test and not changed by background illumination in light. Visual suppression is stronger when the target is closer to the eyes of the subjects. The following abnormalities have been diagnosed by this test: flocculus and nodulus lesions on the side of the lesion; inferior olive lesions; parietal lobe lesions; compensation after unilateral sudden loss of inner ear function.
 ...
PMID:Visual suppression test. 66 72

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.
 ...
PMID:Visual suppression of caloric nystagmus in normal individuals. 85 56

The nystagmus responses of two groups of patients referred for electronystagraphy were compared to test for differences between air and water caloric stimulation. Responses from patients with spontaneous or positional nystagmus or who showed greater than 30% directional preponderance or excitability of labyrinth were removed from the data. The 30 degree C and 44 degree C water and the 24 degree C air produced equivalent responses. The 50 degree C air produced responses with slow component velocities greater than expected; however, the distributions of computed directional preponderance and excitability of labyrinth showed no differences between the air and water caloric stimulation.
 ...
PMID:Nystagmus responses to water and air caloric stimulation in clinical populations. 87 68

A simple modification of caloric vestibular stimulation and its documentation is described to improve the coordination of vestibular investigation in clinics and practice. A volume of 50 cc. 30 degrees and 44 degrees C water is used to irrigate the ear and is administered within a 10 s period. The patient is then evaluated for the rate and duration of nystagmus, using Frenzel lenses. 1182 patients were investigated in this manner and their results were computerized. It was then shown that irrigation with 30 degrees C water was followed by a greater nystagmus reaction (including vertigo and vegetative signs) than with the 44 degrees water.
 ...
PMID:[The caloric vestibular examination: a simplified technique and its normal values (author's transl)]. 90 57

In patients who complain of vertigo or who have equilibrium disorders, it is often difficult to determine the etiology of the disorder, that is to determine whether it is dependent on a peripheral or central vestibular disorder. To attempt to determine the etiology in these cases, we divised a new method, the caloric eye tracking pattern test (CETP-Test). Seventeen normal subjects and 161 patients were tested. The latter group included 33 with peripheral disorders such as Meniere's disease, benign paroxysmal positional nystagmus, and others, and 128 with central disorders such as vertebral basilar artery insufficiency, cervical vertigo, and others, were tested. The cases of central disorders were limited to those patients whose eye tracking pattern before the caloric stimulation was normal. In normal subjects and in patients with peripheral disorders, it is well known that caloric nystagmus has little influence on the eye tracking pattern. In contrast, in patients with central vestibular disorders, caloric nystagmus evokes abnormalities on the eye tracking pattern, either superimposed or saccades, despite the fact that the eye tracking pattern before the caloric stimulation is normal. First we administer the eye tracking stimulation test using a target which moves horizontally at 0.3 cycle per second. Next, we perform the caloric test on the right ear, using 20 c.c. of ice water for 10 seconds. During the evoked caloric nystagmus we administer the eye tracking test once again. The eye tracking pattern is recorded for 20 seconds beginning 50 seconds after the start of the ice water injection. The procedure repeated on the left ear. The results on each case are presented as three patterns of ENG-recording. We may stat that in normal subjects and in patients with peripheral vestibular disorders, visual suppression of caloric nystagmus remains functional. Caloric induced nystagmus does not affect the CETP. In patients with central vestibular disorders, visual suppression of caloric nystagmus does not function properly because of defects in the visual suppression mechanism. Therefore, caloric nystagmus greatly influences the CETP. Consequently, the CETP may not be smooth when CETP test is administered to patients with central vestibular disorders. We may say also that the visual suppression to the vestibular nystagmus is evoked more strongly by pursuing a moving visual stimulus than by gazing a stational target. These results allow for a differential diagnosis between peripheral and central disorders.
 ...
PMID:[Simple method of differential diagnosis of peripheral and central vertigo--development of diagnostic method and studies of 178 cases]. 103 43

To clarify the existence of the vertical component during a caloric nystagmus and the existence of a second phase of the nystagmus, 194 induced incidents of a caloric nystagmus in 29 normal subjects have been analyzed. Each nystagmus episode was recorded by using ENG and an infra-red video camera. The caloric stimuli were given by pouring 5 ml of water at 20 degrees C into the ear at an ear-up position. After irrigation, each subject then assumed a supine or a prone position, with the head bent 30 degrees forward in either position. All recordings contained vertical components that depended on the supine or prone head position and not on the side of the stimulated ear, i.e., an up-beating nystagmus resulted in the supine position and a down-beating nystagmus in the prone position. Further, the vertical component was far stronger in the prone position. In contrast, the horizontal component had larger velocities and was of longer duration in the supine position than in the prone position. When the first phase of the caloric nystagmus ended, the body position was changed 90 degrees, i.e., to a sitting position or a right-ear-down or left-ear-down position. All trials showed a horizontal component during the secondary phase when the head assumed the sitting position. As for the ear-down positions, only when the irrigated ear was moved upwards from the prone position during the secondary phase, an up-beating vertical nystagmus resulted in almost all the trials. These findings suggest that a caloric nystagmus may originate not only from the lateral semicircular canal but also from the vertical canals, and the second phase of a caloric nystagmus may be strongly influenced by the otolithic organs.
 ...
PMID:[The vertical component in a caloric nystagmus and the existence of a second phase of the nystagmus--the possibility of canal otolithic interaction in normal subjects]. 140 29

The aim of this study was to investigate whether caloric nystagmus contains response components that can be attributed to a stimulation of the vertical semicircular canals. Three dimensional eye movement recordings with a dual search coil technique revealed important horizontal, vertical and torsional nystagmus components following irrigation of the external ear canal with cold water in various head positions relative to gravity. Horizontal nystagmus components, i.e. lateral semicircular canal vectors, followed a cosine function of both the pitch and yaw angle of the head relative to gravity, confirming a mainly thermovective mechanism for stimulation of the horizontal canals. Vertical and torsional nystagmus components behaved differently following left and right ear irrigations. Right-left symmetrical vectors emerged only when the vertical and torsional components were transposed into vectors of single semicircular canal directions. The intensity of these vertical semicircular canal vectors as a function of the position of the corresponding canal relative to gravity, however, excludes important thermovective mechanisms acting at the vertical canals. It remains an open question whether these vertical canal vectors represent a non-thermovective caloric stimulation of vertical canal afferents.
 ...
PMID:Three-dimensional analysis of caloric nystagmus in the rhesus monkey. 148 61

Horizontal eye movements in response to vestibular and optokinetic stimulation were investigated in 20 species of marine and fresh water teleosts. Most species performed spontaneous saccadic eye movements in light and in darkness. Successive saccades occurred either at irregular intervals and in different directions (few species), or in bursts of smaller saccades in one direction followed by saccades in the opposite direction (majority of species). Thus, in the latter group the lines of sight shifted cyclically from one side to the other about every 10-15 s. Eye movement responses in goldfish and toadfish were prototypical for two major functional groups. Optokinetic and vestibular nystagmus in the goldfish were much more regular and attained significantly higher gains than in the oyster toadfish. Optokinetic afternystagmus (OKAN) and per-/postrotatory nystagmus lasted about 10-12 s in the goldfish, but only 2-3 s in the oyster toadfish. Bilateral labyrinthectomy in goldfish resulted in optokinetic gains and OKAN durations that were very close to those of intact toadfish. These results indicate the presence (in goldfish) and the absence (in toadfish) of a functioning velocity storage network, respectively. Other non-ostariophysan teleosts failed to show a 'goldfish-like' response pattern as well. Ostariophysan species differed in their reflex performance as well. A 'goldfish-like' response pattern was observed in five of the seven cypriniform species and in two of the four characiform species but not in the four siluriform species. Positively correlated, combined response properties suggest that some species are better equipped for gaze stabilization at higher velocities than other species. These behavioral differences may parallel different specializations in locomotor pattern and mode of life. Absence of a functioning velocity storage network in bottom-dwelling teleosts (as in Amphibia) may be related to the sporadic, slow locomotion of these species and the resulting small requirements for continuous gaze stabilization during self-motion at higher velocities.
 ...
PMID:Differences in optokinetic and vestibular ocular reflex performance in teleosts and their relationship to different life styles. 149 51


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>