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)

Vestibular dysfunction was chemically induced in male meadow voles (Microtus pennsylvanicus) by intratympanic injections (30 mg per side) of sodium arsanilate (atoxyl). The control group received intratympanic injections of isotonic saline. After a one-week recovery period the voles were behaviorally assayed for integrity of their labyrinthine systems. All subjects were tested for the presence of the air-righting reflex and body rotation-induced nystagmus. Three weeks later a multivariate assessment of spontaneous motor activity of the voles was carried out in the automated Digiscan Activity Monitor. In addition, the swimming behavior of the voles was examined. Voles with vestibular dysfunction exhibited pronounced postural abnormalities (head dorsiflexion), were not able to swim with their nose above the water for a 1 min test period, and displayed disorientation and thrashing movements. In the Digiscan activity test the atoxyl-treated voles displayed significantly more activity in the horizontal measures (Ps less than 0.01), including greater distance travelled per movement and greater speed of movements, relative to the control animals. The labyrinthectomized group also spent significantly (P less than 0.05) less time in vertical movements and exhibited significantly more time in stereotypic behavior (P less than 0.01), relative to controls. Atoxyl-treated voles also showed significantly less thigmotaxis (wall-hugging) than the control animals (P less than 0.01). In general, changes in spontaneous behavior observed in the sodium arsanilate-treated voles were consistent with the presence of postural and balance abnormalities and a redirecting of exploratory vertical movements toward horizontal locomotion to the extent that these animals were clearly hyperactive in this dimension. The multivariate behavioral assessment available in the Digiscan Activity Monitoring system, thus seems to be especially useful in the examination of behavioral components affected by vestibular dysfunction.
 ...
PMID:Sodium arsanilate-induced vestibular dysfunction in meadow voles (Microtus pennsylvanicus): effects on posture, spontaneous locomotor activity and swimming behavior. 157 Oct 99

An animal model of experimental perilymphatic fistula (EPLF) was developed in the guinea pig in order to study vestibular pathophysiology. In experimental animals, 4 microL of perilymph was suctioned from one cochlea via the round window membrane. Changes in vestibular function were as follows. 1) During the acute stage (5 hours postoperatively), spontaneous nystagmus directed toward the normal side was noted in 57.4% of the EPLF animals. This lasted less than 24 hours. 2) One week postoperatively, direction-fixed positional nystagmus toward the lesioned ear was present in 22.7% of the EPLF animals, especially when the lesioned ear was positioned inferiorly. 3) With the ice water caloric test, no response was present in 58.1% of the EPLF animals and an irregular response was found in 22.6% of them, 1 week postoperatively. These results tend to indicate that tests of vestibular function may differentiate between patients with Meniere's disease and those with perilymphatic fistula. Histologic findings indicate that a floating labyrinth is the cause of positional nystagmus and caloric irregularity. The absence of caloric responses was associated with collapse of the vestibular labyrinth.
 ...
PMID:Vestibular pathophysiologic changes in experimental perilymphatic fistula. 162 10

A 34-year-old male presented with central diabetes insipidus accompanied by upbeat nystagmus and cerebellar ataxia. The patient without family history of above began to walk at the age of 2 years. Polyposia and polyuria were noted at the age of about 4 years. Dysbasia developed at the age of about 7 years. From the age of 30, lalopathy appeared together with various clinical symptoms including cataracts, disturbed intelligence, upbeat nystagmus, abnormal ocular movements, ataxic speech, cerebellar ataxia and reduction of the muscle tone of the limbs, and hypotonic polyuria. Abnormal laboratory findings included square wave jerks, upbeat nystagmus, and "bow tie" nystagmus by EOG, atrophy of the cerebellum and the brainstem by CT, a slight prolongation of the P300 latency, and a central diabetes insipidus pattern by water deprivation test and Carter-Robbins tests. There have been occasional reports of diabetes insipidus complicated by cerebellar ataxia, but in no earlier reports has diabetes insipidus been concurrent with abnormal ocular movements such as upbeat nystagmus. A degenerative disease primarily of the posterior lobe of the hypophysis, hypothalamus, cerebellum, and brainstem was suspected.
 ...
PMID:[Central diabetes insipidus complicated with upbeat nystagmus and cerebellar ataxia]. 162 38

The term "caloric irregularity" was coined to refer to a gross irregularity in the amplitude and/or frequency of a caloric-induced nystagmus, having a variable slow-phase velocity and prolonged duration. Twelve of 46 guinea pigs with experimentally induced perilymphatic fistula had irregular responses to the ice-water caloric test 1 week after creation of a fistula. The long-term vestibular consequences in animals with caloric irregularities were either resolution and return to normal function (i.e. caloric return) or continuing deterioration to canal paresis. Morphological examination of ears with caloric irregularity revealed that there had been partial collapse of the membranous labyrinth and the creation of a floating labyrinth.
 ...
PMID:Caloric irregularity in experimentally induced perilymphatic fistula. 164 73

Horizontal positional nystagmus having characteristics similar to ice water caloric nystagmus was induced by injecting heavy water into the rabbit middle ear cavity or facial nerve through the stylomastoid foramen. Furthermore, with general administration of glycerol to normal subjects, horizontal positional nystagmus as with general administration of heavy water to experimental animals was observed. It is possible that alteration of the specific gravity arising from infiltration of heavy water or glycerol into the labyrinth accounts for the manifestation of positional nystagmus. These studies on positional nystagmus may be one of the means to elucidate the mechanism of caloric nystagmus and to examine the function of the human blood-labyrinth-barrier.
 ...
PMID:Positional nystagmus due to alteration of the specific gravity in the labyrinth. 165 97

Three types of commercially available caloric irrigation units--air, water, and closed-loop--were evaluated for nystagmus response patterns and comfort. Electronystagmographic recordings were analyzed for slow-phase velocity, response duration, amplitude, frequency, and test-retest reliability. Significant differences were found among the three types of irrigators, between warm and cool irrigators, and between male and female subjects. Test-retest reliability was adequate for all three units. Subjects clearly favored the closed-loop system over the water and air irrigators, but the water irrigator yielded the most robust caloric response.
 ...
PMID:Comparison of responses to air, water, and closed-loop caloric irrigators. 173 67

Caloric nystagmus and post-rotatory nystagmus were recorded with and without head-out water immersion. As water immersion reduces body weight by about 90% owing to buoyancy, it decreases somatosensory inputs. Thus water immersion can be used to simulate a weightless environment. Caloric nystagmus was enhanced significantly by water immersion; however, post-rotatory nystagmus was not. These findings demonstrate that caloric nystagmus is easily affected by water immersion which decreases somatosensory inputs, but that post-rotatory nystagmus is not.
 ...
PMID:Effect of water immersion on post-rotatory and caloric nystagmus. 192 2

It is well known that the development of motor function is frequently retarded in children with congenital deafness, particularly in cases of inner ear anomaly. The relation between the results of vestibular function tests and the development of motor function in 4 children with inner ear anomaly is studied. CT scan obtained from these cases revealed the absence of lateral semicircular canals in both ears. There were no responses to caloric stimulation using 40 ml ice-water. However, damped rotation test elicited per-rotatory nystagmus in all cases. In contrast to this result, the same nystagmus was provoked only in 2 cases in Barany rotation test. Early development of motor functions, especially that of first walk, was more retarded in the 2 cases showing no per-rotatory nystagmus in Barany rotation test than in the other 2 positive cases.
 ...
PMID:The relation between motor function development and vestibular function tests in four children with inner ear anomaly. 192 38

It is well known that inverted caloric nystagmus is seen during air caloric testing in cases of chronic otitis media. The mechanism of inversion and its clinical significance are discussed here. Temperature changes in the tympanic cavity and external ear canal were measured with a microthermister and a digital tester in seventeen ears with tympanic membrane perforation, during bithermal air caloric testing. The tympanic cavity mucosa was cooled by hot stimulation because of the evaporation of heat. When the perforation was closed or humidified air was used, the tympanic cavity mucosa was not cooled by hot stimulation and the inverted caloric nystagmus changed to a normal response. Inverted caloric nystagmus occurred in 30.4% of 335 ears affected by chronic otitis media with perforation. Inverted caloric nystagmus occurred in 90 ears with hot stimulation and in 12 ears with cold stimulation. Inverted caloric nystagmus turned to normal response after myringoplasty in all of 10 ears. The cooling effect caused by evaporation of water from the moist middle ear mucosa during dry air blowing and direct thermal conduction to the vestibulum through a perforation of the ear drum and inversion of the endolymphatic convection seemed to cause the inversion.
 ...
PMID:[Inverted caloric nystagmus of perforated ears upon air caloric stimulation]. 204 Sep 15

Cumulative phase nystagmic responses to caloric stimulation was examined in 72 healthy subjects without any balance disorders and aged 15-55 years. After detailed problem-oriented anamnesis had been taken, vestibular apparatus function was examined by caloric water stimulation using its standard values (44 degrees C, 30 degrees C and if necessary, 18 degrees C) together with electronystagmographic registration of nystagmus. During each labyrinth caloric stimulation, data on vertigo, nausea and vomiting have been recorded. Results have shown that there were 37-74 nystagmic jerks to caloric stimulation, and 24-62 to cold stimulation.
 ...
PMID:[Electronystagmographic values of the caloric vestibular response in the cumulative phase in healthy people]. 207 5


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