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

The effect of ethacrynic acid (ETA) upon pendular rotation nystagmus and paralytic nystagmus was examined using 61 guinea pigs. 100 mg/kg ETA reduced these nystagmus but 30 mg/kg ETA had on effect. Galvanic nystagmus, Bechterew's compensatory nystagmus, OKN and EEG were not affected by 100 ng/kg ETA. These results are highly suggestive that the inhibition of the peripheral vestibular nystagmus by ETA is mainly due to the reduction of the ampullar endolymphatic potential.
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PMID:Effect of ethacrynic acid upon the peripheral vestibular nystagmus. 31 40

A right labyrinthectomy was performed in rats 5 months after a left labyrinthectomy. Spontaneous compensation of balance functions after both operations was assessed by observing nystagmus, rolling about the longitudinal axis, circular walking and head tilt. Decompensation, induced by brief halothane-NO anaesthesia, released predominantly symptoms characteristic for the period after the first labyrinthectomy. Bechterew symptoms could, however, also be decompensated. It is concluded that Bechterew compensation does not re-establish balance in the central vestibular system. Dysbalance and vertigo of vestibular origin is thus conceivable in patients after all peripheral vestibular function has been lost.
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PMID:Bechterew decompensation. 348 11

Bechterew's phenomenon, or reversal of post-unilateral labyrinthectomy spontaneous nystagmus following subsequent contralateral labyrinthectomy in experimental animals, has been known for 100 years. However, it is rarely observed in humans. This paper describes Bechterew's phenomenon in a patient following successful mitral valve replacement and aorto-coronary bypass. The observations are compatible with a recent study which postulates that intervestibular commissural pathways, forming closed loops for neural signals between the vestibular nuclei, may be the main site for vestibular compensation which is associated with the recovery of balanced resting activity in the bilateral vestibular nuclei (Galiana 'et al., 1983). Using simple analytic arguments, it is found that compensation of nystagmus following unilateral labyrinthectomy, the Bechterew's phenomenon and its compensation, and recovery nystagmus could all result from long-term neural changes at the level of commissural connections.
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PMID:Bechterew's phenomenon in humans. A new explanation. 659 21

The nucleus of the optic tract (NOT) is associated with the generation of optokinetic nystagmus (OKN), whereas the olivary pretectal nucleus (ol), which lies embedded in the primate NOT, is believed to be essential for the pupillary light reflex. In this anatomical study of the pretectum, projections from NOT and ol to structures around the oculomotor nucleus were traced in the monkey, to determine which cell groups they innervated. 1. 3[H]-leucine injections were placed into NOT and ol, and labelled terminals were observed just outside the classical oculomotor nucleus (nIII), in the "C-group' and midline cell clusters, both of which contain small motoneurons of the extraocular eye muscles. In addition, there were strong projections to the lateral visceral cell column of the Edinger-Westphal complex (lvc), but not to the Edinger-Westphal nucleus (EW) itself. All of these projections were mainly contralateral. 2. NOT efferents terminated over the ipsilateral medial accessory nucleus of Bechterew (nB), but not over the adjacent nucleus Darkschewitsch. 3. Injections of a retrograde tracer into the oculomotor complex showed that the pretectal afferents described above originated mainly from the dorsomedial part of NOT and from ol. 4. The use of a transsynaptic retrograde tracer, tetanus toxin fragment (BIIb), established the monosynaptic nature of the connection between dorsomedial NOT (contralaterally) and ol (bilaterally), to the small extraocular motoneurons outside classical nIII. The "C-group' motoneurons may play a role in vergence, and lvc in pupillary constriction and depth of focus. Our results imply that NOT and ol participate in the control of some aspects of the near-response, which may be important in the generation of some components of OKN in primates.
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PMID:Pretectal projections to the oculomotor complex of the monkey and their role in eye movements. 869 92

Vestibular compensation for the postural and oculomotor deficits induced by unilateral labyrinthectomy is a model of post-lesional plasticity in the central nervous system. Just after the removal of one labyrinth, the deafferented, ipsilateral vestibular nucleus neurons are almost silent, and the discharge of the contralateral vestibular nucleus neurons is increased. The associated static disorders disappear in a few days, as normal activity is restored in both vestibular nuclei. In this study, we searched for traces of vestibular compensation in isolated whole brains taken from adult guinea-pigs. The electrophysiological responses evoked in control brains were compared to those evoked in brains taken from animals that had previously been labyrinthectomized. Guinea-pigs compensated for an initial labyrinthectomy within three days. In vivo, subsequent deafferentation of vestibular nucleus neurons on the intact side triggered "Bechterew's phenomenon": a new postural and oculomotor syndrome appeared, similar to the one induced by the first lesion, but directed to the newly deafferented side. These disturbances would be caused by the new imbalance between the discharges of neurons in the two vestibular nuclei triggered by the second deafferentation. Experiments were designed to search for a similar imbalance in vitro in brains taken from labyrinthectomized animals, where the intact vestibular nerve is cut during the dissection. Isolated whole brains were obtained from young guinea-pigs at various times (one to seven days) following an initial labyrinthectomy. An imbalance between the resting activities of medial vestibular nucleus neurons on both sides of the brainstem was revealed in brains taken more than three days after the lesion: their discharge was higher on the compensated, initially lesioned side than on the newly deafferented side. In some cases, an oscillatory pattern of discharge, reminiscent of the spontaneous nystagmus associated in vivo with Bechterew's syndrome, appeared in both abducens nerves. These data demonstrate that most of the changes underlying vestibular compensation persist, and can thus be investigated in the isolated whole brain preparation. Brains removed only one day after the lesion displayed normal commissural responses and symmetric spinal inputs to vestibular nucleus neurons. However, an unusually large proportion of the neurons recorded on both sides of the preparation had very irregular spontaneous discharge rates. These data suggest that the first stages of vestibular compensation might be associated with transient changes in the membrane properties of vestibular nucleus neurons. Brains taken from compensated animals displayed a significant, bilateral decrease of the inhibitory commissural responses evoked in the medial vestibular nucleus by single-shock stimulation of the contralateral vestibular nerve. The sensitivity of abducens motoneurons on the initially lesioned, compensated side to synaptic activation from the contralesional vestibular nucleus neurons was also decreased. Both changes may explain the long-term, bilateral decrease of vestibular-related reflexes observed following unilateral labyrinthectomy. Spinal inputs to vestibular nucleus neurons became progressively asymmetric: their efficacy was increased on the lesioned side and decreased on the intact one. This last modification may support a functional substitution of the deficient, vestibular-related synergies involved in gaze and posture stabilization by neck-related reflexes.
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PMID:Plastic changes underlying vestibular compensation in the guinea-pig persist in isolated, in vitro whole brain preparations. 1046 24

Ankylosing spondylitis (AS) is a chronic inflammatory disease of unknown origin affecting up to 1% of the population. Little is known about audiovestibular impairment in patients with AS, especially the presence of cochleovestibular dysfunction in these patients. To investigate audiovestibular manifestations in AS, we studied a series of 50 consecutive patients who fulfilled the modified New York diagnostic criteria for AS and 44 matched controls. Individuals with history of cardiovascular disease, cerebrovascular complications, peripheral artery disease, renal insufficiency, syphilis, Meniere and other vestibular syndromes, infections involving the inner ear, barotrauma, or in treatment with ototoxic drugs were excluded. Most patients with AS were men (80%). The mean age at the time of study was 52.5 years, and mean age at the onset of symptoms was 34.4 years. Twenty-nine (58%) patients showed abnormal hearing loss in the audiogram compared to only 8 (18%) controls (p < 0.001). Values of audiometric tests (pure-tone average and speech reception threshold) yielded significant differences between patients and controls (p < 0.001). It is noteworthy that the audiogram shape disclosed a predominant pattern of high-frequency sensorineural hearing loss in AS patients (50%) compared to controls (18%) (p = 0.002). Also, AS patients exhibited abnormal vestibular tests more commonly than controls. AS patients had an increased frequency of head-shaking nystagmus (20%) compared to controls (0%) (p < 0.001). Moreover, patients (26%) showed a significantly increased frequency of abnormal caloric test compared to controls (0%) (p < 0.001). Finally, a significantly increased frequency of abnormal clinical test of sensory integration and balance with a predominant vestibular loss pattern was observed in patients (36%) compared to controls (5%) (p < 0.001). In conclusion, the current study demonstrates strong evidence for inner ear compromise in patients with AS.
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PMID:Audiovestibular manifestations in patients with ankylosing spondylitis. 2135 43

A patient with downbeat nystagmus subsequent to ankylosing spondylitis was studied. His nystagmus was found to exhibit both increasing- and decreasing-velocity exponential slow phases as well as the linear form more often reported. Alternation between waveforms sometimes occurred on a beat-to-beat or even intrabeat basis. Possible explanations for all three waveforms are presented in terms of short-term gain changes in cerebellar compensation for leaky brainstem neural integrators. A computer model was developed and its results are discussed.
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PMID:Variable waveforms in downbeat nystagmus imply short-term gain changes. 2250 87

In this study, we aimed to evaluate the audiovestibular functions in the patients with ankylosing spondylitis (AS). This prospective study was performed in collaboration by the Otolaryngology and Rheumatology Departments of Bozok University School of Medicine between May 1, 2012, and January 1, 2013. We studied 80 subjects consisting of 40 AS patients (37 men and 3 women) in whom the diagnosis confirmed by the criteria of New York and 40 healthy controls (35 men and 5 women). All participants were evaluated by routine audiologic (including tympanometric evaluation, pure-tone audiograms, speech tests) and vestibular studies (including spontaneous nystagmus, gaze, optokinetic, saccadic movements, smooth pursuit, caloric test and Dix-Hallpike tests). The tympanometric values did not show a statistically significant difference between the AS group and the healthy subjects (p > 0.05). At low frequencies (250, 500, 1,000, and 2,000 Hz) pure-tone audiologic evaluations also proved statistically non-significant results at mean air conduction thresholds (ACT) and bone conduction thresholds (BCT) between the AS and control groups (p > 0.05). At high frequencies (4,000, 6,000, and 8,000 Hz), the ACTs and BCTs in AS group were lower than control group which was statistically significant (p < 0.05). The results of spontaneous nystagmus, gaze, optokinetic, canal paresis and saccadic movement tests between the two groups were statistically insignificant (p > 0.05). The comparison of smooth pursuit and Dix-Hallpike tests reached statistical significance (p < 0.05). Videonystagmographic test (VNG) revealed central abnormalities in 7 patients (17.5 %), peripheral abnormalities in 16 patients (40 %), and mixed abnormalities in 3 patients (7.5 %). Our findings suggest a possible association between AS and audiovestibular system dysfunction. We assume that the hearing and vestibular disturbances in AS are more prevalent than previously recognized.
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PMID:The impact of ankylosing spondylitis on audiovestibular functions. 2409 16