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Query: UMLS:C0028738 (nystagmus)
 7,431 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In a study of vestibular responses to caloric stimulation that controlled opportunity for fixation and state of alertness, we evaluated previous findings of diminished nystagmus in schizophrenia. We failed to replicate earlier reports in these respects: (1) None of the psychotic patient groups, when compared with normal controls, showed lower response intensity, latency, or culmination time of the nystagmic response. (2) The schizophrenic groups did not manifest a prevalence of clinically significant asymmetry. We did, however, observe that chronic deteriorated schizophrenics and recent schizophrenics have significantly greater dysrhythmic responses. This diminished orderliness of nystagmus may explain previous reports of absent or diminished nystagmus in the schizophrenics. The results are not compatible with peripheral vestibular disease in schizophrenia, but they may reflect state-related phenomena consistent with disturbances in alertness, which are not necessarily voluntary or motivational in origin.
Arch Gen Psychiatry 1978 Aug
PMID:Vestibular responses in schizophrenia. 2 3

The vertical vergences are rather weak physiological conjugate movements of the eyes. When the ocular axes approach each other or deviate, a vertical convergence or divergence occurs. These reflex movements are evoked either by visual stimuli (fusional vergence) or by labyrinthine stimuli. In pathological situations vertical vergences may become evident in permanent or alternating hyperphorias, in the strabismus occurring in the Hertwig-Magendie syndrome, in see-saw nystagmus and in labyrinthine lesions (such as Meniere's disease, after labyrinthectomy and after section of the VIIIth nerve).
Arch Ophtalmol Rev Gen Ophtalmol 1975 May
PMID:[Vertical vergences. I. Physiological and pathological aspects]. 13 Aug 71

Vestibular responses to caloric stimulation were measured from birth to age 2 years in ten infants born to schizophrenic mothers. This is part of a study of evolving neurointegrative disorders that may be associated with a genetic risk for schizophrenia. Transiently decreased vestibular responses coincided with several developmental disorders that were related to psychopathology at 10 years. Absent to decreased responses were associated with (1) a "pandevelopmental retardation" involving physical growth as well as postural-motor and visual-motor development, (2) an "abnormally quiet" state in the first month, and (3) failures of bimanual integration between 4 and 6 months. The transitory nature of the decreased nystagmus rules out the possibility of an organic lesion of the vestibular system. Rather, it suggests that some covert decrease in arousal accompanied those periods when central nervous system integration was disrupted.
Arch Gen Psychiatry 1978 Aug
PMID:Vestibular hyporeactivity in infants at risk for schizophrenia. Association with critical developmental disorders. 30 45

1. The effects of some centrally acting muscle relaxants on the post-rotatory nystagmus induced by rotatory stimulation were investigated in the rabbit, to examine the action of the drugs on vestibular function. 2. Tolperisone-HCl (5-10 mg/kg, i.v.) and baclofen (1-3 mg/kg, i.v.) decreased the number of post-rotatory nystagmus beats dose-dependently, whereas mephenesin (40-80 mg/kg, i.v.) and diazepam (0.5-1.0 mg/kg, i.v.) prolonged it dose-dependently. 3. The inhibitory effects of tolperisone-HCl and baclofen may provide some suggestions as to the mechanisms and sites of actions of centrally acting muscle relaxants, while the significance of the prolonging action of mephenesin remains unclear. 4. The prolonging action of diazepam is discussed with reference to GABAergic mechanisms.
Gen Pharmacol 1989
PMID:Effects of centrally acting muscle relaxants on post-rotatory nystagmus in the rabbit. 270 72

1. To determine how the GABAergic mechanism operates in the generation of post-rotatory nystagmus, an experiment was performed with GABAergic drugs in rabbits. 2. Subconvulsive doses of picrotoxin (0.3-0.6 mg/kg, i.v.) and bicuculline (0.1 mg/kg, i.v.) decreased the number of post-rotatory nystagmus beats, whereas strychnine sulphate, at a subconvulsive dose (0.1 mg/kg i.v.), increased it. 3. Diazepam (1 mg/kg, i.v.) remarkably increased the number of post-rotatory nystagmus beats. Pretreatment with picrotoxin (0.45 mg/kg, i.v.), bicuculline (0.1 mg/kg, i.v.) or semicarbazide-HCl (180 mg/kg, i.v.) antagonized the effects of diazepam (1 mg/kg, i.v.). 4. GABAergic mechanisms may play a modulatory role in the production of nystagmus rhythm. Strychnine-sensitive neurons involved in the vestibular mechanism may behave in a different manner from picrotoxin-sensitive neurons.
Gen Pharmacol 1989
PMID:Modulatory roles of GABAergic mechanisms in post-rotatory nystagmus in the rabbit. 271 19

Responses to vestibular stimulation can, under well-controlled experimental conditions, provide a measure of brain-stem function. Autistic children had significantly longer time constants during the primary nystagmus response and significantly fewer beats during the secondary response than normal children when stimulated with constant angular acceleration in complete darkness. These findings could not be attributed to gross differences in arousal, to developmental retardation, to associated clinical conditions, or to either the influence of vision or habituation. Rather, they are suggestive of a neurophysiologic dysfunction, perhaps involving the brain stem, and may be an expression of the process that underlies those autistic behaviors that suggest faulty modulation of sensory input and motor output. Brain-stem centers modulate both general sensory input and motor excitation and may play a role in the elaboration of the more complex adaptive and motivated behaviors that are also disturbed in autism.
Arch Gen Psychiatry 1985 Oct
PMID:Brain-stem dysfunction in autism. Results of vestibular stimulation. 403 85

This study of two types of optokinetic nystagmus (OKN) provides evidence that previously reported pursuit impairments in schizophrenics may be due to a cortical dysfunction. Differences in responses to partial-field and full-field OKN stimuli strongly support the hypothesis that there are two functionally distinct but anatomically overlapping mechanisms that can produce nystagmus responses. Partial-field OKN is composed of alternating phases of pursuit and saccadic movements. The slow phases of partial-field OKN, like pursuit eye movements, are of significantly poorer quality in schizophrenics compared with normal controls. Full-field OKN, however, is intact in both groups. Partial-field OKN is an improved test for pursuit abnormalities that reflect disturbances of nonvoluntary attention.
Arch Gen Psychiatry 1981 Sep
PMID:Optokinetic nystagmus and pursuit eye movements in schizophrenia. 728 72

1. The effect of prostaglandin E1 was investigated with a two-rat model of hearing disturbance and equilibrium dysfunction associated with inner ear microvascular thrombosis. 2. The inner ear microvascular thrombosis was induced by photochemical reaction between Rose Bengal and transmural green light (540 nm). Photochemical reaction causes endothelial injury followed by platelet adhesion, aggregation, and formation of a platelet- and fibrin-rich thrombus. 3. Under anesthesia, the cochlea or the vestibule was irradiated with green light to induce hearing disturbance or equilibrium dysfunction. 4. In the hearing disturbance model, a compound cochlear nerve action potential was recorded by electrocochleography every minute after the beginning of photoirradiation in the presence of Rose Bengal. 5. In the equilibrium dysfunction model, the photoirradiation was applied for 10 min after Rose Bengal administration. The behavior of rats was observed in the swimming test, and nystagmus was observed 24 hr after the end of photoirradiation. 6. Prostaglandin E1 significantly (P < 0.05) prolonged the time required to suppress the action potential. In the swimming test, 3 of the 6 animals treated with prostaglandin E1 did not rotate about their longitudinal axes (equilibrium dysfunction) and the duration of well-balanced swimming was significantly prolonged (P < .001). Prostaglandin E1 significantly (P < 0.05) suppressed the appearance of nystagmus. 7. In conclusion, prostaglandin E1 potentially prevents hearing disturbance and equilibrium dysfunction due to inner ear microvascular disorders.
Gen Pharmacol 1997 Feb
PMID:Effect of prostaglandin E1 on the rat inner ear microvascular thrombosis. 901 98

1. The reflex effect of direct mechanical stimulation of the exposed ampulla of the horizontal canal has been graphically recorded for each of the six extrinsic muscles of the eyeball. 2. Stimulation of a horizontal ampulla evokes a strong contraction of the homolateral rectus internus and of the contralateral rectus externus; at the same time the homolateral rectus externus and the contralateral rectus internus relax. 3. A single mechanical stimulus applied to the horizontal ampulla is sometimes followed by a nystagmus resulting from a series of rhythmic contractions of the externus and internus muscles. 4. Excitation of a horizontal ampulla gives rise to weak contractions of the superior and inferior recti and of the two oblique muscles of both eyes, simultaneously with the stronger contractions of the externus and internus respectively. 5. It is pointed out that the small simultaneous contractions of the four muscles just mentioned provide a virtual axis upon which the eyeball rotates. In other words these four act as fixation muscles. 6. It is suggested that some of the abnormal responses to horizontal rotation, seen in clinical cases, are due to the inaction of one or more of the fixation muscles.
J Gen Physiol 1926 Jun 20
PMID:THE RELATIONS OF THE INDIVIDUAL AMPULLAE OF THE SEMICIRCULAR CANALS TO THE INDIVIDUAL EYE MUSCLES : I. THE HORIZONTAL CANALS. 1987 9

As a potential exemplar for understanding how volitional actions emerged from reflexes, we studied the relationship between an ancient reflexive gaze stabilization mechanism (optokinetic nystagmus [OKN]) and purposeful eye movements (saccades) that target an object. Traditionally, these have been considered distinct (except in the kinematics of their execution) and have been studied independently. We find that the fast-phases of OKN clearly show properties associated with saccade planning: (a) They are characteristically delayed by irrelevant distractors in an indistinguishable way to saccades (the saccadic inhibition effect), and (b) horizontal OKN fast-phases produce curvature in vertical targeting saccades, just like a competing saccade plan. Thus, we argue that the saccade planning network plays a role in the production of OKN fast-phases, and we question the need for a strict distinction between eye movements that appear to be automatic or volitional. We discuss whether our understanding might benefit from shifting perspective and considering the entire "saccade" system to have developed from an increasingly sophisticated OKN system.
J Exp Psychol Gen 2014 Oct
PMID:Saccade-like behavior in the fast-phases of optokinetic nystagmus: an illustration of the emergence of volitional actions from automatic reflexes. 2486 87


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