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At least 667 records · Page 37Linked to original sources
PubMed1979

Abnormal head movements.

Abnormal head movements have been studied in a variety of diseases using objective recording techniques and the data analysed with respect to the frequency content of the movement. Flopping, nodding, tic, chorea, myoclonic jerks, and most head tremors involve frequencies of approximately 2 and 4 Hz which correspond to the natural fundamental and second harmonic resonances of the head as determined by the mechanical properties of the head/neck system. These findings provide a basis for classification of abnormal head movements as well as an explanation of the characteristics of those arising from hypotonia of the neck muscles. The similarities between tremor frequencies and natural resonances suggest that in the case of the head, tremor arises from disorders of neural mechanisms normally responsible for the fine control of voluntary head movement and for stabilisation of the head during disturbance of posture. Head movements in cases of congenital nystagmus were found to be of two types. Some were of bizarre waveform, in no way assisted vision, and were taken to be of primarily pathological origin and classified as tremors. Others were learned adaptive responses which assisted vision either by interrupting the nystagmus, as in the case of spasmus nutans, or by compensating for the nystagmus with an inverse waveform and were called nodding. A prerequisite for true compensatory nodding is modified vestibulo-ocular reflex.

Adult↗
PubMedDate not supplied

Human visuo-vestibular interaction as a basis for quantitative clinical diagnostics.

Visuo-vestibular interaction during randomized and sinusoidal head oscillations (0.5-5.0 Hz) was measured by power spectral analysis. It was shown that visual eye movement programmes can adjust the vestibulo-ocular reflex (VOR) gain at frequencies exceeding the dynamic range of visual tracking: above 3 Hz, gains exceeded unity during attempted fixation of a target moving with the subject whereas unity gains prevailed during fixation of an earth-fixed target. At low frequencies, fixation suppression was more efficient (-10 dB) when sinusoidal stimuli rather than randomized oscillations (-3 dB) were employed. Identical results were obtained when the fixation target moved with a total visual surround or against an earth-fixed visual background. Therefore, peripheral vision is normally not important for visual suppression of the VOR, which is dominated by foveal visual tracking at low frequencies.

Adult↗
PubMed1989

A case of Wallenberg's syndrome: ocular motor abnormalities.

Eye movements were measured objectively in a patient with Wallenberg's syndrome during the course of his 2-year recovery period. The patient exhibited a change in fixational and reading eye movement patterns consistent with concurrent reduction in symptoms. The results demonstrate the importance of clinical eye movement recordings in such patients to understand more fully the relationship between the visually related symptoms and the objective oculomotor correlates.

Eye Movements↗
PubMed1980

[Influence of the cerebellum on ocular statics and visual tracking movements (author's transl)].

It has long been admitted that the vestibular cerebellum plays a major role in the control of slow ocular movements. A study of 12 patients with localized lesions of the paleo- and neo-cerebellum has demonstrated that these recent structures also participate in the organization of visual tracking movements. These patients often have disturbances of ocular statics as well, and this can be the cause of slow movement disturbances. In most cases, however, ataxia of the tracking movement is not related to a statics disorder, but on the contrary, to disturbances of the movement itself. This suggest that the two cerebellar levels involved in ocular motility are related to two different types of movement strategies: vestibular cerebellar tracking having the very elementary function of maintaininf fixation within the overall picture of postural regulation: neo-cerebellar tracking, on the contrary, being already the beginning of voluntary motility.

Adolescent↗
PubMed1975

Strabismus.

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Abducens Nerve↗
PubMed1983

Common clinical configuration of zone of zero-associated phoria.

The four common configurations of the zone of zero-associated phoria are presented based on the results of a clinical study of 156 asymptomatic patients. These configurations and the relative frequencies, constitute normative data against which we can compare similar zones and frequencies in patient populations having certain binocular defects.

Accommodation, Ocular↗
PubMed1980

Increased drift in amblyopic eyes.

Reports are conflicting on the presence of increased drift in amblyopic eyes. Furthermore, the individual effects of either amblyopia or strabismus alone on ocular drift have not been systematically investigated. We therefore used a photoelectric method to record horizontal eye position during monocular and binocular fixation in patients having amblyopia without strabismus, intermittent strabismus, or constant strabismus amblyopia. Our principal finding was increased drift amplitude (up to 3.5 degree) and velocity (up to 3.0 degrees per second) in amblyopic eyes during monocular fixation. While increased drift was found 75% of the time in amblyopia without strabismus and 50% of the time in constant strabismus amblyopia, it was found only 20% of the time in intermittent strabismus. Amblyopic drift could be either error-producing or error-correcting in nature. Increased drift was not present during monocular fixation with the dominant eye or during binocular fixation in any of our 16 patients. We therefore conclude that amblyopia and not strabismus is a necessary condition for the presence of markedly increased fixational drift. Increased drift amplitude but not velocity may adversely affect visual acuity in the amblyopic eye.

Adolescent↗