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C Moschner

Publications and source records attributed to C Moschner.

6 recordsLinked to original sources
PubMed1998

Oculomotor testing in the differential diagnosis of degenerative ataxic disorders.

BACKGROUND: Oculomotor abnormalities have been reported in patients with degenerative ataxic disorders. OBJECTIVE: To assess the diagnostic sensitivity and specificity of oculomotor deficits in patients with Friedreich ataxia (FA), cerebellar atrophy (CA), and olivopontocerebellar atrophy (OPCA). SETTING: Neurology clinic at a university hospital in Lübeck, Germany. PATIENTS: Seven patients with FA, 9 with CA, and 10 with OPCA were studied. These patients were selected from an ongoing follow-up study. MAIN OUTCOME MEASURES: Eye movements were recorded by electro-oculography; an extensive battery of quantitative tests was used. RESULTS: A proven CAG repeat expansion on chromosome 6 or 14 was significantly associated with reduced saccadic eye velocity and vertical gaze palsy (P<.001, Mann-Whitney U test). All 6 patients with OPCA and slow saccades had an autosomal-dominant inheritance; 4 of them were proved to have spinocerebellar atrophy type 1. In 9 of these patients (4 with FA, 1 with CA, and 4 with OPCA), the genetic defect could not be identified. Saccadic dysmetria, impairment of smooth pursuit and optokinetic nystagmus, deficient suppression of the vestibulo-ocular reflex by either visual or otolith input, and pathological nystagmus were attributed to degenerative lesions in different parts of the cerebellum. However, these symptoms failed to clearly distinguish between the different groups of patients, whereas decreased vestibulo-ocular reflex gain, slow saccades, and vertical gaze palsy pointed to an extracerebellar manifestation of the degenerative disease, occurring only in patients with OPCA and FA. CONCLUSIONS: In this prospective study, oculomotor disturbances were mainly related to cerebellar dysfunction. Only a few of them were caused by extracerebellar manifestations of the disease, such as slowing of saccades, which was characteristic for patients with OPCA of autosomal-dominant inheritance.

Adult↗
PubMed1996

Anticipatory smooth eye movements of high velocity triggered by large target steps: normal performance and effect of cerebellar degeneration.

We studied frequencies and dynamic characteristics of anticipatory smooth eye movements (ASEM) in humans who were tracking step target movements of 20-70 deg amplitude. During presentation of periodic steps of constant amplitude healthy subjects showed frequent high velocity ASEM reaching maximal peak velocities of 5-40 deg/sec. There was no effect of ASEM on the frequency of anticipatory saccades. Randomization of target step amplitude or onset reduced the frequency of ASEM but did not completely abolish fast ASEM. In patients with cerebellar degeneration who exhibited impaired smooth pursuit, fast ASEM were absent and the number of slow ASEM was minimal. In conclusion, large sequential target steps can elicit much higher ASEM velocities than typically described in the literature. Similar to slow ASEM triggered by small steps, these fast ASEM do not require specific training and are not canceled by unpredictable step target motion. However, fast ASEM depend on the intact function of the cerebellum which gives further evidence of their generation by the smooth pursuit oculomotor subsystem.

Adolescent↗
PubMed1994

Comparison of oculomotor findings in the progressive ataxia syndromes.

In this study we compare the results of quantitative oculomotor function testing in patients with Friedreich's ataxia (FA), olivopontocerebellar atrophy (OPCA) and cerebello-olivary atrophy (CA). Common features in all three syndromes included gaze-evoked nystagmus, saccade dysmetria and prolonged saccade reaction times. Patients with FA showed a characteristic combination of frequent saccadic intrusions, especially ocular flutter, relatively preserved optokinetic nystagmus (OKN) and smooth pursuit, and impaired vestibulo-ocular reflex (VOR) responses. In patients with CA saccadic intrusions were infrequent, OKN and smooth pursuit were severely impaired and VOR gain was normal or increased. Results in OPCA were more variable. When present, slowing of saccades or the combined loss of pursuit and vestibular function were characteristic for OPCA. The ability to suppress the VOR with a head fixed target was relatively preserved in FA, normal to moderately impaired in OPCA and always severely impaired in CA. We conclude that oculomotor testing is useful in the differential diagnosis of the progressive ataxia syndromes.

Adult↗
PubMed1994

Age-related changes in visual tracking.

BACKGROUND: To reassess conflicting findings in earlier studies on the effect of aging on smooth pursuit and saccadic eye movements, we compared visual tracking in a large number of elderly normal subjects aged 75 to 93 years and a group of young adults aged 18 to 43 years. METHODS: Saccades and smooth pursuit were induced by a laser target projected onto a screen. Eye movements were recorded with electrooculography and analyzed with a digital computer. RESULTS: Smooth pursuit gain was significantly decreased at all target velocities in the older subjects, and the difference between young and old increased with increasing target velocity and acceleration. Peak saccade velocity was significantly slower for amplitudes exceeding 20 degrees, and saccadic reaction times were prolonged in older subjects compared with younger subjects. Mean saccade accuracy was not significantly different between age groups. Within tests, variability increased with aging for smooth pursuit, saccadic reaction time, and saccadic accuracy measurements. CONCLUSION: The increased intratest variability in older subjects probably resulted from nonspecific changes in alertness and attention commonly occurring with aging, whereas the decreased gain of smooth pursuit and saccades with increasing stimulus magnitude most likely resulted from age-related neural degeneration in specific visuomotor pathways.

Adolescent↗
PubMed1993

Preview control of gaze saccades: efficacy of prediction modulates eye-head interaction during human gaze saccades.

Healthy human subjects made orienting saccades towards visual target stimuli, either with the head fixed or during intended time optimal head movements. Four experimental paradigms were used to study the influence of target predictability on eye-head coordination. They represented different sequences of horizontal target steps, that were varied in amplitude, direction and frequency. In some subjects midflight perturbations of the active head movements were applied to examine the intrasaccadic vestibulo-ocular reflex (VOR). In coordinated gaze saccades, latencies and dynamics of the eye saccade and the additional head trajectory demonstrated specific task-related changes with respect to the head fixed condition. Highly predictable target steps result in the relatively earlier onset of the head movement and an increase of the intrasaccadic head contribution to the overall gaze displacement. Differences in the level of VOR suppression became significant when gaze amplitudes exceeded 60 degrees. Consequently, an effective speed up of large gaze saccades was found with increased target predictability. We concluded, that eye-head coordination during human gaze saccades underlies high level preview control mechanisms. A parametric modulation of the intrasaccadic VOR maintains gaze accuracy, although the actual contribution of the more flexible head motor system varied, depending on gaze amplitude and prediction. The efficacy of preview control depends on interaction of these factors.

Adult↗