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Biomedical subjects

R Cerný

Publications and source records attributed to R Cerný.

9 recordsLinked to original sources
PubMed1991

Medial vs lateral frontal lobe lesions and differential impairment of central-gaze fixation maintenance in man.

The ability to maintain central-gaze fixation was studied in 35 patients with unilateral frontal lobe lesions. The stability of central-gaze fixation was tested in 2 oculomotor tasks requiring the suppression of reflexive saccades triggered by the sudden appearance of novel, peripheral visual stimuli. In the first task ('Instructed'), maintenance of gaze fixation was based on verbal instruction, whereas, in the second task ('Non-instructed'), it was based upon a foveating mechanism maintained by sensory stimulation during the performance of a categorization task. Patients with frontal lobe lesions were classified into 3 groups: a ventrolateral (n = 18), a dorsolateral (n = 10) and a medial (n = 7) group. The control group consisted of 20 healthy subjects. In the Non-instructed task, no group differences were found in the rate of reflexive saccades. Thus, lesions of the frontal lobe did not affect reactivity to extraneous stimuli per se. The only exception to this rule was the group of patients with ventrolateral lesions in the left frontal lobe, in which a higher number of reflexive saccades directed to the contralateral hemifield was observed. In the Instructed task, 2 different patterns of deficit in suppression of reflexive saccades were found. First, a bidirectional deficit was noted in the ventrolateral group, which might be attributed to an impairment in either maintaining a selected program of behaviour 'on-line' or suppressing inappropriate alternatives interfering with that program. Second, a unidirectional deficit in voluntary suppression of reflexive saccades triggered from within the contralateral hemifield was observed in the medial group. It is suggested that this type of deficit may reflect malfunctioning of the supplementary motor area--anterior cingulate system involved in the suppression of externally triggered interfering programs. Finally, no significant impairment was found in the dorsolateral group.

Adult↗
PubMed1990

Tonsillolith.

A chance finding of the tonsillolith in the peritonsillar abscess of a 10-year-old girl is reported. The 26 X 4 mm calculus weighing 0.84 grams was analyzed by means of infrared spectroscopy and X-ray difraction, and identified as a dahllite. The concretion surface was documented by a scan. A literary survey of 29 reports of tonsilloliths is presented and their causes in the palatine tonsil are discussed.

Calculi↗
PubMed1990

[A tonsillolith].

The author describes a tonsillolith accidentally detected in a peritonsillar abscess in a 10-year-old girl. The concrement 26 x 4 mm in size, weighing 0.84 g was analyzed by infrared spectroscopy, X-ray diffraction which revealed that it was a dahllite. The surface of the concrement was documented by a scanning microscope. The authors give an account of 29 published cases of tonsilloliths and in the discussion they analyze the causes of development of these concrements in tonsils.

Calculi↗
PubMed1990

[The effect of muscle relaxants on the function of the vestibulo-ocular reflex arc].

Baclofen affects in experiments the reactivity of the vestibuloocular reflex by influencing the time constant of the vestibular nystagmus. The authors compare in three healthy volunteers the reactivity of the vestibular apparatus after administration of Baclofen and a new muscle-relaxant drug tizanidine. The authors evaluate basic parameters of the vestibular and optokinetic nystagmus (gain and time constant), discuss the problem of GABAergic (Baclofen) and monoaminergic (tizanide) receptors kin the area of the vestibular apparatus. As regards the effect on the reactivity of the vestibular system, tizanidine does not affect immediately the response of the vestibuloocular reflex but interferes with processes ensured by the central neuronal integrator.

Adult↗
PubMed1989

Vestibular abnormalities in encephalopathia pugilistica.

Vestibulological examination of boxers revealed that 80% had vestibular abnormalities. These were obvious, but well compensated, so that they remained hidden in everyday life and appeared only on laboratory examination or under stress. Regarding the origin of vestibulo-ocular reflex, abnormalities in boxing contribute three etiopathogenetic factors: the first is the direct traumatization of the vestibular apparatus by a direct blow. The second is the diffuse damage of the brain-stem white matter and of vestibular nuclei. The third factor is the traumatization of the cervical spine via the traumatization of the proprioceptive systems, cervical sympathetic and the adjacent vascular mechanisms. One-third of the abnormalities are caused by direct labyrinthine traumatization. The findings of simultaneous EEG, OKN and ETT abnormalities in one-half of our subjects suggests that there are probably also supratentorial lesions caused by the above-mentioned mechanisms.

Adolescent↗