Search results for "Nystagmu"

Considerazioni su un caso di nistagmo familiare essenziale.

2007

A comparatively rare case of familial nystagmus is reported in a girl whose family tree was studied and the interest of which, apart from the need for greater involvement of health personnel and of school staff in campaigns for prevention of sight disturbances in infancy, was mainly related to the particular recessive trasmission bound to chromosome X with incomplete penetrance. The multiplicity of hereditary trasmission, in fact, explains the relative capricious expressivity of this pathological condition which should be born in mild in the event of genetic consultancy.

Sensorimotor aspects of high-speed artificial gravity: I. Sensory conflict in vestibular adaptation

2003

Short-radius centrifugation offers a promising and affordable countermeasure to the adverse effects of prolonged weightlessness. However, head movements made in a fast rotating environment elicit Coriolis effects, which seriously compromise sensory and motor processes. We found that participants can adapt to these Coriolis effects when exposed intermittently to high rotation rates and, at the same time, can maintain their perceptual-motor coordination in stationary environments. In this paper, we explore the role of inter-sensory conflict in this adaptation process. Different measures (vertical nystagmus, illusory body tilt, motion sickness) react differently to visual-vestibular conflict a…

15. Functional mapping of monaural auditory brainstem responses

2012

Background and aims: The pedunculopontine nucleus (PPN) is a new deep brain stimulation (DBS) target, thought to be particularly for useful in ameliorating gait disturbance in Parkinson’s disease. Recent evidence shows a prominent theta (4–7 Hz) rhythm in the PPN (Tsang et al., Neurology, 2010; Simon et al., J. Neurophysiol., 2010; Shimamoto et al., JNNP, 2010). Given that theta activity is modulated by vestibular signals elsewhere in the brain, e.g. hippocampus, (Shin, Synapse, 2010; Chen et al., Neuroimage, 2010), we assessed whether vestibular signals modulate PPN theta activity. Methods: We recorded local field potentials (LFPs) in three patients with implanted bilateral subthalamic nuc…

Treatment of Specific Types of Nystagmus

2007

■ The function of the ocular motor system is to hold images stable on the fovea. The vestibular system and the vestibulo-ocular reflex (VOR) also play an important role in this function. The VOR connects the peripheral vestibular endorgans – the semicircular canals and otoliths – with their appropriate pair of eye muscles via a three-neuronal arc.

The topographic diagnosis of acquired nystagmus in brainstem disorders.

2002

Evidence is presented for a clinical classification of central vestibular syndromes according to the three major planes of action of the vestibulo-ocular reflex (VOR): yaw, pitch, and roll. The plane-specific vestibular syndromes are determined by ocular motor, postural, and perceptual signs. Yaw plane signs are horizontal nystagmus, horizontal past pointing, rotational and lateral body falls to the right or to the left, and horizontal deviation of perceived straight-ahead. Pitch plane signs are upbeat/downbeat nystagmus, forward/backward tilts and falls, and upward or downward deviations of the perceived horizontal. Roll plane signs are torsional nystagmus, skew deviation, ocular torsion, …

General remarks on the role of the vestibular system in weightlessness

1987

Different methods are described to experimentally achieve weightlessness. Since the function of the otolith system depends on the presence of contact forces opposing gravity, it is disabled in weightlessness and may send misleading positional information to the brain. Without the contributions of the otolith system it is difficult in space to distinguish self-motion from object motion. Furthermore, the disintegration of information from the neck position receptors from those of the otolith system can lead to additional illusory positional sensations. Since the function of the semicircular canal system in previous space flights was found to be essentially undisturbed, the vestibular experime…

Three Determinants of Vestibular Hemispheric Dominance during Caloric Stimulation: A Positron Emission Tomography Study

2003

Optometriskie treniņi pacientiem ar idiopātisku nistagmu.

2020

Maģistra darbs ir uzrakstīts angļu valoda uz 47 lapām. Tas satur 28 attēlus, 2 tabulas un 42 atsauces uz literatūras avotiem. Maģistra darba mērķis ir nodemonstrēt optometrisko rehabilitācijas metožu ietekmi uz infantilu idiopātisko nistagmu (IIN). Desmit pacientiem ar IIN (30 ± 14 g.) tika veiktas sekojošas ārstēšanas metodes: prizmas ar bāzi uz āru, krāsotas kontaktlēcas (zīlītes diametrs 5 mm), audio-biofīdbeka metode. Pirms un pēc ārstēšanas tika novērtēts redzes asums un kontrastredze tālumā un stereoredze tuvumā ar labāko subjektīvo korekciju, nistagma apmlitūda un frekvence. Rezultāti parādīja, ka visas ārstēšanas metodes vienādi ietekmēja redzes asuma, nistagma amplitūdas un frekven…

Nonlinear nystagmus processing causes torsional VOR nonlinearity.

2003

The eye movement component that rotates around the line of sight, i.e., the ocular torsion, is in many aspects different from horizontal and vertical eye movements. While ocular torsion is mediated only by reflexive pathways like the torsional vestibulo-ocular and optokinetic reflexes (TVOR and OKN, respectively), horizontal and vertical components are also subject to intentional control mechanisms that are mediated by the saccadic and the pursuit systems. Dynamic properties of torsional eye movements are also very distinct. While horizontal and vertical VOR components show a gain close to unity and a small neural integration leakage with a time constant around pi=30 s, the TVOR shows a sma…

The Internuclear Ophthalmoplegias

1993

Internuclear ophthalmoplegia (INO), which is caused by an ipsilateral medial longitudinal fasciculus (MLF) lesion, is characterized by adduction paresis of lateral gaze, usually with spared convergence [1–4]. In the opposite eye, abduction nystagmus and hypermetric abduction saccades are the main clinical and electro-oculographic abnormalities [1, 5, 6]. The origin of both is still debated. Abduction nystagmus has been explained by (a) an additional horizontal gaze paresis [7]; (b) vergence mechanisms aimed at alignment of the visual axes [8]; (c) interruption of descending excitatory projections from oculomotor nucleus internuclear neurons to contralateral abducens nucleus motoneurons [9];…