Hemifield visual motion stimulation: an example of interhemispheric crosstalk.

Coherent motion stimulation of the right or left visual hemifield was performed in nine healthy volunteers in order to investigate interhemispheric visuo-visual interaction by means of functional magnetic resonance imaging. The vertical edge of the motion pattern field was located 8 degrees distant from the fixation point to avoid stimulating the vertical meridian, which is represented retinotopically in both hemispheres. Bilateral activation was significant in the middle occipital gyrus (motion-sensitive middle temporal/middle superior temporal areas; BA 19/37).

Mutations in the tropoelastin gene (ELN) were not found in patients with spontaneous cervical artery dissections.

Background And Purpose: The majority of patients with spontaneous cerebral artery dissection show ultrastructural alterations in dermal collagen and elastic fibers.

Methods: We studied the gene encoding tropoelastin (ELN) by reverse transcription-polymerase chain reaction and subsequent sequence analysis in 10 patients with abnormalities in their elastic fibers.

Results: No mutations were found in the whole coding region of the ELN gene.

Differential effects of vestibular stimulation on walking and running.

Prompted by our recent observation that an acute vestibular tone imbalance causes less deviation from the intended path when running than when slowly walking, we examined 10 healthy subjects when walking or running at different step frequencies during galvanic vestibular stimulation. Blindfolded subjects were asked to walk (1 Hz step frequency) or run (3 Hz step frequency) straight ahead toward a previously seen target. The mean gait deviation after 10 s was 6.

Patients with somatoform phobic postural vertigo: the more difficult the balance task, the better the balance performance.

The objective was to test, whether the increased body sway activity, shown in patients with phobic postural vertigo (PPV) in a previous posturographic study, impairs postural balance during demanding balance tasks. In 17 patients with PPV and 15 normal subjects body sway was analyzed for two standing positions on a foam rubber-padded posturographic platform with the eyes open or closed: (a) normal upright stance, (b) tandem stance. During normal upright stance patients showed an increase in body sway activity between 0.

Posterior cerebral artery territory infarcts: clinical features, infarct topography, causes and outcome. Multicenter results and a review of the literature.

Only a few large series of posterior cerebral artery (PCA) stroke exist, and clinical features and causes have not been studied as extensively as in other vascular territories. The PCA syndrome includes more clinical signs than the well-known visual field deficits. Concomitant findings are frequently sensory, slight motor and neuropsychological deficits.

Rotational vertebral artery occlusion syndrome with vertigo due to "labyrinthine excitation".

Leftward head rotations in a patient with a rotational vertebral artery occlusion syndrome elicited recurrent uniform attacks of severe rotatory vertigo and tinnitus in the right ear. These attacks were accompanied by a mixed clockwise torsional downbeat nystagmus with a horizontal component toward the right. A transient ischemia of the right labyrinth probably induced the attacks and led to a combined transient excitation of the right anterior and horizontal semicircular canals as well as the cochlea.

Long chain arginine esters: a new class of cationic detergents for preparation of hydrophobic ion-paired complexes.

The ability of stoichiometric amounts (based on charged groups) of ionic detergents to bind to oppositely charged ionic compounds has been recently reviewed. These hydrophobic ion-paired (HIP) complexes display altered solubility properties. Most of the work to date on HIP compelxes has focused on basic drugs and anionic detergents.

Brain activation studies on visual-vestibular and ocular motor interaction.

Despite their different sensorimotor functions, saccades, pursuit eye movements, small-field optokinetic nystagmus and visual motion stimulation with the eyes stationary evoke a common complex pattern of activation in various cortical, basal ganglia, brain-stem and cerebellar areas. On closer inspection, however, typical subregions can be delineated that allow differentiation of adjacent but separate loci for specific functions (e.g.

["Inner perilymph fistula" of the anterior semicircular canal. A new disease picture with recurrent attacks of vertigo].

In 1998 Minor et al. described a new variant of perilymphatic fistula: the "superior canal dehiscence syndrome". This syndrome is clinically characterized by recurrent attacks of vertigo and oscillopsia induced by loud noises or stimuli that result in changes in intracranial or middle ear pressure.

Cerebellar activation during optokinetic stimulation and saccades.

Objective: To investigate the activation pattern of cerebellar structures during small-field optokinetic stimulation (OKN) by functional MRI (fMRI) and compare it with that obtained during voluntary saccades and fixation suppression of OKN.

Methods: Functional images were acquired from oblique transverse slices of eight healthy, right-handed volunteers using a radio frequency-spoiled, single-slice, fast low-angle shot (FLASH) pulse sequence with high-spatial resolution.

Results: Horizontal OKN and saccades were associated with bilateral activity in the cerebellar hemispheres (superior semilunar lobule, simple lobule, quadrangular lobule, inferior semilunar lobule), the middle cerebellar peduncle, the dentate nucleus, and medially in the culmen and uvula of cerebellar nuclei.

Galvanic stimulation in bilateral vestibular failure: 3-D ocular motor effects.

Bilateral galvanic vestibular stimulation (GVS) with current intensity of 3 mA was applied at mastoid level in 11 patients with chronic bilateral vestibular failure, in order to determine ocular motor responses by 3-D video-oculography. The following abnormal features were found: (1) a predominantly torsional or mixed torsional-horizontal nystagmus at the onset of stimulation with lower current intensities (1.0-3.

[MRI with fat suppression in the visualization of wall hematoma in spontaneous dissection of the internal carotid artery].

Purpose: Comparison of different MR-examination techniques for the diagnosis of acute spontaneous internal carotid artery dissection.

Patients And Methods: 13 patients (age range 23-59 years) with symptomatic spontaneous dissection of the internal carotid artery were examined. The MRI protocol contained a transverse spin echo sequence, a time-of-flight MR-angiography and a coronal fat suppressed T1-weighted sequence.

Subjective straight-ahead during neck muscle vibration: effects of ageing.

The subjective visual straight-ahead (SVA) was measured psychophysically before and during unilateral vibration of the posterior neck muscles in order to determine the particular contribution of neck muscle spindles to the perception of body orientation during ageing. We found a symmetrical increase of the vibration-induced displacement of the SVA with advancing age (R = +0.73, p < 0.

Episodic vertigo related to migraine (90 cases): vestibular migraine?

A retrospective study was conducted on 90 patients with episodic vertigo that could be related to migraine as the most probable pathomechanism. Since the majority of the patients did not fulfill the criteria of the International Headache Society (IHS) for basilar migraine, the diagnosis was substantiated by disease course, medical efficacy in treating (ergotamines) and preventing (metoprolol, flunarizine) attacks, ocular motor abnormalities in the symptom-free interval, and careful exclusion of the most relevant differential diagnoses, such as transient ischemic attacks, Menière's disease, and vestibular paroxysmia. The following clinical features were elaborated.

Simulation of pathological ocular counter-roll and skew-torsion by a 3-D mathematical model.

A basic version of a 3-D mathematical model for simulation of otolithic control of binocular static eye position was extended by introducting excitatory commissural fibers between the vestibular nuclei, and physiological non-linearities: the force-response relationship of utricular neurons and a quadratic relationship between eye muscle innervation and force. These modifications appeared to be necessary in order to simulate the gain asymmetry of ocular counter-roll to lateral head tilt in patients with unilateral utricular loss. The current model can adequately simulate skew-torsion in patients with unilateral utricular loss, lesions of the vestibular nuclei, and central graviceptive pathway lesions.

Distribution of herpes simplex virus type 1 in human geniculate and vestibular ganglia: implications for vestibular neuritis.

Vestibular neuritis is a common cause of partial unilateral vestibular paralysis, which usually spares posterior semicircular canal function. The cause is assumed to be a viral reactivation of latent herpes simplex virus type 1 (HSV-1) in human vestibular ganglia. The existence of an anastomosis between the intermediate nerve and the superior vestibular nerve suggests the question of whether selective affliction of the superior vestibular nerve is the result of migration of HSV-1 from the geniculate ganglion along this faciovestibular anastomosis.

You are better off running than walking with acute vestibulopathy.

Patients with acute vestibular disorder balance better when running than when standing or walking slowly. We suggest that the automatic spinal locomotor programme suppresses destabilising vestibular input.