Search results for "vestibular system"
showing 10 items of 120 documents
Eye closure in darkness animates sensory systems.
2003
Single subject and group analyses (n = 12) showed that the eyes-open and eyes-closed states in complete darkness considerably and consistently differ in the patterns of associated brain activation in fMRI. During nonchanging external stimulation, ocular motor and attentional systems were activated when the eyes were open; the visual, somatosensory, vestibular, and auditory systems were activated when the eyes were closed. These data suggest that there are two different states of mental activity: with the eyes closed, an "interoceptive" state characterized by imagination and multisensory activity and with the eyes open, an "exteroceptive" state characterized by attention and ocular motor act…
Evidence for cortical visual substitution of chronic bilateral vestibular failure (an fMRI study).
2007
Bilateral vestibular failure (BVF) is a rare disorder of the labyrinth or the eighth cranial nerve which has various aetiologies. BVF patients suffer from unsteadiness of gait combined with blurred vision due to oscillopsia. Functional MRI (fMRI) in healthy subjects has shown that stimulation of the visual system induces an activation of the visual cortex and ocular motor areas bilaterally as well as simultaneous deactivations of multisensory vestibular cortex areas. Our question was whether the chronic absence of bilateral vestibular input (BVF) causes a plastic cortical reorganization of the above-described visual-vestibular interaction. We used fMRI to measure the differential effects of…
Evidence for modulation of opioidergic activity in central vestibular processing: A [(18)F] diprenorphine PET study.
2009
Animal and functional imaging studies had identified cortical structures such as the parieto‐insular vestibular cortex, the retro‐insular cortex, or the anterior cingulate cortex belonging to a vestibular cortical network. Basic animal studies revealed that endorphins might be important transmitters involved in cerebral vestibular processing. The aim of the present study was therefore to analyse whether the opioid system is involved in vestibular neurotransmission of humans or not. Changes in opioid receptor availability during caloric air stimulation of the right ear were studied with [(18)F] Fluoroethyl‐diprenorphine ([(18)F]FEDPN) PET scans in 10 right‐handed healthy volunteers and compa…
Cochlear origin of early hearing loss in vestibular schwannoma.
2007
Objective: To test whether early hearing loss (HL) is cochlear in origin in patients with vestibular schwannoma (VS). Study Design: Retrospective case review in an academic tertiary referral center. Methods: A group of 19 VS patients with normal/symmetrical hearing and a group of 20 VS patients with mild HL (threshold at any tested frequency better than 45 dB HL) on the tumor ear side. Differences of the amplitudes of the distortion products of otoacoustic emissions (DPOAEs) between the tumor ear and the nontumor ear were studied at frequencies of 1, 1.4, 2, 2.8, and 4 kHz. The Wilcoxon test was used to compare the ears for both groups and to test for possible differences in tumor size betw…
Sensory strategies of postural sway during quiet stance in patients with haemophilic arthropathy.
2017
Introduction: The sensory strategies of postural control in adult haemophilic arthropathy patients are still poorly understood. Aim: To determine sensorial posture-control strategies through postural sway frequency analysis when in a bipedal quiet stance with and without visual stimulus deprivation in healthy subjects and patients with haemophilic arthropathy. Secondarily, to determine the irregularity of postural balance control through sample entropy (SampEn). Methods: A triaxial accelerometer attached at the L3 level determined the displacement and acceleration of the centre of mass (DCoM and ACoM, respectively) under open-and closed-eyes conditions. Sensorial strategies were studied by …
Comparison of electronystagmography results with dynamic posturography findings in patients with vestibular schwannoma.
2007
Condition-5-score (C5S) and condition-6-score (C6S) of computerized dynamic platform posturography (CDPP) can detect the presence of a functional deficit of the lateral semicircular canal (and the superior vestibular nerve), irrespective of the central vestibular compensatory status, in vestibular schwannoma (VS) patients.To test whether CDPP findings differ between VS patients with and without asymmetry on caloric and/or rotational ENG studies.This was a retrospective review of 216 consecutive patients with VS. C5S and C6S of CDPP (Equitest) were compared among patients with normal caloric and rotational studies, patients with asymmetry on caloric studies and normal rotational studies, and…
Dynamic posturography findings predict balance status in vestibular schwannoma patients.
2007
OBJECTIVE To test whether condition 5 score (C5S) and condition 6 score (C6S) of the sensory organization test of computerized dynamic platform posturography (CDPP) differ between vestibular schwannoma (VS) patients with and without vestibular symptoms. STUDY DESIGN Retrospective review of prospectively collected data. SETTING Tertiary academic referral center. PATIENTS Two hundred and sixteen consecutive patients with a histological diagnosis of a VS (103 women; 113 men; age range, 18-78 years; median, 54 years) who had been preoperatively evaluated by CDPP. A hundred and twelve patients had a history of vertigo, dizziness, and/or imbalance, and 104 patients had neither present nor past ve…
MRI and neurophysiology in vestibular paroxysmia: contradiction and correlation
2013
Background Vestibular paroxysmia (VP) is defined as neurovascular compression (NVC) syndrome of the eighth cranial nerve (N.VIII). The aim was to assess the sensitivity and specificity of MRI and the significance of audiovestibular testing in the diagnosis of VP. Methods 20 VP patients and, for control, 20 subjects with trigeminal neuralgia (TN) were included and underwent MRI (constructive interference in steady-state, time-of-flight MR angiography) for detection of a NVC between N.VIII and vessels. All VP patients received detailed audiovestibular testing. Results A NVC of N.VIII could be detected in all VP patients rendering a sensitivity of 100% and a specificity of 65% for the diagnosi…
Evidence of unilateral isolated utricular hypofunction
2010
The findings demonstrate that an enduring unilateral utricular dysfunction, possibly together with canal hypofunction, can occur after labyrinthine disease or injury. They also suggest that unilateral, isolated utricular dysfunction - or utricle paresis - can occur, representing a novel entity in the differential diagnosis of peripheral vestibular function. The occurrence of subjective visual vertical (SVV) asymmetry in the presence of symmetric vestibular evoked myogenic potentials (VEMPs) also confirms that the information from the utricles, rather than the saccules, dominates SVV estimation.To determine the incidence of unilateral utricular hypofunction.The retrospective clinical study d…
Relationship between video head impulse test (vHIT) and caloric test in patients with vestibular neuritis.
2016
Abstract Introduction and objectives The caloric test is the gold standard for the loss of vestibular function diagnosis. The video head impulse test (vHIT) assesses the same reflex by using a video-assisted examination of the impulsive manoeuvre. We intend to compare the variation of results of the vHIT and the caloric test in patients with vestibular neuritis with respect to their initial condition at two different moments of their evolution and to check the level of correlation between them and with that of the DHI test. Methods We explored 20 patients with neuritis by using both vHIT and the caloric test on the same day. We assessed the correlation between these two tests and with the D…