tilt VOR

BACKGROUND: The velocity storage mechanism of the central vestibular system is closely associated with the vestibulo-ocular reflex (VOR), but also contributes to the sense of orientation in space and the perception of self-motion. We postulate that mal de débarquement syndrome (MdDS) is a consequence of inappropriate sensory adaptation of velocity storage. The premise that a maladapted velocity storage may be corrected by spatial readaptation of the VOR has recently been translated into the development of the first effective treatment for MdDS...

Different head positions affect the responses of the vestibular semicircular canals (SCCs) to angular movement. Specific head positions can relieve vestibular disorders caused by excessive stimulating SCCs. In this study, we quantitatively explored responses of human SCCs using numerical simulations of fluid-structure interaction and vestibulo-ocular reflex (VOR) experiments under different forward-leaning angles of the head, including 0°, 10°, 20°, 30°, 40°, 50°, and 60°...

BACKGROUND: Dynamic cervico- (COR) and vestibulo-ocular reflex (VOR) contribute to stabilise visual images in the retina. The gain in dynamic COR is small in healthy individuals but increases in patients with vestibular dysfunction. Conversely, static COR has not been directly observed in healthy individuals. OBJECTIVES: To elucidate the presence of static COR and quantify it in normal individuals in the roll plane. METHODS: Eleven healthy participants were included in the study...

In studies of vestibulo-ocular reflex (VOR), the horizontal VOR circuit is much clearer than vertical-torsional VOR. The circuit and mechanism of gravity-related vertical-torsional VOR is probably weak. "Somatosensory vestibular interaction" is a known extra source to facilitate VOR, and cervico-ocular reflex is a representative for torsional VOR compensation. Whereas, how the cervical afferents finally reach the oculomotor system is less documented. Actually, when the head tilts, which generates cervico-ocular reflex, not only the neck muscle is activated, but also the jaw muscle is stretched by gravity dragged mandible and/or tissue-muscle connection between the mandible and clavicle...

Introduction: Vestibular sensory hair cells are precisely orientated according to planar cell polarity (PCP) and are key to enable mechanic-electrical transduction and normal vestibular function. PCP is found on different scales in the vestibular organs, ranging from correct hair bundle orientation, coordination of hair cell orientation with neighboring hair cells, and orientation around the striola in otolithic organs. Celsr1 is a PCP protein and a Celsr1 KO mouse model showed hair cell disorganization in all vestibular organs, especially in the canalar ampullae...

The key to the diagnosis of ocular motor disorders is a systematic clinical examination of the different types of eye movements, including eye position, spontaneous nystagmus, range of eye movements, smooth pursuit, saccades, gaze-holding function, vergence, optokinetic nystagmus, as well as testing of the function of the vestibulo-ocular reflex (VOR) and visual fixation suppression of the VOR. This is like a window which allows you to look into the brain stem and cerebellum even if imaging is normal. Relevant anatomical structures are the midbrain, pons, medulla, cerebellum and rarely the cortex...

Matrices that can be collected non-invasively for quantification of a stress response in sheep have received little attention in the veterinary literature. This study examines the suitability of blood, tears and saliva for determining a stress response in sheep undergoing sham foot trimming on a tilt table. The cortisol concentration of blood, tears and saliva and the concentration of cortisol metabolites in faeces were measured in 13 healthy Meat Merino ewes once a day for six days. Sham foot trimming on a tilt table was used as the stressor and was done during a one-hour period on day 4; cortisol concentrations of blood and tears were measured at 0, 10, 20, 30, 40 and 60 minutes...

Episodic ataxia type 2 (EA2) can present diverse ocular motor abnormalities, but few studies have systematically evaluated vestibular function during the interictal periods. This study aimed to determine vestibular impairments in patients with EA2 during the interictal periods. We recruited 17 patients with genetically confirmed EA2 (10 men, age range  =  16-85 years, median  =  32 years). We systematically evaluated the vestibular function by measuring the semicircular canals (SCCs) function with bithermal caloric tests, rotatory chair test, and video head impulse test (vHIT), and the otolith function with subjective visual vertical (SVV) tilt and variability, and cervical and ocular vestibular-evoked myogenic potentials (VEMPs)...

SIGNIFICANCE: Ocular tilt reaction (OTR) is an abnormal eye-head postural reaction that consists of skew deviation, head tilt, and bilateral ocular torsion. Understanding of the pathway of the vestibulo-ocular reflex (VOR) is essential because this will help to localize the pathology. PURPOSE: The aim of this study was to report a case of OTR with contralateral internuclear ophthalmoplegia (INO) and fifth and seventh cranial nerve palsies. CASE REPORT: A 51-year-old gentleman with underlying diabetes mellitus presented with sudden onset of diplopia for 3 days...

From animal experiments by Cohen, Suzuki et al. in the 1960's to first-in-human clinical trials now in progress, prosthetic electrical stimulation targeting semicircular canal branches of the vestibular nerve has proven effective at driving directionally appropriate vestibulo-ocular reflex (VOR) eye movements, postural responses and perception. That work was considerably facilitated by the fact that all hair cells and primary afferent neurons in each canal have the same directional sensitivity to head rotation, the three canals' ampullary nerves are geometrically distinct from one another, and electrically-evoked 3D canal-ocular reflex responses approximate a simple vector sum of linearly independent components representing relative excitation of each of the three canals...

Vestibular migraine (VM) is the most common cause of spontaneous vertigo but remains poorly understood. We investigated the hypothesis that central vestibular pathways are sensitized in VM by measuring self-motion perceptual thresholds in patients and control subjects and by characterizing the vestibulo-ocular reflex (VOR) and vestibular and headache symptom severity. VM patients were abnormally sensitive to roll tilt, which co-modulates semicircular canal and otolith organ activity, but not to motions that activate the canals or otolith organs in isolation, implying sensitization of canal-otolith integration...

The role of the otoliths in mammals in the angular vestibuloocular reflex (VOR) has been difficult to determine because there is no surgical technique that can reliably ablate them without damaging the semicircular canals. The Otopetrin1 (Otop1) mouse lacks functioning otoliths because of failure to develop otoconia but seems to have otherwise normal peripheral anatomy and neural circuitry. By using these animals we sought to determine the role of the otoliths in angular VOR baseline function and adaptation...

OBJECTIVE: To determine the role of the medial longitudinal fasciculus (MLF) in conveying vestibular signals. METHODS: In 10 patients with isolated acute unilateral internuclear ophthalmoplegia (INO) due to an acute stroke, we performed comprehensive vestibular evaluation using video-oculography, head impulse tests with a magnetic search coil technique, bithermal caloric tests, tests for the ocular tilt reaction, and measurements of subjective visual vertical and cervical and ocular vestibular evoked myogenic potentials (VEMPs)...

Patients with bilateral vestibular failure (BVF) suffer from postural and gait unsteadiness with an increased risk of falls. The aim of this study was to elucidate the differential role of otolith, semicircular canal (SSC), visual, proprioceptive, and cognitive influences on the postural stability of BVF patients. Center-of-pressure displacements were recorded by posturography under six conditions: target visibility; tonic head positions in the pitch plane; horizontal head shaking; sensory deprivation; dual task; and tandem stance...

The cerebellar flocculus is a critical structure involved in the control of eye movements. Both static and dynamic abnormalities of the vestibulo-ocular reflex (VOR) have been described in animals with experimental lesions of the flocculus/paraflocculus complex. In humans, lesions restricted to the flocculus are rare so they can become an exceptional model to contrast with the clinical features in experimental animals or in patients with more generalized cerebellar diseases. Here, we examined a 67-year-old patient with an acute vestibular syndrome due to an isolated infarct of the right flocculus...

CONTEXT: Medical Education can be delivered in the traditional classroom or via novel technology including an online classroom. OBJECTIVE: To test the hypothesis that learning in an online classroom would result in similar outcomes as learning in the traditional classroom when using a flipped classroom pedagogy. DESIGN: Randomized controlled trial. A total of 274 subjects enrolled in a Neuro-otology training program for non-Neuro-otologists of 25 h held over a 3-day period...

Prevailing evidence indicates a relatively late life decline in human vestibulo-ocular reflex (VOR) function. Although mice are commonly used in mechanistic studies of vestibular function, it remains unclear whether aging produces a corresponding decline in VOR function in mice. We sought to determine how the baseline VOR and its short-term adaptation were affected by aging. We tested 8 young (3-month old) and 8 aged (30-month old-equivalent to a ∼80-year old human) C57BL/6 mice. We measured their VOR response to whole-body static tilts and during 0...

Vestibulo-ocular reflexes (VOR) ensure gaze stability during locomotion and passively induced head/body movements. In precocial vertebrates such as amphibians, vestibular reflexes are required very early at the onset of locomotor activity. While the formation of inner ears and the assembly of sensory-motor pathways is largely completed soon after hatching, angular and translational/tilt VOR display differential functional onsets and mature with different time courses. Otolith-derived eye movements appear immediately after hatching, whereas the appearance and progressive amelioration of semicircular canal-evoked eye movements is delayed and dependent on the acquisition of sufficiently large semicircular canal diameters...

Migraine is associated with enhanced motion sickness susceptibility and can cause episodic vertigo [vestibular migraine (VM)], but the mechanisms relating migraine to these vestibular symptoms remain uncertain. We tested the hypothesis that the central integration of rotational cues (from the semicircular canals) and gravitational cues (from the otolith organs) is abnormal in migraine patients. A postrotational tilt paradigm generated a conflict between canal cues (which indicate the head is rotating) and otolith cues (which indicate the head is tilted and stationary), and eye movements were measured to quantify two behaviors that are thought to minimize this conflict: suppression and reorientation of the central angular velocity signal, evidenced by attenuation ("dumping") of the vestibuloocular reflex and shifting of the rotational axis of the vestibuloocular reflex toward the earth vertical...

We sought to determine the cerebellar structures responsible for tilt suppression of post-rotatory nystagmus. We investigated ocular motor findings and MRI lesions in 73 patients with isolated cerebellar lesions who underwent recording of the vestibulo-ocular reflex (VOR) using rotatory chair tests. Tilt suppression of post-rotatory nystagmus was diminished in 27 patients (27/73, 37.0 %). The gains of the VOR and the TCs of per- and post-rotatory nystagmus did not differ between the patients with diminished and with normal tilt suppression...