saccule eye movements

Patients with SLC26A4 mutations exhibit highly variable hearing loss and vestibular dysfunction. Although Slc26a4 mutant mice similarly exhibit vestibular deficits, including circling behavior, head tilting, and torticollis, the underlying pathogenesis of the vestibular symptoms remains unclear, hindering its effective management for patients with SLC26A4 mutations. In this study, we evaluated the equilibrium function using the inspection equipment, which can record eye movements against rotational, gravitational, and thermal stimulations...

Vestibular schwannomas (VS) are benign tumors of the vestibular nerve that may trigger hearing loss, tinnitus, rotatory vertigo, and dizziness in patients. Vestibular and auditory tests can determine the precise degree of impairment of the auditory nerve, and superior and inferior vestibular nerves. However, balance is often poorly quantified in patients with untreated vestibular schwannoma, for whom validated standardized assessments of balance are often lacking. Balance can be quantified with the EquiTest...

It has become well established that vestibular information is important for hippocampal function and spatial memory. However, as yet, relatively little is known about how different kinds of vestibular information are 'represented' in different parts of the hippocampus. This study used selective electrical stimulation of each of the 5 vestibular sensors (the horizontal (HC), anterior (AC) and posterior (PC) semi-circular canals, and the utricle and saccule) in the rat and recorded local field potentials (LFPs) across the hippocampus, using a 16 electrode microarray...

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...

OBJECTIVE: We aimed to describe vestibular/oculomotor function of 7-12-year-old children with CP, Gross Motor Function Classification System (GMFCS) levels (I-III), in comparison to an age-matched control group to understand the effect of the vestibular system on activities and participation of children with CP. METHODS: Vestibular, oculomotor and balance function were tested in children with CP. Central and peripheral vestibular function was examined using an enclosed rotary chair and infrared video goggles (100 Hz) that measured eye movements...

Objectives: To review the clinical records of patients that exhibited the clinical features of both vestibular migraine (VM) and Ménière's disease (MD) during each episodic vertigo attack and to discuss the possible pathophysiology of such combination of symptoms. Subjects: Ten patients that were selected according to criteria based on a combination of the diagnostic criteria for definite MD and VM (9 females and one male, age: 22-54 years) were enrolled. They were required to show features of both diseases in each vertigo attack...

This study was conducted to evaluate the linear vestibulo-ocular reflex (lVOR) mediated by the saccule, and to investigate the relationship between the lVOR and the ability to distinguish the direction of centripetal acceleration during centric and eccentric rotation. Participants sat on a chair in darkness, with the right ear facing downwards, either directly above the center of rotation, or with their nose out, nose in, right shoulder out, or left shoulder out against the center of rotation (eccentric rotation)...

The otolith organs consist of the utricle and saccule. The utricle mediates the utriculo-ocular reflex by detecting horizontal head translation and static head tilt. Skew deviation is a vertical strabismus caused by imbalance of the utriculo-ocular reflex pathway and is commonly caused by lesions in the brainstem or cerebellum. It is associated with abnormal utriculo-ocular reflexes including asymmetric reduction of the translational vestibulo-ocular and ocular counterroll responses. Skew deviation is also associated with head position-dependent changes in ocular torsion and vertical strabismus...

Extracellular single neuron recording and labelling studies of primary vestibular afferents in Scarpa's ganglion have shown that guinea-pig otolithic afferents with irregular resting discharge are preferentially activated by 500 Hz bone-conducted vibration (BCV) and many also by 500 Hz air-conducted sound (ACS) at low threshold and high sensitivity. Very few afferent neurons from any semicircular canal are activated by these stimuli and then only at high intensity. Tracing the origin of the activated neurons shows that these sensitive otolithic afferents originate mainly from a specialized region, the striola, of both the utricular and saccular maculae...

OBJECTIVE: To evaluate methods for estimating thresholds of vestibular evoked myogenic potentials (VEMPs) and ocular VEMPs (OVEMPs) produced by impulsive transmastoid acceleration (ITA). DESIGN: VEMPs and OVEMPs were obtained simultaneously from subjects in supine posture with both head and eyes elevated. Thresholds to ITA were measured using four different response identification methods. STUDY SAMPLE: Twelve adult subjects with no history of auditory or vestibular deficits...

The study aimed to measure utricular function by directly quantifying head tilt in vestibular schwannoma (VS) patients using regular video-oculography (VOG) equipment with integrated head-position sensor, and to correlate the results with patients' symptoms and signs. We recorded head tilting after exclusion of visual cues (static head tilt), and after returning to the centre following lateral head rolls towards each side [subjective head vertical (SHV)]. Head tilt in 43 patients was measured preoperatively and approximately 4 months postoperatively, and compared to that of 20 healthy subjects...

INTRODUCTION: A sense of proper sensory processing of head motion and the coordination of visual and postural movements to maintain equilibrium is critical to everyday function. The vestibular system is an intricate organization that involves multiple levels of sensory processing to achieve this goal. PURPOSE: This chapter provides an overview of the anatomical structures and pathways of the vestibular system. SUMMARY: The five major vestibular structures are located in the inner ear and include: the utricle, the saccule, and the lateral, superior, and posterior semicircular canals...

OBJECTIVE: This study applied ocular vestibular-evoked myogenic potential (oVEMP) and cervical VEMP (cVEMP) tests in Ménière's patients with Tumarkin falls to investigate the etiologic role of the saccule/utricle in the event of Tumarkin falls. STUDY DESIGN: Retrospective study. SETTING: University hospital. SUBJECTS: Twenty unilateral definite Ménière's patients were divided into 2 age- and sex-matched groups. Ten patients had a history of drop attacks, and 10 had no history of drop attacks...

BACKGROUND: Although adult vertebrates sense changes in head position by using two classes of accelerometer, at larval stages zebrafish lack functional semicircular canals and rely exclusively on their otolithic organs to transduce vestibular information. RESULTS: Despite this limitation, we find that larval zebrafish perform an effective vestibulo-ocular reflex (VOR) that serves to stabilize gaze in response to pitch and roll tilts. By using single-cell electroporations and targeted laser ablations, we identified a specific class of central vestibular neurons, located in the tangential nucleus, that are essential for the utricle-dependent VOR...

We have previously shown that sinusoidal galvanic vestibular stimulation, a means of selectively modulating vestibular afferent activity, can cause partial entrainment of sympathetic outflow to muscle and skin in human subjects. However, it influences the firing of afferents from the entire vestibular apparatus, including the semicircular canals. Here, we tested the hypothesis that selective stimulation of one set of otolithic organs-those located in the utricle, which are sensitive to displacement in the horizontal axis-could entrain sympathetic nerve activity...

A new test for utricular function has recently been introduced and validated, namely the ocular vestibular-evoked myogenic potential (oVEMP), which refers to the myogenic potentials recorded by surface EMG electrodes beneath both eyes in response to bone conducted vibration (BCV) of the head or air conducted sound (ACS). The oVEMP test differs from another vestibular-evoked myogenic potential recorded by surface EMG electrodes over the sternocleidomastoid muscles in that the cervical vestibular-evoked myogenic potential (cVEMP) due to saccular activation is measured...

To explore the patterns and mechanisms of jerky seesaw nystagmus in internuclear ophthalmoplegia (INO), we analyzed the nystagmus patterns in 33 patients with dissociated torsional-vertical nystagmus and INO. In 11 (33%) patients, the nystagmus was ipsiversive torsional in both eyes with vertical components in the opposite directions. In contrast, 18 (55%) patients showed ipsiversive torsional nystagmus with a larger upbeat component in the contralesional eye. Four (12%) patients exhibited ipsiversive torsional nystagmus with a greater downbeat component in the ipsilesional eye...

Extracellular single neuron recordings of primary vestibular neurons in Scarpa's ganglion in guinea pigs show that low-intensity 500 Hz bone-conducted vibration (BCV) or 500 Hz air-conducted sound (ACS) activate a high proportion of otolith irregular neurons from the utricular and saccular maculae but few semicircular canal neurons. In alert guinea pigs, and humans, 500 Hz BCV elicits otolith-evoked eye movements. In humans, it also elicits a myogenic potential on tensed sternocleidomastoid muscles. Although BCV and ACS activate both utricular and saccular maculae, it is possible to probe the functional status of these two sense organs separately because of their differential neural projections...

CONCLUSION: The static subjective visual horizontal (SVH) test correlates with the dynamic ocular vestibular-evoked myogenic potential (oVEMP) test in healthy and pathological ears, and further confirms that both tests may, at least in part, share the same utricular reflex pathway. OBJECTIVE: This study correlated the SVH test results with those of the oVEMP and cervical VEMP (cVEMP) tests to investigate their relationships. METHODS: Twenty healthy subjects underwent the SVH test at a view pattern angle of 30° or 70° horizontal tilt under various background distractions to establish the optimal stimulation mode for SVH test...

The utricle plays an important role in orientation with respect to gravity. The unilateral centrifugation test allows a side-by-side investigation of both utricles. During this test, the subject is rotated about an earth-vertical axis at high rotation speeds (e.g. 400°/s) and translated along an interaural axis to consecutively align the axis of rotation with the left and the right utricle. A simple sinusoidal translation profile (0.013 Hz; amplitude = 4 cm) was chosen. The combined rotation and translation induces ocular counter rolling (OCR), which is measured using 3-D video-oculography...