Torsional Nystagmus Research Articles

L’anisocorie intermittente comme signe révélateur de la sclérose en plaques récurrente-rémittente

A 36-year-old male presented for an examination reporting intermittent anisocoria of one week duration. Over a period of one-month, ocular findings consisted of intermittent and variable anisocoria, diplopia, and torsional nystagmus. A diagnosis of relapsing-remitting multiple sclerosis (MS) was made using the McDonald criteria based on brainstem syndrome, optic neuropathy, transverse myelitis symptoms, multifocal areas of demyelination in the spinal cord on MRI, and the absence of MS mimickers in lab work. In this case report, eye care providers are alerted to the possibility of intermittent anisocoria as a presenting sign of relapsing-remitting multiple sclerosis.

Anterior Canal BPPV- A Rare Form of Vertical Canaloliathiasis: Series of 11 Cases.

The most common cause of peripheral vertigo is Benign Paroxysmal Positional Vertigo (BPPV) primarily due to involvement of posterior semicircular canal. BPPV due to anterior canal is rare entity. This is a retrospective study, in which data of 628 patients who underwent vertigo test were analyzed. Amongst which 354 were patients of BPPV. It was found that 305 patients had posterior canal BPPV, 18 patients had lateral canal BPPV and 11 patients had anterior canal BPPV. The VNG data of 11 patients with anterior canal BPPV along with their treatment outcomes was analyzed. Of the eleven patients of anterior canal BPPV, ten patients had torsional nystagmus with or without downbeat nystagmus in Deep Head Hanging test. Only one patient had isolated downbeat nystagmus in Supine Head Hanging Test. Patients were treated with modified Yacovino's maneuver. Eight patients had immediate relief with modified Yacovino's repositioning maneuver. One patient had immediate conversion to left posterior canal BPPV and was treated for the same. Two patients presented with delayed conversion to posterior canal BPPV and were treated for the same. Anterior canal BPPV is rare but existent entity. It has a typical torsional and downbeat Nystagmus which is induced by Dix-Hallpike and Deep head hanging test. There is no reversal of nystagmus on getting up. It can be easily corrected by Yacovino's maneuver in the majority of the cases.

Chiari I Malformation Presenting Vertical Gaze-Evoked Nystagmus : A Case Report

Abstract
 Introduction : Chiari malformation is characterized by herniation of posterior cerebellar vermis in which type 1 malformation has coexisting syringomyelia of cervicothoracic spinal cord. This malformation can be congenital or acquired, in which gaze-evoked nystagmus is the typical movement deficit. This case aimed to report a case of vertical gaze-evoked nystagmus as a primary symptom to detect Type I Chiari Malformation.
 Case Illustration : A 44-year-old woman presented with involuntary movements of both eyes in the last 5 months with vision problems in which objects appear to jump or vibrate. Visual acuity was 20/50 in both eyes with 12 prism diopters BI exotropia. We recognized vertical and torsional nystagmus in upgaze without any movement in primary gaze. While performing supraduction, the oscillation was detected and increased. Brain MRI revealed Type I Chiari Malformation.
 Discussion : Nystagmus was seen in many diseases of the central nervous system, in particular those affecting the brainstem and cerebellum. Vertical gaze evoked nystagmus was a disorder of the gaze holding function, purely vertical gaze-evoked nystagmus is observed in midbrain lesions involving the interstitial nucleus of Cajal (INC) as the neural integrator for vertical gaze-holding function. Based on this pathophysiology, the Brain MRI of this patient revealed some degrees of compression in midbrain, and cervico medullary junction due to her brain malformation.
 Conclusion : A sustained gaze-evoked nystagmus is an important ocular finding that may indicate serious neurologic pathology. It is important for an eye care provider to thoroughly examine additional tests to determine the underlying cause of the nystagmus.

Investigation on biomechanical responses in bilateral semicircular canals and nystagmus in vestibulo-ocular reflex experiments under different forward-leaning angles.

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°. It was found that the horizontal nystagmus slow-phase velocity and corresponding biomechanical responses of the cupula in horizontal SCC increased with the forward-leaning angles of the head, reached a maximum when the head was tilted 30° forward, and then gradually decreased. However, no obvious vertical or torsional nystagmus was observed in the VOR experiments. In the numerical model of bilateral SCCs, the biomechanical responses of the cupula in the left anterior SCC and the right anterior SCC showed the same trends; they decreased with the forward-leaning angles, reached a minimum at a 40° forward tilt of the head, and then gradually increased. Similarly, the biomechanical responses of the cupula in the left posterior SCC and in the right posterior SCC followed a same trend, decreasing with the forward-leaning angles, reaching a minimum at a 30° forward tilt of the head, and then gradually increasing. Additionally, the biomechanical responses of the cupula in both the anterior and posterior SCCs consistently remained lower than those observed in the horizontal SCCs across all measured head positions. The occurrence of these numerical results was attributed to the consistent maintenance of mutual symmetry in the bilateral SCCs with respect to the mid-sagittal plane containing the axis of rotation. This symmetry affected the distribution of endolymph pressure, resulting in biomechanical responses of the cupula in each pair of symmetrical SCCs exhibiting same tendencies under different forward-leaning angles of the head. These results provided a reliable numerical basis for future research to relieve vestibular diseases induced by spatial orientation of SCCs.

Update on central oculomotor disorders and nystagmus

The diagnosis of ocular motor disorders and the different forms of a nystagmus is based on a systematic clinical examination of all types of eye movements: 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. Relevant anatomical structures are the midbrain, pons, medulla, cerebellum, and cortex. There is a simple clinical rule: vertical and torsional eye movements are generated in the midbrain, horizontal in the pons. The cerebellum is relevant for almost all types of eye movements; typical pathological findings are saccadic smooth pursuit, gaze-evoked nystagmus or dysmetric saccades.Nystagmus is defined as a rhythmic, most often involuntary eye movement. It normally consists of a slow (pathological) drift of the eyes and a fast central compensatory movement of the eyes back to the primary position (re-fixation saccade). There are three major categories: first, spontaneous nystagmus, i. e. nystagmus which occurs in the gaze straight ahead position as upbeat or downbeat nystagmus; second, nystagmus that becomes visible at eccentric gaze only and third, nystagmus which can be elicited by certain maneuvers, e. g. head-shaking, head positioning, air pressure or hyperventilation, most of which are of peripheral vestibular origin. The most frequent central types of spontaneous nystagmus are downbeat and upbeat, infantile, pure torsional, pendular fixation, periodic alternating, and seesaw nystagmus. Many types of central nystagmus allow a precise neuroanatomical localization: for instance, downbeat nystagmus, which is most often caused by a bilateral floccular lesion or dysfunction, or upbeat nystagmus, which is caused by a lesion in the mesencephalon or medulla oblongata. Examples of pharmacotherapy are the use of 4-aminopyridine for downbeat and upbeat nystagmus, memantine or gabapentin for fixation pendular nystagmus or baclofen for periodic alternating nystagmus.

Three-dimensional characteristics of nystagmus induced by low frequency in semicircular canals of healthy young people.

The study aimed to analyze the three-dimensional characteristics of nystagmus induced by different semicircular canal combinations in healthy young people, and to determine the reference range of nystagmus slow phase velocity (SPV) and its asymmetry. Fifty-two healthy volunteers (26 males and 26 females, aged 17-42 years, average 23.52 ± 6.59), were recruited to perform the manual triaxial rotation testing with a 3D-Videonystagmography (3D-VNG) device (VertiGoggles (ZT-VNG-II), Shanghai ZEHNIT Medical Technology Co., Ltd., Shanghai, China) using a 0.3 Hz prompt beat and a 90° amplitude, respectively. The induced nystagmus around the Z-, X-, and Y-axes were recorded in the yaw, pitch, and roll planes. The directions and slow phase velocities of the horizontal, vertical, and torsional components of the induced nystagmus under different semicircular canal combinations (the left lateral and right lateral semicircular canal combination, bilateral anterior semicircular canals, bilateral posterior semicircular canals combination, and the anterior and posterior semicircular canals combination of each ear), as well as their asymmetry, were taken as the observation indexes to analyze the characteristics of the nystagmus vectors of different combinations. Fifty-two healthy volunteers had no spontaneous nystagmus. The characteristic nystagmus was induced by the same head movement direction in all three axial rotation tests. The SPVs of the left and right nystagmus were 44.45 ± 15.75°/s and 43.79 ± 5.42°/s, respectively, when the subjects' heads were turned left or right around the Z-axis (yaw). The SPVs of vertically upward and downward nystagmus were 31.67 ± 9.46°/s and 30.01 ± 9.20°/s, respectively, when the subjects' heads were pitched around the X-axis (pitch). The SPVs of torsional nystagmus, with the upper poles of the eyes twisting slowly to the right and left ears (from the participant's perspective), were 28.99 ± 9.20°/s and 28.35 ± 8.17°/s, respectively, when the subjects' heads were turned left or right around the Y-axis (roll). There was no significant difference in the SPVs of nystagmus induced by the same rotation axis in two opposite directions (p > 0.05). The reference ranges for the slow phase velocities (SPVs) of nystagmus induced by the triaxial rotation testing were as follows: For the Z-axis (yaw), the SPVs were 13.58-75.32°/s for leftward head rotation and 13.56-74.02°/s for rightward head rotation. For the X-axis (pitch), the SPVs were 13.13-50.21°/s for upward head nystagmus and 11.98-48.04°/s for downward head nystagmus. For the Y-axis (roll), the SPVs were 10.97-47.02°/s for the left-sided head rotation and 12.34-44.35°/s for the right-sided head rotation. This study clarified the three-dimensional characteristics of nystagmus induced by different semicircular canal combinations in healthy young people. It also established a preliminary reference range of SPVs and SPV asymmetry of nystagmus induced by the vertical semicircular canal. It can further provide a basis for the mechanism of semicircular canal-induced nystagmus and the traceability of nystagmus in patients with otogenic vertigo. It is shown that the portable 3D-VNG eye mask can be used for the manual triaxial rotation testing to achieve the evaluation of the low-frequency angular vestibulo-ocular reflex (aVOR) function of the vertical semicircular canal, which is convenient, efficient, and practical.

Upbeat and Direction-Changing Torsional Nystagmus While Straight Head Hanging: A New Sign of Benign Paroxysmal Positional Vertigo Involving Bilateral Posterior Semicircular Canals.

Upbeat and Direction-Changing Torsional Nystagmus While Straight Head Hanging: A New Sign of Benign Paroxysmal Positional Vertigo Involving Bilateral Posterior Semicircular Canals.

Abstract 265: A Curious Case Of Acute Binocular Diplopia, Ischemic Stroke Of The Interstitial Nucleus Of Cajal

Introduction The nuclei in the periaqueductal gray of the midbrain are critical structures that coordinate and control vertical and torsional gaze, as well as crucial components of the vestibulo‐occular reflex. These structures are so fine that they may be missed on routine imaging however, they represent distinct localizations for the neurological exam, with lesions of these structures being important clinical considerations. The Interstitial Nucleus of Cajal (inC) coordinates signals from the saccadic burst neurons in the rostral interstitial nucleus of the medial longitudinal fasiculus (riMLF), vestibular projections (utricular and semicircular canal pathways from the vestibular nuclei via the MLF), and descending pursuit fibers, the paired interstitial nuclei of Cajal act as neural integrators for vertical gaze and torsion. These nuclei lie adjacent but dorsal and caudal to the riMLF, For upgaze, fibers from the inC cross via the posterior commissure, then connect to the contralateral superior rectus and inferior oblique subnuclei. For downgaze, fibers travel across the posterior commissure, then innervate the contralateral inferior rectus subnucleus and fourth nerve nucleus. Blood supply is derived from the terminal branches of the basilar artery. Lesions of these interstitial nuclei and their tracts may produce vertical and torsional gaze‐holding deficits such as impairments in the vertical vestibulo‐occular reflex, hypertropia, counter‐rolling of the eyes, superior oblique palsy, and see‐saw and torsional nystagmus. Methods Case report and review of literature Results 45‐year‐old, right‐handed woman with history of turner syndrome, anemia, nephrolithiasis, horseshoe kidney, premature ovarian failure on hormone replacement therapy (HRT), suspected adrenal mass of undetermined significant, and degenerative disk disease presented to the emergency department with complaints of acute binocular diplopia and dizziness clarified to be sensation of the ground/objects bobbing in visual field. Neurological exam significant for left hypertropia and exotropia in primary gaze, equal in right/left gaze and right/left head tilt, as well as large amplitude medium frequency (see‐saw) nystagmus characterized by upbeat nystagmus with intorsion on the right, and downbeat nystagmus with extorsion left. Visual fields were intact to finger count with binocular diplopia and oscillopsia noted in primary gaze. CT head and CT angiogram of the head and neck were unrevealing. Initial MRI brain negative for diffusion restriction but with flair hyperintensity in periaqueductal gray prompting repeat MRI brain without contrast with thin slices through the brainstem with showed infarct in periaqueductal gray within the region of the interstitial nuclei, with stroke etiology undetermined at the time of presentation but suspicion of small vessel disease vs hypercoagulability given propensity for thrombophilia in Turner syndrome and patient being on HRT. Full dose aspirin and high intensity statin therapy was initiated given presentation out of tPA window, and hypercoagulability workup initiated prior to discharge. Conclusion Acute ischemic stroke and lesions of the interstitial nuclei in the periaqueductal gray are important, under recognized considerations for the evaluation of binocular diplopia, that may represent an opportunity for thrombolytic administration if providers had a higher index of suspicion. Hypercoagulability and Turner syndrome are also unique qualifiers, underscoring a nuanced approach to determination of stroke diagnosis and etiology in cases of isolated ocular symptomology.

Diagnostic Criteria of Benign Paroxysmal Positional Vertigo

Benign paroxysmal positional vertigo (BPPV) is the mos common cause of peripheral vertigo. The pathophysiology of BPPV is canalolithiasis which includes free-floating otoconial debris within the endolymph of a semicircular canal, or cupulolithiasis comprising otoconial debris adherent to the cupula. The posterior and/or lateral semicircular canals are often affected in BPPV. It is characterized by a brief episode of rotatory vertigo associated with positional and/or positioning nystagmus, which is elicited by specific head positions or changes in head position relative to gravity. In the case of the posterior canal type of BPPV, torsional nystagmus is induced by the Dix-Hallpike test. In patients of lateral canal type of BPPV, horizontal geotropic or apogeotropic nystagmus is induced by the supine roll test. The observation of positional and/or positioning nystagmus is needed for the diagnosis of BPPV. The treatment of BPPV includes canalith repositioning procedure (CRP). By series of head position changes, the CRP moves the otoconial debris from the involved semicircular canal to the utricle. This review article presents operational diagnostic criteria for BPPV, formulated by the Committee for Classification of Vestibular Disorders of the Barany Society. This classification reflects the current knowledge of the clinical aspect and pathophysiology of BPPV. These diagnostic criteria will be helpful for the understanding of the disease and will lead to further development in the management of BPPV.

Relationship between the Presence of Nystagmus in the Fourth Position of the Epley Maneuver and Treatment Efficacy for PSC BPPV: A Prospective Study.

To investigate whether a specific nystagmus observed during the Epley maneuver can enable immediate reassessment of patients, eliminating the need for deferred diagnosis. Prospective cohort. Tertiary center. Patients with posterior semicircular canal (PSC) benign paroxysmal positional vertigo (BPPV) diagnosed by the Dix-Hallpike test between March 2022 and March 2023. All patients were treated with the Epley maneuver. The presence and the characteristics of the nystagmus were recorded in each of the four intermediate positions of the maneuver. Fifteen minutes later, all patients were reevaluated with the Dix-Hallpike test to determine the therapeutic success. Outcome of the Epley maneuver and its relationship with nystagmus characteristics during the four positions of the maneuver. Sixty-six patients (77.3% female) were included in the study, of which 66.7% exhibited right PSC BPPV. Therapeutic success of the first Epley maneuver was 74.2%. Almost one third (30.3%) of patients presented with nystagmus in the second and third positions of the Epley maneuver. All patients with down-beating and torsional nystagmus toward the opposite direction of the diagnostic nystagmus in the fourth position of the Epley maneuver needed a second rehabilitative maneuver. None of the patients without nystagmus in this fourth position remained with active BPPV after the first Epley maneuver. The presence of nystagmus in the fourth position of the Epley maneuver appears to have a high predictive value, reducing waiting time for a second diagnostic maneuver. Its absence may exempt subsequent reevaluation.

Torsional nystagmus recognition based on deep learning for vertigo diagnosis.

Detection of torsional nystagmus can help identify the canal of origin in benign paroxysmal positional vertigo (BPPV). Most currently available pupil trackers do not detect torsional nystagmus. In view of this, a new deep learning network model was designed for the determination of torsional nystagmus. The data set comes from the Eye, Ear, Nose and Throat (Eye&ENT) Hospital of Fudan University. In the process of data acquisition, the infrared videos were obtained from eye movement recorder. The dataset contains 24521 nystagmus videos. All torsion nystagmus videos were annotated by the ophthalmologist of the hospital. 80% of the data set was used to train the model, and 20% was used to test. Experiments indicate that the designed method can effectively identify torsional nystagmus. Compared with other methods, it has high recognition accuracy. It can realize the automatic recognition of torsional nystagmus and provides support for the posterior and anterior canal BPPV diagnosis. Our present work complements existing methods of 2D nystagmus analysis and could improve the diagnostic capabilities of VNG in multiple vestibular disorders. To automatically pick BPV requires detection of nystagmus in all 3 planes and identification of a paroxysm. This is the next research work to be carried out.

Abnormal Nystagmus Induced by Peripheral Vestibular Disorders

Electrophysiological measurement of the eye rotation axis using stimulation of a single semicircular canal nerve showed that the eye rotated around the axis perpendicular to the plane of the stimulated semicircular canal. Therefore, the affected semicircular canal can be identified by analyzing the eye rotation axis in cases of abnormal nystagmus. When the main component of the abnormal nystagmus is horizontal, the origin of the nystagmus is the lateral semicircular canal. When the main component of the abnormal nystagmus is torsional, the origin of the nystagmus is the anterior and/or posterior semicircular canal. The eye rotation axis in cases of excitatory nystagmus is quite the same as that in cases of inhibitory nystagmus, although the direction of eye rotation is opposite between cases of excitatory and inhibitory nystagmus. Vestibular neuritis mostly involves the superior vestibular nerve. The superior vestibular nerve transmits sensory information transmitted by from the vestibular hair cells located in the anterior and lateral semicircular canals. Therefore, patients with vestibular neuritis exhibit nystagmus with both horizontal and torsional components caused by inhibition of both the anterior and lateral semicircular canals. In patients with Ménière's disease, during a vertigo attack, excitatory nystagmus of anterior and/or posterior and/or lateral semicircular canal origin can be seen. Because the involving ratio of each contributing ratios of the three semicircular canals to nystagmus can vary, the ratio of the torsional component of the nystagmus to the horizontal component also varies. While nystagmus is purely horizontal in some cases, it is purely torsional in others. In the posterior canal type of BPPV, during the Dix-Hallpike maneuver, transient torsional nystagmus with the torsional component directed toward the affected side can be seen. In the lateral canal type of BPPV (canalolithiasis), geotropic positional nystagmus can be seen when the patient is supine. In the lateral canal type of BPPV (cupulolithiasis), apogeotropic positional nystagmus can be seen when the patient is supine.

Palato-ocular synchrony: Seeing what is behind closed eyelids in palatal tremor (P5-11.010)

<h3>Objective:</h3> To call attention to palato-ocular synchrony, a little-known manifestation of palatal tremor. <h3>Background:</h3> Palatal tremor due to a lesion of the dentato-rubro-olivary pathway (Guillain-Mollaret triangle) may spread to contiguous or remote muscles. When it involves the eyes it is known as oculopalatal tremor (OPT) manifesting as pendular nystagmus, typically vertical and/or torsional, causing oscillopsia. Nystagmus may be minimal or absent with eyes open and appear only under closed eyelids, a phenomenon described in 1976 by Jacobs and Bender, and called palato-ocular synchrony (Arch Neurol;33:289). These authors observed that palato-ocular synchrony was caused by eyelid closure rather than simply the removal of vision. <h3>Design/Methods:</h3> Two illustrative video case reports. <h3>Results:</h3> Following brainstem hemorrhage (patient 1 – midbrain; patient 2 – pons) involving the Guillain-Mollaret triangle, two patients developed hypertrophic olivary degeneration and asymptomatic palatal tremor. In patient 1, there was no nystagmus with eyes open, but under closed eyelids, vertical oscillations were readily apparent. In patient 2, there was very subtle torsional pendular nystagmus without oscillopsia, but large vertical oscillations were apparent with eyelid closure that were synchronous with PT. The mechanism of palato-ocular synchrony is unknown but may be related to the observation that palatal tremor, due to a lesion of the Guillain-Mollaret triangle, is one of the few movement disorders that persist during sleep, and this may simply reflect eyelid closure. <h3>Conclusions:</h3> A lesion, typically stroke, involving the Guillain-Mollaret triangle often leads to delayed development of palatal tremor. Such patients should undergo a careful ocular motor examination looking for oculopalatal tremor; if absent, then the globes should be observed during active eye closure. A visible or palpable ocular oscillation under closed eyelids is known as palato-ocular synchrony, an underappreciated phenomenon that extends the spectrum of manifestations of palatal tremor. <b>Disclosure:</b> Dr. Reich has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Best Doctors. Dr. Reich has received personal compensation in the range of $500-$4,999 for serving as a Consultant for UpToDate. Dr. Reich has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Enterin. Dr. Reich has received personal compensation in the range of $0-$499 for serving on a Scientific Advisory or Data Safety Monitoring board for NIH. Dr. Reich has received personal compensation in the range of $10,000-$49,999 for serving as an Expert Witness for Various law firms. The institution of Dr. Reich has received research support from ninds. Dr. Reich has received publishing royalties from a publication relating to health care. Dr. Reich has received publishing royalties from a publication relating to health care. Dr. Gold has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Springer .

Visual Fixation-Induced Hemi-Seesaw Nystagmus

Seesaw nystagmus (SSN) is characterized by conjugate torsional nystagmus with opposite vertical components in the two eyes. The waveform may be pendular or jerk (hemi-seesaw nystagmus, HSSN), in which the slow phase corresponds to one half-cycle and the quick phase to the other. Pendular SSN and HSSN have distinct clinical presentations and underlying causes. The pathophysiology of pendular SSN may be instability of visuovestibular interactions, while the underlying mechanism for HSSN may be related to the ocular tilt reaction or an imbalance in vestibular pathways. We report a patient with HSSN due to unilateral mesodiencephalic infarction that becomes apparent during visual fixation only.

Clinical Characteristics of Benign Paroxysmal Positional Vertigo Positive on Bilateral Dix-Hallpike Test

Objectives: The purpose of this study is to investigate the clinical characteristics of benign paroxysmal positional vertigo (BPPV) which showed torsional nystagmus on bilateral Dix-Hallpike test, and to analyze the clinical features of pseudo-bilateral BPPV.Methods: This study is a retrospective chart review of a total of 341 patients diagnosed with BPPV of posterior canal (PC-BPPV). Among them, patients who showed torsional nystagmus on bilateral Dix-Hallpike test were defined as “bilateral DixHallpike positive patients,” who were classified into true- and pseudo-bilateral PC-BPPV group through analysis of nystagmus direction. And pseudo-bilateral PC-BPPV were categorized into two subtypes according to their pathomechanisms. Clinical characteristics including sex, age, underlying vestibular disorders, recurrence and the number of Epley maneuvers were analyzed. Student &lt;i&gt;t&lt;/i&gt;-test and Mann-Whitney &lt;i&gt;U&lt;/i&gt;-test were used for statistical analysis.Results: Among 341 patients, 27 patients (7.9%) were “bilateral Dix-Hallpike positive patients”. They received more Epley maneuvers than the group of unilateral PC-BPPV until the resolution of nystagmus (2.3 vs. 1.4, &lt;i&gt;p&lt;/i&gt;＜0.001). Fifteen patients out of 27 were diagnosed with pseudo-bilateral PC-BPPV, who were classified into two subtypes according to their pathomechanisms. The number of Epley maneuvers was not different between true- and pseudo-bilateral PC-BPPV.Conclusions: Patients with pseudo-bilateral PC-BPPV were common among “bilateral Dix-Hallpike positive patients.” For their better treatment, understanding of possible pathophysiology, accurate Dix-Hallpike test and detailed analysis of nystagmus direction are necessary.

Bilateral Superior Semi-Circular Canal Dehiscence Presenting as Conductive Hearing Loss with Vestibular Symptoms: A Client Centre Case Report

Background: Superior semicircular canal dehiscence (SSCD) is a rare bone defect in the petrous part of the temporal bone. In this syndrome, a third window is created between the middle cranial fossa and the bony labyrinth of the inner ear which can lead to stimulation of the vestibular system by sound. Patients usually have symptoms such as vertigo, imbalance, autophony, pulsatile tinnitus, and aural fullness. The clinical symptoms of this disease vary from person to person. The Case: This study reports a case of a rare bilateral SSCD in a 39-year-old woman with imbalance and autophony problems. The audiological findings showed a bilateral mild conductive hearing loss at low frequencies with symptoms of vertigo and torsional nystagmus. The SSCD was diagnosed by computed tomography. Then, the patient underwent bone repair surgery. Auditory and balance tests were performed again after the surgery to evaluate the extent of recovery. Conclusion: The SSCD can be diagnosed by using the mentioned test battery. By choosing the appropriate treatment methods and following up of the outcomes, most of the problems of patients with SSCD can be solved. Keywords: Superior semicircular canal dehiscence; bilateral; conductive hearing loss

Nystagmus patterns classification framework based on deep learning and optical flow

Benign paroxysmal positional vertigo (BPPV) is the most common vestibular peripheral vertigo disease characterized by brief recurrent vertigo with positional nystagmus. Clinically, it is common to recognize the patterns of nystagmus by analyzing infrared nystagmus videos of patients. However, the existing approaches cannot effectively recognize different patterns of nystagmus, especially the torsional nystagmus. To improve the performance of recognizing different nystagmus patterns, this paper contributes an automatic recognizing method of BPPV nystagmus patterns based on deep learning and optical flow to assist doctors in analyzing the types of BPPV. Firstly, we present an adaptive method for eliminating invalid frames that caused by eyelid occlusion or blinking in nystagmus videos and an adaptive method for segmenting the iris and pupil area from video frames quickly and efficiently. Then, we use a deep learning-based optical flow method to extract nystagmus information. Finally, we propose a nystagmus video classification network (NVCN) to categorize the patterns of nystagmus. We use ConvNeXt to extract eye movement features and then use LSTM to extract temporal features. Experiments conducted on the clinically collected datasets of infrared nystagmus videos show that the NVCN model achieves an accuracy of 94.91% and an F1 score of 93.70% on nystagmus patterns classification task as well as an accuracy of 97.75% and an F1 score of 97.48% on torsional nystagmus recognition task. The experimental results prove that the framework we propose can effectively recognize different patterns of nystagmus.

The Head-Bending Test in Posterior Semicircular Canal Benign Paroxysmal Positional Vertigo

Objectives: This study aimed to investigate clinical significance of a head-bending test in benign paroxysmal positional vertigo (BPPV) involving the posterior semicircular canal (PC-BPPV).Methods: We retrospectively recruited 256 patients with unilateral PC-BPPV between January 2016 and December 2021, and assessed the clinical characteristics of patients showing head-bending nystagmus (HBN).Results: Of 256 patients, 138 (53.9%) showed HBN. Most patients (n=136, 98.6%) had downbeat nystagmus with (n=38) or without (n=98) torsional component. The remaining two patients had pure upbeat and torsional nystagmus, respectively. The torsional component was directed to the contralesional side in all. Between patients with and without HBN, there were no significant differences in clinical characteristics such as age, lateralization, types of BPPV (canalolithiasis or cupulolithiasis), and success rate of repositioning maneuver.Conclusions: Head-bending test may be useful in predicting the diagnosis and lateralization of PC-BPPV.

Measuring torsional optokinetic nystagmus in virtual reality

A torsional optokinetic stimulus drives torsional nystagmus, and a tilted frame during a rod and frame subjective visual vertical (SVV) task affects SVV and biases torsional eye position. We posit that a visual gravity cue provided by a frame in a torsional optokinetic stimulus would further bias torsional nystagmus. In order to test this theory, we use a FOVE VR headset (FOVE Inc., Tokyo, JP, model FOVEVR) to place the subject in a virtual room with circles forming either a rectangular room or a tubular room (frame/no frame). We placed a fixation point at the center of the room while the room rotates at 0°/s, ±6°/s, or ±12°/s. In addition, we had the subject perform a rod and frame SVV task, 0° ± 12° (upright) with nine equidistant divisions, asked twice per condition set. Preliminary data (N = 3) shows that the virtual reality setup produced the expected relationship between the speed of the rotation of the room and the slow-phase velocity of the induced nystagmus as well as the bias in the perception of upright. With the perceived upright tilted in the direction of the rotation. Additionally, we did not find a difference in torsional slow phase velocity (SPV), ocular torsion position, or perception of upright, between the frame and no frame condition across all rotation velocities and no significant difference in the SVV in intersubject results.

Adverse effect of the Epley maneuver: Anterior canal crisis

ObjectiveIn the Epley maneuver performed on patients with posterior semicircular canal-benign paroxysmal positional vertigo-canalolithiasis (P-BPPV-Can), an intense downbeat nystagmus and retropulsion rarely appear as soon as they reach the last upright sitting position. It is considered an anterior canal crisis that appears when the otoliths move to the ampullofugal direction in the anterior semicircular canal by changing head and body positions from the healthy-ear-down 135° head position (the third head position) to the upright sitting position (the fourth head position). This study aimed to determine the prevention of this anterior canal crisis. MethodsThe anterior canal crisis frequency was compared among the 178 cases that underwent general Epley maneuver (uncorrected Epley maneuver) and the 228 cases that underwent Epley maneuver (corrected Epley maneuver) by preventing head rotation beyond 135° to the healthy ear and the top of the head going down at the third head position. ResultsIn 6% of patients with P-BPPV-Can who underwent the Epley maneuver, a transient mixed downbeat and torsional nystagmus to the affected ear and retropulsion were observed at the fourth head position (anterior canal crisis). The corrected Epley maneuver significantly reduced the incidence of unpredictable anterior canal crisis (p = 0.017). Additionally, there was no difference in the effect of the Epley maneuver the next day regardless of the anterior canal crisis appearance. ConclusionAnterior canal crisis is an adverse effect of the Epley maneuver, and its prevention is important for safety. Avoiding head rotation beyond 135° to the healthy ear and/or the top of the head going down at the healthy-ear-down 135° head position is expected to reduce anterior canal crisis.