Impact of Clinician Training Background and Stroke Location on Bedside Diagnostic Test Accuracy in the Acute Vestibular Syndrome - A Meta-Analysis.

OBJECTIVE: Acute dizziness/vertigo is usually due to benign inner-ear causes but is occasionally due to dangerous neurologic ones, particularly stroke. Because symptoms and signs overlap, misdiagnosis is frequent and overuse of neuroimaging is common. We assessed the accuracy of bedside findings to differentiate peripheral vestibular from central neurologic causes. METHODS: We performed a systematic search (MEDLINE and Embase) to identify studies reporting on diagnostic accuracy of physical examination in adults with acute, prolonged dizziness/vertigo ("acute vestibular syndrome" [AVS]). Diagnostic test properties were calculated for findings. Results were stratified by examiner type and stroke location. RESULTS: We identified 6,089 citations and included 14 articles representing 10 study cohorts (n = 800). The Head Impulse, Nystagmus, Test of Skew (HINTS) eye movement battery had high sensitivity 95.3% (95% confidence interval [CI] = 92.5-98.1) and specificity 92.6% (95% CI = 88.6-96.5). Sensitivity was similar by examiner type (subspecialists 94.3% [95% CI = 88.2-100.0] vs non-subspecialists 95.0% [95% CI = 91.2-98.9], p = 0.55), but specificity was higher among subspecialists (97.6% [95% CI = 94.9-100.0] vs 89.1% [95% CI = 83.0-95.2], p = 0.007). HINTS sensitivity was lower in anterior cerebellar artery (AICA) than posterior inferior cerebellar artery (PICA) strokes (84.0% [95% CI = 65.3-93.6] vs 97.7% [95% CI = 93.3-99.2], p = 0.014) but was "rescued" by the addition of bedside hearing tests (HINTS+). Severe (grade 3) gait/truncal instability had high specificity 99.2% (95% CI = 97.8-100.0) but low sensitivity 35.8% (95% CI = 5.2-66.5). Early magnetic resonance imaging (MRI)-diffusion-weighted imaging (DWI; within 24-48 hours) was falsely negative in 15% of strokes (sensitivity 85.1% [95% CI = 79.2-91.0]). INTERPRETATION: In AVS, HINTS examination by appropriately trained clinicians can differentiate peripheral from central causes and has higher diagnostic accuracy for stroke than MRI-DWI in the first 24-48 hours. These techniques should be disseminated to all clinicians evaluating dizziness/vertigo. ANN NEUROL 2023;94:295-308.

Videoocular assessment of eye movement activity in an ataxia-telangiectasia: a case study.

PURPOSE: Ataxia-telangiectasia (A-T) is an autosomal recessive disorder characterized by progressive neurological deficits, including prominent oculomotor dysfunction. We report 5 cases of eye movement assessment in children 9-15 years old with A-T. METHODS: Three different oculomotor tasks (gaze holding, visually guided saccades and visual search) were used, and video-oculography was performed. Additionally, the scale for the assessment and rating of ataxia (SARA) score was used to assess severity of the cerebellar ataxia. RESULTS: Unstable gaze holding, nystagmus and saccadic intrusions were found. In addition to psychophysiological assessment results, we provide quantitative analysis of oculomotor activity, revealing a specific abnormal oculomotor pattern, consisting of (i) marked saccade hypermetria, (ii) unstable gaze holding, and (iii) gaze-evoked nystagmus. CONCLUSION: Our study opens the prospect to evaluate efficacy and safety of alternative methods for supporting the patient and improving his/her life quality.

Multimodal deep learning-based diagnostic model for BPPV.

BACKGROUND: Benign paroxysmal positional vertigo (BPPV) is a prevalent form of vertigo that necessitates a skilled physician to diagnose by observing the nystagmus and vertigo resulting from specific changes in the patient's position. In this study, we aim to explore the integration of eye movement video and position information for BPPV diagnosis and apply artificial intelligence (AI) methods to improve the accuracy of BPPV diagnosis. METHODS: We collected eye movement video and diagnostic data from 518 patients with BPPV who visited the hospital for examination from January to March 2021 and developed a BPPV dataset. Based on the characteristics of the dataset, we propose a multimodal deep learning diagnostic model, which combines a video understanding model, self-encoder, and cross-attention mechanism structure. RESULT: Our validation test on the test set showed that the average accuracy of the model reached 81.7%, demonstrating the effectiveness of the proposed multimodal deep learning method for BPPV diagnosis. Furthermore, our study highlights the significance of combining head position information and eye movement information in BPPV diagnosis. We also found that postural and eye movement information plays a critical role in the diagnosis of BPPV, as demonstrated by exploring the necessity of postural information for the diagnostic model and the contribution of cross-attention mechanisms to the fusion of postural and oculomotor information. Our results underscore the potential of AI-based methods for improving the accuracy of BPPV diagnosis and the importance of considering both postural and oculomotor information in BPPV diagnosis.

A new roll test to diagnose posterior semicircular canal benign paroxysmal positional vertigo.

BACKGROUND: The Dix-Hallpike (DH) test is a gold standard for diagnosing benign paroxysmal positional vertigo (BPPV). However, lateral semicircular canal BPPV is not rare. We have been performing the new roll test that begins from the sitting position and contains a head-hanging position, in order not to overlook lateral canal BPPV. We noticed that transient vertical/torsional nystagmus sometimes occurs during the new roll test. OBJECTIVE: To clarify the value of the new roll test in diagnosing posterior canal BPPV and elucidate the position that elicits nystagmus. MATERIALS AND METHODS: The subjects were 100 consecutive patients (79 were female, 21 were male) with posterior canal BPPV. We classified the patients into four types based on a position that induced nystagmus. RESULTS: The patient's position that elicited nystagmus varied. The supine type accounted for 24 %, the lateral type accounted for 62 %, the head-hanging type accounted for 9 %, and the DH type accounted for 5 %. CONCLUSION: The new roll test is valuable for diagnosing posterior canalolithiasis cases. Most patients reveal vertical/torsional nystagmus in the supine or lateral position. Therefore, performing the new roll test first is efficient at the initial visit.

The acute vestibular syndrome: prevalence of new hearing loss and its diagnostic value.

OBJECTIVES: To assess the prevalence of new hearing losses in patients with acute vestibular syndrome (AVS) and to start to evaluate its diagnostic value for the differentiation between peripheral and central causes. DESIGN: We performed a cross-sectional prospective study in AVS patients presenting to our Emergency Department (ED) from February 2015 to November 2020. All patients received an MRI, Head-impulse test, Nystagmus test and Test of skew ('HINTS'), caloric testing and a pure-tone audiometry. RESULTS: We assessed 71 AVS patients, 17 of whom had a central and 54 a peripheral cause of dizziness. 12.7% had an objective hearing loss. 'HINTS' had an accuracy of 78.9% to diagnose stroke, whereas 'HINTS' plus audiometry 73.2%. 'HINTS' sensitivity was 82.4% and specificity 77.8% compared to 'HINTS' plus audiometry showing a sensitivity of 82.4% and specificity of 70.4%. The four patients with stroke and minor stroke had all central 'HINTS'. 55% of the patients did not perceive their new unilateral hearing loss. CONCLUSIONS: We found that almost one-eighth of the AVS patients had a new onset of hearing loss and only half had self-reported it. 'HINTS' plus audiometry proved to be less accurate to diagnose a central cause than 'HINTS' alone. Audiometry offered little diagnostic accuracy to detect strokes in the ED but might be useful to objectify a new hearing loss that was underestimated in the acute phase. Complete hearing loss should be considered a red flag, as three in four patients suffered from a central cause.

Deep Learning-Based Nystagmus Detection for BPPV Diagnosis.

In this study, we propose a deep learning-based nystagmus detection algorithm using video oculography (VOG) data to diagnose benign paroxysmal positional vertigo (BPPV). Various deep learning architectures were utilized to develop and evaluate nystagmus detection models. Among the four deep learning architectures used in this study, the CNN1D model proposed as a nystagmus detection model demonstrated the best performance, exhibiting a sensitivity of 94.06 ± 0.78%, specificity of 86.39 ± 1.31%, precision of 91.34 ± 0.84%, accuracy of 91.02 ± 0.66%, and an F1-score of 92.68 ± 0.55%. These results indicate the high accuracy and generalizability of the proposed nystagmus diagnosis algorithm. In conclusion, this study validates the practicality of deep learning in diagnosing BPPV and offers avenues for numerous potential applications of deep learning in the medical diagnostic sector. The findings of this research underscore its importance in enhancing diagnostic accuracy and efficiency in healthcare.

[Update on central oculomotor disorders and nystagmus]. / Okulomotorikstörungen und 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.

Posterior semicircular canal cupulolithiasis during acute pontomedullary demyelination.

Positional vertigo poses a diagnostic challenge in people with multiple sclerosis (MS). The characteristics of positional nystagmus and its response to repositioning manoeuvres are usually sufficient to diagnose benign paroxysmal positional vertigo (BPPV). However, certain BPPV variants respond poorly to repositioning manoeuvres and their nystagmus pattern can resemble that of central positional vertigo caused by infratentorial demyelination. This diagnostic difficulty is particularly challenging if positional vertigo occurs during an MS relapse. We describe a woman with MS who developed a sixth nerve palsy and gaze-evoked nystagmus, caused by demyelination near or within areas classically involved in central positional vertigo. However, she also had positional vertigo from coincident BPPV (and not central positional vertigo). This was initially a treatment resistant-posterior semicircular canal cupulolithiasis but it later progressed to a posterior semicircular canal canalolithiasis, with symptoms promptly resolving after a repositioning manoeuvre.

Ophthalmologic and neuro-ophthalmologic findings in children with Down syndrome.

Down syndrome, also known as Trisomy 21, is a genetic disorder associated with mild-to-moderate intellectual disability, delays in growth, and characteristic facial features. A wide range of ocular complications are seen in children with Down syndrome, including strabismus, nystagmus, refractive errors, congenital cataracts, the presence of keratoconus, and decreased visual acuity. Early ophthalmic examination is needed for early diagnosis and treatment in patients. This narrative review examines ocular manifestations in children with Down syndrome and the importance of prompt ophthalmic interventions for treatment.

Upbeat Nystagmus with an Unusual Velocity-Decreasing and Increasing Waveform: a Sign of Gaze-Holding Dysfunction in the Paramedian Tracts in the Medulla?

We report a patient with spontaneous upbeat nystagmus (UBN) due to an ischemic lesion involving the paramedian tract (PMT) in the medulla. Eye movement recordings, using an infrared video-oculography (VOG) system, showed that the slow phase of the nystagmus was initially velocity-decreasing but gradually became velocity-increasing. Simulation of the nystagmus with a mathematical model supports a role for the PMT in relaying premotor signals for vertical gaze holding to the cerebellum. Our model shows that the disruption in cerebellar input from PMT can lead to the velocity-increasing waveform of the nystagmus, whereas the velocity-decreasing waveform could be related to a mismatch between the innervational commands to the ocular muscles (the pulse and step) needed to hold gaze steady.

Acute truncal ataxia without nystagmus in patients with acute vertigo.

BACKGROUND AND PURPOSE: Differentiating between peripheral and central aetiologies can be challenging in patients with acute vertigo, given substantial symptom overlap. A detailed clinical history and focused physical eye movement examination such as the HINTS eye examination appear to be the most reliable approach to identify acute cerebellar/brainstem stroke, outperforming even acute brain imaging. We have observed, however, that isolated vertigo of central cause may be accompanied by acute truncal ataxia, in the absence of nystagmus. METHODS: We explored the frequency of ataxia without concurrent nystagmus in a cross section of patients with acute vertigo who presented to the emergency department at two centres in Argentina (Group A) and the UK (Group B). Patients underwent detailed clinical neuro-otological assessments (Groups A and B), which included instrumented head impulse testing and oculography (Group B). RESULTS: A total of 71 patients in Group A and 24 patients in Group B were included in this study. We found acute truncal ataxia-without nystagmus-in 15% (n = 14) of our overall cohort. Lesions involved stroke syndromes affecting the posterior inferior cerebellar artery, anterior inferior cerebellar artery, and superior cerebellar artery, thalamic stroke, cerebral hemisphere stroke, multiple sclerosis, and a cerebellar tumour. Additional oculomotor deficits did not reliably identify a central cause in these individuals, even with oculography. CONCLUSIONS: We have identified a significant subpopulation of patients with acute vertigo in whom the current standard approaches such as the HINTS examination that focus on oculomotor assessment may not be applicable, highlighting the need for a formal assessment of gait in this setting.

Meta-Analysis of the Use of Head Impulse Test and Head Impulse Test with Direction Changing Nystagmus and Test of Skew Deviation in the Diagnosis of Peripheral Vertigo and Stroke.

INTRODUCTION: The head impulse test (HIT) and HIT combined with direction-changing Nystagmus-Test of Skew deviation (HINTS) have been proposed as bedside tests to differentiate between peripheral and central causes of vertigo in the emergency department (ED). We conducted a meta-analysis of the HIT and HINTS tests to diagnose peripheral vertigo (PV) and central vertigo. METHODS: Pubmed, Google Scholar, EmBase, and articles references published in English up to July 2021 were searched for keywords "vertigo" or "acute vestibular syndrome" or "dizziness" and "head impulse" and "stroke." The bivariate method for meta-analysis was used to calculate positive (PLR) and negative likelihood ratios (NLR) and summary receiver operating characteristics area under the curve (AUC). RESULTS: A total of 11 studies were included analysing both HIT (8 studies, N = 417) and HINTS (6 studies, N = 405). HIT and HINTS were performed within 24 h in 4 of 11 studies. PLR and NLR for HIT in PV was 4.85 (95% CI: 2.83-8.08) and 0.19 (95% CI: 0.12-0.29, I2 63.25%), respectively. The AUC for HIT the diagnosis of PV and stroke was 0.90 and 0.92, respectively. PLR and NLR for a negative HIT in stroke was 5.85 (95% CI: 3.07-10.6) and 0.17 (95% CI: 0.08-0.30), respectively. PLR and NLR for peripheral HINTS pattern for PV was 17.3 (95% CI: 8.38-32.1) and 0.15 (95% CI: 0.07-0.26), respectively. PLR and NLR for central HINTS pattern for stroke: 5.61 (95% CI: 4.19-7.7) and 0.06 (95% CI: 0.03-0.12). In all included studies, HIT and HINTS exams were administered by neurology residents or neurology specialists with additional neuro-otology or neuro-ophthalmology subspeciality experience, and two studies included ED physicians. Raters reported high degree of bias and high concern regarding applicability in most domains of the quality assessment of diagnostic accuracy studies (QUADAS-2) tool. Meta-regression did not demonstrate a statistically significant effect of publication year, time to test, and type of assessor on sensitivity or false positive rate. CONCLUSION: The HIT and HINTS exams appear to be moderately good discriminators of central and PV. However, in most papers, the tests were administered by neurologists and were evaluated beyond 24 h, which may limit utility in the ED setting.

Head impulse, nystagmus, and test of skew examination for diagnosing central causes of acute vestibular syndrome.

BACKGROUND: Dizziness is a common reason for people to seek medical care. Acute vestibular syndrome (AVS) is a specific type of dizziness, which can include severe vertigo, nausea and vomiting, nystagmus, or unsteadiness. Acute vestibular syndrome can be due to peripheral or central causes. It is important to determine the cause, as the intervention and outcomes differ if it is from a peripheral or central cause. Clinicians can assess for the cause using risk factors, patient history, examination findings, or advanced imaging, such as a magnetic resonance imaging (MRI). The head impulse, nystagmus, test of skew (HINTS) examination is a three-part examination performed by clinicians to determine if AVS is due to a peripheral or central cause. This includes assessing how the eyes move in response to rapidly turning a person's head (head impulse), assessing the direction of involuntary eye movements (nystagmus), and assessing whether the eyes are aligned or misaligned (test of skew). The HINTS Plus examination includes an additional assessment of auditory function. OBJECTIVES: To assess the diagnostic accuracy of the HINTS and HINTS Plus examinations, with or without video assistance, for identifying a central etiology for AVS. SEARCH METHODS: We searched CENTRAL, MEDLINE, Embase, Google Scholar, the International HTA database, and two trials registers to September 2022. SELECTION CRITERIA: We included all retrospective and prospective diagnostic test accuracy studies that evaluated the HINTS or HINTS Plus test used in a primary care clinic, an urgent care clinic, the emergency department, or during inpatient hospitalization against a final diagnosis of a central etiology of AVS, as defined by the reference standard of advanced imaging or final diagnosis by a neurologist. DATA COLLECTION AND ANALYSIS: Two review authors independently determined eligibility of each study according to eligibility criteria, extracted data, assessed the risk of bias, and determined the certainty of evidence. Disagreements were adjudicated by consensus or a third review author if needed. The primary outcome was the diagnostic accuracy of the HINTS and HINTS Plus examinations for identifying a central etiology for AVS, conducted clinically (clinician visual assessment) or with video assistance (e.g. video recording with goggles); we independently assessed the clinical and video-assisted examinations. Subgroup analyses were performed by provider type (e.g. physicians, non-physicians), time from symptom onset to presentation (e.g. less than 24 hours, longer than 24 hours), reference standard (e.g. advanced imaging, discharge diagnosis), underlying etiology (e.g. ischemic stroke, alternative etiologies [hemorrhagic stroke, intracranial mass]), study setting (e.g. outpatient [outpatient clinic, urgent care clinic, emergency department], inpatient), physician level of training (e.g. resident, fellow/attending), physician specialty (e.g. otolaryngology, emergency medicine, neurology, and neurologic subspecialist [e.g. neuro-ophthalmology, neuro-otology]), and individual diagnostic accuracy of each component of the examination (e.g. head impulse, direction-changing nystagmus, test of skew). We created 2 x 2 tables of the true positives, true negatives, false positives, and false negatives and used these data to calculate the sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio with 95% confidence intervals (95% CI) for each outcome. MAIN RESULTS: We included 16 studies with a total of 2024 participants (981 women and 1043 men) with a mean age of 60 years. Twelve studies assessed the HINTS examination; five assessed the HINTS Plus examination. Thirteen studies were performed in the emergency department; half were performed by neurologists. The clinical HINTS examination (12 studies, 1890 participants) was 94.0% (95% confidence interval [CI] 82.0% to 98.2%) sensitive, and 86.9% (95% CI 75.3% to 93.6%) specific (low-certainty evidence). The video-assisted HINTS examination (3 studies, 199 participants) was 85.0% to 100% sensitive (low-certainty evidence), and 38.9% to 100% specific (very low-certainty evidence). The clinical HINTS Plus examination (5 studies, 451 participants) was 95.3% (95% CI 78.4% to 99.1%) sensitive, and 72.9% (95% CI 44.4% to 90.1%) specific (low-certainty evidence). The video-assisted HINTS Plus examination (2 studies, 163 participants) was 85.0% to 93.8% sensitive, and 28.6% to 38.9% specific (moderate-certainty evidence). Subgroup analyses were limited, as most studies were conducted in the emergency department, by physicians, and with MRI as a reference standard. Time from symptom onset to presentation varied across studies. Three studies were at high risk of bias and three studies were at unclear risk of bias for participant selection. Three studies were at unclear risk of bias for the index test. Four studies were at unclear risk of bias for the reference standard. Two studies were at unclear risk of bias for flow and timing. One study had unclear applicability concerns for participant selection. Two studies had high applicability concerns for the index test and two studies had unclear applicability concerns for the index test. No studies had applicability concerns for the reference standard. AUTHORS' CONCLUSIONS: The HINTS and HINTS Plus examinations had good sensitivity and reasonable specificity for diagnosing a central cause for AVS in the emergency department when performed by trained clinicians. Overall, the evidence was of low certainty. There were limited data for the role of video-assistance or specific subgroups. Future research should include more high-quality studies of the HINTS and HINTS Plus examination; assessment of inter-rater reliability across users; accuracy across different providers, specialties, and experience; and direct comparison with no HINTS or MRI to assess the effect on clinical care.

Case Report: Multiple Sclerosis Presenting as Unilateral Gaze-evoked Nystagmus.

SIGNIFICANCE: Unilateral gaze-evoked nystagmus is a rare neurologic finding that is largely diagnosed in connection with ischemic stroke. Gazed-evoked nystagmus is also a rare initial presentation of multiple sclerosis. PURPOSE: This study aimed to report a rare presentation of gaze-evoked nystagmus in a patient with multiple sclerosis and review the mechanism underlying the gaze-evoked nystagmus. CASE REPORT: A 32-year-old man presented with a 1-week history of diplopia. Neurologic examination revealed right-sided gaze-evoked nystagmus and right-sided ataxia. Laboratory test revealed a positive result for oligoclonal bands. Contrast brain MRI revealed multiple hyperintense T2 lesions including a hyperintense patch at the right inferior cerebellar peduncle. A diagnosis of multiple sclerosis was made. The patient received methylprednisolone 500 mg intravenously for 14 days. The diplopia and gaze-evoked nystagmus resolved and remained stable 2 months later. CONCLUSIONS: Our case demonstrates that damage to the inferior cerebellar peduncle may result in ipsilesional gaze-evoked nystagmus and ipsilesional ataxia, in contrast to ipsilesional gaze-evoked nystagmus and contralesional ataxia.

Ocular Torsional Instability-A Neurodiagnostic Sign of Prenuclear Disease.

BACKGROUND: Accurate diagnosis of efferent visual system disease in neuro-ophthalmology involves the classification of clinical signs as prenuclear, nuclear, or infranuclear in origin. Over many years, I have come to recognize ocular torsional instability as a clinical sign of prenuclear disease. METHODS: Retrospective chart review of patients in whom ocular torsional instability was diagnosed using indirect ophthalmoscopy. RESULTS: Twenty patients were diagnosed as having ocular torsional instability (OTI). Eight had neuro-ophthalmologic disease caused by structural injury to prenuclear ocular motor areas. Six of these had structural lesions primarily involving the cerebellum, one had a midbrain glioma, and one had traumatic encephalomalacia. Eight additional patients had infantile strabismus (esotropia in 7, exotropia in 1) associated with various combinations of monocular nasotemporal optokinetic asymmetry, latent nystagmus, and dissociated vertical divergence (DVD), indicating prenuclear involvement of subcortical visuovestibular pathways within the brain. Three additional patients presented with intermittent exotropia with DVD signifying early onset, while 2 had acquired esotropia that was noninfantile in origin. One had partially accommodative esotropia with bilateral inferior oblique overaction, and one presented with acquired esotropia followed by spontaneous secondary exotropia. CONCLUSIONS: OTI provides a useful clinical sign of prenuclear ocular motor dysfunction. When detected in patients without any signs of infantile or early-onset strabismus, OTI signifies the need for neuroimaging to rule out neurovestibular or cerebellar causes of prenuclear disease.

Centripetal Nystagmus, Slow Saccades, Cerebellar Ataxia, and Parkinsonism in a Patient With Anti-GAD65-Associated Stiff Person Syndrome Spectrum Disorder.

ABSTRACT: A 68-year-old woman with positional dizziness and progressive imbalance presented for vestibular evaluation. Examination was notable for spontaneous downbeat nystagmus (DBN), horizontal and vertical gaze-evoked nystagmus (GEN) with centripetal and rebound nystagmus, and positional apogeotropic nystagmus. There was also mild-moderate slowing of saccades horizontally and vertically and poor fast phases with an optokinetic stimulus. Further consultation by a movement disorder specialist uncovered asymmetric decrementing bradykinesia and rigidity, masked facies, and a wide-based stance without camptocormia. Screening serum laboratory results for metabolic, rheumatologic, infectious, heavy metal, endocrine, or vitamin abnormalities was normal. Surveillance imaging for neoplasms was unremarkable, and cerebrospinal fluid (CSF) analysis was negative for 14-3-3 and real-time quaking-induced conversion (RT-QuIC). However, her anti-glutamic acid decarboxylase-65 (GAD65) immunoglobulin G (IgG) level was markedly elevated in serum to 426,202 IU/mL (reference range 0-5 IU/mL) and in CSF to 18.1 nmol/L (reference range <0.03 nmol/L). No other autoantibodies were identified on the expanded paraneoplastic panel. The patient was referred to neuroimmunology, where torso rigidity, spasticity, and significant paravertebral muscle spasms were noted. Overall, the clinical presentation, examination findings, and extensive workup were consistent with a diagnosis of anti-GAD65-associated stiff person syndrome-plus (musculoskeletal plus cerebellar and/or brainstem involvement). She was subsequently treated with intravenous immunoglobulin (IVIg) and has been stable since commencing this therapy. In patients with centripetal nystagmus, especially in association with other cerebellar findings, an autoimmune cerebellar workup should be considered.

Three-dimensional analysis of per-rotational nystagmus.

BACKGROUND: Head rotation produces a vestibulo-ocular reflex (VOR). In horizontal rotation, not only lateral semicircular canals but also posterior semicircular canals are stimulated, because posterior canals cupulae are not horizontal in the sitting position. Therefore, theoretical nystagmus is horizontal and torsional. Convection of endolymph does not occur, because the centre of head rotation is a dens of the second cervical vertebra, not the center of lateral canal. Although per-rotational nystagmus is a result of VOR, whether it could be explained by the movement of cupula remains undetermined. To answer this question, we analysed per-rotational nystagmus using three-dimensional video-oculography. OBJECTIVE: To clarify whether per-rotational nystagmus is the same as the physical movement of cupula (theoretical nystagmus). MATERIALS AND METHODS: Five healthy human were evaluated. The participant's head was rotated (sinusoidal yaw rotation) manually (frequency, 0.33 Hz; amplitude, 60°). The experiment was performed in a dark, with the participant's eyes open. Nystagmus was recorded and converted into digital data. RESULTS: In all participants, the direction of nystagmus was rightward on rightward rotation and leftward on leftward rotation. In all participants, nystagmus was purely horizontal. CONCLUSIONS: Practical per-rotational nystagmus differs completely from the theoretical nystagmus. Therefore, VOR is strongly influenced by the central nervous system.

Analysis of 30 patients with cupulolithiasis of the posterior semicircular canal.

BACKGROUND: The diagnostic characteristics of patients with cupulolithiasis of the posterior semicircular canal are persistent torsional nystagmus in the supine position and persistent torsional nystagmus (opposite direction) in the nose-down position, which are caused by the affected canal becoming gravity sensitive. OBJECTIVE: To investigate the clinical features of posterior cupulolithiasis. MATERIALS AND METHODS: We interviewed 30 consecutive patients with cupulolithiasis of the posterior canal and categorized them by onset time into the following four groups: (1) during sleep; (2) at the time of awakening; (3) morning; and (4) afternoon. We defined disease duration as the period from onset to the day when we detected remission of positional nystagmus. RESULTS: Time of awakening was the most common onset time. The mean disease duration was 18.2 days, and 90% of patients achieved cure within 1 month. CONCLUSIONS: Physicians should take into account the duration of nystagmus, because cupulolithiasis of posterior canal exists. The etiology of posterior cupulolithiasis is closely related to sleep, because time of awakening is the most common onset time of vertigo. Most patients with posterior cupulolithiasis cure within 1 month.

Direction-changing spontaneous nystagmus in patients with dizziness.

PURPOSE: The present study aimed to investigate the clinical features of patients with direction-changing spontaneous nystagmus (DCSN) and gain insight into its underlying mechanisms. METHODS: Medical records and vestibular function test results collected in our dizziness clinic between February 2013 and February 2020 were retrospectively reviewed. Spontaneous nystagmus was recorded while sitting upright using videonystagmography for 2 min to confirm the spontaneous changes in nystagmus direction. Causative disease diagnoses were based on the patients' clinical history, audiometry results, vestibular function tests, and imaging studies. RESULTS: Of 4786 patients, DCSN was observed in 41 (0.86%). Causative disease diagnoses included vestibular neuritis (n = 9), lateral semicircular canal cupulopathy (n = 9), cerebellopontine angle tumor (n = 8), vestibular paroxysmia (n = 2), vestibular migraine (n = 2), vestibular nucleus infarction (n = 1), sudden sensorineural hearing loss with vertigo (n = 2), Meniere's disease (n = 2), Ramsay Hunt syndrome (n = 1), labyrinthine fistula due to middle ear cholesteatoma (n = 1), lateral semicircular canal dysplasia (n = 1), post tympanomastoidectomy dizziness (n = 1), and head trauma (n = 2). CONCLUSIONS: Although the periodicity of DCSN could not be determined because of insufficiently long observation times, it was observed in various central and peripheral vestibulopathies. Careful examination of spontaneous nystagmus over a sufficient period may ensure the detection of DCSN when evaluating dizziness.

A new portable Fresnel magnifying loupe for nystagmus observation: a clinical education and clinical practice setting study.

BACKGROUND: Dizziness is a common complaint of patients treated by primary care physicians. It is predominantly caused by peripheral vestibular disorders; however, central nervous system disorders should be excluded. Examination of the eye movements and nystagmus can help differentiate the disorders of the central nervous system from the peripheral vestibular disorders; however, it is often not performed appropriately. In medical education practice, nystagmus observation may facilitate an understanding of vestibular function and nystagmus characteristics. Thus, we proposed a medical education practice to master nystagmus observation using a recently developed portable Fresnel magnifying loupe that could be shielded by one eye. METHODS: Thirty-three students from the Department of Physical Therapy and the Department of Speech, Language, and Hearing Therapy of the Mejiro University participated in this study. Postrotatory nystagmus was measured and compared using the new loupe and control methods, namely the naked eye and Frenzel goggles; we rated the ease of visibility using a five-point scale. RESULTS: The number of detected cases of nystagmus was significantly higher with the new loupe than with the naked eye (p = 0.001). In addition, there were no significant differences in the nystagmus counts between the observations using the new loupe and Frenzel goggles (p = 0.087). No significant difference was observed in the visibility of eye movements between the loupe and naked eye (p = 1.00). The Frenzel goggles provided better visibility compared to that by the loupe (p = 0.034); however, none of the participants reported poor visibility using any of these methods. CONCLUSIONS: Our newly developed Fresnel loupe allows for the observation of nystagmus counts a level of reduction in fixation suppression similar to that of Frenzel goggles in an educational practice setting. Furthermore, it enables the detection of significantly more nystagmus counts compared to that by the naked eye. It offers several advantages over Frenzel goggles, including its lightweight, thin, durable, and portable design. Additionally, the loupe does not rely on a power source and can be used under normal room lighting conditions. TRIAL REGISTRATION: This study was approved by the Medical Research Ethics Committee of Mejiro University (approval number: 21medicine-021).