Clinical Assessment of the Nystagmus Fixation Suppression Test: An Experimental Study.

BACKGROUND:  Assessment of nystagmus fixation suppression can be used as an additional diagnostic tool for patients with an acute vestibular syndrome to distinguish between a central or peripheral cause. We investigated the ability of physicians to detect fixation suppression using a nystagmus simulation model. METHODS:  We used a nystagmus simulator to measure the accuracy of the nystagmus fixation suppression test. Fixation suppression was assessed randomly in 6170 trials by 20 otorhinolaryngologists and neurologists, segregated into 2 groups based on their neurootological experience, a beginner and an experienced group. The simulator presented random nystagmus slow velocity (SPV) reductions and presented 3 conditions with either changed nystagmus frequency, amplitude, or both. RESULTS:  The cutoff for the discernment of fixation suppression ranged from 1.2 to 14°/s nystagmus velocity difference. The more intense the baseline nystagmus was, the more difficult was the detection of fixation suppression. There was not significant difference (P >.05) in the cutoff values in the experts group compared to the novices for all 3 different conditions. Both, novices and experts, detected frequency changes easier than differences of the nystagmus amplitude. Test sensitivity was very low (19%-65%) for discernment of small nystagmus velocity differences of <2°/s by experts. CONCLUSION:  In our study, there was no difference between experts and novices in detection of nystagmus suppression by visual fixation. The examiners could only detect large suppression effects at low-intensity baseline nystagmus. Overall, the sensitivity and accuracy of a clinical fixation suppression test is low and the assistance with a video-oculography device is highly recommended.

Hyperventilation-Induced Nystagmus in Acute Unilateral Vestibulopathy: A Correlation with Vestibulo-ocular Reflex Gain and Clinical Implication.

Hyperventilation-induced nystagmus test (HINT) is capable of generating a response in 77.2% of cases of acute unilateral vestibulopathy (AUVP); both nystagmus toward the affected side (excitatory pattern) and toward the healthy side (inhibitory pattern) have been described. The aim of the study is to investigate the clinical and prognostic role of the test by evaluating its correlation with vestibulo-ocular reflex (VOR) gain. We evaluated 33 AUVP patients by performing the HINT and video head impulse test (V-HIT) during the acute phase and then at 15 and 90 days after the onset of the symptoms. The correlation between the VOR gain of the affected side and test responses was evaluated first, phase by phase, and then considering the pattern shown during the first assessments. Patients with a negative HINT had a higher mean VOR gain than patients with a positive test at both 15 and 90 days. Patients who showed an inhibitory pattern at the first assessment had a continuous improvement in V-HIT performance, while patients with an initial excitatory response had a transient decrease in gain at the subsequent evaluation (P=.001). No difference between these 2 groups emerged at 90 days (P=.09). The finding of a negative HINT during the follow-up correlates with good V-HIT performance and could be an indicator of good recovery. The inhibitory pattern is associated with a subsequent improvement; and it would be indicative of compensation. but, despite this, the prognostic value of the test is limited.

Prevalence of benign paroxysmal positional vertigo in a population-based setting among 75-year-olds.

BACKGROUND: Benign paroxysmal positional vertigo (BPPV) is one of the most frequently diagnosed cause of dizziness among older adults. OBJECTIVE: To investigate the prevalence of BPPV and positional symptoms of dizziness and nystagmus among 75-year-olds and to identify factors associated with BPPV and positional dizziness and nystagmus. METHODS: In this cross-sectional population-based study of 75-78-year-olds in Gothenburg, 887 participants were examined with questions regarding dizziness and health and social factors. A total of 681 participants underwent the Dix-Hallpike test or the side-lying test for BPPV using Video Frenzel goggles. RESULTS: In total 32% reported problems with dizziness (n = 887). The prevalence of BPPV was 4% in the unweighted and 4.5% in the weighted analyses, compensating for selective attrition of women and participants with previous positional dizziness. Positional dizziness without nystagmus was found in 2% and nystagmus without dizziness was found in 9%. Individuals with BPPV and positional dizziness experienced more dizziness in everyday life compared with those with normal tests, while those with positional nystagmus did not. CONCLUSIONS: The estimated prevalence of BPPV among 75-year-olds was 4.5%. Despite weighted analyses, the true prevalence may be higher since many participants with dizziness refused testing. Dizziness was associated with fear and discomfort so strong that around 20% of the participants declined testing.

Horizontal Pendular Nystagmus and Ataxia Secondary to Severe Hypomagnesemia.

Background: Severe hypomagnesemia is an increasingly recognized cause of acute and reversible cerebellar ataxia, often accompanied by cerebellar oculomotor signs such as jerky horizontal or downbeat nystagmus and very rarely ocular flutter. Phenomenology Shown: This video illustrates horizontal pendular nystagmus in a patient with acute onset cerebellar ataxia associated with severe hypomagnesemia. Educational value: Acquired pendular nystagmus can be distinguished from macrosaccadic oscillations and ocular flutter in that the former is composed of two slow phases of equal velocity and the latter of two fast phases of saccadic type with or without intersaccadic interval, respectively. It is most commonly associated with demyelinating, toxic, metabolic, and genetic disorders, but has not been reported in association with severe hypomagnesemia.

Effect of nystagmus on VEP-based objective visual acuity estimates.

In order to determine the effect of nystagmus on objective visual acuity (VA) estimates, we compared subjective (VApsych) and objective (VEP, VAVEP) VA estimates in participants with nystagmus. For this purpose, 20 participants with nystagmus (NY) caused by idiopathic infantile nystagmus, albinism, achiasma or acquired nystagmus were recruited in this study. Estimates of BCVA (best corrected visual acuity) were determined psychophysically (VApsych; FrACT, Freiburg visual acuity test) and electrophysiologically (VAVEP; EP2000) according to ISCEV (International Society of Clinical Electrophysiology of Vision) guidelines. For each participant the eye with the stronger fixation instability [Nidek microperimeter (MP-1), Nidek Instruments] was included for further analysis. VApsych vs VAVEP were compared via paired t-tests and the correlation of the difference between VApsych and VAVEP (∆VA) vs the degree of fixation instability was tested with Pearson correlation (r). We found VAVEP to be better than VApsych [by 0.12 Logarithm of the Minimum Angle of Resolution (logMAR); mean ± standard error (SE) of VAVEP vs VApsych: 0.176 ± 0.06 vs. 0.299 ± 0.06, P = 0.017] and ∆VA to be correlated linearly with the degree of fixation instability (r2 = 0.21,p = 0.048). In conclusion, on average we report a small VA overestimation, around 1 line, for VAVEP compared to VApsych in NY. This overestimation depended on the magnitude of the fixation instability. As a rule of thumb, a reduction of the fixation probability in the central 4° from 100 to 50% leads on average to a VAVEP overestimation of around 0.25 logMAR, i.e. 2.5 lines.

A Quantitative Study of the Head Pitching Test for Lateral Canal BPPV.

OBJECTIVES: Lateral semicircular canal BPPV (LSC-BPPV) is diagnosed with the Head Yaw Test (HYT) by observing nystagmus direction and comparing the nystagmus intensity on both sides according to Ewald's laws. Head Pitching Test (HPT) is a diagnostic maneuver performed in the upright position by bending the patient's head forward (bowing) and backward (leaning) and observing the evoked nystagmus. We aimed to assess the sensitivity of HPT in correctly diagnosing LSC-BPPV through the quantitative measurement of Bowing and Leaning nystagmus slow-phase velocity (SPV). METHODS: One hundred cases of LSC-BPPV were prospectively enrolled. HPT was performed, looking for pseudospontaneous, bowing, and leaning nystagmus. HYT was considered for the "final diagnosis." HPT was defined as "diagnostic" if the nystagmus was present in at least one position, "undiagnostic" if no nystagmus was detectable. The direction and the SPV of nystagmus in all positions were analyzed and compared to determine the degree of agreement between HPT and HYT. OUTCOMES: Sixty-four geotropic and 36 apogeotropic forms were diagnosed. HPT was diagnostic in 80 cases, with no difference between the two forms. According to Ewald's laws, the direction of stronger nystagmus evoked by HPT agreed with the HYT results in 39/52 (75%) cases in geotropic forms and 21/28 (75%) cases in apogeotropic forms. The agreement between HPT and HYT was "substantial" considering all the cases and "almost complete" considering only the patients with diagnostic HPT. CONCLUSION: Quantitative HPT is a valid test in diagnosing the affected side and form of LSC-BPPV, even if less reliable than HYT.

Positional End-Point Nystagmus in Patients with Diagnosis of Acute Unilateral Vestibulopathy.

INTRODUCTION: Recently, end-point nystagmus, traditionally observed in an upright position, has been identified in the Dix-Hallpike position among healthy subjects, suggesting a physiological origin.However, its characteristics in individuals with vestibular hypofunction remain unexplored. OBJECTIVE: To elucidate the impact of vestibular hypofunction on the characteristics of positional end-point nystagmus. METHODS: Thirty-one patients diagnosed with acute unilateral vestibulopathy according to Bárány Society criteria were selected. A video head impulse test was conducted in all participants, followed by McClure and Dix-Hallpike maneuvers with and without gaze fixation, and with the initial position of the eye in the straight-ahead position or in the horizontal end-point position. Nystagmus direction, sense, latency, slow-phase velocity, and duration were recorded. The relationship between these characteristics and video head impulse test values was analyzed. RESULTS: Positional end-point nystagmus was observed in 92.6% of subjects with vestibular hypofunction, significantly more than in healthy individuals. Nystagmus direction varied depending on the performed positional test and on the vestibulo-ocular reflex gains. Gaze occlusion and the initial horizontal end-point position increased its frequency. CONCLUSION: Vestibular hypofunction influences the manifestation of positional end-point nystagmus. Recognizing this nystagmus can aid in resolving diagnostic uncertainties and preventing the misdiagnosis of benign paroxysmal positional vertigo in subjects with acute unilateral vestibulopathy.

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.

Long-term visual outcomes in spasmus nutans.

BACKGROUND: The long-term visual outcomes in spasmus nutans patients is largely unknown. The purpose of this study was to characterize visual outcomes and identify comorbid ophthalmic conditions in patients with spasmus nutans. METHODS: We retrospectively reviewed the charts of consecutive patients diagnosed with spasmus nutans between 2000 and 2020. Demographic information, ophthalmic characteristics, and neuroimaging results were assessed over time. RESULTS: Of the 32 patients included in the study, 13 (41%) were female. Underlying medical conditions included a diagnosis of Trisomy 21 in 6 (19%) and prematurity in 8 (25%). Twenty-one patients (66%) self-reported as a race other than Caucasian. 18 patients (56%) had non-private health insurance and 1 (3%) was uninsured. Mean age at diagnosis and resolution were 16 months (range 45 months) and 48 months (range 114 months), respectively. All 32 patients had nystagmus, 31 (97%) had head nodding and 16 (50%) had ocular torticollis. Mean follow-up was 66 months (range 185 months). On initial presentation, 6/32 (19%) had an amblyogenic refractive error and mean best-corrected visual acuity (BCVA) in the better-seeing eye was 0.78 Logarithm of the Minimum Angle of Resolution (LogMAR) (range 1.24). In a sub-analysis that included patients with > 1 exam (n = 23), 17/20 (85%) had an amblyogenic refractive error and mean BCVA in the better-seeing eye was 0.48 LogMAR (range 1.70). At the final exam, 12 patients had measurable stereopsis, eight had strabismus, and three had undergone strabismus surgery. Eight patients required treatment for amblyopia. CONCLUSIONS: We found a high prevalence of amblyogenic refractive error, strabismus and amblyopia among patients with spasmus nutans. Children with spasmus nutans benefit from ongoing ophthalmic follow-up until they are past the amblyopic age range, even after resolution of nystagmus.

Central Positional Nystagmus Can Be the Sole Presentation of Cerebellar Nodulus Infarction.

OBJECTIVES: To draw attention to acute positional vertigo and central positional nystagmus (CPN) developing as the sole features of cerebellar nodulus infarction. BACKGROUND: The cerebellar nodulus is vascularized by the medial branch of the posterior inferior cerebellar artery, which also supplies the uvula, tonsil, tuber, and pyramid of the vermis, and the inferior part of the cerebellar hemisphere, making isolated cerebellar nodulus infarction extremely rare. CPN occurs after a change in head position with respect to gravity and is caused by pathologies involving the vestibulo-cerebellar pathways. CPN is rarely seen in isolation. Additional neurological signs and ocular motor abnormalities are generally present. METHODS: A 62-year-old man was admitted to the emergency department with acute-onset positional vertigo and CPN as the sole finding on examination. Cranial magnetic resonance imaging revealed an acute infarction involving the nodulus. Results: Infarcts restricted to nodulus can cause positional vertigo and CPN without any associated neurological signs or ocul ar motor abnormalities. CONCLUSION: Though very rare, cerebellar nodulus stroke must be searched in patients with positional vertigo of acute onset and isolated CPN on examination.

Nystagmus and Foveal Hypoplasia in a Carrier of Oculocutaneous Albinism.

We report a 23-year-old female patient with ophthalmic features of albinism, including refractive errors, nystagmus, depigmented fundus, and foveal hypoplasia. She presented for a rhegmatogenous retinal detachment, which was surgically reattached with no complications. Further genetic testing revealed the presence of a heterozygous pathogenic oculocutaneous albinism OCA2 gene mutation, conferring carrier status. To the best of our knowledge, this is the first reported case of typical ocular phenotype of albinism, specifically nystagmus, in a patient who is carrier for oculo-cutaneous albinism. Further research is required to expand the genotype-phenotype relationship in carriers of oculocutaneous albinism. [Ophthalmic Surg Lasers Imaging Retina 2024;55:349-353.].

Use of the Head Impulse, Nystagmus, Test of Skew ('HINTS') assessment to aid differential diagnosis in acute vestibular syndrome in the hyperacute stroke setting.

BACKGROUND: Differential diagnosis of acute vertigo syndrome is challenging given the similarities between clinical presentations of posterior circulation stroke and peripheral vestibular dysfunction. The Head Impulse, Nystagmus, Test of Skew ('HINTS') assessment is a clinical bedside test used to aid diagnosis. METHODS: Comprehensive training on use of the Head Impulse, Nystagmus, Test of Skew assessment was provided to one stroke consultant, and the effectiveness of the test in that setting was assessed. Further education was completed with more members of the stroke and emergency department multi-disciplinary team. Quality improvement measures including magnetic resonance imaging use and bed utilisation were explored. RESULTS: Following training of one stroke consultant, the Head Impulse, Nystagmus, Test of Skew assessment was found to be a feasible, accurate bedside test within this acute stroke service. Further training for the multi-disciplinary team was completed, but outcome measures were not explored because of the coronavirus disease 2019 pandemic and maternity leave. CONCLUSION: There is a role for trained members of the multi-disciplinary team to successfully use the Head Impulse, Nystagmus, Test of Skew assessment in hyperacute stroke settings, to aid diagnosis in acute vertigo syndrome.

Advances in the diagnosis and management of acute vertigo.

BACKGROUND: Patients presenting to the emergency department with acute vertigo pose a diagnostic challenge. While 'benign' peripheral vestibulopathy is the most common cause, the possibility of a posterior circulation stroke is paradoxically the most feared and missed diagnosis in the emergency department. OBJECTIVES: This review will attempt to cover the significant advances in the ability to diagnose acute vertigo that have occurred in the last two decades. The review discusses the role of neurological examinations, imaging and specific oculomotor examinations. The review then discusses the relative attributes of the Head Impulse-Nystagmus-Test of Skew plus hearing ('HINTS+') examination, the timing, triggers and targeted bedside eye examinations ('TiTrATE'), the associated symptoms, timing and triggers, examination signs and testing ('ATTEST') algorithm, and the spontaneous nystagmus, direction, head impulse testing and standing ('STANDING') algorithm. The most recent technological advancements in video-oculography guided care are discussed, as well as other potential advances for clinicians to look out for.

Accuracy of the Bedside Examination in Patients With Suspected Acute Unilateral Peripheral Vestibulopathy.

OBJECTIVE: Acute unilateral peripheral vestibulopathy (AUPVP) is a frequent form of peripheral vestibular vertigo characterized by unilateral vestibular organ dysfunction. Diagnostic challenges in anamnesis and bedside examination can lead to potential misdiagnoses. This study investigated the sensitivity of bedside examinations in diagnosing AUPVP. METHODS: This retrospective analysis examined 136 AUPVP inpatients at a level 3 university hospital between 2017 and 2019. Demographic data and bedside test results were collected. Instrumental otoneurological tests included caloric testing and video head impulse test (HIT). The sensitivity of each bedside parameter was computed based on the instrumental diagnostics, and statistical analyses were performed. RESULTS: The study included 76 men and 60 women, with a mean age of 59.2 years. Spontaneous nystagmus exhibited a sensitivity of 92%, whereas the absence of skew deviation was identified with a sensitivity of 98%. Abnormal bedside HIT showed a sensitivity of 87%. The combined HINTS (HIT, nystagmus, and test of skew) had a sensitivity of 83%. The Romberg test and Fukuda test demonstrated sensitivities of 26% and 48%, respectively. CONCLUSION: The sensitivity of bedside tests varied from 26% to 98%. This aligns with previous literature, highlighting the challenge of differentiating AUPVP from vestibular pseudoneuritis solely through bedside examination. Although the tests excel in excluding central causes, they are insufficient for diagnosing AUPVP with certainty. In addition, the bedside examination sensitivities vary widely, and early radiological imaging can be misleading. Therefore, this study underlines the necessity of prompt otoneurological testing for accurate exclusion of vestibular pseudoneuritis and thus improve patient outcomes.

Vertical infantile nystagmus: Explanation of why the direction of nystagmus is vertical.

This case report presents a rare case of infantile nystagmus syndrome (INS) in which the direction of infantile nystagmus (IN) was vertical. A 66-year-old woman was referred to our department for investigation of abnormal eye movements. She showed a disordered field of view with a homonymous hemianopia in the lower left quadrant and vertical gaze-evoked nystagmus, but there were no other abnormal neurological findings. She did not complain of an oscillopsia. Imaging revealed that the cause of hemianopia was atrophy and low cerebral blood flow in the right occipital lobe. The vertical nystagmus became strong when attempting to fixate to stationary targets. A reversed optokinetic nystagmus response was observed in the vertical optokinetic nystagmus test. From these eye movements, we diagnosed her nystagmus as vertical IN. Patients with INS see everything by saccades. IN consists of the alternate appearance of saccades and preceding slow eye movements. For these eye movements, a wide visual field is necessary. In this case, vertical IN was caused by the wider vertical than horizontal visual field resulting from homonymous hemianopia. Therefore, the direction of IN is horizontal in most patients with INS because their horizontal visual field is the widest field.