Disrupted Rotational Perception During Simultaneous Stimulation of Rotation and Inertia.

Two vestibular signals, rotational and inertial cues, converge for the perception of complex motion. However, how vestibular perception is built on neuronal behaviors and decision-making processes, especially during the simultaneous presentation of rotational and inertial cues, has yet to be elucidated in humans. In this study, we analyzed the perceptual responses of 20 participants after pairwise rotational experiments, comprised of four control and four test sessions. In both control and test sessions, participants underwent clockwise and counterclockwise rotations in head-down and head-up positions. The difference between the control and test sessions was the head re-orientation relative to gravity after rotations, thereby providing only rotational cues in the control sessions and both rotational and inertial cues in the test sessions. The accuracy of perceptual responses was calculated by comparing the direction of rotational and inertial cues acquired from participants with that predicted by the velocity-storage model. The results showed that the accuracy of rotational perception ranged from 80 to 95% in the four control sessions but significantly decreased to 35 to 75% in the four test sessions. The accuracy of inertial perception in the test sessions ranged from 50 to 70%. The accuracy of rotational perception improved with repetitive exposure to the simultaneous presentation of both rotational and inertial cues, while the accuracy of inertial perception remained steady. The results suggested a significant interaction between rotational and inertial perception and implied that vestibular perception acquired in patients with vestibular disorders are potentially inaccurate.

Expanding Clinical Spectrum of Anti-GQ1b Antibody Syndrome: A Review.

Importance: The discovery of the anti-GQ1b antibody has expanded the nosology of classic Miller Fisher syndrome to include Bickerstaff brainstem encephalitis, Guillain-Barré syndrome with ophthalmoplegia, and acute ophthalmoplegia without ataxia, which have been brought under the umbrella term anti-GQ1b antibody syndrome. It seems timely to define the phenotypes of anti-GQ1b antibody syndrome for the proper diagnosis of this syndrome with diverse clinical presentations. This review summarizes these syndromes and introduces recently identified subtypes. Observations: Although ophthalmoplegia is a hallmark of anti-GQ1b antibody syndrome, recent studies have identified this antibody in patients with acute vestibular syndrome, optic neuropathy with disc swelling, and acute sensory ataxic neuropathy of atypical presentation. Ophthalmoplegia associated with anti-GQ1b antibody positivity is complete in more than half of the patients but may be monocular or comitant. The prognosis is mostly favorable; however, approximately 14% of patients experience relapse. Conclusions and Relevance: Anti-GQ1b antibody syndrome may present diverse neurological manifestations, including ophthalmoplegia, ataxia, areflexia, central or peripheral vestibulopathy, and optic neuropathy. Understanding the wide clinical spectrum may aid in the differentiation and management of immune-mediated neuropathies with multiple presentations.

Prediction of High-Risk Neuroblastoma Among Neuroblastic Tumors Using Radiomics Features Derived from Magnetic Resonance Imaging: A Pilot Study.

PURPOSE: This study aimed to predict high-risk neuroblastoma among neuroblastic tumors using radiomics features extracted from MRI. MATERIALS AND METHODS: Pediatric patients (age≤18 years) diagnosed with neuroblastic tumors who had pre-treatment MR images available were enrolled from institution A from January 2010 to November 2019 (training set) and institution B from January 2016 to January 2022 (test set). Segmentation was performed with regions of interest manually drawn along tumor margins on the slice with the widest tumor area by two radiologists. First-order and texture features were extracted and intraclass correlation coefficients (ICCs) were calculated. Multivariate logistic regression (MLR) and random forest (RF) models from 10-fold cross-validation were built using these features. The trained MLR and RF models were tested in an external test set. RESULTS: Thirty-two patients (M:F=23:9, 26.0±26.7 months) were in the training set and 14 patients (M:F=10:4, 33.4±20.4 months) were in the test set with radiomics features (n=930) being extracted. For 10 of the most relevant features selected, intra- and inter-observer variability was moderate to excellent (ICCs 0.633-0.911, 0.695-0.985, respectively). The area under the receiver operating characteristic curve (AUC) was 0.94 (sensitivity 67%, specificity 91%, and accuracy 84%) for the MLR model and the average AUC was 0.83 (sensitivity 44%, specificity 87%, and accuracy 75%) for the RF model from 10-fold cross-validation. In the test set, AUCs of the MLR and RF models were 0.94 and 0.91, respectively. CONCLUSION: An MRI-based radiomics model can help predict high-risk neuroblastoma among neuroblastic tumors.

Efficacy of vestibular rehabilitation and its facilitating and hindering factors from real-world clinical data.

Background and purpose: Customized vestibular rehabilitation improved dizziness and imbalance in several randomized controlled trials. In the present study, we determined the efficacy of customized vestibular rehabilitation using real-world observational data. Methods: In this retrospective observational study, we recruited 64 patients (median age = 60, interquartile range = 48-66.3) who completed the customized vestibular rehabilitation from January to December 2022. The outcomes of rehabilitation were evaluated using the dizziness handicap inventory (DHI) or vestibular disorders activities of daily living scale (VADL). The factors associated with outcomes were assessed with a generalized linear model, of which covariates included patients' age, sex, duration of illness, type of vestibular disorders, initial DHI and VADL scores, exercise compliance, and initial hospital anxiety and depression scale (HADS) scores. Results: After the median of 6 (4-6) weeks of rehabilitation, DHI and VADL scores significantly improved in patients with either peripheral or central vestibular disorders (Wilcoxon signed-rank test, p < 0.05). The initial DHI and VADL scores showed a positive while the sum of HADS scores showed a negative correlation with the outcome. In contrast, the age, sex, duration of illness, types of vestibular disorders, and exercise compliance did not affect the outcome. Discussion and conclusion: Customized vestibular rehabilitation is effective for central as well as peripheral disorders, especially when the symptoms are severe and the psychological distress is mild.

Effects of Baclofen on Central Paroxysmal Positional Downbeat Nystagmus.

Paroxysmal positional nystagmus frequently occurs in lesions involving the cerebellum, and has been ascribed to disinhibition and enhanced canal signals during positioning due to cerebellar dysfunction. This study aims to elucidate the mechanism of central positional nystagmus (CPN) by determining the effects of baclofen on the intensity of paroxysmal positional downbeat nystagmus due to central lesions. Fifteen patients with paroxysmal downbeat CPN were subjected to manual straight head-hanging before administration of baclofen, while taking baclofen 30 mg per day for at least one week, and two weeks after discontinuation of baclofen. The maximum slow phase velocity (SPV) and time constant (TC) of the induced paroxysmal downbeat CPN were analyzed. The positional vertigo was evaluated using an 11-point numerical rating scale (0 to 10) in 9 patients. After treatment with baclofen, the median of the maximum SPV of paroxysmal downbeat CPN decreased from 30.1°/s [interquartile range (IQR) = 19.6-39.0°/s] to 15.2°/s (IQR = 11.2-22.0°/s, Wilcoxon signed rank test, p < 0.001) with the median decrement ratio at 40.2% (IQR = 28.2-50.6%). After discontinuation of baclofen, the maximum SPV re-increased to 24.6°/s (IQR = 13.1-34.4°/s, Wilcoxon signed rank test, p = 0.001) with the median increment ratio at 23.5% (IQR = 5.2-87.9%). In contrast, the TCs of paroxysmal downbeat CPN remained unchanged at approximately 3.0 s throughout the evaluation. The positional vertigo also decreased with the medication (Wilcoxon signed rank test, p = 0.020), and remained unchanged even after discontinuation of medication (Wilcoxon signed rank test, p = 0.737). The results of this study support the prior presumption that paroxysmal CPN is caused by enhanced responses of the semicircular canals during positioning due to cerebellar disinhibition. Baclofen may be tried in symptomatic patients with paroxysmal CPN.

Comparison of elasticity changes in the paraspinal muscles of adolescent patients with scoliosis treated with surgery and bracing.

Scoliosis is a three-dimensional spinal deformity, and paraspinal muscles play an important role as stabilizers of the spinal curve. In this prospective study, we compared elasticity changes in the paraspinal muscles of adolescent patients with scoliosis after surgery or bracing. Elasticity was measured on the concave and convex sides of the paraspinal muscles at the apex of the curve at the beginning of treatment and 6 and 12 months after treatment. Twenty-six patients with correction surgery (n = 15) or bracing (n = 11) were included. At initial evaluation, the Cobb angle was larger in the surgery group (72.3 ± 20.2° in surgery vs. 30.6 ± 5.1° in brace, p < 0.001). The estimated mean elasticity value of the paraspinal muscles was lower in the surgery group at baseline on the convex side (15.8 vs. 22.8 kPa, p = 0.037) and 6 months on both the concave (12.1 vs. 22.7 kPa, p = 0.004) and convex (13.4 vs. 23.8 kPa, p = 0.005) sides. There was a significant stiffness decrease from baseline to 6 months on the concave side in the surgery group (5.9 kPa, p = 0.025). However, the elasticity change recovered at 12 months without significant differences between the two groups.

Sonographic observation of the paradoxical masseteric bulging and clinical implication of functional compartment.

Masseter are commonly botulinum neurotoxin targeted muscle for facial contouring in aesthetic field. However, paradoxical masseteric bulging is common adverse effect that has not been discussed with ultrasonographic observations. Retrospective study has been conducted from October, 2021 to January, 2023, out of 324 patients have done blinded botulinum neurotoxin injection in the masseter at the middle and lower portion of the masseter with each side of 25 units (letibotulinum neurotoxin type A), 3 patients demonstrated paradoxical masseteric bulging has been reported and the image observed by ultrasonography by physician. Based on the observations made, we can infer that the function of the moving muscle involves twisting of the muscle fibers during contraction, along with the twisting of the deep inferior tendon, which causes the muscle to be divided into anterior and posterior compartments rather than into superficial and deep compartments of masseter. In ultrasonographic observe the skin surface of a patient with paradoxical masseteric bulging, it is observable that either the anterior or posterior part contracts significantly. The functional units of anterior and posterior compartment are observable as muscular contraction of inward movement of the muscle from either the anterior or posterior functional unit.

Ocular motor and vestibular dysfunction in central nervous system lymphoma.

BACKGROUND AND PURPOSE: Diagnosis of lymphoma involving the central nervous system (CNS) is challenging. This study aimed to explore the abnormal vestibular and ocular motor findings in CNS lymphoma. METHODS: A retrospective search of the medical records identified 30 patients with CNS lymphoma presenting ocular motor and vestibular abnormalities from four neurology clinics of university hospitals in South Korea (22 men, age range 14-81 years, mean 60.6 ± 15.2). The demographic and clinical features and the results of laboratory, radiological and pathological evaluation were analyzed. RESULTS: Patients presented with diplopia (13/30, 43%), vestibular symptoms (15/30, 50%) or both (2/30, 7%). In 15 patients with diplopia, abnormal ocular motor findings included ocular motor nerve palsy (n = 10, 67%), internuclear ophthalmoplegia (n = 2, 13%), external ophthalmoplegia (n = 2, 13%) and exophoria (n = 1, 7%). The vestibular abnormalities were isolated in 14 (82%) of 17 patients with vestibular symptoms and included combined unilateral peripheral and central vestibulopathy in three from lesions involving the vestibular nuclei. CNS lymphoma involved the brainstem (53%), cerebellum (33%), leptomeninges (30%), deep gray nuclei (23%) or cranial nerves (17%). Two patients showed the "double-panda" sign by involving the midbrain. CONCLUSIONS: This study expands the clinical and radiological spectra of CNS lymphoma. Neuro-ophthalmological and neuro-otological evaluation may guide the early diagnosis of CNS lymphoma.

Auto-segmentation of Adult-Type Diffuse Gliomas: Comparison of Transfer Learning-Based Convolutional Neural Network Model vs. Radiologists.

Segmentation of glioma is crucial for quantitative brain tumor assessment, to guide therapeutic research and clinical management, but very time-consuming. Fully automated tools for the segmentation of multi-sequence MRI are needed. We developed and pretrained a deep learning (DL) model using publicly available datasets A (n = 210) and B (n = 369) containing FLAIR, T2WI, and contrast-enhanced (CE)-T1WI. This was then fine-tuned with our institutional dataset (n = 197) containing ADC, T2WI, and CE-T1WI, manually annotated by radiologists, and split into training (n = 100) and testing (n = 97) sets. The Dice similarity coefficient (DSC) was used to compare model outputs and manual labels. A third independent radiologist assessed segmentation quality on a semi-quantitative 5-scale score. Differences in DSC between new and recurrent gliomas, and between uni or multifocal gliomas were analyzed using the Mann-Whitney test. Semi-quantitative analyses were compared using the chi-square test. We found that there was good agreement between segmentations from the fine-tuned DL model and ground truth manual segmentations (median DSC: 0.729, std-dev: 0.134). DSC was higher for newly diagnosed (0.807) than recurrent (0.698) (p < 0.001), and higher for unifocal (0.747) than multi-focal (0.613) cases (p = 0.001). Semi-quantitative scores of DL and manual segmentation were not significantly different (mean: 3.567 vs. 3.639; 93.8% vs. 97.9% scoring ≥ 3, p = 0.107). In conclusion, the proposed transfer learning DL performed similarly to human radiologists in glioma segmentation on both structural and ADC sequences. Further improvement in segmenting challenging postoperative and multifocal glioma cases is needed.

Etiological distribution of isolated oculomotor nerve palsy: analysis of 633 patients and literature review.

BACKGROUND AND PURPOSE: The etiological distribution of oculomotor nerve palsy has varied amongst the studies. This study aimed to define the clinical features and underlying etiologies of isolated oculomotor nerve palsy by recruiting patients from all departments in a referral-based university hospital. METHODS: The medical records of 672 patients who had a confirmed diagnosis of isolated oculomotor nerve palsy at all departments of Seoul National University Bundang Hospital, Seongnam, South Korea, from 2003 to 2020 were reviewed. A proportion of the etiology of isolated oculomotor nerve palsy was also compared with that of patients pooled from the previous studies that were searched on PubMed in May 2022. RESULTS: The most common etiology was microvascular (n = 168, 26.5%), followed by vascular anomalies (n = 110, 17.4%), neoplastic (n = 86, 13.6%), inflammatory (n = 79, 12.5%), idiopathic (n = 60, 9.5%) and traumatic (n = 53, 8.4%). Neurologists were mainly involved in the management of microvascular and inflammatory oculomotor nerve palsies whilst ophthalmologists mainly participated in the care of idiopathic, neoplastic and traumatic palsies. Neurosurgeons mostly took care of oculomotor nerve palsy due to vascular anomalies. CONCLUSIONS: The proportion of etiologies of isolated oculomotor nerve palsy may differ according to the specialties involved in the management. The results of previous studies on the etiological distribution of isolated oculomotor nerve palsy should be interpreted with this consideration.

Abnormal vestibular-evoked myogenic potentials as a risk factor for unpredicted falls in spinocerebellar ataxia: a preliminary study.

OBJECTIVE: This study aimed to correlate the symptoms and signs with the findings of laboratory vestibular function tests in patients with spinocerebellar ataxia (SCA). METHOD: We retrospectively recruited 26 patients with SCA (9 men, median age: 52, age range: 21-67). Assessments included Dizziness Handicap Inventory, EuroQoL Five-Dimension, symptom questionnaires manifesting during walking in daily life, the Scale for the Assessment and Rating of Ataxia (SARA), and vestibular function tests including 3D video-oculography, video head impulse test, subjective visual vertical, and cervical and ocular vestibular evoked myogenic potentials (VEMP). RESULTS: Cross-analyses revealed that the patients with VEMP abnormalities showed higher SARA (p = 0.014) and prevalence of unpredictable falls (p = 0.046). The patients with SCA1 more frequently had unpredictable falls (75%, p = 0.038) and VEMP abnormalities (88%, p = 0.001) compared to SCA2 (29% falls, 17% VEMP abnormalities) and SCA6 (no falls or VEMP abnormalities). CONCLUSION: Abnormal VEMPs are strongly associated with unpredicted falls in patients with SCA, particularly in those with SCA1. Impaired processing of otolithic information may contribute to falls in SCAs, and VEMP may help identifying the patients with a risk for unpredicted falls and preventing fall-related injuries in SCA. Limited number of patients with lower SARA scores warrant further confirmatory studies.

Vestibular syncope.

PURPOSE OF REVIEW: This review considers recent observations on vestibular syncope in terms of clinical features, laboratory findings, and potential mechanisms. RECENT FINDINGS: Vestibular syncope, potentially associated with severe fall-related injuries, may develop multiple times in about one-third of patients. Meniere's disease and benign paroxysmal positional vertigo are the most common causes of vestibular syncope, but the underlying disorders remain elusive in 62% of cases with vestibular syncope. The postictal orthostatic blood pressure test exhibits a lower diagnostic yield. Vestibular function tests, such as cervical vestibular-evoked myogenic potentials and video head impulse tests, can reveal one or more abnormal findings, suggesting compensated or ongoing minor vestibular dysfunctions. The pathomechanism of syncope is assumed to be the erroneous interaction between the vestibulo-sympathetic reflex and the baroreflex that have different operating mechanisms and action latencies. The central vestibular system, which estimates gravity orientation and inertia motion may also play an important role in abnormal vestibulo-sympathetic reflex. SUMMARY: Vestibular disorders elicit erroneous cardiovascular responses by providing false vestibular information. The results include vertigo-induced hypertension or hypotension, which can ultimately lead to syncope in susceptible patients.

Evolution of Vestibular Findings During and Between the Attacks of Meniere Disease: Update.

Purpose of Review: The diagnosis of Meniere disease (MD) has based on characteristics of vertigo and findings of audiologic evaluation. This review focuses on the recent findings of the evolution of vestibular function and their underlying physiology during and between the attacks of MD and thus aims to help identify this common disorder with many faces according to the phase. Recent Findings: During the attacks, the direction of spontaneous nystagmus changes over time, beating initially toward the affected ear (irritative nystagmus), then toward the healthy ear (paretic nystagmus), and finally back toward the affected ear again (recovery nystagmus). Apart from these direction changes, atypical forms of spontaneous nystagmus, such as downbeat, discordant horizontal-torsional, and aperiodic alternating nystagmus, can be observed. Head impulse tests (HITs) are mostly normal during the irritative/recovery phases, but positive in more than half of patients during the paretic phase. By contrast, caloric tests are usually abnormal irrespective of the phases, although paradoxical caloric hyper-responsiveness can be observed in 18% of patients during the irritative/recovery phases. Thus, dissociation in the findings of caloric tests-HITs can be observed during and between the attacks. Horizontal head shaking tends to augment spontaneous nystagmus during each phase, while skull vibration mostly induces nystagmus beating toward the healthy ear irrespective of the phases. During the attacks, ocular vestibular-evoked myogenic potentials (VEMPs) may be enhanced, whereas cervical VEMPs are usually decreased during stimulation of the involved ear. Summary: Recognizing these evolutions of vestibular findings during and between the attacks of MD would provide insights into its pathophysiology and aid in treatments and diagnosis.

James Sharpe's Contributions to Neurology and Neuro-ophthalmology: A Posthumous Tribute 10 Years On.

Dr. Sharpe was a leading eye movement researcher who had also been the editor of this journal. We wish to mark the 10th anniversary of his death by providing a sense of what he had achieved through some examples of his research.