Red flags alerting a posterior cranial fossa tumor from audiovestibular perspectives - a review.

BACKGROUND: There is no comprehensive and up-to-date overview of audiovestibular approach to the posterior fossa tumors in the literature. OBJECTIVE: This paper reviewed the literature relating to tumors at the posterior cranial fossa to find red flags alerting a posterior fossa lesion from audiovestibular perspectives. METHODS: This review was developed from articles published in those journals listed on the journal citation reports. Through the PubMed database, Embase, Google Scholar, and Cochrane library, 60 articles were finally obtained based on the PRISMA guidelines for reporting reviews. RESULTS: The presence of one red flag indicates a positive predictive value of 33% for detecting a posterior fossa lesion. Clinical features, namely, 1) mid-frequency sudden sensorineural hearing loss (SNHL), 2) bilateral sudden SNHL, and 3) rebound nystagmus may indicate a posterior fossa lesion, representing one, two, and three red flags, respectively. CONCLUSION: Those with 1) mid-frequency sudden SNHL, 2) bilateral sudden SNHL, and 3) rebound nystagmus trigger one, two, and three red flags, respectively, alerting clinicians the possibility of a posterior fossa lesion, which warrant MR imaging to exclude life-threatening or treatable conditions. SIGNIFICANCE: Patients with posterior fossa tumors may have potential life-threatening outcome.

Nystagmus in a child with nephrotic syndrome.

We report a child with steroid-dependent nephrotic syndrome presenting with excessive irritability, double vision and inability to walk for 5 days. On examination, the child was irritable with Glasgow coma sccale (GCS of 12/15, had bilateral convergent squint (R>L), vertical nystagmus, ataxia without any focal neurological deficits and normal fundus. MRI brain with venogram showed bilateral symmetric FLAIR hyperintensity in the medial thalamus and periaqueductal grey matter showing diffuse restriction with normal venogram. A possibility of Wernicke encephalopathy (WE) was considered and the child was started on thiamine supplementation, following which he had significant improvement in his symptoms. His irritability reduced with significant improvement in the range of eye movements and vertical nystagmus. At 3-month follow-up, the child is asymptomatic with normal gait. Although WE is uncommon in children with nephrotic syndrome, the possibility has to be kept in mind when a child presents with atypical neurological symptoms.

Teaching Video NeuroImage: Monocular Rotational Nystagmus Caused by Superior Oblique Myokymia.

A 61-year-old man presented with 2 days of "flickering" vision. The symptom resolved with closure of the left eye. Examination demonstrated involuntary high-frequency, low-amplitude intorting movements of the left eye, consistent with superior oblique myokymia (Video 1). Ocular ductions were full, and there were no abnormal movements of the right eye.

EEG based oculographic analysis of epileptic nystagmus.

Epileptic nystagmus (EN) is a subtle seizure semiology, most commonly seen in seizures originating in the posterior cortical regions. EN is broadly categorized into type I and type II. Type I EN consists of contralateral repetitive saccadic eye movements alternating with post-saccadic slow drifts with an overall contralateral deviation. Type II EN is characterized by ipsilateral slow drift alternating with contralateral corrective saccades. In this article, we report a method to perform oculographic analysis of eye movements using EEG only. We used this method to classify the type of EN in three patients with parieto-occipital seizures. In all three patients, the ictal EEG demonstrated repetitive saccadic eye movements, directed contralateral to the seizure onset zone. With prolonged time constant, we were able to identify this eye movement pattern as EN with distinct slow and fast phases. We were able to further characterize the type of EN as type I and type II. In all three patients, the direction of EN (direction of fast phase or saccades) was contralateral to the seizure onset zone. EN can be easily missed on video-electroencephalography (vEEG) recordings because of various reasons. Our study demonstrates a systematic method of eye movement analysis on EEG, which can be used to not only identify EN as seizure semiology but also classify it, without requiring additional electrodes.

Post Cochlear Implantation Vertigo: Ictal Nystagmus and Audiovestibular Test Characteristics.

OBJECTIVE: To investigate ictal nystagmus and audiovestibular characteristics in episodic spontaneous vertigo after cochlear implantation (CI). STUDY DESIGN: Retrospective and prospective case series. PATIENTS: Twenty-one CI patients with episodic spontaneous vertigo after implantation were recruited. INTERVENTIONS: Patient-initiated home video-oculography recordings were performed during one or more attacks of vertigo, using miniature portable home video-glasses. To assess canal and otolith function, video head-impulse tests (vHITs) and vestibular-evoked myogenic potential tests were conducted. MAIN OUTCOME MEASURES: Nystagmus slow-phase velocities (SPVs), the presence of horizontal direction-changing nystagmus, and post-CI audiovestibular tests. RESULTS: Main final diagnoses were post-CI secondary endolymphatic hydrops (48%) and exacerbation of existing Ménière's disease (29%). Symptomatic patients demonstrated high-velocity horizontal ictal-nystagmus (SPV, 44.2°/s and 68.2°/s in post-CI secondary endolymphatic hydrop and Ménière's disease). Direction-changing nystagmus was observed in 80 and 75%. Two were diagnosed with presumed autoimmune inner ear disease (SPV, 6.6°/s and 172.9°/s). One patient was diagnosed with probable vestibular migraine (15.1°/s).VHIT gains were 0.80 ± 0.20 (lateral), 0.70 ± 0.17 (anterior), and 0.62 ± 0.27 (posterior) in the implanted ear, with abnormal values in 33, 35, and 35% of each canal. Bone-conducted cervical and ocular vestibular-evoked myogenic potentials were asymmetric in 52 and 29% of patients (all lateralized to the implanted ear) with mean asymmetry ratios of 51.2 and 35.7%. Reversible reduction in vHIT gain was recorded in three acutely symptomatic patients. CONCLUSION: High-velocity, direction-changing nystagmus time-locked with vertigo attacks may be observed in post-CI implant vertigo and may indicate endolymphatic hydrops. Fluctuating vHIT gain may be an additional marker of a recurrent peripheral vestibulopathy.

Do monosymptomatic stroke patients with dizziness present a vestibular syndrome without nystagmus? An underestimated entity.

BACKGROUND AND PURPOSE: Vestibular symptoms are common in emergency department (ED) patients and have various causes, including stroke. Accurate identification of stroke in patients with vestibular symptoms is crucial for timely management. We conducted a prospective cross-sectional study from 2015 to 2019 to determine stroke prevalence and associated symptoms in ED patients with vestibular symptoms, aiming to improve diagnosis and outcomes. METHODS: As part of the DETECT project, we screened 1647 ED patients with acute vestibular symptoms. Following a retrospective analysis of 961 head and neck magnetic resonance imaging (MRI) scans, we included 122 confirmed stroke cases and assessed them for vestibular signs and symptoms. RESULTS: Stroke prevalence in dizzy patients was 13% (122/961 MRI scans). Most patients (95%) presented with acute vestibular symptoms with or without nystagmus, whereas 5% had episodic vestibular syndrome (EVS). Nystagmus was present in 50% of stroke patients. Eighty percent had a purely posterior circulation stroke, and nystagmus was absent in 46% of these patients. Seven patients (6%) had lesions in both the anterior and posterior circulation. Vertigo was experienced by 52% regardless of territory. CONCLUSIONS: A stroke was identified in 13% of ED patients presenting with acute vestibular symptoms. In 5%, it was EVS. Most strokes were in the posterior circulation territory; vertigo occurred with similar frequency in anterior and posterior circulation stroke, and absence of nystagmus was common in both.

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.

Benign paroxysmal positional vertigo in a young child.

A girl in her early childhood presented to a regional otolaryngology outpatient clinic with classic signs of benign paroxysmal positional vertigo (BPPV). She reported episodic dizziness when rolling in a supine position. She did not convey any other associated audiovestibular symptoms. A bedside Dix-Hallpike test confirmed geotropic rotational nystagmus indicative of lateral canal BPPV. Due to her young age, limited communicative abilities and concerns for more sinister underlying pathology, a complete neurological examination, MRI and pure tone audiometry were performed. After two sessions of Epley's manoeuvre, she was symptom-free. At her 3-month follow-up, the patient denied any recurrent episodes of vertigo.

Pearls for the Emergency Clinician: Posterior Circulation Stroke.

BACKGROUND: Posterior circulation (PC) stroke in adults is a rare, frequently misdiagnosed, serious condition that carries a high rate of morbidity. OBJECTIVE OF THE REVIEW: This review evaluates the presentation, diagnosis, and management of PC stroke in the emergency department (ED) based on current evidence. DISCUSSION: PC stroke presents most commonly with dizziness or vertigo and must be distinguished from more benign diagnoses. Emergency clinicians should consider this condition in patients with dizziness, even in younger patients and those who do not have traditional stroke risk factors. Neurologic examination for focal neurologic deficit, dysmetria, dysarthria, ataxia, and truncal ataxia is essential, as is the differentiation of acute vestibular syndrome vs. spontaneous episodic vestibular syndrome vs. triggered episodic vestibular syndrome. The HINTS (head impulse, nystagmus, and test of skew) examination can be useful for identifying dizziness presentations concerning for stroke when performed by those with appropriate training. However, it should only be used in patients with continuous dizziness who have ongoing nystagmus. Contrast tomography (CT), CT angiography, and CT perfusion have limited sensitivity for identifying PC strokes, and although magnetic resonance imaging is the gold standard, it may miss some PC strokes early in their course. Thrombolysis is recommended in patients presenting within the appropriate time window for thrombolytic therapy, and although some data suggest endovascular therapy for basilar artery and posterior cerebral artery infarcts is beneficial, its applicability for all PC strokes remains to be determined. CONCLUSIONS: An understanding of PC stroke can assist emergency clinicians in diagnosing and managing this disease.

The effects of continuous administration of diazepam on the recovery of lesion-induced nystagmus in unilaterally labyrinthectomised rats.

BACKGROUND: Diazepam, a gamma-aminobutyric acid type A receptor agonist, is classified as a vestibular suppressant and is effective in treating acute vertigo. However, its effects on vestibular compensation (VC) remain unclear. OBJECTIVES: We examined the effects of continuous administration of diazepam on the frequency of spontaneous nystagmus (SN) after unilateral labyrinthectomy (UL) as an index of the initial process of VC in rats. MATERIALS AND METHODS: Diazepam was continuously administered at doses of 3.5 and 7.0 mg/kg/day, intraperitoneally, via an osmotic minipump. The frequency of SN beating against the lesion side after UL was measured. Potassium chloride (KCl) solution (1 M) was injected intratympanically to induce SN beating to the injection side. RESULTS: Continuous administration of diazepam significantly and dose-dependently decreased the frequency of SN after UL, and also reduced the x intercept of the nonlinear regression curve of the decline in UL-induced SN with time in rats. However, the continuous administration of diazepam did not affect the frequency of intratympanic KCl-induced SN in the rats. CONCLUSION: These findings suggested that continuous administration of diazepam accelerates the initial process of VC; however, it does not suppress the nystagmus-driving mechanisms in rats.

Periodic vertigo and downbeat nystagmus while supine: Dysfunction of Purkinje cells coding gravity.

Cerebellar nodulus and uvula and their connections with the vestibular nuclei form the so-called velocity-storage circuit. Lesions involving the velocity-storage circuit give rise to positional vertigo and nystagmus. Herein, we present a 32-year-old man with cerebellar nodulus and uvular hemorrhage who showed periodic vertigo and downbeat nystagmus in the supine position. To explain this unusual pattern, we adopted velocity-storage model with a lesion on the neural connection between the gravity and inertia estimators, resulting in periodic neural impulses and a gravity bias in a specific position. This report expands the spectrum of central positional nystagmus due to dysfunction of the velocity-storage mechanism.

Vestibular seizures and spontaneous downbeat nystagmus of ganglioglioma origin: a case report.

BACKGROUND: Low-grade gangliogliomas (GGs) are typically epileptogenic intracranial neoplasms. Yet, the presentation of simplex vertiginous experience and spontaneous downbeat nystagmus (DBN) has not been reported to date. CASE PRESENTATION: We present the case of a 26-year-old male with focal onset impaired awareness seizures, characterized by vertigo due to right temporal lobe epilepsy caused by ganglioglioma. As rare presentations, a spontaneous, consistent DBN in the absence of vertiginous experience was noticed. MRI suggested lesion in the right temporal pole. Twenty-four-hour continuous electroencephalogram (EEG) monitoring recorded periodic sharp and slow waves, originating from the right temporal lobe. The patient was completely relieved of the symptoms after surgical removal of the tumor, which was histologically confirmed as Grade I Ganglioglioma. CONCLUSIONS: Asides from the cortical pathogenesis of epileptic vertigo, this case also provides insight into the DBN secondary to tumor of the temporal lobe. Moreover, the 24-h EEG is advantageous to recognize vestibular seizures and localize the ictal onset areas.

Characteristics and Possible Mechanisms of Direction-Reversing Nystagmus During Positional Testing in Patients With Benign Paroxysmal Positional Vertigo.

OBJECTIVES: The occurrence of direction-reversing nystagmus during positional testing in patients with benign paroxysmal positional vertigo (BPPV) is not uncommon. Further in-depth analysis of the characteristics and possible mechanisms of direction-reversing nystagmus will help us to diagnose and treat BPPV more precisely. The study aimed to analyze the incidence and characteristics of direction-reversing nystagmus during positional testing in BPPV patients, evaluate the outcomes of canalith repositioning procedure for these patients, and further explore the possible mechanism of reversal nystagmus in BPPV patients. STUDY DESIGN: Retrospective study. SETTING: Single-center study. PATIENTS: A total of 575 patients with BPPV who visited the Vertigo Clinic of our hospital between April 2017 and June 2021 were enrolled. MAIN OUTCOME MEASURES: Dix-Hallpike and supine roll tests were performed. The nystagmus was recorded using videonystagmography. The characteristics of direction-reversing nystagmus and the possible underlying mechanism were analyzed. RESULTS: Patients with BPPV who showed reversal nystagmus accounted for 9.39% (54 of 575) of all BPPV patients visiting our hospital during the same period, of which 5.57% (32 of 575) had horizontal semicircular canal BPPV (HC-BPPV), and 3.83% (22 of 575) had posterior semicircular canal BPPV (PC-BPPV). The maximum slow-phase velocities (mSPVs) of the first-phase nystagmus were greater in HC-BPPV and PC-BPPV patients with reversal nystagmus than those without ( p = 0.04 and p = 0.01, respectively). In all HC-BPPV and PC-BPPV patients with reversal nystagmus, the mSPV of the first-phase nystagmus was greater than that of the second-phase nystagmus ( p < 0.01). The duration of the second-phase nystagmus was longer than 60 seconds in 93.75% (30 of 32) of the HC-BPPV patients and 77.27% (17 of 22) of the PC-BPPV patients ( p = 0.107, Fisher exact test). HC-BPPV and PC-BPPV patients with reversal nystagmus both required more than one canalith repositioning procedure compared with those without (HC-BPPV: 75 versus 28.13%, p < 0.001; PC-BPPV: 59.09 versus 13.64%, p = 0.002). CONCLUSIONS: The cause of second-phase nystagmus in BPPV patients with direction-reversing nystagmus may be related to the involvement of central adaptation mechanisms secondary to the overpowering mSPV of the first-phase nystagmus.

Bilateral Internuclear Ophthalmoplegia Caused by Dengue Fever.

A 22-year-old male was referred from the medicine department with the chief complaint of double vision for 2 months. The patient had suffered from dengue viral hemorrhagic encephalitis for 2 months for which intensive medical care was given. On ocular examination, both eyes (OU) showed limited adduction with contralateral abducting nystagmus on attempted horizontal gaze. Magnetic resonance imaging of brain showed pontine and midbrain hemorrhages which involved the region of medial longitudinal fasciculus and caused bilateral internuclear ophthalmoplegia (INO). Bilateral INO is very rare and most commonly caused by multiple sclerosis. The presentation of dengue fever causing midbrain and pontine hemorrhages which resulted in bilateral INOs has not been previously reported, to our knowledge.