Video head impulse testing in patients with isolated (hemi)nodular infarction

Usefulness of Nystagmus Patterns in Distinguishing Peripheral From Central Acute Vestibular Syndromes at the Bedside: A Critical Review

Vertigo and dizziness are amongst the most frequent presenting symptoms in the emergency room, accounting for up to 4% of all emergency consultations. The broadness of their differential diagnosis and the often transient nature of these symptoms pose a significant challenge to the treating physician. Combining various subtle oculomotor signs at the bedside has been very successful in distinguishing peripheral from central causes in acutely dizzy patients meeting diagnostic criteria for the acute vestibular syndrome (i.e., acute and prolonged vertigo or dizziness accompanied by nausea or vomiting, gait imbalance, motion intolerance, and [not mandatory] nystagmus). While the diagnostic accuracy of the HINTS (Head-Impulse-Nystagmus-Test-of-Skew) algorithm has been studied extensively, less is known about the value of various nystagmus patterns seen at the bedside in patients with an acute vestibular syndrome. Here we review both spontaneous and triggered presenting nystagmus patterns and discuss their impacts and limitations, including primary-gaze horizontal, vertical, and torsional nystagmus, nystagmus during eccentric gaze, and nystagmus triggered by stimuli such as head-shaking, hyperventilation, positional testing, vibration, and the Valsalva maneuver. We conclude that the usefulness of nystagmus patterns in discriminating peripheral and central causes strongly depends on the pattern seen and the type of testing performed, being highly predictive of a central cause for torsional and vertical spontaneous nystagmus, downbeat, or apogeotropic horizontal and treatment-refractory positional nystagmus. The predictive value for central causes was moderate only for vertical nystagmus after horizontal head-shaking ("perverted" head-shaking nystagmus) since it can also occur in peripheral cases, while the predictive value was low for vibration-induced nystagmus and Valsalva-induced nystagmus.

Dorsolateral pontine lesions produce distinct ocular motor abnormalities with anatomical correlations

BACKGROUND AND PURPOSE

The dorsolateral portion of the caudal pons contains the vestibular nucleus (VN) and inferior cerebellar peduncle (ICP) that play important roles in conveying and processing vestibular and ocular motor signals. This study aimed to characterize ocular motor abnormalities along with their anatomical correlations in dorsolateral pons (DLP) lesions.

METHODS

We analyzed clinical features, and results of neuro-otological evaluations and neuroimaging of 18 patients with unilateral DLP lesions (17 with DLP infarction and 1 with cavernous malformation) from among 506 patients with pontine infarction in a stroke registry.

RESULTS

Most of the patients (n = 16) presented with isolated acute vestibular syndrome (AVS). The involved structures within the DLP were the ICP in four patients and the VN in the remaining 14. The unilateral ICP lesions were associated with consistent abnormalities in vestibular and ocular motor tests, including ipsilesional nystagmus without gaze-evoked nystagmus (GEN), and normal head impulse tests (HITs) and caloric response. In contrast, lesions of the VN were associated with a broader range of eye-movement abnormalities, including ipsi- or contralesional nystagmus with GEN, positive HITs, normal or abnormal caloric responses, and fixation nystagmus. Initial diffusion-weighted magnetic resonance imaging (within 48 h) was falsely negative in 41% (n = 7) of the DLP infarction cases.

CONCLUSIONS

This study demonstrates that unilateral DLP lesions frequently present with isolated AVS and diverse ocular motor abnormalities. These characteristics may be due to the complex involvement of afferent or efferent fibers to and from the VN.

Diagnosis of Isolated Central Vertigo: Report for a Series Cases

Vertigo, including central and peripheral causes, is one of the common symptoms in patients who are admitted to neurological outpatient and emergency rooms. Despite the advancements in imaging techniques in recent years, central vertigo is difficult to identify and is often misdiagnosed in clinical practice. In this study, 4 patients were admitted to the hospital with complaints of dizziness or vertigo. Information about their symptoms, physical examinations and imaging were collected. Two patients were accurately diagnosed using diffusion-weighted imaging (DWI), a specific type of brain MRI. They received targeted treatments, which led to significant improvement, and were discharged nearly cured within a week. One patient with dorsolateral medullary infarction was misdiagnosed due to atypical symptoms, such as vertigo without the typical lateral medullary syndrome signs, and was discharged with a mild swallowing disorder after 2 weeks of treatment. One patient was diagnosed with both central and peripheral vertigo. It was observed that the symptoms of isolated vertigo caused by an acute lacunar infarction resolved more quickly than the accompanying physical symptoms. In summary, more attention should be paid to the diagnosis of isolated central vertigo, as early identification and intervention can improve a patient's prognosis and reduce medical expenses.

Video head impulse test in stroke: a review of published studies

Accurate and timely diagnosis of posterior circulation stroke in patients with acute dizziness is a challenge that can lead to misdiagnosis and significant harm. The present review sought to identify and describe published research on the clinical application of vHIT in posterior circulation stroke. vHIT, a portable device, has gained prominence in evaluating peripheral vestibular disorders and offers potential applications in diagnosing neurological disorders, particularly posterior circulation stroke. Several studies have shown that vHIT can differentiate between stroke and vestibular neuritis based on VOR gain values, with high sensitivity and specificity. The manuscript also discusses vHIT's performance in differentiating between types of posterior circulation stroke, such as PICA, AICA, and SCA strokes. While vHIT has demonstrated promise, the review emphasizes the need for further research to validate its use as a tool to rule out stroke in acute dizziness patients in the emergency department. In conclusion, the manuscript underscores the potential of vHIT as a valuable addition to the diagnostic arsenal for acute dizziness, particularly in the context of posterior circulation stroke. It calls for further research and wider adoption of vHIT in clinical settings to improve patient care and reduce unnecessary costs associated with misdiagnoses.