Ataxia in posterior circulation stroke: Clinical–MRI correlations

Frequency, phenotypes, and neuroimaging of early post stroke movement disorders: a prospective study

Background

A prospective observational study recruited patients with acute stroke. Patients were assessed for the presence of post-stroke movement disorders PSMDs during the first week of stroke. This study aimed to identify the frequency, clinical characteristics, and neuroimaging of early PSMDs (within the first week) and followed for 1 year.

Results

A total of 600 patients were recruited; 21 patients (3.5%) with PSMDs were detected. Thirteen (2.2%) patients presented with intention tremor/ataxia and eight (1.3%) presented with other movement disorders (most commonly, chorea and tremor). One patient presented with periodic left upper limb shaking with right subcortical watershed infarction, and one patient developed palatal myoclonus with right middle cerebral artery infarction. Patients with PSMDs had significantly lower stroke severity (NIHSS) and were more likely to have lacunar strokes (p < 0.001 and < 0.006, respectively) than patients without PSMDs. Early PSMDs were more associated with posterior circulation strokes (84.25%).

Conclusions

Early PSMDs are commonly hyperkinetic, more associated with small vessel disease, and less severe and posterior circulation strokes, implying their clinical importance for the proper management of stroke patients.

Distinguishing Peripheral from Central Causes of Dizziness and Vertigo without using HINTS or STANDING

Three validated diagnostic algorithms for diagnosing patients with acute onset dizziness or vertigo (HINTS, HINTS-plus and STANDING) exist. All are extremely accurate in distinguishing peripheral from central causes of dizziness when done by experienced clinicians. However, uptake of these diagnostic tools in routine emergency medicine practice has been sub-optimal, in part, due to clinicians' unease with the head impulse test, the most useful component contained of these algorithms. Use of these validated algorithms is the best way to accurately diagnose patients with acute dizziness. For clinicians who are unfamiliar with or uncomfortable performing or interpreting HINTS and STANDING, this article will suggest alternative approaches to help with accurate diagnosis of patients with acute dizziness or vertigo.

R-cVR, a two-step bedside algorithm for the differential diagnosis of acute dizziness and vertigo

Background

The ability to quickly and accurately differentiate between peripheral and central dizziness or vertigo is vital. We developed the R-cVR algorithm for the early identification of central-type dizziness or vertigo.

Methods

In this single-center, retrospective cohort study, we assessed patients with isolated dizziness or vertigo between December 10, 2023, and February 28, 2024. Classification into central or peripheral types was based on magnetic resonance imaging (MRI)-diffusion-weighted imaging (DWI) results. We reevaluated the diagnostic value of the Romberg test for acute dizziness or vertigo by quantifying the duration of standing and created the R-cVR algorithm. The algorithm's accuracy was subsequently validated against the MRI-DWI results.

Results

After screening, 109 patients were recruited and divided into central (n = 25) and peripheral (n = 84) groups. The central group had a high incidence of cerebral infarction (88.0 %), whereas the peripheral group included patients with vestibular neuronitis, benign paroxysmal positional vertigo, and Meniere's disease (96.4 %). Significant disparities in the incidence of balance disorders were noted between the groups (92.0 % vs. 15.5 %, p < 0.001). Multivariate logistic regression revealed an odds ratio of 61.82 for balance disorders (p < 0.001). The R-cVR algorithm, which integrates the Romberg test and the V-shaped stance with closed-eyes protocol, was tested against MRI-DWI and yielded high diagnostic agreement (kappa = 0.80), with a sensitivity and specificity of 88.0 % and 94.0 %, respectively. There was no significant difference in the diagnostic efficacy of this algorithm for acute dizziness or vertigo with or without nystagmus.

Conclusion

The R-cVR algorithm effectively identifies central-type dizziness or vertigo and is simple for general practitioners to use without specialized equipment, which may be valuable in various clinical settings.

Utilizing machine learning to facilitate the early diagnosis of posterior circulation stroke

BACKGROUND

Posterior Circulation Syndrome (PCS) presents a diagnostic challenge characterized by its variable and nonspecific symptoms. Timely and accurate diagnosis is crucial for improving patient outcomes. This study aims to enhance the early diagnosis of PCS by employing clinical and demographic data and machine learning. This approach targets a significant research gap in the field of stroke diagnosis and management.

METHODS

We collected and analyzed data from a large national Stroke Registry spanning from January 2014 to July 2022. The dataset included 15,859 adult patients admitted with a primary diagnosis of stroke. Five machine learning models were trained: XGBoost, Random Forest, Support Vector Machine, Classification and Regression Trees, and Logistic Regression. Multiple performance metrics, such as accuracy, precision, recall, F1-score, AUC, Matthew's correlation coefficient, log loss, and Brier score, were utilized to evaluate model performance.

RESULTS

The XGBoost model emerged as the top performer with an AUC of 0.81, accuracy of 0.79, precision of 0.5, recall of 0.62, and F1-score of 0.55. SHAP (SHapley Additive exPlanations) analysis identified key variables associated with PCS, including Body Mass Index, Random Blood Sugar, ataxia, dysarthria, and diastolic blood pressure and body temperature. These variables played a significant role in facilitating the early diagnosis of PCS, emphasizing their diagnostic value.

CONCLUSION

This study pioneers the use of clinical data and machine learning models to facilitate the early diagnosis of PCS, filling a crucial gap in stroke research. Using simple clinical metrics such as BMI, RBS, ataxia, dysarthria, DBP, and body temperature will help clinicians diagnose PCS early. Despite limitations, such as data biases and regional specificity, our research contributes to advancing PCS understanding, potentially enhancing clinical decision-making and patient outcomes early in the patient's clinical journey. Further investigations are warranted to elucidate the underlying physiological mechanisms and validate these findings in broader populations and healthcare settings.

Guidelines for reasonable and appropriate care in the emergency department 3 (GRACE-3): Acute dizziness and vertigo in the emergency department

This third Guideline for Reasonable and Appropriate Care in the Emergency Department (GRACE-3) from the Society for Academic Emergency Medicine is on the topic adult patients with acute dizziness and vertigo in the emergency department (ED). A multidisciplinary guideline panel applied the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach to assess the certainty of evidence and strength of recommendations regarding five questions for adult ED patients with acute dizziness of less than 2 weeks' duration. The intended population is adults presenting to the ED with acute dizziness or vertigo. The panel derived 15 evidence-based recommendations based on the timing and triggers of the dizziness but recognizes that alternative diagnostic approaches exist, such as the STANDING protocol and nystagmus examination in combination with gait unsteadiness or the presence of vascular risk factors. As an overarching recommendation, (1) emergency clinicians should receive training in bedside physical examination techniques for patients with the acute vestibular syndrome (AVS; HINTS) and the diagnostic and therapeutic maneuvers for benign paroxysmal positional vertigo (BPPV; Dix-Hallpike test and Epley maneuver). To help distinguish central from peripheral causes in patients with the AVS, we recommend: (2) use HINTS (for clinicians trained in its use) in patients with nystagmus, (3) use finger rub to further aid in excluding stroke in patients with nystagmus, (4) use severity of gait unsteadiness in patients without nystagmus, (5) do not use brain computed tomography (CT), (6) do not use routine magnetic resonance imaging (MRI) as a first-line test if a clinician trained in HINTS is available, and (7) use MRI as a confirmatory test in patients with central or equivocal HINTS examinations. In patients with the spontaneous episodic vestibular syndrome: (8) search for symptoms or signs of cerebral ischemia, (9) do not use CT, and (10) use CT angiography or MRI angiography if there is concern for transient ischemic attack. In patients with the triggered (positional) episodic vestibular syndrome, (11) use the Dix-Hallpike test to diagnose posterior canal BPPV (pc-BPPV), (12) do not use CT, and (13) do not use MRI routinely, unless atypical clinical features are present. In patients diagnosed with vestibular neuritis, (14) consider short-term steroids as a treatment option. In patients diagnosed with pc-BPPV, (15) treat with the Epley maneuver. It is clear that as of 2023, when applied in routine practice by emergency clinicians without special training, HINTS testing is inaccurate, partly due to use in the wrong patients and partly due to issues with its interpretation. Most emergency physicians have not received training in use of HINTS. As such, it is not standard of care, either in the legal sense of that term ("what the average physician would do in similar circumstances") or in the common parlance sense ("the standard action typically used by physicians in routine practice").

Clinical Characteristics and Clinical Course of Body Lateropulsion in 47 Patients with Brainstem Infarctions

BACKGROUND

In patients with lower lateral medullary infarction (LMI) located under the vestibular nucleus, proprioceptive impairment due to dorsal spinocerebellar tract (DSCT) is considered a pathological condition for body lateropulsion. In patients with brainstem infarction located at or above the level of the vestibular nucleus, other pathways, such as the crossed vestibulothalamic tract (CVTT), are considered responsible.

RESEARCH QUESTION

The clinical course of body lateropulsion between each anatomical level of infarction remains unclear. Further, whether body lateropulsion refers to a static or a dynamic symptom also remains unclear.

METHODS

We examined 47 patients who exhibited body lateropulsion and categorized them into four groups: lower LMI under the vestibular nucleus, LMI at the level of the vestibular nucleus, pontine infarction, and midbrain infarction. The patients' time to acquire static upright standing position and gait in a straight line were statistically analyzed by a log-rank test using the Kaplan-Meier method.

RESULTS

Body lateropulsion in the static upright position was less frequent in the lower LMI group than in the other groups.

SIGNIFICANCE

Lower LMI primarily affected body lateropulsion in gait. DSCT damage could affect ipsilateral hip joint or leg coordination, causing body lateropulsion in dynamic situation.

Current concepts of cross-sectional and functional anatomy of the cerebellum: a pictorial review and atlas

Recognition of key concepts of structural and functional anatomy of the cerebellum can facilitate image interpretation and clinical correlation. Recently, the human brain mapping literature has increased our understanding of cerebellar anatomy, function, connectivity with the cerebrum, and significance of lesions involving specific areas.Both the common names and numerically based Schmahmann classifications of cerebellar lobules are illustrated. Anatomic patterns, or signs, of key fissures and white matter branching are introduced to facilitate easy recognition of the major anatomic features. Color-coded overlays of cross-sectional imaging are provided for reference of more complex detail. Examples of exquisite detail of structural and functional cerebellar anatomy at 7 T MRI are also depicted.The functions of the cerebellum are manifold with the majority of areas involved with non-motor association function. Key concepts of lesion-symptom mapping which correlates lesion location to clinical manifestation are introduced, emphasizing that lesions in most areas of the cerebellum are associated with predominantly non-motor deficits. Clinical correlation is reinforced with examples of intrinsic pathologic derangement of cerebellar anatomy and altered functional connectivity due to pathology of the cerebral hemisphere. The purpose of this pictorial review is to illustrate basic concepts of these topics in a cross-sectional imaging-based format that can be easily understood and applied by radiologists.

ACR Appropriateness Criteria® Ataxia

Ataxia can result from an abnormality in the cerebellum, spinal cord, peripheral nerves, and/or vestibular system. Pathology involving the brain, such as infarct or hydrocephalus, can also present with ataxia as part of the symptom constitution, or result in symptoms that mimic ataxia. Clinical evaluation by history and careful neurological examination is important to help with lesion localization, and helps determine where imaging should be focused. In the setting of trauma with the area of suspicion in the brain, a head CT without intravenous contrast is the preferred initial imaging choice. If vascular injury is suspected, CTA of the neck can be helpful. When the area of suspicion is in the spine, CT or MRI of the spine can be considered to assess for bony or soft-tissue injury, respectively. In the setting of ataxia unrelated to recent trauma, MRI is the preferred imaging modality, tailored to assess the brain or spine depending on the area of suspected pathology. The use of intravenous contrast is generally helpful. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Prognostic Importance of Lesion Location on Functional Outcome in Patients with Cerebellar Ischemic Stroke: a Prospective Pilot Study

To date, few studies focused on prediction of functional recovery after cerebellar stroke. The main aim of this prospective pilot study was to determine the association between cerebellar lesion location and functional outcome in adults with acute cerebellar infarction. We examined 14 patients with first-ever unilateral cerebellar ischemic stroke within 7 days and at 90 days from the onset of stroke by means of the International Cooperative Ataxia Rating Scale. Cerebellar lesions were traced from magnetic resonance imaging performed within 72 h since stroke and region of interest were generated. The association between the International Cooperative Ataxia Rating Scale score and lesion location was determined with the voxel-based lesion-symptom mapping methods implemented in the MRIcro software. Colored lesion-symptom maps representing the z statistics were generated and overlaid onto the MNI-ICBM 152 linear probabilistic atlas of the human brain and the Johns Hopkins University white matter templates. Our results documented that injuries to the V, VI, VIIA Crus I, VIIA Crus II, VIIB, VIIIA, and VIIIB lobules and the middle cerebellar peduncle are significantly associated with the International Cooperative Ataxia Rating Scale (ICARS) score at 1 week after the onset of stroke. Furthermore, we found that injuries to the VI, VIIA Crus I, VIIA Crus II, VIIB, VIIIA, and VIIIB lobules, the dentate nucleus, and the middle cerebellar peduncle are significantly associated with the ICARS score at 3 months since the cerebellar stroke onset. The findings of this pilot study might improve prognostic accuracy of functional outcome in patients with acute cerebellar infarction.

The Usefulness of the TOAST Classification and Prognostic Significance of Pyramidal Symptoms During the Acute Phase of Cerebellar Ischemic Stroke

Cerebellar stroke is a rare condition with very nonspecific clinical features. The symptoms in the acute phase could imitate acute peripheral vestibular disorders or a brainstem lesion. The aim of this study was to assess the usefulness of the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification in cerebellar stroke and the impact of clinical features on the prognosis. We retrospectively analyzed 107 patients with diagnosed ischemic cerebellar infarction. We studied the clinical features and compared them based on the location of the ischemic lesion and its distribution in the posterior interior cerebellar artery (PICA), superior cerebellar artery (SCA), and anterior inferior cerebellar artery (AICA) territories. According to the TOAST classification, stroke was more prevalent in atrial fibrillation (26/107) and when the lesion was in the PICA territory (39/107). Pyramidal signs occurred in 29/107 of patients and were more prevalent when the lesion was distributed in more than two vascular regions (p = 0.00640). Mortality was higher among patients with ischemic lesion caused by cardiac sources (p = 0.00094) and with pyramidal signs (p = 0.00640). The TOAST classification is less useful in assessing supratentorial ischemic infarcts. Cardioembolic etiology, location of the ischemic lesion, and pyramidal signs support a negative prognosis.

Dystonia and cerebellar degeneration in the leaner mouse mutant

Cerebellar degeneration is traditionally associated with ataxia. Yet, there are examples of both ataxia and dystonia occurring in individuals with cerebellar degeneration. There is also substantial evidence suggesting that cerebellar dysfunction alone may cause dystonia. The types of cerebellar defects that may cause ataxia, dystonia, or both have not been delineated. In the current study, we explored the relationship between cerebellar degeneration and dystonia using the leaner mouse mutant. Leaner mice have severe dystonia that is associated with dysfunctional and degenerating cerebellar Purkinje cells. Whereas the density of Purkinje cells was not significantly reduced in 4 week-old leaner mice, approximately 50% of the neurons was lost by 34 weeks of age. On the other hand, the dystonia and associated functional disability became significantly less severe during this same interval. In other words, dystonia improved as Purkinje cells were lost, suggesting that dysfunctional Purkinje cells, rather than Purkinje cell loss, contribute to the dystonia. These results provide evidence that distorted cerebellar function may cause dystonia and support the concept that different types of cerebellar defects can have different functional consequences.

Ischemic posterior circulation stroke: a review of anatomy, clinical presentations, diagnosis, and current management

Posterior circulation strokes represent approximately 20% of all ischemic strokes (1, 2). In contrast to the anterior circulation, several differences in presenting symptoms, clinical evaluation, diagnostic testing, and management strategy exist presenting a challenge to the treating physician. This review will discuss the anatomical, etiological, and clinical classification of PC strokes, identify diagnostic pitfalls, and overview current therapeutic regimens.

Hemi- and monoataxia in cerebellar hemispheres and peduncles stroke lesions: topographical correlations

Limb ataxia of sudden onset is due to a vascular lesion in either the cerebellum or the brainstem (posterior circulation, PC, territory). This sign can involve both the upper and the lower limb (hemiataxia) or only one limb (monoataxia). The topographical correlates of limb ataxia have been studied only in brainstem strokes. Therefore, it is not yet known whether this sign is useful to localize the lesion within the entire cerebellar system, both the cerebellar hemisphere and the cerebellar brainstem pathways. Limb ataxia was semi-quantified according to the International Cooperative Ataxia Rating Scale in 92 consecutive patients with acute PC stroke. Limb ataxia was present in 70 patients. Four topographical patterns based on magnetic resonance imaging findings were identified: picaCH pattern (posterior inferior cerebellar artery infarct); scaCH pattern (superior cerebellar artery infarct); CH/CP pattern (infarct involving both the cerebellum and the brainstem cerebellar pathways); and CP pattern (infarct involving the brainstem cerebellar pathways). Hemiataxia was present in (47/70; 67.1%) and monoataxia in (23/70; 32.9%) of patients. Monoataxia involved the upper limb in (19/70; 27.1%) and the lower limb in (4/70; 5.7%) of patients. Limb ataxia usually localized the lesion ipsilaterally (picaCH, scaCH, CH/CP, and CP patterns involving the medulla and sometimes the pons) (53/70; 75.7%), but it might be due also to contralateral (CP pattern involving the pons or midbrain) (16/70; 22.9%) or bilateral lesions (1/70). Limb ataxia usually localizes the lesion ipsilaterally but the infarct might be sometimes contralateral. The occurrence of monoataxia may suggest that the cerebellar system is somatotopically organized.