Altered static and dynamic cerebellar-cerebral functional connectivity in acute pontine infarction.

This study investigates abnormalities in cerebellar-cerebral static and dynamic functional connectivity among patients with acute pontine infarction, examining the relationship between these connectivity changes and behavioral dysfunction. Resting-state functional magnetic resonance imaging was utilized to collect data from 45 patients within seven days post-pontine infarction and 34 normal controls. Seed-based static and dynamic functional connectivity analyses identified divergences in cerebellar-cerebral connectivity features between pontine infarction patients and normal controls. Correlations between abnormal functional connectivity features and behavioral scores were explored. Compared to normal controls, left pontine infarction patients exhibited significantly increased static functional connectivity within the executive, affective-limbic, and motor networks. Conversely, right pontine infarction patients demonstrated decreased static functional connectivity in the executive, affective-limbic, and default mode networks, alongside an increase in the executive and motor networks. Decreased temporal variability of dynamic functional connectivity was observed in the executive and default mode networks among left pontine infarction patients. Furthermore, abnormalities in static and dynamic functional connectivity within the executive network correlated with motor and working memory performance in patients. These findings suggest that alterations in cerebellar-cerebral static and dynamic functional connectivity could underpin the behavioral dysfunctions observed in acute pontine infarction patients.

Body representation after a stroke in the brainstem.

BACKGROUND: Lesion occurring in the brainstem may cause a postural tilt and balance disorders, which could be due to an inaccurate perception of the body orientation. The objective of this study was to determine the effects of a brainstem stroke on body representation in horizontal and frontal plane, and links with impaired posture and neuroanatomy. METHODS: Forty patients with stroke in left brainstem (L-BS) or right (R-BS) were compared with 15 matched control subjects (C). The subjective straight-ahead (SSA) was investigated using a method disentangling lateral deviation and tilt components of error. RESULTS: The L-BS patients had contralesional lateral deviation of SSA. In addition, they showed an ipsilesional tilt, more severe for the trunk than for the head. By contrast, in R-BS patients, the representation of the body midline was fairly accurate in both the horizontal and frontal planes and did not differ from that of control subjects. CONCLUSION: This work highlights an asymmetry of representation of body associated with left brainstem lesions extending to the right cerebral hemisphere. This deviation appears only after a left lesion, which may point to a vestibular dominance. These results open a new perspective of neuro-rehabilitation of postural disorders after a stroke, with the correction of the representation of body orientation.

Body Lateropulsion in Stroke: Case Report and Systematic Review of Stroke Topography and Outcome.

INTRODUCTION: Body lateropulsion (BLP) is seen in neurological lesions involving the pathways responsible for body position and verticality. We report a case of isolated body lateropulsion (iBLP) as the presentation of lateral medullary infarction and conducted a systematic literature review. METHODS: MEDLINE and EMBASE databases were searched up to December 3, 2020. INCLUSION CRITERIA: age ≥ 18, presence of BLP, confirmed stroke on imaging. EXCLUSION CRITERIA: age < 18, qualitative reviews, studies with inadequate patient data. Statistical analysis was performed using IBM® SPSS® Statistics 20. RESULTS: A 64-year-old man presented with acute-onset iBLP. Brain MRI demonstrated acute infarction in the right caudolateral medulla. His symptoms progressed with ipsilateral Horner syndrome over the next 24 hours and contralateral hemisensory loss 10 days later. Repeat MRI showed an increase in infarct size. BLP resolved partially at discharge. Systematic review: 418 abstracts were screened; 59 studies were selected reporting 103 patients. Thirty-three patients had iBLP (32%). BLP was ipsilateral to stroke in 70 (68%) and contralateral in 32 (32%). The most common stroke locations were medulla (n = 63, 59%), pons (n = 16, 15%), and cerebellum (n = 16, 15%). Four strokes were cortical, 3 frontal and 1 temporoparietal (3%). The most common etiology was large-artery atherosclerosis (LAA) in 20 patients (32%), followed by small-vessel occlusion in 12 (19%). Seventeen (27%) had large-vessel occlusion (LVO), 12 involving the vertebral artery. Sixty (98%) had some degree of resolution of BLP; complete in 41 (70%). Median time-to-resolution was 14 days (IQR 10-21). There was no relationship between time-to-resolution and age, sex, side of BLP or side of stroke. CONCLUSION: BLP was commonly seen with medullary infarction and was the isolated finding in one-third. LAA and LVO were the most common etiologies. Recovery of BLP was early and complete in most cases.

Acute Unilateral Masseter Muscle Paralysis Caused by Pontine Infarction.

In the present report, we discussed the case of a 57-year-old man with unilateral masticatory muscle weakness, nystagmus, skew deviation and facial hypesthesia due to pontine tegmental infarction. Trigeminal motor neuropathy attributed to brain infarction is very rare. Brain magnetic resonance imaging revealed a small dot-like infarction lesion in the pontine tegmentum. Masticatory muscle weakness was confirmed by an electrophysiological study performed on the day after admission in which there was an incomplete interference pattern without spontaneous denervation activity, suggesting that the patient's masseter muscle weakness was caused by an infarction of the trigeminal motor nucleus proper or trigeminal motor nerve fascicles rather than Wallerian degeneration of the trigeminal nerve or the progression of masseter muscle degeneration.

Recurrent Pontine Strokes in a Young Male.

A 34-year-old patient presented to the emergency department with recurrent neurologic symptoms of sudden onset. MRI showed white matter hyperintensities consistent with small vessel disease, predominantly in the pons. There were no known cardiovascular risk factors (CVRF) and extensive workup for vasculitis was negative. The preliminary diagnosis was small vessel primary central nervous system vasculitis, but immunosuppressive treatment did not stop a progression of the disease over 6 months. Repeated negative diagnostic workup for vasculitis, lack of response to therapy, young age, and predominant involvement of the pons were compatible with pontine autosomal dominant microangiopathy and leukoencephalopathy (PADMAL), which is a very rare monogenic cause of cerebral small vessel disease due to upregulation of collagen type-IV. Correspondingly, a COL4A1 mutation was found. Therapy was immediately stopped in favour of more strict adjustment of the CVRF including lowering of LDL < 70 mg/dl and extensive monitoring of blood-pressure.

Bilateral, vertical supranuclear gaze palsy following unilateral midbrain infarct.

A 60-year-old man recently admitted for bipedal oedema, endocarditis and a persistently positive COVID-19 swab with a history of anticoagulation on rivaroxaban for atrial fibrillation, transitional cell carcinoma, cerebral amyloid angiopathy, diabetes and hypertension presented with sudden onset diplopia and vertical gaze palsy. Vestibulo-ocular reflex was preserved. Simultaneously, he developed a scotoma and sudden visual loss, and was found to have a right branch retinal artery occlusion. MRI head demonstrated a unilateral midbrain infarct. This case demonstrates a rare unilateral cause of bilateral supranuclear palsy which spares the posterior commisure. The case also raises a question about the contribution of COVID-19 to the procoagulant status of the patient which already includes atrial fibrillation and endocarditis, and presents a complex treatment dilemma regarding anticoagulation.

Case Report: Ocular Tilt Reaction with Internuclear Ophthalmoplegia and Multiple Cranial Nerve Palsies.

SIGNIFICANCE: Ocular tilt reaction (OTR) is an abnormal eye-head postural reaction that consists of skew deviation, head tilt, and bilateral ocular torsion. Understanding of the pathway of the vestibulo-ocular reflex (VOR) is essential because this will help to localize the pathology. PURPOSE: The aim of this study was to report a case of OTR with contralateral internuclear ophthalmoplegia (INO) and fifth and seventh cranial nerve palsies. CASE REPORT: A 51-year-old gentleman with underlying diabetes mellitus presented with sudden onset of diplopia for 3 days. On examination, his visual acuity was 20/30 bilaterally without a relative afferent pupillary defect. He had a right OTR consisting of a right head tilt, a skew deviation with a left eye hypertropia, and bilateral ocular torsion (right excyclotorsion and left incyclotorsion) with nystagmus. He also had a left adduction deficit and right abduction nystagmus consistent with a left INO. Ocular examination revealed evidence of proliferative diabetic retinopathy bilaterally. Two days after the initial presentation, the patient developed left seventh and fifth cranial nerve palsies. MRI showed left pontine infarction and multiple chronic lacunar infarctions. There was an incidental finding of a vascular loop compression on cisternal portions of the left trigeminal, facial, and vestibulocochlear nerves. Antiplatelet treatment was started on top of a better diabetic control. The diplopia was gradually resolved with improved clinical signs. In this case, the left pontine infarction had likely affected the terminal decussated part of the vestibulocochlear nerve from the right VOR pathway, medial longitudinal fasciculus, and cranial nerve nuclei in the left pons. CONCLUSIONS: The OTR can be ipsilateral to the lesion if the lesion is before the decussation of the VOR pathway in the pons, or it can be contralateral to the lesion if the lesion is after the decussation. In case of an OTR that is associated with contralateral INO and other contralateral cranial nerves palsy, a pathology in the pons that is contralateral to the OTR should be considered. Neuroimaging study can hence be targeted to identify the possible cause.

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.

Isolated Infarction of the Medullary Pyramid - A Rare Pure Motor Stroke.

Acute pure motor hemiparesis can occur due to a vascular insult along the cortico spinal pathway. Rarely such a stroke can occur as a result of involvement of the pyramids located on the ventral aspect of the medulla. Neurological localization can be difficult in such strokes and moreover they can also pose imaging challenges since they are missed on the CT scans. So far only 4 such cases have been reported in literature. Here we present two cases of pure motor strokes caused by infarction of the medullary pyramids. We have described the anatomical correlates of the symptoms and signs and also highlight the importance of MRI in picking up these rare strokes.

Global multisensory reorganization after vestibular brain stem stroke.

OBJECTIVE: Patients with acute central vestibular syndrome suffer from vertigo, spontaneous nystagmus, postural instability with lateral falls, and tilts of visual vertical. Usually, these symptoms compensate within months. The mechanisms of compensation in vestibular infarcts are yet unclear. This study focused on structural changes in gray and white matter volume that accompany clinical compensation. METHODS: We studied patients with acute unilateral brain stem infarcts prospectively over 6 months. Structural changes were compared between the acute phase and follow-up with a group of healthy controls using voxel-based morphometry. RESULTS: Restitution of vestibular function following brain stem infarcts was accompanied by downstream structural changes in multisensory cortical areas. The changes depended on the location of the infarct along the vestibular pathways in patients with pathological tilts of the SVV and on the quality of the vestibular percept (rotatory vs graviceptive) in patients with pontomedullary infarcts. Patients with pontomedullary infarcts with vertigo or spontaneous nystagmus showed volumetric increases in vestibular parietal opercular multisensory and (retro-) insular areas with right-sided preference. Compensation of graviceptive deficits was accompanied by adaptive changes in multiple multisensory vestibular areas in both hemispheres in lower brain stem infarcts and by additional changes in the motor system in upper brain stem infarcts. INTERPRETATION: This study demonstrates multisensory neuroplasticity in both hemispheres along with the clinical compensation of vestibular deficits following unilateral brain stem infarcts. The data further solidify the concept of a right-hemispheric specialization for core vestibular processing. The identification of cortical structures involved in central compensation could serve as a platform to launch novel rehabilitative treatments such as transcranial stimulations.

Vestibular nuclear infarction: Case series and review of the literature.

BACKGROUND AND PURPOSE: Acute vestibular syndrome (AVS) is a common cause of emergency admittance and has very rarely been reported due to a vestibular nucleus infarction. Initial magnetic resonance imaging studies (MRIs) including diffusion-weighted images may reveal normal results and even bedside examination tests like HINTS battery which involves head impulse test (HIT), nystagmus and test of skew can be challenging in differing a peripheral vestibulopathy from a central lesion. METHODS: Four patients seen in the emergency department with AVS and evaluated with HINTS battery, cervical vestibular-evoked myogenic potentials (cVEMP) and cranial MRI revealing infarcts restricted to vestibular nuclei were evaluated. RESULTS: In two patients spontaneous nystagmus beating towards the unaffected side was present. In one patient spontaneous nystagmus changed direction on looking to the affected side. In the fourth gaze evoked nystagmus was present without any spontaneous nystagmus. In all, HIT was positive to the affected side. In three cVEMPs was studied revealing delayed latency, reduced amplitude p13/n23 potentials on the lesioned side in two of them. Initial MRIs including diffusion-weighted images disclosed acute infarction in the area of the vestibular nuclei in two patients, with normal results in the other two. Follow-up MRI's performed 48 hours later revealed vestibular nuclear infarction. CONCLUSION: It is not always easy to differentiate small lesions restricted to central vestibular structures from peripheral vestibular lesions both on clinical and radiological grounds. Follow-up cranial MRI is necessary in patients with known vascular risk factors.

Prospective investigation of cerebellar cognitive affective syndrome in a previously non-demented population of acute cerebellar stroke.

OBJECTIVE: In this prospective study, we aimed to investigate the presence and evolution of cerebellar cognitive affective syndrome in a cohort of isolated cerebellar stroke with no known cognitive or psychiatric impairment. We tried to distinguish the unconfounded effect of cerebellar lesions on neuropsychological processing. METHODS: After a meticulous exclusion procedure based on possible confounders, we recruited 14 patients and 13 age-matched healthy controls to the study, prospectively. All of the patients had a detailed initial neuropsychological assessment at the first week and a follow-up assessment at the 4th month after stroke. RESULTS: The prevalence of cognitive or behavioral-affective abnormalities in our cohort were 86% and 64% respectively. The patients exhibited mild and transient affective-behavioral abnormalities except for depressive symptoms that persisted in the subacute stage. They scored lower in general cognitive performance as revealed by mini mental test (p=0.001). Memory, executive functions, attention and working memory, central processing speed, and linguistic abilities were impaired (p<0.001; p=0.001; p=0.007; p=0.05; p<0.001 respectively). Improvement was evident only in memory domain of the cognitive functions in the subacute stage. Cognitive impairment was more likely with a medial or posterolateral infarct (p=0.014). Behavioral-affective abnormalities were not associated with a specific location in our cohort. Age seemed to negatively correlate with the recovery in general cognitive performance on the follow-up. CONCLUSIONS: These findings show that acute denervation of cerebellocortical projections leads to mild affective-behavioral abnormalities, and full-blown cerebellar cognitive affective syndrome is rare. However, cognition was significantly affected after an acute cerebellar infarct even in a previously healthy, non-demented pure population.

The Medial Pontine Mid-Tegmentum Syndrome.

Isolated pontine infarcts are common and are often associated with well-described syndromes that are classified based on their specific clinical presentation and arterial stroke territories. Here we present a case of acute combined diplopia and unilateral lower extremity sensory abnormality. Diffusion-weighted magnetic resonance imaging revealed a punctate area of acute ischemia in the right medial pontine mid-tegmentum. These findings suggest a unique pontine stroke syndrome characterized by acute ischemic injury at the intersection of the medial lemniscus and cranial nerve VI.

Predictors of Early Neurologic Deterioration in Acute Pontine Infarction.

Background and Purpose- The relationship between infarct dimensions and neurological progression in patients with acute pontine infarctions remains unclear. This study aimed to investigate the morphometric predictive value of magnetic resonance imaging for early neurological deterioration (END) in acute pontine infarction. Methods- We included all patients admitted to our department having an acute ischemic stroke in the pons. The ventrodorsal length multiplied by thickness was measured as parameters of infarct size. END was defined as an incremental increase in the National Institutes of Health Stroke Scale score by ≥1 point in motor power, or ≥2 points in the total score within the first week after admission. Results- We enrolled 407 patients, and 114 (28.0%) patients were diagnosed with END. Adjusted logistic regression analyses showed the maximum length multiplied by thickness was independently associated with END (odds ratio, 4.580 [95% CI, 2.909-7.210]). The sensitivity, specificity, and area under the curve were 77.2%, 79.2%, and 0.843, respectively, in the receiver operating characteristic curve analysis of maximum length multiplied by thickness for predicting END. Conclusions- These results suggest that the maximum length multiplied by thickness may be a possible predictor in the evaluation of progression with isolated acute pontine infarction. The extent of the pontine infarction along the conduction tract may contribute to deterioration.

Which Factors Affect the Severity of Dysphagia in Lateral Medullary Infarction?

The purpose of this study was to identify factors associated with the severity of dysphagia after lateral medullary infarction (LMI). Patients with dysphagia after lateral medullary infarction who were admitted to a rehabilitation unit were included and divided into two groups (non-severe vs. severe). Severe dysphagia was defined as the condition showing decreased bilateral pharyngeal constriction without esophageal passage in a videofluoroscopic swallowing study that initially required enteral tube feeding. Their clinical data (age, sex, lesion side, duration of the illness, penetration-aspiration scale, functional oral intake scale, Modified Barthel index, National Institutes of Health Stroke Scale, and anatomical lesion on diffusion-weighted MRI) were compared to find differences between the two groups. Twelve patients had absence of esophageal passage among a total of 30 patients with dysphagia after LMI. Only anatomical lesion location and extent were significantly different between the two groups. The severe group showed posterolateral involvement in the upper and lower parts of the medulla. Otherwise, there were no significant differences between the two groups. The location and extent of involvement in the medulla were the most important factors associated with the severity of dysphagia after LMI.

Differential involvement of rubral branches in chronic capsular and pontine stroke.

BACKGROUND AND PURPOSE: Early studies have indicated that the cortico-rubro-spinal tracts play important roles in motor dysfunction after stroke. However, the differential involvement of the rubral branches in capsular and pontine stroke, and their associations with the motor impairment are still unknown. METHODS: The present study recruited 144 chronic stroke patients and 91 normal controls (NC) from three hospitals, including 102 cases with capsular stroke (CS) and 42 cases with pontine stroke (PS). The rubral branches, including bilateral corticorubral tracts (CRT), dentatorubral tracts (DRT), and rubrospinal tracts (RST), and the cortico-spinal tract (CST) were reconstructed based on the dataset of the Human Connectome Project. Group differences in diffusion scalars of each rubral branch were compared, and the associations between the diffusion measures of rubral branches and the Fugl-Meyer assessment (FMA) scores were tested. RESULTS: The bilateral CRT of the CS cases showed significantly lower factional anisotropy (FA) than in the NC. The bilateral DRT of the PS cases had lower FA than in the NC. Both CS and PS cases had significantly lower FA of the bilateral RST than the NC. Besides, the stroke patients demonstrated significantly lower FA in bilateral CSTs than the NC. Partial correlation analysis identified significantly positive correlations between the FA of the ipsilesional and CRT and the FMA scores in the CS group, and significantly positive correlations between the FA of the RST bilaterally and the FMA scores in the CS and PS groups. Furthermore, the association between RST integrity and FMA scores still survived after controlling for the effect of the CST. Finally, multiple regression modelling found that rubral tract FA explained 39.2% of the variance in FMA scores for CS patients, and 48.8% of the variance in FMA scores for PS patients. CONCLUSIONS: The bilateral rubral branches were differentially involved in the chronic capsular and pontine stroke, and the impairment severity of each rubral branch was dependent on lesion locations. The integrity of the rubral branches is related to motor impairment in both the chronic capsular and pontine stroke.

Magnetic resonance imaging evaluation of Wallerian degeneration of bilateral middle cerebellar peduncles after pontine infarction.

We aimed to present a case of symmetrical Wallerian degeneration (WD) in the middle cerebellar peduncles (MCPs) after a unilateral paramedian pontine infarction, which was examined by multimodality magnetic resonance imaging (MRI). In addition, we summarize the small number of reported cases. In our clinic, we observed a case of symmetrical WD of bilateral MCPs that occurred 6 months after the onset of a pontine infarction. We searched the Wanfang (Chinese) and PubMed databases and found 23 reported cases of this condition with characteristic similar to our patient. From the 24 cases, the detection time of WD ranged from 3 to 33 weeks. Symmetrical WD in the bilateral MCPs can occur after unilateral paramedian pontine infarction. Most cases were in Stages 2 and 3 of the disease and showed good clinical prognoses.