Syndromes of pontine base infarction. A clinical-radiological correlation study

Pontine ischaemic stroke syndromes

Classic Raymond syndrome is a rare neurological presentation comprising ipsilateral abducens palsy, contralateral facial paresis and contralateral hemiparesis. We present a man in his late 60s who presented with diplopia, dysarthria and right-sided limb weakness. This syndrome is one of a group of 'crossed paralyses' of the caudal pons.

Morphological predictors of neurological deterioration in patients with acute isolated pontine infarct

OBJECTIVE

To investigate morphological predictors of neurological deterioration (ND) in patients with acute isolated pontine infarct.

METHODS

Acute isolated pontine infarct patients within 7 days after onset of stroke symptoms were included retrospectively and classified into ND and non-ND groups. Morphological phenotypes (paramedian pontine infarct [PPI], atypical PPI, small deep infarct, and other types), topographical location, and lesion size were evaluated on axial diffusion-weighted imaging.

RESULTS

There were 210 eligible patients, of whom 62 patients had ND (29.5%). The proportion of PPI was significantly higher in ND than that in non-ND (62.9% vs 39.6%). ND occurred more frequently in PPI patients than non-PPI patients (39.8% vs 20.5%). PPI located more frequently in lower pontine (20.4% vs 8.0%) and less in upper pontine (17.3% vs 30.4%, P = 0.028), and had larger ventro-dorsal length (13.8 ± 3.8 vs 9.9 ± 3.1) and width (8.3 ± 2.3 vs 6.2 ± 1.8) than non-PPI patients. The morphological phenotype of PPI was an independent risk factor for ND (OR 4.81, 95%CI 1.54-15.07, P = 0.007) in patients with isolated pontine infarct. The ventro-dorsal length of pontine infarct lesion was associated with ND (OR 1.18, 95%CI 1.01, 1.37, P = 0.034) in PPI patients.

CONCLUSIONS

The morphological phenotype of PPI was a potential predictor for ND in patients with acute isolated pontine infarct. The ventro-dorsal length of pontine infarct lesion was possibly associated with ND in PPI patients.

Investigation of inpatient convalescent rehabilitation outcomes in branch atheromatous disease

PURPOSE

We investigated inpatient convalescent rehabilitation outcomes of Branch atheromatous disease (BAD).

SUBJECTS AND METHODS

The subjects were 116 patients with lenticulostriate artery territory - BAD (LSA-BAD) and 29 with paramedian pontine artery territory - BAD (PPA-BAD). For all patients, the National Institutes of Health Stroke Scale (NIHSS), Functional Independence Measure (FIM) scores, and Brunnstrom recovery stages (BRS) of the upper limb, fingers, and lower limb were measured on admission and at discharge.

RESULTS

There were no significant differences in clinical characteristics on admission between the LSA-BAD and PPA-BAD groups. The neurological severity of PPA-BAD, as measured by the NIHSS, was significantly milder compared with that of LSA-BAD upon admission (p = 0.015) and at discharge (p = 0.001). Patients with LSA-BAD had significantly less improvement in the BRS of the upper limb (p = 0.001), fingers (p < 0.001), and lower limb (p = 0.007) at discharge. Furthermore, they had significantly smaller changes in BRS between admission and discharge for the upper limb (p = 0.033) and fingers (p = 0.014) compared with patients with PPA-BAD. The improvement in BRS for patients with LSA-BAD tended to be limited to two stages; however, both patients with LSA-BAD and PPA-BAD saw sufficient gains in FIM at discharge.

CONCLUSION

Rehabilitation outcomes following BAD in the convalescent period should be assessed in terms of improvements in pure-motor hemiparesis and activities of daily living. Furthermore, the disturbance patterns in the corticospinal tract by ischemic stroke lesions may be different between LSA-BAD and PPA-BAD.

Effects of Home-Based Boxing Training on Trunk Performance, Balance, and Enjoyment of Patients With Chronic Stroke

OBJECTIVE

To investigate the effect of 6 weeks of home-based boxing training on trunk performance, balance, fear of falling, and level of therapy enjoyment in individuals with chronic stroke.

METHODS

Eighteen participants with chronic stroke were randomly divided into boxing and control groups (9 patients per group). The boxing group received home-based boxing training for 25 minutes plus balance and trunk exercise training for 15 minutes, while the control group received only home-based balance and trunk exercise training for 40 minutes, three days a week for 6 weeks. The Trunk Impairment Scale (TIS), Mini-Balance Evaluation Systems Test (Mini-BESTest), Activities-specific Balance Confidence (ABC) scale, and Physical Activity Enjoyment Scale (PACES) were assessed at baseline, and at 2, 4, and 6 weeks post-training. The Wilcoxon signed rank test and Mann-Whitney U-test were used to determine differences between pre- and post-training within and between groups. Statistical significance was set at p<0.05.

RESULTS

The TIS scores significantly increased from 13 to 17 points in the boxing group (p<0.05) compared to an increase from 15 to 17 points in the control group (p<0.05). The Mini-BESTest scores significantly increased from 14 to 22 points in the boxing group (p<0.05) compared to an increase from 17 to 20 points in the control group (p<0.05). There were no differences in the TIS, Mini-BESTest, ABC, and PACES scores between the two groups.

CONCLUSION

Home-based boxing training with balance and trunk exercise training had a similar training effect compared to home-based balance and trunk exercise training.

Mapping pontocerebellar connectivity with diffusion MRI

The cerebellum's involvement in cognitive, affective and motor functions is mediated by connections to different regions of the cerebral cortex. A distinctive feature of cortico-cerebellar loops that has been demonstrated in the animal work is a topographic organization that is preserved across its corticopontine, pontocerebellar, and cerebello-thalmo-cortical segments. Here we used tractography derived from diffusion imaging data to characterize the connections between the pons and the individual lobules of the cerebellum and generate a parcellation of the pons and middle cerebellar peduncle based on the pattern of connectivity. We identified a rostral to caudal gradient in the pons, similar to that observed in the animal work, such that rostral regions were preferentially connected to cerebellar lobules involved in non-motor, and caudal regions with motor regions. These findings advance our fundamental understanding of the cerebellum, and the parcellations we generated provide context for future research into the pontocerebellar tract's involvement in health and disease.

Neuroanatomical regions associated with non-progressive dysarthria post-stroke: a systematic review

Background

Dysarthria is a common and persisting sequela to stroke. It can have a negative influence on psychological wellbeing, and quality of life. This systematic review aimed to describe and identify the neuroanatomical regions associated with non-progressive dysarthria following stroke.

Methods

A systematic search of PubMed, Ovid Medline, CINAHL, Cochrane, Scopus, and ScienceDirect was conducted to identify all relevant articles published in peer-reviewed journals up to December 2021. Following data extraction, the National Institutes of Health (NIH) quality assessment tools were used to evaluate the methodological quality of the included studies.

Results

Out of 2186 papers found in the literature related to dysarthria post-stroke, 24 met the inclusion criteria. Eligible articles assessed 1150 post-stroke subjects. Out of them, 420 subjects had dysarthria from isolated lesions. Regarding dysarthric subjects with ischemic strokes, 153 sustained supratentorial infarctions, while 267 had infratentorial infarctions. The majority had pontine infarctions (n = 142), followed by infarctions in the corona radiata (n = 104), and the cerebellum (n = 64).

Conclusion

This systematic review is the first step toward establishing a neuroanatomical model of dysarthria throughout the whole brain. Our findings have many implications for clinical practice and provide a framework for implementing guidelines for early detection and management of dysarthria post-stroke.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02877-x.

Risk factors for early neurological deterioration in acute isolated pontine infarction without any causative artery stenosis

BACKGROUND

This study aimed to investigate the risk predictors for early neurological deterioration (END) in isolated acute pontine infarction without any causative artery stenosis.

METHODS

In this retrospective study, patients with isolated acute pontine infarction within 72 h of symptom onset were enrolled between October 2017 and December 2021. END was defined as an increase in the National Institutes of Health Stroke Scale (NIHSS) score ≥ 2 points within the first week postadmission. Patients were divided into the END and the non-END groups. Multiple logistic regression analysis was used to evaluate independent predictors of END in patients with isolated acute pontine infarction.

RESULTS

A total of 153 patients were included in the final study (62 females; mean age, 67.27 ± 11.35 years), of whom 28.7% (47 of 153) experienced END. Multiple logistic regression analyses showed that infarct volume (adjusted odds ratio [aOR], 1.003; 95% CI, 1.001-1.005; P = 0.002) and basilar artery branch disease  (aOR, 3.388; 95% CI, 1.102-10.417; P = 0.033) were associated with END. The combined ROC analysis of the infarct volume and basilar artery branch disease for predicting END showed that the sensitivity and specificity were 80.9% and 72.6%, respectively.

CONCLUSION

Basilar artery branch disease and infarct volume were associated with END in acute isolated pontine infarction and may be useful prognostic factors for neurological progression.

Anatomic and MRI bases for pontine infarctions with patients presentation

OBJECTIVES

There are scarce data regarding pontine arteries anatomy, which is the basis for ischemic lesions following their occlusion. The aim of this study was to examine pontine vasculature and its relationships with the radiologic and neurologic features of pontine infarctions.

MATERIALS AND METHODS

Branches of eight basilar arteries and their twigs, including the larger intrapontine branches, were microdissected following an injection of a 10% mixture of India ink and gelatin. Two additional brain stems were prepared for microscopic examination after being stained with luxol fast blue and cresyl violet. Finally, 30 patients with pontine infarctions underwent magnetic resonance imaging (MRI) in order to determine the position and size of the infarctions.

RESULTS

The perforating arteries, which averaged 5.8 in number and 0.39 mm in diameter, gave rise to paramedian and anteromedial branches, and also to anterolateral twigs (62.5%). The longer leptomeningeal and cerebellar arteries occasionally gave off perforating and anterolateral twigs, and either the lateral or posterior branches. Occlusion of some of these vessels resulted in the paramedian (30%), anterolateral (26.7%), lateral (20%), and combined infarctions (23.3%), which were most often isolated and unilateral, and rarely bilateral (10%). They were located in the lower pons (23.3%), middle (10%) or rostral (26.7%), or in two or three portions (40%). Each type of infarction usually produced characteristic neurologic signs. The clinical significance of the anatomic findings was discussed.

CONCLUSIONS

There was a good correlation between the intrapontine vascular territories, the position, size and shape of the infarctions, and the type of neurologic manifestations.

Millard-Gubler Syndrome Associated with Cerebellar Ataxia in a Patient with Isolated Paramedian Pontine Infarction - A Rarely Observed Combination with a Benign Prognosis: A Case Report

Isolated pontine infarction accounts for 7% of all ischemic strokes. Millard-Gubler syndrome is a clinical syndrome which occurs following lesions involving the ventral portion of the caudal pons, resulting in classic clinical features such as ipsilateral abducens and facial nerve palsy and contralateral hemiparesis. We report the case of a 55-year-old male patient having presented to the Yehuleshet Specialty Clinic 6 years back with sudden-onset dysarthria and appendicular ataxia of 10 days duration. He reported having right hemibody weakness and blurred vision, which have significantly improved since then. He had a history of smoking of 30 pack-years. However, he quit smoking 8 years ago. There was no history of prior stroke, transient ischemic attack, diabetes, hypertension, head trauma, or dyslipidemia. On examination, he had horizontal left gaze palsy with horizontal nystagmus suggesting left-sided 6th cranial nerve palsy. He had mild left-sided facial palsy causing dysarthric speech. Right upper limb dysmetria was observed during examination; otherwise, motor, sensory, fundus, and gait examination results were normal. He had low serum vitamin D. Brain magnetic resonance imaging examination showed a 25 × 10 mm segmental lesion in the left median pons involving the basis pontis and tegmentum section. The lesion had T2 and T1 abnormal prolongation with no diffusion restriction, suggesting a subacute pontine infarct. The patient was managed with aspirin 325 mg, atorvastatin 80 mg, physical therapy, and vitamin D supplementation, and advised on behavioral risk factors. Six years after his isolated pontine infarction, the patient is fully recovered from dysarthria, facial palsy, hemiparesis, right-sided appendicular ataxia, and horizontal nystagmus, and the follow-up brain MRI showed radiological evidence of chronic paramedian pontine perforator infarction. Millard-Gubler syndrome may present with cerebellar ataxia if the paramedian pontine infarction area slightly extends laterally, affecting the middle cerebellar peduncles. Isolated pontine infarction may have a good prognosis if diagnosed and managed early.

Dramatic motor recovery following recanalization in bilateral pontine infarct with restricted diffusion

On findings of restricted diffusion in a bilateral pontine infarct, imaging solely may not predict a poor clinical outcome as a full motor recovery is possible. Hence, recanalization of an acutely occluded basilar artery should be carefully considered on a case by case basis.

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.

Branch atheromatous disease diagnosed as embolic stroke of undetermined source: A sub-analysis of NAVIGATE ESUS

BACKGROUND

Branch atheromatous disease (BAD) is distinctive from large and small arterial diseases, which is single subcortical infarction larger than lacunar stroke in the territories of deep perforators without relevant arterial stenosis. BAD meets the current criteria of embolic stroke of undetermined source. We performed an exploratory analysis of BAD in patients recruited to NAVIGATE embolic stroke of undetermined source, a randomized controlled trial to compare rivaroxaban and aspirin in embolic stroke of undetermined source patients.

METHODS AND RESULTS

Among 3972 stroke patients in cerebral hemispheres with intracranial arterial imaging, 502 (12.6%) patients met the criteria for BAD. BAD was associated with younger age (years; OR: 0.97, 95% CI: 0.96-0.98), race (Asian; OR: 1.78, 95% CI: 1.44-2.21), region (Eastern Europe; OR: 2.49, 95% CI: 1.87-3.32), and higher National Institute of Health Stroke Scale (OR: 1.17, 95% CI: 1.12-1.22) at randomization. During follow-up, stroke or systemic embolism (2.5%/year vs. 6.2%/year, p = 0.0022), stroke (2.1%/year vs. 6.2%/year, p = 0.0008), and ischemic stroke (2.1%/year vs. 5.9%/year, p = 0.0013) occurred less frequently in BAD than non-BAD patients. There were no differences in annual rates of stroke or systemic embolism (2.5%/year vs. 2.5%/year, HR: 1.01, 95% CI: 0.33-3.14) or major bleeding (1.3%/year vs. 0.8%/year, HR: 1.51, 95% CI: 0.25-9.05) between rivaroxaban and aspirin groups among BAD patients.

CONCLUSIONS

BAD was relatively common, especially in Asian and from Eastern Europe among embolic stroke of undetermined source patients. Stroke severity was higher at randomization but recurrence of stroke was fewer in BAD than non-BAD patients. The efficacy and safety of rivaroxaban and aspirin did not differ among BAD patients.

Twenty-and-a-half syndrome: a case report

Background

In the list of named numerical neuro-ophthalmological syndromes, such as one-and-a-half syndrome and others, we report for the first time twenty-and-a-half syndrome, which is characterized by one-and-a-half syndrome with bilateral seventh and right fifth nerve palsy (1.5 + 7 + 7 + 5 = 20.5) in a patient with ischemic stroke.

Case presentation

A 45-year-old Asian Hindu woman presented with vomiting and imbalance of 1 day’s duration. She had left-sided ataxic hemiparesis with one-and-a-half syndrome with bilateral seventh and right fifth nerve palsy. Magnetic resonance imaging of her brain revealed acute non-hemorrhagic infarct in the right posterolateral aspect of pons and medulla, with normal brain vessels angiography. We described her disorder as twenty-and-a-half syndrome. She was put on antiplatelet therapy.

Conclusions

Twenty-and-a-half syndrome is reported for the first time. It is due to posterior circulation stroke; in our case, it was due to lacunar infarcts in the pons and medulla, manifesting as one-and-a-half syndrome with bilateral seventh and right fifth nerve palsy.

Brainstem lesions and gait

The brainstem contains virtually all of the important structures involved in experimental models of locomotion, encompassing control of upright posture, balance, and stepping. The physiologic basis for these functions is intricately related. Studies of the effects of lesions and disease on these functions in humans are limited to clinical observation and hampered by the anatomic complexity of closely spaced structures and lack of selectivity of lesions. Accordingly, any description of the clinical effects of brainstem lesions on gait and posture is imprecise because weakness and ataxia either predominate over or obscure any selective disturbance of the control of locomotion that may be correlated with the findings in experimental models. New and more sophisticated methods of brain imaging along with physiologic studies of balance and stepping may provide advances in human gait disorders, especially in relation to the brainstem control of locomotion.

A cohort study of isolated brainstem infarction based on head MR imaging and clinical findings

Objective

The prognosis of patients with isolated brainstem infarction (BSI) differs on an individual patient basis. This study was undertaken to analyze the influences of different imaging and clinical features with the prognosis of patients with BSI.

Methods

The study population was derived from a multicenter study of intracranial atherosclerosis in China. In the present study, 300 patients were selected who had experienced non-cardiogenic brain stem infarction within the prior 7 days. Evaluations included clinical characteristics, location and size of the brainstem infarction, and whether the infarction was located in multiple perforating branches of the brainstem. Poor prognosis was defined as the presence of disability within 1 year from the onset of disease.

Results

In total, 281 patients were followed up at 1 year post-infarction. Of these 281 patients, 84 (29.9%) exhibited disability at 1 year; these patients showed a median National Institutes of Health Stroke Scale score of 6 on admission. Multiple logistic regression analysis showed that patients with BSI located in the territory of multiple perforating arteries, who were discharged without administration of statins, showed a poor 1-year prognosis.

Conclusion

Isolated BSI involving multiple perforating arteries, without statin medication at discharge, indicated poor prognosis for patients with BSI.

Basilar Artery Plaque and Pontine Infarction Location and Vascular Geometry

Background and Purpose

Subclinical atherosclerotic plaques are common in patients with pontine infarctions (PIs) but without basilar artery (BA) stenosis. We hypothesized that BA plaque locations may differ by PI type and vertical location as well as vertebrobasilar artery geometry.

Methods

Ninety-six patients with PI but without BA stenosis on magnetic resonance imaging (MRI) and magnetic resonance angiography were enrolled. PIs were classified by type (paramedian, deep, or lateral) and vertical location (rostral, middle, or caudal). Patients underwent high-resolution MRI to evaluate BA plaque location (anterior, posterior, or lateral). The mid-BA angle on anteroposterior view and angle between the BA and dominant vertebral artery (BA-VA angle) on lateral view were measured.

Results

The PIs were paramedian (72.9%), deep (17.7%), and lateral (9.4%) type with a rostral (32.3%), middle (42.7%), and caudal (25.0%) vertical location. The BA plaque locations differed by PI type (P=0.03) and vertical location (P<0.001); BA plaques were most frequent at the posterior wall in paramedian (37.1%) and caudal (58.3%) PIs and at the lateral wall in lateral (55.5%) and middle (34.1%) PIs. The BA-VA and mid-BA angles differed by BA plaque and PI vertical location; the greatest BA-VA angle was observed in patients with posterior plaques (P<0.001) and caudal PIs (P<0.001). Greatest mid-BA angles were observed with lateral BA plaques (P=0.03) and middlelocated PIs (P=0.03).

Conclusions

Greater mid-BA angulation may enhance lateral plaque formation, causing lateral and middle PIs, whereas greater BA-VA angulation may enhance posterior plaque formation, causing paramedian or caudal PIs.

Dysphagia in patients with isolated pontine infarction

Little is known about dysphagia after pontine infarction. In this study, we evaluated the incidence of dysphagia after isolated pontine infarction and identified the predictive factors for the occurrence of dysphagia. A total of 146 patients were included in this study. All patients underwent clinical testing for dysphagia within 1 day after admission and at the time of discharge. We compared the incidence of dysphagia between patients with unilateral pontine infarction and those with bilateral pontine infarction. To evaluate the functional status of patients, we investigated their initial modified Rankin Scale (mRS) score and initial National Institutes of Health Stroke Scale (NIHSS) score within 1 day of admission. Of 146 patients, 50 (34.2%) had dysphagia initially within 1 day after admission. At the second evaluation at the time of discharge, dysphagia was diagnosed in 24 patients (16.4%). Patients with bilateral pontine infarction were more likely to present with dysphagia. In addition, clinical severity (in terms of mRS and NIHSS scores) was identified as a predictor of dysphagia in patients with cerebral infarction (multiple binary logistic regression analysis, mRS: P = 0.011, NIHSS: P = 0.004). Dysphagia frequently occurs in patients with isolated pontine infarction. Clinicians should pay particular attention to the occurrence of dysphagia, especially in patients with bilateral pontine infarction or high functional disability.

Progressive deficit in isolated pontine infarction: the association with etiological subtype, lesion topography and outcome

It is important to predict progressive deficit (PD) in isolated pontine infarction, a relatively common problem of clinical stroke practice. Traditionally, lacunar infarctions are known with their progressive course. However, few studies have analyzed the branch atheromatous disease subtype as a subtype of lacunar infarction, separately. There are also conflicting results regarding the relationship with the topography of lesion and PD. In this study, we classified etiological subtypes and lesion topography in isolated pontine infarction and aimed to investigate the association of etiological subtypes, lesion topography and clinical outcome with PD. We analyzed demographics, laboratory parameters, and risk factors of 120 patients having isolated pontine infarction and admitted within 24 h retrospectively. PD was defined as an increase in the National Institutes of Health Stroke scale ≥2 units in 5 days after onset. Patients were classified as following: large artery disease (LAA), basilar artery branch disease (BABD) and small vessel disease (SVD). Upper, middle and lower pontine infarcts were identified longitudinally. Functional outcome at 3 months was determined according to modified Rankin scores. Of 120 patients, 41.7% of the patients were classified as BABD, 30.8% as SVD and 27.5% as LAA. 23 patients (19.2%) exhibited PD. PD was significantly more frequent in patient with BABD (p 0.006). PD was numerically higher in patients with lower pontine infarction. PD was associated with BABD and poor functional outcome. It is important to discriminate the BABD neuroradiologically from other stroke subtypes to predict PD which is associated with poor functional outcome in patients with isolated pontine infarctions.

Prediction of motor outcome using remaining corticospinal tract in patients with pontine infarct: Diffusion tensor imaging study

The aim of this study was to investigate the relationship between the remaining corticospinal tract (CST) as determined by diffusion tensor imaging (DTI) and 6-month motor outcome in patients with pontine infarct. Ratios of fractional anisotropy (FA), fiber number (FN), and CST area were calculated, and the FN ratio and CST area ratio showed significant correlation with all 6-month motor outcome. Thus, the remaining CST in the pons measured using DTI at early stage of stroke could predict motor outcome in patients with pontine infarct.

Stroke Subtypes and Topographic Locations Associated with Neurological Deterioration in Acute Isolated Pontine Infarction

OBJECTIVE

This study investigated predictors of neurological deterioration (ND) in acute isolated pontine infarction.

METHODS

Two hundred fifty-nine patients with acute isolated pontine infarctions identified using diffusion-weighted imaging were retrospectively analyzed. The patients were divided according to the presence/absence of ND, defined as increased (≥2 units) National Institutes of Health Stroke Scale scores 5 days after onset. Pontine infarctions comprised 3 stroke subtypes: vertebrobasilar large-artery disease, basilar artery branch disease (BABD), and small-artery disease (SAD), according to basilar artery atherosclerosis severity and lesion extent of the transverse axial plane. Topographic locations of longitudinal pontine infarctions in the axial plane were divided into upper, middle, lower, and whole.

RESULTS

Of the 259 patients (male : female = 136:123, 68.84 ± 10.24), only 27.4% exhibited ND. The prevalence was significantly increased in females, whereas smoking was significantly decreased in patients with ND. BABD and lower pontine infarctions were significantly more frequent in patients with ND (70.4% and 43.7%, respectively) than in patients without ND (51.6% and 30.3%, respectively). SAD and upper pontine infarctions were significantly less frequent in patients with ND (16.9% and 7.0%, respectively) than in patients without ND (30.3% and 23.4%, respectively). BABD and lower pontine infarctions were positively related to ND.

CONCLUSIONS

This is the first study to demonstrate that BABD and lower pons lesions are predictors of ND in acute isolated pontine infarction. These findings indicate the potential importance of early identification of stroke subtypes and topographic locations in the prevention of ND in patients with suspected pontine infarction.

What drives progressive motor deficits in patients with acute pontine infarction?

Progressive motor deficits are relatively common in acute pontine infarction and frequently associated with increased functional disability. However, the factors that affect the progression of clinical motor weakness are largely unknown. Previous studies have suggested that pontine infarctions are caused mainly by basilar artery stenosis and penetrating artery disease. Recently, lower pons lesions in patients with acute pontine infarctions have been reported to be related to progressive motor deficits, and ensuing that damage to the corticospinal tracts may be responsible for the worsening of neurological symptoms. Here, we review studies on motor weakness progression in pontine infarction and discuss the mechanisms that may underlie the neurologic worsening.

Progressing small vessel pontine infarction includes different etiologies

Background

The aim of this study was to investigate the clinical features of progressing stroke of pontine infarction as small vessel disease.

Methods

Enrolled 38 acute pontine infarctions were confirmed by magnetic resonance imaging and magnetic resonance angiography at the first and seventh days. Ten patients (26.3%) presented progression (NIH Stroke Scale ≥2 increase within 72 h).

Results

Progressing patients showed no relation to the size and the distribution of lesion. Expansion of ischemic lesion showed correlation with basilar artery atherosclerosis. Stable lesion related to delayed worsening.

Conclusion

These findings suggest that progressing stroke may be caused by not only the worsening of blood flow of ischemic lesion but also delayed neuronal death.

Stroke recovery and lesion reduction following acute isolated bilateral ischaemic pontine infarction: a case report

BACKGROUND

Although pontine strokes account for a small percentage of all ischaemic events, they can be associated with significant initial disability. These lesions may be missed on computed tomography and therefore magnetic resonance imaging is generally preferred for the assessment of brainstem strokes. The aetiopathogenesis of isolated pontine infarcts, not due to a significant compromise (occlusion or dissection) in the vertebrobasilar territory, still remains to be fully characterised. These strokes present with different symptoms, depending on the lesion location and size, partly reflecting the anatomical variability of the vertebrobasilar vessels. Progressive neurological deterioration is relatively common and has been associated with the extension of such lesions. However, many patients with significant infarcts in the pons will do well in the future and initial diffusion-weighted imaging may not add useful prognostication to the clinical assessment. We discuss here a case where an initially progressive presentation was associated with a marked improvement in both clinical and radiological assessments at 42 days.

CASE PRESENTATION

A 49-year-old white British man presented with left-sided weakness, incoordination, unsteadiness, cerebellar ataxic dysarthria and dysphonia. A baseline magnetic resonance imaging scan with diffusion-weighted imaging, T1-weighted and T2-weighted sequences showed an acute bilateral pontine infarct. On a repeat scan at 42 days, there was a 57.5% decrease in the size of the lesion on the high-resolution three-dimensional T1-weighted image and a corresponding improvement in the symptoms and the clinical assessments of this patient. The reduction in infarct size was also comparable to the decrease calculated between the baseline diffusion-weighted and the follow-up fluid attenuated inversion recovery sequences.

CONCLUSION

This case report discusses the significant clinical improvement and corresponding lesion reduction in a patient that presented with worsening neurological symptoms and was diagnosed with acute bilateral ischaemic pontine infarction. Further studies, utilising structural and functional magnetic resonance imaging with follow-up scans, are needed to provide better insights into the underlying aetiopathology and recovery mechanisms of pontine stroke. These will help define the relationship between imaging parameters and outcome allowing for better prognosis along with the development of relevant rehabilitation programs for this group of patients.

Characteristics of corticospinal tract area according to pontine level

Diffusion tensor imaging (DTI) allows to isolate the corticospinal tract (CST) area from adjacent structures. Using DTI, we investigated the characteristics of the CST areas according to the pontine level in the normal human brain. We recruited 33 healthy subjects and DTIs were acquired using a sensitivity-encoding head coil on a 1.5-T Philips Gyroscan Intera. We measured the size and fractional anisotropy (FA) value of the CST area at the upper, middle, and lower pons. The size of the CST area in the lower pons was smaller than those of the mid-pons and upper pons, and the size of the CST area in the mid-pons was smallerthan that of the upper pons (p<0.05). FA values of the lower pons were larger than those of the mid-pons and upper pons, and the FA value of the mid-pons was also larger than that of the upper pons (p<0.05). In summary, we found a smaller size and higher FA value of the CST area from rostral to caudal direction in the pons. These results suggest a more compact neural structure of CST areas from rostral to caudal direction in the pons.

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.

Pontine reference frames for the sensory guidance of movement

The pontine nuclei (PN) are the major intermediary elements in the corticopontocerebellar pathway. Here we asked if the PN may help to adapt the spatial reference frames used by cerebrocortical neurons involved in the sensory guidance of movement to a format potentially more appropriate for the cerebellum. To this end, we studied movement-related neurons in the dorsal PN (DPN) of monkeys, most probably projecting to the cerebellum, executing fixed vector saccades or, alternatively, fixed vector hand reaches from different starting positions. The 83 task-related neurons considered fired movement-related bursts before saccades (saccade-related) or before hand movements (hand movement-related). About 40% of the SR neurons were "oculocentric," whereas the others were modulated by eye starting position. A third of the HMR neurons encoded hand reaches in hand-centered coordinates, whereas the remainder exhibited different types of dependencies on starting positions, reminiscent in general of cortical responses. All in all, pontine reference frames for the sensory guidance of movement seem to be very similar to those in cortex. Specifically, the frequency of orbital position gain fields of SR neurons is identical in the DPN and in one of their major cortical inputs, lateral intraparietal area (LIP).

Basilar artery atherosclerotic disease is related to subacute lesion volume increase in pontine base infarction

BACKGROUND

Although basilar artery atherosclerotic disease (BAD) is frequent in patients with pontine base infarction, it remains unknown whether BAD is related to the lesion size or clinical outcome.

METHODS

We studied 56 patients with unilateral pontine base infarction who underwent (i) diffusion-weighted MRI within 48 h after stroke onset and (ii) follow-up MRI and MR angiography in the subacute stage. Neurologic progression was defined as increased National Institutes of Health Stroke Scale score by > or = 2 during admission. Clinical outcome was dichotomized as good and poor (> or = 3) according to the modified Rankin Scale at 1 month after stroke onset.

RESULTS

Twenty-two patients (39%) had BAD and 15 patients (27%) had neurologic progression. Follow-up MRI performed at median 3.5 +/- 1.1 days after the initial MRI showed the lesion volume significantly increased (P < 0.001). The BAD was not significantly related to demographic characteristics, risk factors, initial and follow-up lesion volume, neurologic progression and clinical outcome, but was closely related to the subacute increase in lesion volume (P = 0.004 for 20% increase, P = 0.029 for 50% increase).

CONCLUSIONS

BAD is related to subacute increase in lesion volume, but not to ultimate poor clinical outcome in patients with pontine base infarction.

Pontine infarction with pure motor hemiparesis or hemiplegia: a prospective study

Background

The study aimed to prospectively observe the clinical and neuroimaging features of pontine infarction with pure motor hemiparesis (PMH) or hemiplegia at early stage.

Methods

In 118 consecutive selected patients with the first-ever ischemic stroke within 6 hours after onset, fifty of them presented with PMH or hemiplegia and had negative acute computed tomography (CT) scans, then magnetic resonance imaging (MRI) confirmed the corresponding infarcts in pons or cerebrum. The clinical and neuroimaging features of the pontine infarctions were compared with those of cerebral infarctions.

Results

The pontine infarction with PMH or hemiplegia accounted for 10.2% (12/118) of all first-ever ischemic stroke patients and 24% (12/50) of the patients with both PMH or hemiplegia and acute negative CT scans. Compared to the patients with cerebral infarction, the patients with pontine infarction had more frequency of diabetes mellitus (50.0% vs 5.3%, P = 0.001), nonvertiginous dizziness at onset (58.3% vs 21.1%, P = 0.036) and a progressive course (33.3% vs 2.6%, P = 0.011).

Conclusion

The pontine infarction may present as PMH or hemiplegia with more frequency of nonvertiginous dizziness, a progressive course and diabetes mellitus. MRI can confirm the infarct location in the basal pons at early stage after stroke onset.

Localization of arm representation in the cerebral peduncle of the non-human primate

Motor deficit severity and the potential for recovery in patients with brain injury depend on the integrity of descending corticofugal projections. Clinical assessment of these conditions following subtotal brain trauma requires a comprehensive understanding of the anatomical structures involved in the lesion as well as those structures that are spared. To assist in this endeavor, we investigated motor fiber organization in the crus cerebri of the cerebral peduncle (ccCP) in the rhesus monkey. Fibers originating from the arm representations of the primary (M1), supplementary (M2), rostral cingulate (M3), caudal cingulate (M4), dorsolateral pre- (LPMCd) and ventrolateral pre- (LPMCv) motor cortices were studied. The projections from the frontal and cingulate motor cortices formed descending longitudinal bundles that occupied the medial three-fifths of the ccCP at superior and middle levels. Although considerable overlap characterized these corticofugal projections, a general topography was discernable. Fibers from M1 and M4 occupied the central subsector of the ccCP, and fibers from M3 resided medially. The main distribution of LPMCd, LPMCv, and M2 fibers occupied the centromedial region and overlapped extensively. Progressing inferiorly, all fiber bundles in the central and centromedial sectors gradually extended medially, and overlap increased. A common location of fiber passage occurred at the midbrain-pontine isthmus where all of the fiber bundles overlapped. Our findings indicate that the widespread distribution of corticofugal motor projections may account for the favorable levels of motor recovery that accompany subtotal midbrain injury. At superior and mid-levels of the ccCP anteromedial lesions may disrupt projections from M3, whereas anterolateral lesions may disrupt projections from M1 and M4. Fibers from M2, LPMCv, and LPMCd may be compromised to some degree in both situations. The compact and commixed nature of motor fiber organization at inferior levels and the midbrain-pontine isthmus suggests a vulnerable region of passage for comprehensive disruption of frontal and cingulate corticofugal projection fibers.

Isolated pontine infarcts: etiopathogenic mechanisms

Although there are several clinico-topographical studies of pontine infarcts, few include vascular studies. To clarify the etiopathogenic mechanisms of pontine infarcts we analyzed the vascular findings and their association with MRI lesions. The clinical features and vascular findings on transcranial Doppler (TCD) or MR angiography (MRA) of 67 patients with acute infarcts involving the pons were studied. Functional outcome was assessed by modified Rankin Scale (mRS) scores on admission and 2 months later. Two groups of isolated pontine infarcts were found on the basis of lesion location on MRI, according to the extent or not to the anterior surface of the pons: paramedian pontine infarcts (PPI, n = 36) and lacunar pontine infarcts (LPI, n = 31). Hypertension was the most common vascular risk factor and pure motor syndrome was the most frequent clinical profile in both groups. Basilar artery stenosis found on TCD or MRA was significantly more frequent amongst the PPI group (P < 0.05). On admission and 2 months later, the mRS scores of the PPI group were significantly worse (P < 0.0001) than those of the LPI group. Patients with PPI have a significantly higher frequency of basilar artery stenosis and they have a worse prognosis than patients with LPI.

Aetiopathogenesis and long-term outcome of isolated pontine infarcts

BACKGROUND AND PURPOSE

Isolated pontine strokes cause characteristic neurological syndromes and have a good short-term prognosis. The aim of this study was to examine the long-term survival, cumulative recurrence rate and clinical handicap of patients with isolated pontine infarcts of different aetiology.

METHODS

One hundred consecutive patients with an isolated pontine infarction were identified by imaging studies and evaluated prospectively. After extensive study, cases were classified according to the aetiopathogenetic mechanisms: stroke due to basilar artery branch disease (BABD), small-artery disease (SAD) and large-artery-occlusive disease (LAOD). During a mean follow-up period of 46 months, stroke presentation and initial course, early and long-term mortality, disability and recurrence were evaluated.

RESULTS

BABD was the most frequent cause of isolated pontine ischaemia (43%), followed by SAD (34%) and LAOD (21%). Hypertension was the most prominent risk factor, especially among patients with SAD (94.1%). Neurological impairment on admission was more severe in the LAOD group, followed by BABD. After 1 month patients with LAOD had the highest cumulative mortality (14.3%, p = 0.026) and more severe disability (61.1%, p = 0.001). Five-year mortality rate was 20.6%, 14% and 23.8% in the SAD-, BABD- and in LAOD-group respectively (p = 0.776). Cumulative 5-year recurrence rate was 2.3 % for BABD, 14.3 % for LAOD, and 29.4 % for SAD (p = 0.011).

CONCLUSIONS

Overall long-term survival of patients with isolated pontine infarcts is good. Initial differences regarding short-term outcome in infarctions of different aetiology resolve with time. Effective secondary prevention among SAD patients may limit stroke recurrence and positively influence long-term prognosis.

Motor projections to the basis pontis in rhesus monkey

Motor corticopontine studies suggest that the pons is topographically organized, but details remain unresolved. We used physiological mapping in rhesus monkey to define subregions in precentral motor cortex (M1), injected isotope tracers into M1 and the supplementary motor area (SMA), and studied projections to the basis pontis. Labeled fibers descend in the internal capsule (SMA in anterior limb and genu; M1 in posterior limb) and traverse the midsection of the cerebral peduncle, where SMA fibers are medial, and face, arm, and leg fibers are progressively lateral. Each motor region has unique terminations in the ipsilateral basis pontis and nucleus reticularis tegmenti pontis. Projections are topographically organized, preferentially in the caudal half of the pons, situated in close proximity to traversing corticofugal fibers. In nuclei that receive multiple inputs, terminations appear to interdigitate. Projections from the SMA-face region are most medial and include the median pontine nucleus. M1-face projections are also medial but are lateral to those from SMA-face. Hand projections are in medially placed curved lamellae in mid- and caudal pons. Dorsal trunk projections are in medial and ventral locations. Ventral trunk/hip projections encircle the peduncle in the caudal pons. Foot projections are heaviest caudally in laterally placed, curved lamellae. These results have relevance for anatomical clinical correlations in the human basis pontis. Furthermore, the dichotomy of motor-predominant caudal pons projections to cerebellar anterior lobe, contrasted with associative-predominant rostral pons projections to cerebellar posterior lobe, is consistent with new hypotheses regarding the cerebellar contribution to motor activity and cognitive processing.

Ataxia after pontine stroke: insights from pontocerebellar fibers in monkey

Basis pontis lacunes cause contralateral but rarely ipsilateral ataxia. We explored this phenomenon with isotope tract tracing in the rhesus monkey. Labeled pontocerebellar fibers cross midline and disperse widely in the opposite hemipons before coalescing in the brachium pontis. This anatomical arrangement suggests that small pontine strokes spare sufficient decussating pontocerebellar fibers to prevent ipsilateral dysmetria, and that ipsilateral dysmetria after large pontine stroke represents a disconnection syndrome.

Clinical study of 35 patients with dysarthria-clumsy hand syndrome

OBJECTIVES

Although dysarthria-clumsy hand syndrome (DCHS) is a well known and infrequent lacunar syndrome, there are few data regarding the spectrum of associated clinical characteristics, anatomical site of lesion, and aetiopathogenetic mechanisms. We report a clinical description of this subtype of lacunar stroke based on data collected from a prospective acute stroke registry.

METHODS

From 2500 acute stroke patients included in a hospital based prospective stroke registry over a 12-year period, 35 patients were identified as having DCHS.

RESULTS

DCHS accounted for 1.6% of all acute stroke patients (35/2110), 1.9% of acute ischaemic stroke (35/1840), and 6.1% of lacunar syndromes (35/570) admitted consecutively to a neurology department and included in the stroke registry over this period. The results supported the lacunar hypothesis in 94.3% of patients (n = 33). Atherothrombotic and cardioembolic infarction occurred in only one patient each (2.9%). No patient with DCHS had an intracerebral haemorrhage. Outcome was good (mortality in hospital 0%, symptom free at discharge 45.7%). After multivariate analysis, absence of limitation at discharge, limb weakness but not cerebellar-type ataxia, and internal capsule (40%), pons (17%), and corona radiata (8.6%) location were significantly associated with DCHS.

CONCLUSIONS

DCHS is a rare cerebrovascular syndrome, and supports the criteria of the lacunar hypothesis. The majority of patients in this study had internal capsule infarcts. The prognosis is good with striking similarity compared with other types of lacunar strokes. There are important differences between DCHS and non-lacunar strokes. Internal capsule and pons are the most frequent cerebral sites.