Hemiparesia atáxica: estudio de 23 pacientes

The Potential Impact of Neuroimaging and Translational Research on the Clinical Management of Lacunar Stroke

Lacunar infarcts represent one of the most frequent subtypes of ischemic strokes and may represent the first recognizable manifestation of a progressive disease of the small perforating arteries, capillaries, and venules of the brain, defined as cerebral small vessel disease. The pathophysiological mechanisms leading to a perforating artery occlusion are multiple and still not completely defined, due to spatial resolution issues in neuroimaging, sparsity of pathological studies, and lack of valid experimental models. Recent advances in the endovascular treatment of large vessel occlusion may have diverted attention from the management of patients with small vessel occlusions, often excluded from clinical trials of acute therapy and secondary prevention. However, patients with a lacunar stroke benefit from early diagnosis, reperfusion therapy, and secondary prevention measures. In addition, there are new developments in the knowledge of this entity that suggest potential benefits of thrombolysis in an extended time window in selected patients, as well as novel therapeutic approaches targeting different pathophysiological mechanisms involved in small vessel disease. This review offers a comprehensive update in lacunar stroke pathophysiology and clinical perspective for managing lacunar strokes, in light of the latest insights from imaging and translational studies.

Role of Cortico-ponto-cerebellar Tract from Supplementary Motor Area in Ataxic Hemiparesis of Supratentorial Stroke Patients

Cortical lesions of the supplementary motor area (SMA) are important in balance control and postural recovery in stroke patients, while the role of subcortical lesions of the SMA has not been studied. This study aimed to investigate the subcortical projections of the SMA and its relationship with ataxia in supratentorial stroke patients. Thirty-three patients with hemiparesis were divided into 3 groups (severe ataxia, n = 9; mild to moderate ataxia, n = 13; no ataxia, n = 11). Ataxia severity was assessed using the Scale for Ataxia Rating Assessment. Diffusion tensor imaging analysis used the fractional anisotropy (FA) values and tract volume as parameters of white matter tract degeneration. The FA values of regions related to ataxia were analyzed, that is the SMA, posterior limb of the internal capsule, basal ganglia, superior cerebellar peduncle, middle cerebellar peduncle, inferior cerebellar peduncle, and cerebellum. Tract volumes of the corticostriatal tract and cortico-ponto-cerebellar (CPC) tract originating from the SMA were evaluated. There were significant differences among the 3 groups in FA values of the subcortical regions of the CPC tract. Furthermore, the volume of the CPC tract originating from the SMA showed significant negative correlation with ataxia severity. There was no correlation between ataxia and corticostriatal tract volume. Therefore, we found that subcortical lesions of the CPC tract originating from the SMA could contribute to ataxia severity in stroke patients with ataxic hemiparesis.

Advancements in understanding the mechanisms of symptomatic lacunar ischemic stroke: translation of knowledge to prevention strategies

Symptomatic lacunar ischemic stroke (25% of all brain infarctions) results from occlusion of a single penetrating artery by microatheromas or lipohyalinosis and rarely from an intracranial atheromatous branch disease. Recurrent lacunar stroke may be associated with more severe clinical features and has been involved in producing lacunar state and vascular subcortical dementia. In the first multicenter randomized clinical trial (SPS3) focused on stroke prevention among patients with recent lacunar stroke, the addition of clopidogrel to aspirin not only did not reduced significantly the risk of recurrent stroke, but also increased significantly the likelihood of hemorrhage and fatal outcome. If lacunar stroke is primarily non-atherothromboembolic, secondary prevention aimed at preventing atheroma progression may not be very effective. The efficacy of drugs that improve endothelial function in lacunar stroke patients remains to be studied in the future.

Lacunar stroke

Lacunar infarcts or small subcortical infarcts result from occlusion of a single penetrating artery and account for one quarter of cerebral infarctions. Patients with a lacunar infarct usually present with a classical lacunar syndrome (pure motor hemiparesis, pure sensory syndrome, sensorimotor stroke, ataxic hemiparesis or dysarthria-clumsy hand) and, less frequently, an atypical lacunar syndrome. Hypertension and diabetes mellitus are major risk factors for lacunar stroke. Lacunar infarcts show a paradoxical clinical course with a favorable prognosis in the short term, characterized by a low early mortality and reduced functional disability on hospital discharge, but with an increased risk of death, stroke recurrence and dementia in the mid- and long term. Asymptomatic progression of small-vessel disease is a typical feature of the lacunar infarcts. For this reason, lacunar infarction should be regarded as a potentially severe condition rather than a relatively benign disorder and, therefore, lacunar stroke patients require adequate and rigorous management and follow-up. Antiplatelet drugs, careful blood pressure control, the use of statins and modification of lifestyle risk factors are key elements in secondary prevention after lacunar stroke.

Diffusion weighted imaging in ataxic hemiparesis

OBJECTIVE

Ataxic hemiparesis (AH) is a well recognised lacunar syndrome involving homolateral ataxia with accompanying corticospinal tract impairment. Most previous studies of lesion location in AH did not use diffusion weighted MRI (DW MRI). The purpose of this study was to use DW MRI to evaluate the radiological correlation in patients presenting with AH.

METHODS

Retrospectively, we studied 29 patients with AH using DW MRI.

RESULTS

All patients were scanned within 4 days of onset. Acute infarction was identified in 28 of 29 (97%) patients. A single lesion was identified in 26

PATIENTS

pons (n = 8), internal capsule (n = 6), corona radiata (n = 2), distended internal capsule from corona radiate (n = 7), frontal subcortical area (n = 1) and precentral with or without postcentral gyrus (n = 2). Two lesions were found in two patients: in the pons and corpus callosum of one patient, and in the corona radiata and subcortical white matter of the other.

CONCLUSIONS

AH is mainly caused by pontine or internal capsule/corona radiata lesions. It also occurs in the precentral gyrus, including the precentral knob, with or without postcentral gyrus lesions. Fibres of the fronto-ponto-cerebellar system may originate from the frontal cortex, including the precentral gyrus, probably near the pyramidal tract. Damage at this location may cause AH.

Ataxic hemiparesis from strategic frontal white matter infarction with crossed cerebellar diaschisis

BACKGROUND

Ataxic hemiparesis is a classic lacunar syndrome that most often localizes to the pons.

RESULTS

We report 3 patients who presented with left-sided ataxic hemiparesis and were found on imaging to have small right frontal subcortical white matter infarcts in similar locations by diffusion-weighted MRI. [99mTc]hexamethylpropylenamine oxime single-photon emission computed tomography (SPECT) scans in all 3 patients showed decreased metabolism in the contralateral cerebellar hemisphere, indicative of crossed cerebellar diaschisis (CCD).

CONCLUSIONS

CCD is under-recognized in ataxic hemiparesis and may have implications for functional recovery after this type of ischemic stroke.