Syndromes of Pontine Base Infarction

Abstract

Background and Purpose Although there have been sporadic reports of lacunar syndromes due to pontine base infarction, studies of clinical-radiological correlation in sufficient numbers of patients have not yet been reported. Methods We studied the clinical features of 37 patients with acute infarcts that mainly involved the base of the pons and correlated the clinical syndromes with the radiological findings. Results The clinical presentations included pure motor hemiparesis (PMH) in 17, sensorimotor stroke in 3, ataxic hemiparesis (AH) in 4, and dysarthria–clumsy hand (DA-CH) syndrome in 6 patients. Variants of AH included 1 patient with dysarthria-hemiataxia and 2 with quadrataxic hemiparesis, and in 4 patients dysarthria–facial paresis syndrome was considered a variant of DA-CH syndrome. Hypertension was the single most common and important risk factor, and the pathogenetic mechanisms of ischemia were likely to be small arterial (lacunar) occlusion or basilar atheromatous branch occlusion in most of the patients. Our clinical-radiological correlation study suggested that large lesions involving the paramedian caudal or middle pons correlate with severe hemiparesis (PMH), whereas lesions of similar size located in the paramedian rostral pons tended to produce DA-CH syndrome. Lesions producing AH were located variously but tended to spare the pyramidal tracts. The prognosis of these patients is fair or good, although residual hemiparesis remained in patients with initially severe hemiparesis. Conclusions Our data suggest that the various lacunar syndromes that follow pontine base infarcts reflect the balance of the involvement of the corticospinal, corticopontocerebellar, and corticobulbar tracts. Analysis of radiological findings aids in determining the clinical-anatomic correlation in patients with pontine base infarction.