Isolated pontine infarction versus pontine plus infarction: prevalence, pathogenic mechanism, and outcomes

Pontine infarctions are often associated with extrapontine infarcts. We aimed to elucidate differences in clinical characteristics, mechanisms, and functional outcomes between isolated pontine infarction (IPI) and pontine plus infarction (PPI).

We studied patients with acute pontine infarction between January 2019 and August 2021 and divided them into IPI and PPI according to diffusion-weighted magnetic resonance image. Vertical locations were classified into rostral, middle, and caudal, and horizontal locations were categorized as basal/tegmental and unilateral/bilateral. Factors associated with poor 90-day outcome (modified Rankin scale 3-6) were analyzed.

Among 241 patients, 170 (70.5%) had IPI and 71 (29.5%) had PPI. The most frequently observed extrapontine areas were cerebellar (59.1%), followed by posterior cerebral artery territory (45.1%). Mental status changes, sensory changes, and ataxia were more common, and motor dysfunction was less common in PPI patients. The PPI patients more often had rostral (P < 0.001), bilateral lesions (P < 0.001), and moderate/severe vascular stenosis and atrial fibrillation; therefore, large artery disease (LAD) and cardioembolism were more common stroke mechanisms (P < 0.001). In IPI patients, high initial National Institutes of Health Stroke Scale (NIHSS) (adjusted Odds ratio (OR) = 1.38; P = 0.001) and old age (aOR = 1.05; P = 0.049) were associated with poor functional outcome, whereas moderate/severe stenosis (Reference: no stenosis, aOR = 7.17; P = 0.014) and high initial NIHSS (aOR = 1.39; P = 0.006) were related to unfavorable outcomes in PPI patients.

PPI patients more often had extensive pontine lesions, LAD and cardioembolism, and their outcome was more often influenced by underlying severe vascular diseases. These differences need to be considered in the prevention and therapeutic strategies.