Paramedian Pontine Infarction

Abstract

Background and Purpose There have been few reports of pontine syndromes secondary to paramedian pontine infarctions. To clarify the clinicotopographical correlation and prognosis of paramedian pontine infarct syndromes, we analyzed the clinical signs and their association with MRI findings. Methods We studied 49 patients with acute paramedian pontine infarcts and classified them into three subtypes on the basis of lesion location on MRI. Patient clinical status was assessed by Rankin Disability Scale (RDS) scores on admission and at 60 days after onset of stroke. Results Twenty-seven patients had basal infarcts. Clinical findings included dysarthria (n=27), hemiparesis with upper extremity predominance (n=15), brachial monoparesis (n=4), and pathological laughing (n=3). Fifteen patients had basal-tegmental infarcts. Clinical findings presented with hemiparesis and horizontal gaze abnormalities, including abducens nerve palsy (n=1), internuclear ophthalmoplegia (INO) (n=5), horizontal gaze palsy (n=1), one-and-a-half syndrome (n=1), and superficial or proprioceptive sensory dysfunction (n=8). Seven patients had tegmental infarcts. Clinical findings included INO (n=1), horizontal gaze palsy (n=2), one-and-a-half syndrome (n=3), and sensory changes (n=2). On both admission and 60 days later, the RDS scores of the patients with upper pontine lesions were significantly better than those with lower pontine lesions ( P <.01). The RDS scores of the patients with basal-tegmental infarct in the upper pons were significantly better than those with infarct in the lower pons ( P <.02). Conclusions Paramedian pontine infarcts, which are usually due to thrombosis of perforating arteries, presented with a faciobrachial dominant hemiparesis with dysarthria, somatosensory disturbance, and horizontal gaze abnormalities. The favorable outcome may be related to the level of the pontine lesion, which influences the effect on the corticospinal tract.