Putting pontine anatomy into clinical practice: the 16 syndrome.

The anatomical localisation of brainstem syndromes is the domain of the clinical neurologist, though MRI has made an encyclopaedic knowledge of neuroanatomy less crucial. Isolated pontine syndromes comprise ∼20% of the brainstem lacunar syndromes. Typical presentations such as pure motor hemiparesis and ataxic hemiparesis are easily recognisable but atypical syndromes, particularly when bilateral, may present with puzzling signs. We discuss a patient with an unusual acute bilateral brainstem syndrome, in whom MRI was contraindicated. We use the relevant neuroanatomy to support the likely diagnosis of bilateral caudal pontine tegmentum infarction due to occlusion of a single paramedian pontine tegmental perforating artery.