Percheron artery syndrome: variability in presentation and differential diagnosis

Synchronous bilateral paramedian thalamic stroke (SBPTS), usually equated to Percheron artery infarction, is considered to be uncommon and difficult to diagnose clinically. Its characterization is based on the original description plus a few small series. To characterize SBPTS clinically by collecting cases and identifying the key difficulties for an early diagnosis. Six cases at our centre plus another 115 located by systematic literature search and critical reading of articles fulfilled the criteria for SBPTS. An analysis was made of the variables age, gender, vascular risk factors, aetiology, alterations and fluctuations of consciousness, need for intubation, cognitive-behavioural disorders, pupillary changes, other neurological focal disorders and brainstem involvement on imaging studies. Of note in our series were disorders of consciousness (n=5), their fluctuations (n=3) and the diagnostic delay (seven days, with MRI in four patients). In only one case was a bilateral thalamic lesion seen on the initial CT. Joint analysis of all the cases showed a mean age of 61 years, a predominance of men (58%), the presence of vascular risk factors in 77%, a mainly cardioembolic aetiology (34% among those that were specified), sensory involvement in 75% (intubation in 7% and fluctuations in 16.5%), cognitive-behavioural disorders in 43%, oculomotor in 73%, pupillary in 31%, other in 67% and specified brainstem lesion in 37%. The SBPTS syndrome has a variable presentation with a low sensitivity on the initial CT, requiring brain MRI for typification. This explains the diagnostic difficulty and the fact that its frequency is probably underestimated.