Diagnosis of posterior fossa lesions by angiography.

Abstract Characteristic angiographic changes found in posterior fossa mass lesions are described. The importance and reliability of landmarks such as the anterior ponto-mesencephalic vein, the precentral cerebellar vein, the superior vermal branch of the superior cerebellar artery and the cranial loop of the posterior inferior cerebellar artery are emphasised. Measurements considered helpful are: (a) distance between the clivus and the colliculo-central point of the precentral cerebellar vein: normal variation is between 36 and 43 mm; (b) distance between the interpeduncular loop of the anterior ponto-mesencephalic vein and the colliculocentral point: normal variation is between 19 and 24 mm; (c) position of the cranial loop of the posterior inferior cerebellar artery reported with a perpendicular to the Twining's line: normal variation is between 52 and 60 per cent from the tuberculum sellae.