Eighty-four patients with ischaemic cerebral lesions are described, in whom no lesion of the cortex could be demonstrated by CT. Lacunar lesions of the basal ganglia up to 2 cm. usually fail to show any angiographic findings. The clinical prognosis in these cases is favourable. Lesions larger than 2 cm. are usually due to haemodynamically significant stenoses. Prognosis depends not only on the size of the lesion, but also on its localisation, particularly its relationship to the motor radiation. The indications for angiography and therapy depend in part on a proper evaluation of the differential diagnosis of the lesions.
