Parenchymal brain lesions in spontaneously hypertensive stroke-prone rats

The gross and histological features of 189 parenchymal brain lesions in 57 spontaneously hypertensive stroke prone rats are described. There were 127 lesions many of them cystic, showing evidence of old haemorrhage. Of these, 71 also showed recent haemorrhage and there were 26 lesions showing recent haemorrhage only. There were 21 small focal lesions with necrosis and scarring but without any old or recent haemorrhage and 15 other lesions showing focal oedema with microcysts. Undoubted histological evidence of recent ischaemic necrosis was not seen. In this animal model which spontaneously develops severe hypertension, the brain lesions are predominantly the result of leakage of blood components from small vessels.