Twenty-four patients of comparable age, blood pressure, and degree of dementia were classified by an "Ischemic Score" based on clinical features into "multi-infarct" and "primary degenerative" dementia. Regional cerebral blood flow (CBF) was measured by the intracarotid xenon 133 method. Both groups showed a decreased proportion of rapidly clearing brain tissue (largely gray matter). Cerebral blood flow per 100 gm brain per minute was normal in the primary degenerative group but low in the multi-infarct group. This suggests the blood flow is adequate for metabolic needs of the brain in patients with primary degenerative dementia but inadequate for those with multi-infarct dementia. There was no correlation between degree of dementia and CBF in the primary degenerative group but an inverse relationship existed in the multi-infarct group. Reactivity of blood vessels to reduction of arterial carbon dioxide pressure was normal in both groups.

The authors have reviewed 167 cases of subarachnoid hemorrhage (SAH) occurring in patients aged 20 years and younger in a 23-year period. The modes of presentation and etiology of SAH are similar in childhood and adolescence and in the adult population, but there was a different incidence of the specific pathology producing the bleeding in this series. Twenty-six percent of cases were due to bleeding arteriovenous malformations, 52% were due to ruptured aneurysms, and in 19% no cause was found. Aneurysms in this young age group differed in several important respects from those in the adult population: there was a male predominance, a higher incidence of internal carotid bifurcation aneurysms was seen, and multiple aneurysms were encountered less commonly.

Eight cases of vertebral haemangioma causing spinal cord or nerve root compression are described, together with one other which was not causing organic signs or symptoms. The compression was due to extradural tumour in 5 cases, bony expansion encroaching on the neural canal in 2 cases, and a combination of bony expansion and extradural tumour in one case. When present the classical radiological appearance of accentuated vertical striation or honeycomb pattern is easily recognized, but atypical features, such as apparent pedicular erosion, paravertebral soft tissue mass and bony expansion, may occur, making diagnosis more diffcult. In 2 cases the correct diagnosis was not made before surgery. In one of these there were no plain film changes and in the other a metastasis was considered the more likely diagnosis. In the asymptomatic case the absence of extra-osseous extension was an important factor in excluding any possible clinical significance of the haemangioma. The great importance of pre-operative spinal angiography is stressed.

We report the radiological appearances of 5 children with hemimegalencephaly. There are few reports of this rare condition in the radiological literature. Two of the children have hemimegalencephaly as an isolated finding while the other three have Proteus syndrome. Four children have seizures which commenced within the first 6 months of life and two of these subsequently required hemispherectomy. In addition to the typical radiological features of hemimegalencephaly there was a high incidence of other brain anomalies. These include hypoplasia of the corpus callosum and crus cerebri, grey and white matter calcification and cortical migration/organisational disorders.