Cerebral blood flow was measured both under conditions of normocapnia and hypercapnia in 22 diabetic patients and 20 normal control subjects, using either the intravenous 133Xe method or the closely comparable 133Xe inhalation method. While 19 out of 20 control subjects responded appropriately to hypercapnia with an increase in flow, eight of the diabetic patients failed to respond normally, this difference being significant (p = 0.03). Those manifesting an abnormal response included young, insulin-dependent patients with a short duration of diabetes and no clinical evidence of complications.

1 Cerebral blood flow (CBF) was measured by the 133xenon inhalation method in 33 newly‐diagnosed hypertensive patients prior to commencing therapy. 2 Blood pressure was treated by using a varying sequence of four different drugs, namely labetalol, metoprolol, oxprenolol and sotalol, each of which is a beta‐adrenergic receptor blocking agent, but with differing additional properties. 3 CBF measurements were repeated when blood pressure was controlled. No significant change in CBF was found with any of the four drugs, in contrast to the fall which has been reported when drugs of this type are administered acutely.

Summary A 60 year old woman with idiopathic Parkinson's disease had been prescribed thioridazine for schizophrenia. Five months after this was stopped, Sinemet also considered of dubious therapeutic value, was withdrawn. One week later she developed features of the neuroleptic malignant syndrome (NMS) accompanied by myoglobinuric renal failure. Post-mortem examination confirmed Lewy body degeneration in the substantia nigra. It is proposed that NMS may be caused by levodopa withdrawal in Parkinson's disease, and that it is withdrawal of dopaminergic drive that causes the syndrome.

1 Diazoxide 300 mg and labetalol 150 mg were each injected intravenously on separate occasions into five patients with essential hypertension. The reduction in BP caused by labetalol was slightly greater than that produced by diazoxide. 2 In contrast the reduction in cerebral blood flow (CBF) by labetalol was not statistically significant, whereas diazoxide gave a greater and statistically significant reduction in CBF. 3 These observations suggest that labetalol may have an advantage over diazoxide for the rapid reduction in BP.

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