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A 38-year-old woman suffered a spontaneous basilar artery dissection leading to bilateral occipital, right thalamic and cerebellar infarction and a dorsal midbrain syndrome. Computerized tomography showed left cerebellar, right thalamic and bilateral occipital infarctions and selective angiography showed a narrowed segment in the basilar artery, absent filling of the right superior cerebellar artery and narrowing of the right posterior cerebral artery. She improved rapidly without specific therapy and made a near full recovery. Basilar artery dissection, while often fatal, may have a benign outcome and we review the literature in this regard.

The objective of this paper is to describe clinical applications of magnetic resonance angiography. The data used were obtained from recent articles on vascular and flow magnetic resonance imaging retrieved from Index Medicus 1988-91. Other contributions were from the 19th Annual Meeting of the American Society of Neuroradiology held in Washington DC in June 1991 and the 10th Annual Conference of the Society of Magnetic Resonance in Medicine in August 1991. The data are presented in such a way as to give the reader unfamiliar with magnetic resonance a basic insight into some of the new imaging techniques. Magnetic resonance imaging is advancing at a rapid rate. Magnetic resonance angiography is already finding many areas of clinical use with concomitant reduction in conventional angiographic and duplex Doppler ultrasound procedures.

The pathogenesis of perioperative stroke is not clear from the literature. To explore the influence of various risk factors we examined the clinical, Duplex ultrasound and computerised tomography findings of all cases suffering cerebral infarction within 24 hours of surgery in a prospective series of 358 coronary or peripheral vascular reconstructive operations. Four patients (1.1%) had cerebral infarcts within 24 hours of surgery, all associated with perioperative systolic blood pressures of less than 90 mmHg. The other significant risk factor was previous cerebral ischaemic symptoms. Haemodynamic cerebral ischaemia occurred immediately after operation in 2 of 10 cases with severe symptomatic carotid stenosis or occlusion (stroke risk 20%; 95% confidence interval 2.52%-55.61%). Two cases with mild carotid disease had cerebral infarcts in previously asymptomatic hemispheres following coronary artery bypass graft surgery. One of these had clinical and computerised tomographic evidence of cortical watershed infarction. We conclude that cerebral haemodynamics are important in perioperative stroke and that symptomatic patients with severe carotid disease may be at high risk of perioperative watershed infarction.

Bilateral simultaneous blood samples were taken from the inferior petrosal sinuses of nine patients with Cushing's disease for measurement of adrenocorticotropin (ACTH), vasopressin (AVP), prolactin, growth hormone, luteinising hormone (LH), and follicle stimulating hormone (FSH). Inter-sinus gradients for ACTH (range 3.3-18.2) and AVP (2.0-375) correctly lateralised the microadenoma in seven of these patients. One additional patient showed an increased gradient for AVP but not ACTH on the side of the tumour. The correlation between the AVP and ACTH concentrations in the petrosal sinus draining the microadenoma was significant. Petrosal sinus plasma concentrations of prolactin and growth hormone were also significantly higher on the side of the tumour than on the non-tumour side. Evidence against a non-specific tumour effect on the secretion of all pituitary hormones was the fact that in most cases the gradients for LH and FSH were not significant. It is proposed that increased delivery of AVP to part of the pituitary may result from an aberrant blood supply, and that AVP may interact with corticotropin releasing factor to promote tumour growth and ACTH release.

Over recent years empty sella turcica has become more frequently diagnosed with high resolution computerized tomography and the associated clinical abnormalities have been better described. In this article the spectrum of clinical presentation is based on a review of 26 cases with six illustrative case reports. Recommendations for management and further assessment are presented. It is important for clinicians to be aware of the varying presentations of this syndrome, since it should not be considered simply as an incidental finding. A patient diagnosed with empty sella syndrome requires clinical and endocrine evaluation, and appropriate follow-up as determined by initial test results.

The syndrome of low intracranial pressure may develop in a variety of circumstances, e.g. after lumbar puncture, following head injury and intracranial operations. It sometimes occurs after viral meningitis. The case history is described of a woman in whom the disorder was unusually severe and persistent. Interesting radiological features were observed, the appearances being those of herniation of the brain towards the tentorial opening. Simple measures of treatment produced dramatic and lasting relief.

Pre-operative bilateral simultaneous inferior petrosal sinus sampling with assessment of ACTH levels in the left and right sinuses and the periphery was performed in 9 patients with pituitary dependent Cushing's disease who were subsequently found at surgery to have basophil microadenomata. The novel observation of this study was the pattern of secretion of other pituitary hormones so that significant inter-sinus gradients greater than or equal to 1.4:1 were seen for beta-endorphin (2.8 +/- 1.3, mean +/- SEM), PRL (4.2 +/- 1.3) and GH (6.9 +/- 2.4) as well as for ACTH (5.1 +/- 1.1). There was no inter-sinus gradient for LH, FSH and TSH. In these 9 patients with adenomata, the correlations between the inter-sinus gradients for ACTH and beta-endorphin were r = 0.95 (P less than 0.01), ACTH and PRL r = 0.90 (P less than 0.01) and for ACTH and GH r = 0.89 (P less than 0.05). This close association between the gradients for ACTH and other anterior pituitary hormones could be due either to co-secretion of beta-endorphin, PRL and GH by the ACTH-producing pituitary adenomata or to a paracrine effect of beta-endorphin from the tumours on adjacent pituitary tissue. By reflecting the central pituitary hormone milieu, petrosal sinus sampling can give information about pituitary function unobtainable from peripheral hormone levels.

In view of the diagnostic value of bilateral simultaneous inferior petrosal sinus sampling (BSIPSS) in localising preoperatively the site of the microadenoma in pituitary dependent Cushing's disease, the clinical value of BSIPSS was evaluated in five acromegalic patients with equivocal or negative pituitary CT scans. Intersinus GH gradients were obtained for all patients (range 1.6-4.2) but in only one case was the gradient correctly localised to the side of the tumour. Gradients of several other pituitary hormones, particularly prolactin (range 1.6-4.0), also demonstrated gradients parallel to the GH intersinus gradients. Despite the paradoxical intersinus GH gradients, the surgeon was able to readily identify the tumour at the time of surgery. Thus BSIPSS is of little assistance to the surgeon for the preoperative radiological evaluation in acromegaly and these results caution against the universal adoption of the BSIPSS technique in the radiological assessment of all secretory pituitary microadenomas.