Duplication of the vertebro-basilar system.

During the examination of 75 fixed brains and 2086 vertebral angiograms we encountered two cases of fenestration of the vertebral artery and two cases of partial duplication of the basilar artery. In the first case, an 81 year old male, there was fenestration, of the basilar artery at the union of the two vertebral arteries. The fenestration was 9mm long with no associated vascular disease. The other partial duplication of the basilar artery was observed in the upper portion of the artery in a 54 year old male patient investigated angiographically for subarachnoid haemorrhage. The fenestration of the third case was demonstrated in the intracranial part of the right vertebral artery of a 50 year old female patient during digital subtraction angiography for subarachnoid haemorrhage. In the fourth case, the fenestration was found angiographically at the atlanto-axial level in the extracranial portion of the left vertebral artery in a 37 year old female patient with subarachnoid haemorrhage from an arteriovenous malformation in the left cerebral hemisphere. The embryonic, histological and radiological implications of the duplication are discussed.

Rapid Doppler screening test for internal carotid disease.

There is increasing evidence that only hemodynamically significant internal carotid lesions (of more than 50% diameter stenosis or occlusion) rather than minor lesions are the precursors of stroke. A Doppler test combining periorbital and direct audible interpretation of internal carotid Doppler signals was performed on 67 patients (134 internal carotids) and the results were compared with those from conventional biplane angiography. The test was 100% sensitive and had a positive predictive value of 91% for hemodynamically significant lesions. Negative predictive value for normal or less than 50% stenosis was 100%. Carotid bifurcation bruits were heard over only 25% of internal carotids with significant stenosis and nearly 60% of bruits were heard over internal carotids with minor disease. The equipment was portable and relatively inexpensive. The test could be performed by vascular technicians in less than 12 minutes with minimal patient discomfort, thus meeting most of the criteria for an ideal non-invasive screening test.

Distinguishing aldosterone-producing adenoma from other forms of hyperaldosteronism and lateralizing the tumour pre-operatively.

In 14 hypertensive patients aldosterone/cortisol ratio was always lower in a peripheral vein or low IVC than in either adrenal vein. In four patients with a right-sided aldosterone-producing adenoma (APA), the aldosterone/cortisol ratio in peripheral vein was always higher than in the left adrenal vein. If only the left adrenal vein is cannulated, right-sided APA can still be diagnosed with certainty. In three patients with glucocorticoid-suppressible hyperaldosteronism, urinary excretion of both 18-oxocortisol and 18-hydroxycortisol was elevated. In four patients with APA excretion of 18-oxocortisol was elevated. In two of three patients with bilateral adrenal hyperplasia (BH), excretion of both steroids was normal. 75Se-selenomethylcholesterol scanning correctly lateralized five APA, but falsely lateralized a patient with BH. Results with CT scans were often misleading.

The absence of the internal carotid artery: report of two cases.

The absence of the internal carotid artery (ICA) is a very rare anomaly. Since the first description of the condition in 1787, only 60 cases have been reported in the literature. We report two cases of absence of the left ICA amongst 2195 carotid angiograms performed in the Department of Neuroradiology at the Royal Brisbane Hospital over a period of 4 years. The first patient was suffering from obstructive hydrocephalus; the second from right cerebellopontine angle syndrome. Cerebral angiography by catheterization of the aorta revealed the absence of the left ICA. The collateral circulation to the left cerebral hemisphere was provided by the vertebrobasilar system via a dilated left posterior communicating artery. In the first patient, the absence of the ICA was coincidental with other congenital anomalies of the cervico-occipital junction. In the second patient, the dilated vertebrobasilar system was responsible for compressing the right cranial nerves VII and VIII. It is emphasized that in some cases of cerebellopontine angle syndromes, thorough investigation of the cerebral vessels is necessary.

Cerebral torulosis: clinical features and correlation with computed tomography.

Cryptococcus neoformans (Torula histolytica) is an uncommon cause of infection in the central nervous system. We review 15 cases from all over Queensland which have presented in the last 6 years. Computed tomography (CT) studies were abnormal in 73.5%, with mass lesions and hydrocephalus being the commonest findings. Notable findings were: the disproportionate severity of clinical signs and symptoms as compared with the CT findings, which often were either normal or demonstrated only small granulomas without significant mass effect, absence of enhancement in granulomas in two cases and observation of calcification during treatment in one patient.

Association of intracranial aneurysm and arteriovenous malformation.

In a series of 252 patients (47 with arteriovenous malformation, 205 with aneurysms), two patients had a coexisting intracranial aneurysm and an arteriovenous malformation. In one patient, the aneurysm was proximal to the main feeding arteries of the arteriovenous malformation. In the other patient, there was no anatomical relationship between the two lesions. These findings illustrate different views on the pathogenesis of the rare association of the two conditions.