Magnetic resonance angiography of giant aneurysms. Pitfalls and surgical implications

OBJECTIVE

Magnetic resonance angiography (MRA) can be used to identify cerebral aneurysms. In this report, techniques for the diagnosis of giant cerebral aneurysm using MRA are discussed. Pitfalls in the diagnosis are presented.

BACKGROUND

Giant cerebral aneurysms, which can be partially or totally thrombosed, or may have slow flow, can be confusing and difficult to diagnose. Giant cerebral aneurysms with thrombus formation, produce an artifact in time-of-flight MRA in which the thrombus simulates flowing blood.

METHOD

Five consecutive patients with the suspected diagnosis of giant cerebral aneurysm by MRA were analyzed. Neuroradiological studies were reviewed.

RESULTS

In 20% of the cases, the correct diagnosis was made using MRA; in 60% of the cases, a correct diagnosis was made, but the size or the presence of flow was not correctly identified; in 20% of the cases, the diagnosis was incorrect. Four patients with giant cerebral aneurysms who presented a diagnostic and a therapeutic challenge are discussed.

CONCLUSION

Unless MRA findings are combined with computed tomography scan and magnetic resonance imaging findings, the exact nature of the sac contents of giant cerebral aneurysms cannot be identified.

Cystic meningiomas: a review

Cystic meningiomas are uncommon tumors that are easily confused with metastatic or glial tumors that have cystic components. We have retrospectively reviewed all of the meningiomas operated on at the University of Puerto Rico in a 5-year period (1989-1993) and found only five cystic meningiomas (4.3% of total meningiomas). There is still debate about the etiology of the cyst wall; thus, multiple biopsies and frozen sections are recommended. Magnetic resonance imaging has improved diagnostic accuracy with its ability to demonstrate the dural attachment of the tumor.

Thoracic spine osteochondroma causing spinal cord compression. An unusual cause of paraparesis

A case of a thoracic osteochondroma with compression of the spinal cord is reported. The neuroimaging studies are described.

Pleomorphic xanthoastrocytoma with invasion of the tentorium and falx

A case of a 21-year-old patient with a recurrent pleomorphic xanthoastrocytoma with invasion of the tentorium and falx cerebri is reported. Dural attachment has been reported in some cases. Invasion of the dura of the falx cerebri and complete infiltration of the left tentorium by the tumor were found intraoperatively. This is the first case in the literature which shows invasion of the dura in a pleomorphic xanthoastrocytoma.

Sudden appearance of multiple brain lesions in Aids after a cerebral biopsy. Case report

A unique case of cerebral toxoplasmosis which had an acute appearance of multiple discrete lesions following a biopsy and its neuroradiological findings are reported in detail. Possible pathophysiological mechanism are presented.

Shunt nephritis. Case report

The incidence of shunt nephritis has decreased over the past several years due to the increased use of ventriculoperitoneal (VP) shunts rather than the ventriculovascular systems for which this complication was originally reported in 1965. Despite this trend, the syndrome has been reported in cases of VP shunting and, for this reason, merit a renewed look. Shunt nephritis is thought to be secondary to immune complex formation and deposition in the kidney in response to Staphylococcus epidermidis. The diagnostic workup and management of this disease is discussed.

Acute abdominal manifestations in patients with ventriculo-peritoneal shunts

Five patients with acute abdominal manifestations after revision of ventriculo-peritoneal shunt were identified. Abdominal pain, nausea, vomiting and distention prompted surgical intervention. Clinical evidence of increased intracranial pressure or shunt malfunction were not prominent findings. Exteriorization of the distal (peritoneal) catherer resolved the acute abdominal findings promptly.

Metamorphopsia and permanent cortical blindness after a posterior fossa tumor

A case of posterior fossa tumor associated with supratentorial symptoms is presented. The pattern of symptoms that developed after operation follow the description of metamorphospsia. The condition progressed to permanent cortical blindness. Tumoral vasospasm is suggested as a possible etiological mechanism for the clinical picture.

Cerebrospinal fluid ascorbic acid levels in neurological disorders

The ascorbic acid/dehydroascorbic acid system was analyzed in the cerebrospinal fluid (CSF) of 41 patients with different neurological disorders. The chi-square test of covariance analysis revealed in this sample significant differences in the CSF levels of total ascorbic acid when patients were classified by diagnostic categories. The population analyzed contained a group of 18 patients (back pain/sciatica group) in whom no overt neurological abnormalities were disclosed upon evaluation. Taking the CSF levels of total ascorbic acid and dehydroascorbic acid in these patients as the reference (3.57 +/- 0.87 (SD)/100 ml and 0.53 +/- 0.19 mg/100 ml, respectively), it was found that head-traumatized patients showed a significant reduction in the concentration of total ascorbic acid in the CSF. CSF ascorbic acid levels were also significantly lower in patients with increased intracranial pressure (noninfected hydrocephalus group) and in patients with cerebral tumors. Although the CSF concentration of dehydroascorbic acid did not correspondingly increase over the reference values in these three groups of patients, the tendency existed for dehydroascorbic acid to represent in them a higher percentage of total ascorbic acid. After examining different alternatives, it is concluded that the hypothesis of free radical damage to the central nervous system after certain types of injury (trauma, ischemia, and tumors) may provide a satisfactory explanation of our findings. A rationale for the use of vitamin C in the management of some neurological patients is also derived from this work.