The role of computed tomographic angiography in the assessment of intracranial vascular disease.

Both technical and clinical implications of three-dimensional computed tomographic angiography in the evaluation of intracranial circulation, and in particular cerebral aneurysms, are presented. Three-dimensional computed tomographic angiography allows excellent visualization of the aneurysm, its neck, and its relationship with the parent artery and important adjacent bony structures. This technique has a major role in the evaluation of difficult aneurysms. In addition, advantages and disadvantages are discussed in comparison with more conventional techniques such as magnetic resonance imaging, magnetic resonance angiography, and digital subtraction angiography. Three-dimensional computed tomographic angiography will continue to develop with the advent of more rapid computed tomography scanners, playing a key role in the investigation and screening of patients with a family history of cerebral aneurysms.

Conservative therapy of atlantoaxial osteomyelitis. A case report.

STUDY DESIGN: A rare case of C1-C2 vertebral osteomyelitis treated conservatively is described. The radiologic findings as well as the follow-up evaluation are reported. OBJECTIVE: To increase knowledge about the pathogenesis and treatment of vertebral osteomyelitis in the high cervical region. SUMMARY OF BACKGROUND DATA: This is one of the first cases reported of successful conservative treatment of osteomyelitis at this level. METHODS: In a 58-year-old man with lumbar staphylococcal infection, a subsequent cervical infection developed. Because the lumbar spondylitis was treated promptly, the cervical osteomyelitis was treated at a very early stage of development. RESULTS: Operative decompression is the treatment most often used in osteomyelitis at the C1-C2 level. This is an extremely unusual circumstance in which early treatment of the infection negated the need for surgery. CONCLUSION: Conservative treatment of osteomyelitis at the C1-C2 level can be efficacious in the correct setting.

The negative angiogram in subarachnoid haemorrhage.

Our purpose was to review the incidence of negative cerebral panangiography in acute nontraumatic subarachnoid haemorrhage (SAH); to document the amount and distribution of subarachnoid blood on CT and determine its relationship to findings on repeat angiography; and to study the outcome of these patients from the time of presentation to hospital discharge. From 1983 to 1992, 295 patients underwent cerebral angiography for acute SAH at our institution. The CT, angiographic and MRI findings and clinical course of patients with initially negative angiograms were reviewed retrospectively. The overall incidence of negative cerebral panangiography was 31% (92/295). An aneurysm was disclosed on a second angiogram in 4 cases, and on a third angiogram in 1, giving a total false negative rate of 5%. In 55% of cases, only a small amount of SAH was present on CT. The distribution of the subarachnoid blood was nonspecific and resembled the pattern seen in aneurysmal SAH. Ninety-four percent of the patients presented in Hunt-Hess grades I and II. The complications of conservative treatment were few: a rebleed rate of 4%, delayed cerebral ischemia in 4%, cerebral infarcts in 8% and hydrocephalus requiring shunting in 3%. On discharge, 93% of patients had recovered completely and the others were left with moderate disability. There were two deaths related to massive rebleeding. Patients with perimesencephalic SAH (35%) fared particularly well; none developed complications during their hospital stay and repeat angiograms never revealed an underlying aneurysm. In such cases, further angiographic investigations do not seem warranted.

Extension of a cerebellar cystic astrocytoma into the cervical canal, demonstrated by magnetic resonance imaging.

One characteristic feature of ependymomas of the fourth ventricle is a tendency to extend through the foramina, specifically the foramina of Luschka and Magendie, the foramen magnum and the aqueduct of Sylvius. The authors report a case of pilocytic astrocytoma of the cerebellum that mimicked such extension into the upper cervical canal. This finding was revealed by magnetic resonance imaging and confirmed at surgery.

Cerebral vein thrombosis due to hereditary antithrombin III deficiency.

Cerebral vein thrombosis, also called superior sagittal sinus thrombosis, is a well recognized clinical and radiologic entity associated with a variety of medical disorders. We report a patient with fatal cerebral vein thrombosis following myelography, in whom the cause was familial antithrombin III (AT3) deficiency. Unsuspected AT3 deficiency should be considered in cases of unexplained cerebral venous thromboses.

Leptomeningeal gliomatosis: MR findings.

We report a case of primary diffuse leptomeningeal gliomatosis documented by MR. The radiological findings guided the surgical biopsy toward the area involved. Pathological examination confirmed the diagnosis. The patient could consequently benefit from treatment, i.e., radiation therapy, which was followed by clinical relief.

MRI of amygdala and hippocampus in temporal lobe epilepsy.

In this study we compared the results of qualitative visual analysis of MRI with volumetric studies of the amygdala (AM) and hippocampal formation (HF) in a group of 31 patients. Twenty-six patients with temporal lobe epilepsy (TLE) and six with non-TLE had MRI studies using a 1.5 T Gyroscan following a specific protocol for scan acquisition. The MR images were interpreted by two blinded radiologists and by a third if discrepancy arose. Volumetric studies were carried out by one or two raters. The volumetric measurements of AM and HF were accurate in lateralizing the epileptogenic area in patients with TLE, concordant with the EEG in 92%; there was no false lateralization. In those patients who underwent surgery, there was a correlation between the degree of mesial temporal sclerosis demonstrated by histopathology, the amount of volume reduction, and the asymmetry. In patients with non-TLE, there was no volume asymmetry of AM or HF. The MR qualitative assessment yielded positive lateralization in patients with TLE in 56%, conflicting lateralization in 20%, and lateralization contralateral to the focus in 12%. A hyperintense signal in mesial structures was found ipsilateral to the focus in 40% and contralateral in 12% of patients with TLE. Volumetric study improves the diagnostic yield of MRI evaluation in patients with TLE not related to gross structural lesions. The interrater variability is low and the data are accurate and reproducible. Because they are quantitative, volumetric studies permit better comparison of results in different subgroups of patients with TLE.

Porcine respiratory coronavirus in Quebec: Serological studies using a competitive inhibition enzyme-linked immunosorbent assay.

Porcine respiratory coronavirus (PRCV) was identified for the first time in Quebec, using a blocking enzyme-linked immunosorbent assay (ELISA). Unlike the virus neutralization test (VNT), this ELISA was able to distinguish transmissible gastroenteritis virus (TGEV) from PRCV. Among the 15 seropositive fattening herds from group A, sera containing PRCV antibodies represented 74.8%, whereas those with TGEV antibodies represented only 7.2%. In group B, which consisted of 15 sow herds, nine herds expressed only PRCV-specific antibodies while the other herds had animals positive for TGEV-specific antibodies.

Low-grade myxoid chondrosarcoma of the base of the skull: CT, MR, and histopathology.

A retrospective CT, MR, and histopathologic study was performed in five patients with histologically verified low-grade myxoid chondrosarcoma of the base of the skull. In four patients, the tumor originated off the midline and was associated with bone destruction at the petrous apex near the petrooccipital fissure. Tumor extent included the cerebellopontine angle in three patients and the parasellar area in two patients. The fifth tumor originated on the midline and was associated with destruction at the dorsum sellae. Three tumors contained calcifications, whereas two lesions were mostly isodense with brain on CT scan. All tumors were hypointense on T1-weighted MR images and very intense on T2-weighted images except for areas of signal void consistent with calcifications. Light microscopy revealed islands of mature hyaline cartilage in an abundant myxoid ground substance. Histology and immunocytochemical analysis were consistent with a low-grade myxoid chondrosarcoma. The CT and MR features of low-grade myxoid chondrosarcoma are comparable with those of chordoma. Chordoma usually arises from the midline, but cases with origin from the lateral portion of the clivus or the petrous apex have been described. Low-grade myxoid chondrosarcoma has distinct histologic and immunocytochemical features and includes lesions formerly called "chondroid chordomas."

Hydrocephalus and prominence of the choroid plexus: an unusual computed tomographic presentation of cerebral toxoplasmosis in AIDS.

Toxoplasmosis is a frequent cause of infection of the central nervous system (CNS) in patients with acquired immunodeficiency syndrome. Computed tomography (CT) usually shows solitary or multiple parenchymal lesions, which are most often located in the cortex, the juxtacortical white matter and the basal ganglia. The authors describe a 30-year-old immunocompromised Haitian woman with pathologically proven CNS toxoplasmosis who presented with hydrocephalus and prominence of the choroid plexus; there was no evidence of focal parenchymal lesions in contrast-enhanced CT scans. An autopsy revealed diffuse destruction of the ependyma of the lateral, the third and the fourth ventricles. Necrosis was evident, and the periventricular tissues and the choroid plexus were infiltrated with neutrophils and macrophages. Pseudocysts of Toxoplasma were identified near the ventricular surface.

Multiple occult vascular malformations of the brain and spinal cord: MRI diagnosis.

We report a patient with multiple angiographically occult vascular malformations in the brain and spine. Magnetic resonance imaging showed multiple lesions in brain and spine with hypointense areas on both T1 and T2-weighted images. These hypointense areas are usually secondary to hemosiderin deposits consistent with remote bleeding in the lesions. We conclude that when magnetic resonance reveals an intraspinal lesion with signal intensity characteristics consistent with a vascular malformation, an examination of the brain should be performed to rule out associated intracranial lesions. The finding of multiple lesions in the brain with identical signal intensity characteristics reinforces the diagnosis of vascular malformation.

Neuronal migration disorders: a contribution of modern neuroimaging to the etiologic diagnosis of epilepsy.

Computed tomography and magnetic resonance imaging enable the identification of neuronal migration disorders during life. Several specific syndromes have been identified and early diagnosis of previously unrecognized entities is now possible. We report 51 patients with imaging. Thirty-two had a single widespread cortical dysplastic lesion. Twenty-eight had focal corticectomies. From a pathological standpoint, these encompassed focal cortical dysplasia (14 cases) and forme fruste of tuberous sclerosis (10 cases). These two groups of patients were indistinguishable from the clinical and radiological standpoint. In only two was the MRI examination normal. In addition, there were 10 with bilateral perisylvian dysplasia, four with diffuse cortical dysplasia or the "double cortex" syndrome, three with hemimegalencephaly, one with megalencephaly, and one with nodular neuronal heterotopia. The electroclinical and imaging findings led to the development of specific surgical strategies for the alleviation of the intractable seizures in each of these radiologically-defined syndromes.

Multiple intracerebral cavernous angiomas.

Eight patients (seven women and one man) with multiple intracerebral cavernous angiomas (cavernomas), also known as angiomatosis cerebri, were examined with high-field magnetic resonance imaging (MRI). Although previous articles have referred to such cases, a series similar to the one reported here has apparently not been described in the radiology literature. The patients presented with seizures, progressive neurologic deficit or cerebral hemorrhage. In all eight cases the multiplicity of the lesions was an incidental finding in the magnetic resonance images. The MRI appearance of the cavernomas, although characteristic, is similar to that of other angiographically occult intracranial vascular malformations, in particular thrombosed arteriovenous malformations and mixed vascular malformations, as well as that of hemorrhagic metastases. Additional criteria, such as the absence of edema, the presence of calcifications and the temporal evolution of the cavernomas on serial scans, should allow cavernomas to be differentiated from hemorrhagic metastases. The exquisite sensitivity in detecting angiomatosis cerebri and the ability to show the evolution of internal hemorrhage in individual lesions make MRI the method of choice for diagnosing and following this condition.

Magnetic resonance imaging of hypothalamic hamartomas causing gelastic epilepsy.

Hypothalamic hamartomas may cause a peculiar epileptic syndrome characterized by seizures of laughter and precocious puberty. Four mentally handicapped patients suffering from gelastic epilepsy were referred to our institution for investigation; three of them also presented with precocious puberty. In all four cases magnetic resonance imaging (MRI) revealed a space-occupying lesion of the hypothalamus that was considered to be a hamartoma. Biopsies were not performed. Hamartomas appear isodense in plain computed tomography scans, and they do not enhance. Such lesions display an isointense signal in T1-weighted magnetic resonance images and a hyperintense signal in proton density and T2-weighted images. MRI is the procedure of choice for detecting such lesions at the base of the brain.

Intracerebral gangliogliomas in patients with partial complex seizures: CT and MR imaging findings.

The clinical and radiologic findings in 19 patients with partial complex seizures and surgically proved intracerebral gangliogliomas were reviewed to characterize the radiologic features of these lesions. The CT and MR findings were not specific. On CT the gangliogliomas can be hypodense with no enhancement and they often have calcifications. On MR these tumors have a wide variety of signals. In five of our cases the tumor had a high-intensity signal with a cystlike component on proton density- and T2-weighted images. In five cases the lesion had an inhomogeneously intense signal on proton density-weighted images and high signal intensity on T2-weighted images. The tumor had high-intensity signal on both proton density- and T2-weighted images in four patients. Finally, in two cases the MR findings were normal. We recommend MR as the examination of choice for patients with partial complex seizures because it allows an artifact-free evaluation of the temporal region. However, CT should also be performed in order to recognize calcifications that may be missed on the MR examination.

Spinal cord distraction: an in vitro study of length, tension, and tissue pressure.

Since the Scoliosis Research Society released a report on cord injury related to Harrington rod instrumentation for scoliosis, little has been published on the pathophysiology of this disorder. Dolan et al. (4) described diminished cord blood flow associated with spinal distraction in a cat model, but failed to demonstrate its cause. In this article, we describe a series of in vitro experiments performed on dog and sheep cadaver spinal cords. Controlled distractive forces were applied to spinal cords while monitoring both cord interstitial pressure and cord elongation. A close (Ravg = 0.986) correlation was noted between applied tensile forces and cord interstitial pressure. At 1,000-g loads, the average tissue pressure obtained was 29.5 cm H2O, ranging from 17 to 47 cm H2O. However, it was noted that the cord demonstrated nonlinear tensile elastic properties that appeared exponential in the range examined. These properties are consistent with those described for collagen-containing compounds. We conclude that spinal cord distraction is capable of generating cord tissue pressures that could cause a spinal cord compartment syndrome and thereby seriously impair spinal cord blood flow causing spinal cord injury.