St Louis encephalitis: a review of 11 cases in a 1995 Dallas, Tex, epidemic.

OBJECTIVE: To update some of the clinical features of St Louis encephalitis (SLE), a common arboviral infection that occurs in epidemic patterns in the south-central and midwestern United States. METHODS: Eleven patients with SLE from a 1995 epidemic in Dallas, Tex, were studied clinically, radiologically, neurophysiologically, and neuropathologically (in 1 case). RESULTS: The electroencephalograms and magnetic resonance imaging (MRI) scans of our patients revealed features that have received little attention in previous studies. Of the 9 patients who were examined with electroencephalography, all 9 had seizures or other abnormalities, and 1 had nonconvulsive status epilepticus. Two of 6 patients who had MRIs showed substantia nigra edema. Finally, 2 (18%) of our patients had coinfection with the human immunodeficiency virus. CONCLUSIONS: The MRI findings of substantia nigra edema in patients with SLE have not been previously reported. Nonconvulsive status epilepticus can occur in patients with SLE and should be considered in patients with prolonged encephalopathy. Finally, human immunodeficiency virus coinfection may be a risk factor for symptomatic SLE infection.

MR imaging of intracranial cysticercosis: comparison with CT and anatomopathologic features.

Eight patients with neurocysticercosis were studied with CT and magnetic resonance (MR) imaging. Two cysts were shown better with MR than with CT. A conspicuous, high-intensity mural nodule containing the scolex allowed specific identification of intraventricular and parenchymal cysticerci. CT evidence of calcification and metrizamide enhancement in the nodule was also noted in one case. Racemose cysts were seen in the cerebellopontine angle and under the anterior septum pellucidum. Fluid in apparently live cysticerci and in racemose cysts had MR signal properties closely paralleling CSF. A thin subependymal or subpial rim of high signal intensity around the intraventricular and one of the racemose cysts was consistent with tissue reaction and aided diagnosis. While MR showed only one of numerous calcifications, it may be more sensitive than CT in the recognition of perifocal edema and of parenchymal and subarachnoid cysts, may replace invasive ventriculography in the diagnosis of intraventricular cysts, and may be useful in determining the viability of cysts and their response to therapy.

Intracranial arteriovenous malformations associated with aneurysms.

The presence of intracranial aneurysm in association with arteriovenous malformation has been well documented. Aneurysms have been described in typical proximal sites along the feeding system to the arteriovenous malformation, in abnormal distal locations along feeding vessels, and in sites remote and apparently hemodynamically unrelated to the arteriovenous malformation. Little attention has been focused on the most appropriate medical and surgical care of patients harboring these lesions. Since 1977, 22 patients with this combination of lesions have been evaluated at our institution. Nine patients (41%) presented after intracranial hemorrhage. The remaining 13 patients were investigated because of seizures in 5 patients (23%), headaches in 4 patients (18%), and progressive ischemia in 4 patients (18%). Among the patients suffering intracranial hemorrhage, 78% had bled from an aneurysm, with 22% having hemorrhaged from their arteriovenous malformation. All 7 of the patients who suffered aneurysmal hemorrhage bled from atypical distal aneurysms on major feeding vessels. Our experience and that of others has led us to believe that the safest approach to patients with this combination of lesions is to treat the aneurysm before microsurgical resection of the associated arteriovenous malformation. Hemodynamic changes associated with the abrupt elimination of an arteriovenous malformation may place associated aneurysms at immediate risk.

Magnetic resonance imaging vs computed tomography. Comparison in imaging oral cavity and pharyngeal carcinomas.

Twenty-one patients with oral cavity and pharyngeal carcinomas were enrolled in a prospective protocol to study the diagnostic efficacy of magnetic resonance imaging vs computed tomography. Magnetic resonance imaging was found to be superior to computed tomography in the area of tumor contrast (conspicuity) and equal or inferior in edge definition, delineation of regional disease, and lymph node metastasis. These findings are consistent with the current applications and limitations of magnetic resonance imaging.

Recurrent subarachnoid hemorrhage complicating a traumatic carotid-cavernous fistula.

Recurrent subarachnoid hemorrhage complicated a traumatic carotid-cavernous fistula in a young man. The fistula drained predominantly into the deep venous system of the brain, where the hemorrhage was thought to have occurred.

Evaluation of NMR versus CT for parotid masses: a preliminary report.

Twelve patients with various parotid masses were prospectively studied by both nuclear magnetic resonance (NMR) imaging and intravenously enhanced computed tomography (CT). These imaging techniques were then correlated with the disease process and clinical relevance of both forms of imaging assessed. Our results suggest high resolution, spin-echo NMR offers several advantages over CT, and is likely to become the preferred method of evaluating a parotid mass.

Intracerebral hematoma secondary to lightning stroke: case report and review of the literature.

A young boy sustained a lightning stroke to his head. He was rendered immediately unconscious and hemiplegic. Computed tomography revealed three discrete basal ganglia hematomas. This patient's management is discussed, and a review of lightning injuries to the central nervous system is presented.

Unilateral posterior arch fractures of the atlas.

Unilateral posterior arch fractures of the atlas are discussed with two clinical examples and an experimental study of their mechanism. Laboratory fracturing of posterior arches of atlas specimens with a specially adapted universal testing machine produced nonsimultaneous fractures of the two sides in four of six specimens. In three of these specimens, a complete fracture on one side was temporarily displaced because the orientation of the leverage acting on the other side changed from sagittal to oblique. The consequent increase in the effective length of the lever arm reduced the angular deformation and strain on the second side. The second fracture occurred only after additional deflection of the posterior tubercle by up to 3 mm reproduced on the second side about the same angle of deformation that had caused the first fracture. A posterior arch fracture occurring by this mechanism will remain unilateral if the deflection is arrested before failure of the second side.

Multiple cerebral hemorrhages following chymopapain chemonucleolysis. Case report.

A case of multiple cerebral hemorrhages following chymopapain chemonucleolysis is reported. The authors believe the probable etiology was intrathecal extravasation of chymopapain after injection of the drug into a lumbar disc space.

Capillary hemangioma of the sphenoid bone.

A capillary hemangioma in the body of the sphenoid bone produced unilateral optic atrophy in a 13-year-old boy. The typical reticulated appearance of an osseous hemangioma was clearly demonstrated only on direct magnification radiographs. At angiography, patchy filling occurred through vessels arising from the internal carotid and internal maxillary arteries bilaterally. The few other reports of sphenoid hemangiomas are reviewed.

Myelography in achondroplasia: value of a lateral C1-2 puncture and non-ionic, water-soluble contrast medium.

Because of technical difficulties and diagnostic limitations encountered with other myelographic techniques in patients with achondroplasia, the authors employed a lateral C1-2 puncture and non-ionic, water-soluble contrast medium in 18 achondroplastic patients with spinal compression (21 procedures). This technique proved most appropriate for identifying the upper limit of degenerative osteophytes causing exacerbation of congenital spinal stenosis, which is crucial in planning decompressive surgery. A potentially important additional finding was the presence of degenerative lower cervical spine disease in the majority of patients. There were no serious complications. The authors recommend this technique as safe and effective in achondroplastic patients with severe congenital spinal stenosis.

Pseudospread of the atlas: false sign of Jefferson fracture in young children.

Jefferson fractures are rare prior to teen-age. Three young children examined after trauma exhibited the characteristic spread appearance of the atlas, but fractures were excluded radiographically and clinically. A retrospective study demonstrated a similar appearance, termed "pseudospread," in most children aged 3 months to 4 years, including over 90% during the second year. Pseudospread results from a discrepancy between the "neural" growth pattern of the atlas and the "somatic" pattern of the axis. An "atlas spread index" is defined and a normal range presented. When an atlas fracture is suggested by apparent lateral spread of the lateral atlas masses, computed tomography is useful to demonstrate an intact atlas ring.