Carbamazepine inhibits angiotensin I-converting enzyme, linking it to the pathogenesis of temporal lobe epilepsy.

We find that a common mutation that increases angiotensin I-converting enzyme activity occurs with higher frequency in male patients suffering from refractory temporal lobe epilepsy. However, in their brains, the activity of the enzyme is downregulated. As an explanation, we surprisingly find that carbamazepine, commonly used to treat epilepsy, is an inhibitor of the enzyme, thus providing a direct link between epilepsy and the renin-angiotensin and kallikrein-kinin systems.

Brain changes on computed tomography following metrizamide myelography. Significance and therapeutic implications.

Three cases of seizures and marked behavioral changes that occurred after intrathecal metrizamide administration are reported. In each case a cranial computed tomographic scan obtained within 24 hours of the ictus showed hyperdensity of the gray matter, and created an optical illusion of diffuse white matter edema. The literature on adverse reactions and their pathogenesis and on brain parenchymal penetration of metrizamide is reviewed.

Supratentorial ependymomas. Neuroimaging and clinicopathological correlation.

In 10 patients with supratentorial ependymomas, the tumors exhibited hyperdensity on computerized tomography (CT) scanning prior to contrast infusion and, with one exception, all tumors were mixed lesions with the low densities suggesting cystic or necrotic portions. Eighty percent of the tumors contained small calcifications. Characteristically, the tumors were well demarcated and demonstrated moderate to marked enhancement after the intravenous administration of contrast material. Angiograms obtained in some patients showed mild hypervascular tumor staining and absence of large feeding arteries. The degree of contrast enhancement, angiographic vascularity, and tumor stain was compared to the pathological anaplasia of the tumors. No correlation was observed. Of four patients who were still alive during a follow-up period of 4 years or longer, three had recurrences with inoperable tumors; the remaining patient is without recurrence after craniospinal radiation. This same patient belonged to a group of five patients with a diagnosis of high-grade ependymoma, four of whom had recurrence. Follow-up CT accurately recorded the clinical course of each patient. Annual routine follow-up examinations are proposed for patients with low-grade ependymomas, and for those with high-grade ependymomas follow-up CT should be performed every 6 months. The characteristic appearance and behavior of these tumors include several distinctive features on angiographic and CT images.

Osteology of the skull as it affects halo pin placement.

Twenty-seven cadaver skulls and 20 CT scans of skulls were measured above the orbital rim and ear but below the greatest diameter to determine optimal placement of halo pin sites. At the antero- and posterolateral portions of the calvaria, the outer table averaged 2 mm, the diploe 3 mm, and the inner table 2 mm. At the temporal fossa, the outer cortex averaged 1.7 mm, the diploe 2.0 mm, and the inner table 1.6 mm. Average distance between the anterior edge of the temporal fossa and the frontal sinus approximated 3 cm. These data confirm previously recommended halo pin insertion sites, anterolaterally and posterolaterally, where the bone is thickest and the thinner frontal sinus and temporal fossae are avoided.

Streptokinase clot lysis in acute occlusions of the cranial circulation: study in rabbits.

An animal model of acute cerebrovascular thromboembolism was developed to evaluate the feasibility of selective fibrinolysis. In 20 Flemish Giant rabbits, autologous clot was deposited via selected catheterization of the distal end of the common carotid artery. The rates of clot lysis with streptokinase were compared in eight control rabbits and after three different dosage regimens in four rabbits each. Group A received selective infusion of 5000 U/hr; group B received 4000 U/min for 1 hr, 3000 U/min for 2 hr, and 5000 U/hr for 2 hr; and group C was treated similar to group B plus receiving an initial 20,000 U bolus of streptokinase. Lysis was evaluated by serial angiograms obtained hourly for up to 6 hr after the clot was deposited. Five proximal vessels arising from the common carotid artery were chosen for the angiographic grading system. The control group showed beginning lysis after 5-6 hr. Group A appeared to show a slight improvement about 4 hr after clotting. Group B demonstrated an early and greater improvement at 2 hr that appeared to be sustained throughout the experiment. Group C showed no difference compared with the control group. The Dunnet t procedure and the Kruskel-Wallis nonparametric analysis of variance were used for comparing the angiograms of the treatment groups with those of the control group at corresponding study times. The results of these animal experiments do not indicate a definite benefit of streptokinase treatment alone over no treatment. Further controlled studies are needed before the value of streptokinase in routine clinical practice can be determined.

CT evaluation of Haemophilus influenzae meningitis with clinical and pathologic correlation.

Ten proven cases of Haemophilus influenzae meningitis have been reviewed, in which all had CT scans during their first 3 weeks of illness. An attempt was made to correlate the neuropathologic basis of the disease with the CT findings. Progression of the CT changes with the course of illness and treatment is emphasized. Usual indications for CT imaging of the brain in patients with meningitis are: detection of subdural empyema or effusion, hydrocephalus, infarct, cerebritis and abscess. Widespread cerebral damage can be more fully evaluated with iodine contrast infusion if clinically indicated. CT scanning has proven to be a valuable indicator of such complications and useful predictor of clinical recovery or residual neurologic sequelae.

Neurotoxicity of iohexol: a new nonionic contrast medium.

The neurotoxicity of iohexol was evaluated and compared with the neurotoxicity of sodium diatrizoate, meglumine iothalamate, and metrizamide. Direct neurotoxicity was evaluated with in vitro rat hippocampal slices, and angiographic neurotoxicity was studied in a cat's spinal cord following thoracic aortography. In the experiments with the hippocampal slices, the ionic agents, sodium diatrizoate and meglumine iothalamate, and metrizamide caused early excitatory changes in electrical activity and later inhibition, but iohexol caused only inhibition. In the experiments with the cat's spinal cord, the ionic contrast materials produced an increase in the ventral root reflexes, and iohexol and metrizamide produced no significant effect. These results indicate that iohexol is less neurotoxic than metrizamide and the ionic contrast materials and may be a very useful angiographic and/or myelographic contrast agent.

CT scanning in rhinocerebral mucormycosis and aspergillosis.

Patients with rhinocerebral mucormycosis and rhinocerebral aspergillosis had computed tomography (CT) as well as other studies. Characteristic sinus involvement was demonstrated by CT and conventional tomography, but the latter produced a better image of bone destruction. CT was clearly superior in demonstrating orbital involvement, the most common of which included lateral displacement of a thickened medial rectus muscle, increased density of the orbital apex, and often enlargement of the optic nerve. Orbital venography and carotid arteriography were diagnostically helpful. Recognition of the characteristic pattern of sinus and orbital involvement should be helpful in leading to early biopsy and treatment.