metrizamide and Disease-Models--Animal

A subarachnoid haemorrhage (SAH) in the squirrel monkey was produced by injection of blood via a permanently implanted catheter connected to the cisterna magna and a cannula stereotactically inserted into the interpeduncular cistern. Repeated angiographic examinations of the vertebro-basilar and right internal carotid arteries revealed a biphasic vasospasm with a maximal acute spasm at ten minutes and maximal late spasm at six days after blood injection. The present study has shown that a reproducible biphasic vasospasm can be produced in the squirrel monkey and evaluated by repeated angiographic examinations. The model is suitable in the study of basic mechanisms underlying vasospasm in a primate and, due to the size of the animal, autoradiographic evaluation of the cerebral blood flow and metabolism can be performed at an acceptable cost.

Topics: Animals; Cerebral Angiography; Disease Models, Animal; Female; Intracranial Pressure; Ischemic Attack, Transient; Male; Metrizamide; Saimiri; Subarachnoid Hemorrhage; Vertebrobasilar Insufficiency

The value of various enhancement techniques as opposed to nonenhanced CT scanning was compared in 15 baboons with cerebral infarction secondary to embolization of the left middle cerebral artery. The most prominent CT findings in infarction included an area of low absorption in the opercula--basal ganglia--centrum semiovale region and generalized lateral ventricular enlargement. Intravenous enhancement of the low-density region occurred in 25% of the animals and often obscured the preenhancement abnormality. However, a rapid bolus injection of contrast material followed by immediate consecutive CT scans (computed angiotomography) permitted prominent visualization of early-shunting veins. Delayed scanning following intrathecal enhancement better defined small infarctions that did not exhibit the usual cerebral blush. The CT imaging of inhaled xenon provides a new technique for evaluating subtle abnormalities in cerebral perfusion, even when the routine CT scan shows no abnormality.

Topics: Animals; Cerebral Infarction; Disease Models, Animal; Injections, Spinal; Metrizamide; Papio; Radiographic Image Enhancement; Tomography, X-Ray Computed

Myelography in monkeys was performed with either meglumine iocarmate or metrizamide. The severity of resultant arachnoiditis in each animal 12 weeks later was evaluated by repeat myelography and by histologic study of the arachnoid. Three of the four animals examined with meglumine iocarmate had severe arachnoiditis; none of the four animals examined with metrizamide had as severe changes. The difference between the two groups was statistically significant (P less than .05).

Topics: Animals; Arachnoiditis; Disease Models, Animal; Haplorhini; Iothalamate Meglumine; Macaca; Metrizamide; Myelography

Myelography was performed on 80 monkeys to study postmyelographic arachnoiditis. Metrizamide myelography caused arachnoiditis when high concentrations were used, but not with the usual clinical concentrations. Arachnoiditis resulted after myelography with meglumine iocarmate; however, the risk of arachnoiditis was reduced by diluting the contrast medium. Prophylactic intrathecal methylprednisolone was not effective in preventing arachnoiditis. Blood in the cerebrospinal fluid did not affect the degree of arachnoiditis.

Topics: Animals; Arachnoiditis; Disease Models, Animal; Haplorhini; Iothalamate Meglumine; Methylprednisolone; Metrizamide; Myelography; Spinal Diseases

After myelography with either metrizamide (300mg l/ml) or meglumine iocarmate (280 mg l/ml), mild to severe arachnoid fibrosis was demonstrated radiographically and histologically in primates. Intrathecal injections of metrizamide (170 mg l/ml) or autologous cerebrospinal fluid produced less arachnoiditis. The risk of arachnoiditis is probably minimized by the use of reduced volumes and concentrations of water-soluble media. Controlled studies of arachnoiditis following myelography are probably more reliable in the primate model than in other experimental animals.

Topics: Animals; Arachnoiditis; Disease Models, Animal; Haplorhini; Iodobenzoates; Iothalamate Meglumine; Iothalamic Acid; Macaca; Metrizamide; Myelography; Solubility; Water