Delayed visual loss due to trauma of the internal carotid artery.

The group of six patients in this study experienced delayed visual loss following head trauma. Visual loss occurred from 1 day to 13 years after the initial injury. All patients suffered indirect trauma to the internal carotid artery resulting in formation of either an aneurysm or pseudoaneurysm or a carotid-cavernous fistula. Review of the radiologic and clinical findings was performed in six patients. The diagnosis was established by computed tomography, magnetic resonance imaging, and angiography. All patients had follow-up clinical evaluation and imaging studies. Treatment by neurosurgical or interventional neuroradiologic procedures resulted in significant visual improvement in five patients. Different pathophysiologic mechanisms could be correlated with the delayed visual loss produced by the two types of lesions. The pathologic changes associated with the aneurysms/pseudoaneurysms included direct compression of optic nerves and/or chiasm and intracranial hematoma. A carotid-cavernous fistula caused delayed visual loss by either hematoma at the orbital apex or compression of the chiasm and/or optic nerves by saccular dilatation of the cavernous sinus. The delayed onset of decreased vision following head trauma should alert the physician to the possibility of a traumatic aneurysm/pseudoaneurysm or a carotid-cavernous fistula. Different neuro-ophthalmologic symptoms can usually be correlated with the pathologic changes demonstrated by neuroimaging procedures.

Flow dynamics of lateral carotid artery aneurysms and their effects on coils and balloons: an experimental study in dogs.

PURPOSE: To investigate the hemodynamic characteristics of lateral carotid artery aneurysms in a canine model and to determine their influence on coils and balloons. MATERIALS AND METHODS: Forty aneurysms were created in fourteen dogs and their hemodynamic characteristics and influence on coils and balloons were evaluated with angiography and color Doppler pre- and postplacement. Twenty aneurysms were treated with coils, eight with balloons, and 12 aneurysms served as controls. RESULTS: The aneurysms demonstrated three distinct zones of flow: 1) an inflow zone entering at the distal aspect of the aneurysm ostium, 2) an outflow zone exiting at the proximal ostium, and 3) a central slow flow vortex. The inflow zone is a determining factor in the placement and stability of coils and balloons placed within the aneurysm and in the thrombosis of an aneurysm. The force of the inflow is considerable and can alter the shape of coils and displace both coils and balloons positioned within the aneurysm. CONCLUSIONS: Coils and balloons need to be of shapes and sizes that do not conform to the inflow and outflow zones. Filling the aneurysm and blocking or displacing the inflow zone can produce thrombosis of an aneurysm with preservation of the parent artery.

Treatment of carotid artery aneurysms with platinum coils: an experimental study in dogs.

The objectives of this study were to investigate the consistency, patency, and natural history of a vein graft canine aneurysm model and to determine the effectiveness of various coil designs on inducing aneurysm thrombosis. Twenty-one sacculuslike aneurysms were created in mongrel dogs by anastomosing a vein pouch to the common carotid artery. The model produced wide-neck aneurysms with 100% patency. The canine vein graft aneurysm provided an excellent model for the evaluation of endovascular devices. Three types of specially designed platinum coils were placed in the aneurysms: those with simple curves, those with complex curves, and those with flower petal curves and silk fibers. These coils were placed by the endovascular route by means of microcatheters. Flower petal coils with silk fibers were effective in producing thrombosis of the aneurysms, suggesting that coils of the appropriate design may be useful in the endovascular treatment of aneurysms. The other coil designs evaluated, those with simple and complex curves without silk fibers, demonstrated insufficient thrombogenicity and spatial stability.

Biocompatibility of 1-French polyethylene catheters used in interventional neuroradiology procedures: a study with rats and dogs.

This study was designed to investigate the thrombogenicity, inflammatory response, and endothelial response to the presence of sterilized, 1-French polyethylene catheters implanted into the arterial system and subcutaneous tissues of 18 rats and two dogs. At time periods ranging from 1 week to 6 months, repeat angiography was done, the animals sacrificed, and the tissues containing the catheter removed for histologic study. In the subcutaneous tissues the catheter became encased in a very thin (less than 0.5 mm) coating of fibrous tissue with no evidence of inflammation. In large vessels, the catheter at all time periods appeared identical both angiographically and histologically to that at the time of implantation. In small to medium-sized vessels a slight increase in vessel size (25% increase in diameter of the rat iliac) was observed angiographically. On histologic evaluation, there was evidence of myointimal hypertrophy, which was asymmetrically placed, centered around the position of the catheter. There was no evidence of thrombi or of incorporation of the catheter itself into the hypertrophic tissue. In dogs and rats, an implanted 1-French polyethylene catheter is well tolerated: the animals showed no evidence of thrombotic, thromboembolic, or inflammatory complications. Myointimal hypertrophy was observed in small to medium-sized arteries, which is of unknown significance.

Rasmussen encephalitis: epilepsia partialis continua secondary to chronic encephalitis.

Rasmussen encephalitis is a disease consisting of chronic encephalitis with progressive neurologic deficits and focal intractable seizure activity. The etiology is unknown, but pathologic specimens revealed changes consistent with viral encephalitis. Even though neuro-imaging techniques, such as positron emission tomography and magnetic resonance imaging, offer the prospect of specific, presurgical diagnostic criteria, the initial diagnosis usually is made on a clinical basis. Treatment modalities, including a wide variety of antiepileptic drug therapies and surgical interventions, may result in significant physical and mental impairments. We summarize the clinical presentation, diagnostic considerations, and different treatment protocols in a patient with this rare and debilitating disorder.

Transvenous coil embolization for treatment of patent ductus venosus in a dog.

A congenital intrahepatic portosystemic shunt was successfully closed in a 3-month-old Golden Retriever by use of a transvenous coil embolization procedure. The pup's patent ductus venosus was occluded by placing 8 Dacron fiber-covered, stainless steel, spring embolization coils into the shunt vessel through a catheter placed through the jugular vein. Four separate embolization procedures were performed to gradually close the portosystemic shunt and to allow intrahepatic portal perfusion to reform. Transvenous embolization may prove to be a better therapeutic alternative than surgery for correction of intrahepatic shunts because of its decreased invasiveness, lower mortality, and ability to gradually narrow the shunt lumen.

Calcium-dependent desensitization of adenylate cyclase in rat cerebral cortical slices.

Incubation of slices of rat cerebral cortical grey matter in Krebs-Ringer bicarbonate-glucose buffer induced a rapid decline in the responsiveness of the adenylate cyclase in subsequently prepared membrane preparations to stimulation by various activators of the enzyme. The loss of responsiveness was time- and temperature-dependent, showed an absolute dependence on extracellular calcium ions, and was mimicked by the presence of serine proteases in the incubation medium. The resultant adenylate cyclase preparation was partially responsive to activation by fluoride and guanylylimidodiphosphate but had become virtually unresponsive to activation by ganglioside, trypsin, or beta-adrenergic agonists. The loss of responsiveness of adenylate cyclase was not altered if slices were incubated with depolarizing agents, putative neurotransmitters, receptor blockers, serine protease inhibitors, or adenosine deaminase. The nature of the calcium-dependent mechanism involved in the loss responsiveness of membranal adenylate cyclase is unknown. A suggested mechanism for the loss of sensitivity is the action of a membrane-bound, calcium-dependent protease.

Regulation of cyclic AMP formation in brain tissue by alpha-adrenergic receptors: requisite intermediacy of prostaglandins of the E series.

The accumulations of cyclic AMP elicited by norepinephrine in slices of rat cerebral cortex or hypothalamus were markedly reduced after incubations with prostaglandin synthetase (8,11,14-eicosatrienoate, hydrogen-donor:oxygen oxidoreductase, EC 1.14.99.1) inhibitors such as indomethacin, aspirin, flufenamic acid, and acetoaminophen. Responses of cyclic AMP-generating systems to beta-adrenergic agonists or adenosine were unchanged by treatment with indomethacin and the reduction in the norepinephrine response appeared due primarily to a loss of the alpha-adrenergic component. The accumulation of cyclic AMP elicited by prostaglandin E2 [mean effective dose (EC50) 4 micro M] was increased by 2-fold by treatment with indomethacin. The alpha-adrenergic component of the norepinephrine response was fully restored by very low concentrations of prostaglandin E2 (EC50 20 nM). Prostaglandins of the F series had no effect on cyclic AMP generation under a variety of conditions. It appears that low levels of prostaglandins of the E series are required--perhaps by a calcium-dependent mechanism--for the expression of alpha-adrenergic receptor-mediated activation of cyclic AMP formation in brain tissue.

MR imaging of spinal pachymeningitis.

We report a case with pathologic correlation that demonstrates the magnetic resonance imaging characteristics of spinal pachymeningitis. Contrast enhanced T1-weighted images clearly demonstrated the thickened contrast enhancing meninges in a patient with progressive radiculomyelopathy who had both clinical and imaging evidence of progression of disease.

Familial cerebellar ataxia with hydrocephalus in bull mastiffs.

Familial cerebellar ataxia with concurrent hydrocephalus has previously been described in a family of bull mastiff pups, and recently has been identified in a litter from Louisiana. The 4 affected pups had ataxia, hypermetria, conscious proprioceptive deficits, behavioral abnormalities, and a visual deficit. In magnetic resonance imaging of the brain of two of the pups, there were symmetric hydrocephalus and two focal areas of increased signal intensity within the central nuclei of the cerebellum. Histopathologically there was vacuolization and mild astrogliosis within the deep cerebellar nuclei (dentate, interpositus, fastigial), caudal colliculi, and lateral vestibular nuclei. Although the postmortem results were not exactly the same as in the previously published report, the clinical features and histopathologic findings strongly support the diagnosis. This disorder is most likely inherited in an autosomal recessive manner.