Production of uric acid in cerebrospinal fluid after subarachnoid hemorrhage in dogs: investigation of the possible role of xanthine oxidase in chronic vasospasm

Based on accumulating evidence of the role of xanthine oxidase (XO) in generating oxygen free radicals and causing tissue damage during ischemia, we examined the possible role of XO in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH). After inducing SAH in dogs by two autologous blood injections 2 days apart, chronic vasospasm of the basilar artery was reliably produced. There was a 3.5-fold elevation in uric acid (UA), the product of XO, in the cerebrospinal fluid (CSF) of these animals. Parenteral administration of allopurinol (i.v., 25 mg/kg, every 6 hours), a specific blocker of XO, successfully abolished the elevation in CSF uric acid levels due to SAH. However, angiographic vasospasm measured on Day 7, morphological changes observed by electron microscope, and elevated CSF prostaglandin levels were not altered by the treatment. It can be concluded that the observed activation of the enzyme XO, which is a well-known source of oxygen free radicals in ischemia in various organs, is not playing a major role in the pathogenesis of chronic cerebral vasospasm in this animal.     

Preliminary report: effects of high dose methylprednisolone on delayed cerebral ischemia in patients at high risk for vasospasm after aneurysmal subarachnoid hemorrhage

Mounting evidence suggests that chronic cerebral vasospasm may be linked to the inflammatory response that follows subarachnoid hemorrhage. Twenty-one patients judged to be at high risk for vasospasm because of either poor admitting grade or a large amount of subarachnoid blood shown by computed tomography were treated with a course of high dose methylprednisolone, and management results were compared to those of a cohort of contemporary control patients matched for grade, number of hemorrhages, time from hemorrhage to admission, time from hemorrhage to operation, aneurysm location, age, and sex. Patients treated with high dose methylprednisolone were twice as likely to have an excellent result and half as likely to die as those who were not treated. The incidence and severity of delayed cerebral ischemia were reduced in treated patients when compared to control patients. None of the treated patients developed a serious side effect that could be attributed to steroid treatment. These findings are consistent with the conclusion that chronic vasospasm is an inflammatory vasculopathy and suggest that early treatment with high dose methylprednisolone may benefit this high risk group of patients.     

Carotid body tumors: a subject review and suggested surgical approach

Carotid body tumors are a rare but potentially difficult surgical entity. Their pathology, physiology, and natural history are reviewed along with surgical results reported in the literature. A surgical approach for removal of these tumors is presented which differs significantly from the recommended techniques in that emphasis is placed on intraoperative monitoring of cerebral blood flow, the the selective use of shunts, a tumor-adventitial plane of dissection, preservation of the carotid artery complex, and mobilization of the parotid gland. Thirteen cases using these techniques are reviewed. The mortality rate and the incidence of cerebrovascular sequelae were both 0%. The major morbidity consisted of injury to the lower cranial nerves in five patients (39%) with tumors larger than 5 cm in length.