Diagnosis and management of brain abscess.

Over the past 20 years, the diagnosis and management of brain abscess has been facilitated by a number of technologic advances that have resulted in a significant reduction in mortality. Despite these advances in technology, however, brain abscess remains a serious disease. In this article the nature, pathogenesis, and diagnosis of brain abscesses are discussed.

Stem pressure at the origin of intracranial collateral vessels.

The relationship between pressure at the functional site of origin of intracranial collateral channels (Pstem) and systemic pressure allows an estimation of the size of vascular channels from which collateral vessels originate. In this study, Pstem was determined in anesthetized dogs. A branch of the middle cerebral artery was perfused through a closed system with autologous blood.

Diagnosis and management of nontraumatic subarachnoid hemorrhage in elderly patients.

Subarachnoid hemorrhage is a significant problem in the geriatric population. The most common causes of nontraumatic subarachnoid hemorrhage in elderly patients are ruptured aneurysms or arteriovenous malformations. Aggressive therapy for aneurysmal subarachnoid hemorrhage is warranted in many patients whereas conservative treatment of arteriovenous malformations is customarily warranted in this age group.

Studies of collateral perfusion to canine middle cerebral artery territory.

Previous studies of intracranial collateral circulation have not distinguished between true "collateral" blood flow (flow to a region that occurs only when a primary artery is occluded) and "overlap" flow (flow to a region that is present under both normal and demand conditions). These experiments had three purposes: 1) to identify tissues that were truly collateral dependent, 2) to determine potential for true collateral flow in the absence of overlap flow, and 3) to determine whether an anatomical basis for overlap flow could be demonstrated. Branches (700-900 microns) of the dog middle cerebral artery (MCA) were perfused with autologous blood.

Carcinoma metastatic to a cerebellar vascular malformation: case report.

A 73-year-old woman with a spontaneous intracerebellar hemorrhage was seen and was found to have metastatic adenocarcinoma within a vascular malformation. There was no evidence of other metastatic disease. The association of these two lesions is uncommon and has rarely been reported.

Management of cervical spine injuries in patients with ankylosing spondylitis.

Eleven patients with ankylosing spondylitis and traumatic fracture/dislocation of the spine were identified in a retrospective review of all cases of cervical spine injury treated on the neurosurgical service over a 10-year period. Injury was most often secondary to minor trauma or a motor-vehicle accident, and the level of vertebral involvement was most frequently between C-5 and T-1. Neurological symptoms at presentation ranged from neck pain alone to complete loss of function distal to the level of injury.

EEG changes during carotid occlusion and hypotension in the rat: the effects of nitrous oxide.

It has been suggested that N2O may alter the sensitivity of the brain to ischemia. To test this hypothesis. we examined the effects of N2O on the development of left-right hemispheric asymmetry in the electroencephalogram (EEG) during hemorrhagic hypotension in rats subjected to unilateral carotid occlusion.

A randomized trial of aspirin or heparin in hospitalized patients with recent transient ischemic attacks. A pilot study.

In a randomized pilot study we compared the efficacy of temporary anticoagulation with intravenous heparin sodium to the efficacy of aspirin in preventing cerebral infarction in hospitalized patients with recent (less than 7 days) transient ischemic attacks (TIAs). Fifty-five patients (33 men, 22 women) aged 36-81 (mean 62.7) years met entry criteria and agreed to participate.

Effects of hypercapnia on cerebral blood flow following prophylactic and delayed experimental superficial temporal artery-middle cerebral artery bypass.

Cerebral blood flow was studied in dogs to ascertain whether preexisting superficial temporal artery-middle cerebral artery bypass could preserve hypercapnic reactivity following acute ischemia and whether postischemic-delayed revascularization would restore hypercapnic reactivity. In six dogs flow was preserved and some degree of hypercapnic response remained following proximal occlusion with a patent bypass. During complete ischemia (bypass occluded) there was no hypercapnic reactivity in the ischemic zone.

Correlation of experimental rCBF determinations in goats with flow measurements from a Doppler-modified carotid artery shunt.

A carotid artery shunt system has been developed that continuously monitors blood flow rates by embedding a Doppler crystal in the shunt wall. The crystal ranges through a "liquid lens" that enables it to be placed without violation of the shunt lumen. Because the crystal is at a fixed angle (45 degrees) to the axis of blood flow and the diameter of the lumen remains constant, a linear relationship exists between flow rates and the Doppler velocity signal.

Cerebral autoregulation following prophylactic and delayed experimental STA-MCA bypass.

Cerebral autoregulation is impaired in ischaemic regions. We hypothesized that pre-existing STA-MCA bypass would be superior to delayed revascularization in maintaining ipsilateral rCBF and preserving cerebral autoregulation following experimental stroke. Two series of dogs were tested to evaluate this hypothesis, but which was disproved for the chosen experimental conditions.

Sequential measurement of somatosensory evoked potentials in a canine model of hemispheric ischaemia.

We have previously shown that occlusion of 6 canine intracranial vessels produces profound hemispheric ischaemia and abolishes the ipsilateral SSEP. In the present study, this work was extended to ascertain the differential contributions of 6 intracranial vessels to SSEP function. Five dogs underwent craniotomy, brain retractions, and ipsilateral arterial microdissection, and were prepared for SSEP recordings.

Is duplex follow-up cost-effective in the first year after carotid endarterectomy?

Recent reports have suggested that duplex scanning is an ideal method to noninvasively assess the incidence of recurrent carotid stenosis. However, the timing and frequency of the follow-up studies are controversial. In the present study, 150 patients underwent 173 carotid endarterectomy procedures over a 2 year period.

Carotid endarterectomy in symptomatic elderly patients.

Fifty-three of 203 consecutive carotid endarterectomies (26%) performed on the Neurosurgical Service at the University of Iowa were in patients over 70 years of age (mean age, 73.4). This series included 38 men and 15 women.

Dose-escalation study of intravenous nicardipine in patients with aneurysmal subarachnoid hemorrhage.

A dose-escalation study of the calcium ion entry blocking drug nicardipine was performed using large dose infusions in 67 patients with recent aneurysmal subarachnoid hemorrhage (SAH). A safe, potentially therapeutic dose of the drug was determined. Patients admitted within 7 days of SAH from a documented cerebral aneurysm were entered into the study if no spasm was present on the initial angiogram.

Technical note: in vitro evaluation of an in-line Doppler flow-metering system for carotid artery shunts.

Carotid artery shunts are used extensively during carotid artery surgery to maintain cerebral perfusion. Blood flow through such shunts may be compromised by thrombosis, incorrect placement, or inadvertent clamping of the shunt. Currently, however, no direct method exists to detect poor shunt flow that might precipitate cerebral ischemia.

Combination of aminocaproic acid and nicardipine in treatment of aneurysmal subarachnoid hemorrhage.

Antifibrinolytic drugs reduce the risk of rebleeding during the first 2 weeks after aneurysmal subarachnoid hemorrhage. However, they do not lower overall mortality, largely because of an increased incidence of cerebral ischemia. The usefulness of antifibrinolytic drugs might be increased if a method to prevent or control vasospasm in patients were to be developed.

Measurement of regional cerebral blood flow and somatosensory evoked potentials in a canine model of hemispheric ischemia.

Regional cerebral blood flow (rCBF) was studied using the radiolabeled microsphere technique in a canine model of hemispheric ischemia that others have previously examined morphologically with carbon perfusion. It was our goal to ascertain whether this ischemic model, which involves easily accessible occlusions of the ipsilateral circle of Willis, could produce reproducible and significant reduction of hemispheric cerebral blood flow. Seven animals underwent the surgical procedure with measurements of rCBF at base line, after arterial microdissection and brain retraction only, and finally after creation of the lesion.

Effects of preexisting bypass graft on rCBF and SSEP's following acute stroke in dogs.

Regional cerebral blood flow (rCBF) was measured with radiolabeled microspheres in a canine model of superficial temporal artery-middle cerebral artery (STA-MCA) bypass and acute ischemia. Ischemic zone flows in seven dogs with the bypass first closed and then open showed no significant contribution of bypass flow in the intact vascular system. Following acute proximal occlusion, rCBF was preserved by bypass flow.

Management of radiation-induced accelerated carotid atherosclerosis.

Patients with long survival following cervical irradiation are at risk for accelerated carotid atherosclerosis. The neurologic presentation in these patients mimics naturally occurring atheromatous disease, but patients often present at younger ages and with less concurrent coronary or systemic vascular disease. Hypercholesterolemia also contributes to this accelerated arteriosclerosis.

Technical controversies in carotid artery surgery.

Carotid endarterectomy has become a routine and safe therapeutic strategy in most neurovascular centers. Wide diversity of opinion and considerable debate, however, persists concerning the ideal methods of anesthetic management, cerebral protection, intraoperative monitoring, and arterial repair. We have examined and summarized the current status of these controversies and have identified several new techniques that hold promise for further development.

Isolated central nervous system angiitis first presenting as spontaneous intracranial hemorrhage.

Two cases of isolated central nervous system angiitis presenting as spontaneous intracranial hemorrhage are reported. The usefulness and limitations of cortical/leptomeningeal biopsy in this condition is described. Emphasis is placed on the clinical awareness of this unusual association to ensure early recognition and prompt management with immunosuppressive therapy.