Glenn W. Kindt

Treatment of Patients with Neurological Deficits Associated with Cerebral Vasospasm by Intravascular Volume Expansion

Four patients, including one preoperative patient, developed neurological deficits associated with angiographically proven cerebral vasospasm and were treated with intravascular volume expansion. Indicator dilution techniques were employed to monitor intravascular volume and cardiac functions during treatment. All four patients improved promptly. None of the patients developed cardiac or pulmonary dysfunction despite marked increase in intravascular volume and despite several risk factors such as cardiac symptoms, electrocardiographic abnormalities, and advanced age. The techniques of monitoring and controlling intravascular volume are described. We believe that this is an important therapeutic adjunct for certain aneurysm patients.

Treatment of patients with neurological deficits associated with cerebral vasospasm by intravascular volume expansion

Four patients, including one preoperative patient, developed neurological deficits associated with angiographically proven cerebral vasospasm and were treated with intravascular volume expansion. Indicator dilution techniques were employed to monitor intravascular volume and cardiac functions during treatment. All four patients improved promptly. None of the patients developed cardiac or pulmonary dysfunction despite marked increase in intravascular volume and despite several risk factors such as cardiac symptoms, electrocardiographic abnormalities, and advanced age. The techniques of monitoring and controlling intravascular volume are described. We believe that this is an important therapeutic adjunct for certain aneurysm patients.

Syringoperitoneal Shunt for Syringomyelia: A Preliminary Report

Syringoperitoneal shunting has been used in the treatment of 4 patients with idiopathic syringomyelia. The procedures have been performed without morbidity or mortality. Postoperative observation, ranging from 7 to 23 months, has not revealed progression of symptoms or failure of the shunt. The pathophysiological theories of syringomyelia are discussed, and various surgical procedures for syringomyelia are reviewed and their results compared to the effectiveness of the syringoperitoneal shunt.

Gradual carotid artery occlusion in the treatment of inaccessible internal carotid artery aneurysms

The authors discuss 21 cases of large or surgically inaccessible internal carotid artery aneurysms treated with gradual occlusion of the cervical portion of the internal carotid artery. Eighty-five per cent of the patients experienced relief or marked improvement of their symptoms after treatment. Two early cases developed postligation ischemic deficits that partially resolved. After the introduction of expansion of circulating blood volume and induced hypertension as adjuncts to graded carotid occlusion, no ischemic complications occurred.

New implantable continuous administration and bolus dose intracarotid drug delivery system for the treatment of malignant gliomas

A totally implantable system for the continuous and bolus delivery of intra-arterial chemotherapeutic agents to patients with malignant gliomas is described. The system utilizes an Infusaid pump (Infusaid Corp., Sharon, Massachusetts), which discharges the drug directly into the internal carotid artery and is percutaneously refillable. This system has been utilized experimentally in primates and in the treatment of six patients with malignant gliomas. It seems that this system can be utilized safely as an experimental technique in the treatment of malignant gliomas.

Modification of focal cerebral ischemia by cardiac output augmentation

Intravascular volume expansion has been employed successfully for treatment of ischemic stroke from cerebral vasospasm and from cerebrovascular occlusive disease. The physiologic mechanism responsible for this success has not previously been delineated in controlled experimentation. The objective of this investigation was to delineate the effects of cardiac output and of hemodilution in a primate model of focal cerebral ischemia. Two groups of anesthetized rhesus monkeys received extensive cardiovascular monitoring, and local cerebral blood flow (lCBF) was determined in both ischemic and nonischemic brain regions by the hydrogen clearance method. Both groups were subjected to unilateral middle cerebral artery occlusion. One group then underwent blood volume expansion with Dextran 40 (cardiac output augmentation), and one group underwent isovolemic hemodilution with Dextran 40, cardiac output being maintained constant. Significant increases in lCBF occurred in ischemic regions only and occurred only in response to augmentation of cardiac output. Isovolemic hemodilution failed to produce any changes in lCBF. This investigation indicates that ischemic brain regions are selectively vulnerable to alterations in cardiac output, these effects being independent of alterations in blood pressure. Blood viscosity changes may play only a minor role. This study strongly suggests an important role of intravascular volume expansion and cardiac output augmentation in treatment of acute ischemic stroke.

The effects of primary elevation of cerebral venous pressure on cerebral hemodynamics and intracranial pressure

The dynamics of an elevated cerebral venous pressure and its effect on cerebrospinal fluid (CSF) pressure have been studied in considerable detail in the past [ 1, 4, 11, 14, 151. However, controversy still exists over the relationships between these pressures. As early as 1887 Falkenheim and Naunyn [5] observed that venous occlusion at the right atrium resulted in a rise in intracranial pressure (ICP). Queckenstedt [ 131 in 1916 demonstrated the clinical importance of the relationship between cerebral venous pressure and ICP. The results of the previous studies have varied; some showing ICP consistently greater than cerebral venous pressure and others showing the reverse to be true. More recently, investigators have concerned themselves principally with the effects of primary elevation of ICP on the sagittal sinus wedge pressure and cerebral blood flow (CBF) [ 4, 10, 12, 141. There have been few reports concerning primary elevation of cerebral venous pressure and its effect upon CBF and ICP. Also, no reports are available on the effects of marked (over 30 mm Hg) elevations of cerebral venous pressure. For this report, a series of experiments were performed on the primate to determine the effect on ICP of a primary elevation of cerebral venous pressure. During each experiment the cerebral venous pressure was raised slowly to the systemic arterial pressure (SAP) while the effect on CBF was investigated. The pial vessels were observed directly through a watertight window as part of the experiment.

Carotid endarterectomy: technical improvements.

The immediate surgical results of 163 consecutive carotid endarterectomies performed in a neurosurgical training center are presented. The mortality rate was 0.6% and the permanent neurological morbidity rate was 2.5%. Several factors in the surgical technique including the use of magnified vision, full heparinization, the liberal use of intimal tacking sutures, and the employment of an indwelling shunt are thought to be responsible in part for the improved surgical results. (Neurosurgery, 7: 309-312, 1980).

Vertebral artery disease: Radiological evaluation, medical management, and microsurgical treatment

The neuroradiological evaluation, perioperative medical management, and microsurgical treatment of variously located vertebral artery lesions are presented. Four types of surgical procedures were undertaken: proximal vertebral artery to common carotid artery end-to-side anastomosis; external carotid artery to midcervical vertebral artery end-to-side anastomosis; external carotid artery to distal cervical vertebral artery end-to-end anastomosis; and occipital artery to posterior inferior cerebellar artery end-to-side anastomosis. Each case is used to demonstrate the evaluation and management involved, the type of and rationale for the surgical procedure selected, and the patency of the anastomosis performed. Two points are emphasized. One is that, after careful angiographic evaluation and improved perioperative medical management, lesions of the vertebral artery are indeed amenable to microsurgical intervention with relatively low risk to the patient. The other is that, whenever possible, anastomosis of the largest caliber of vessels with the least number of suture lines is the surgical treatment of choice.

Experimental acute hepatic encephalopathy: relationship of pathological cerebral vasodilation to increased intracranial pressure.

In clinical reports of encephalopathy and pediatric trauma, acute brain swelling has been postulated to be secondary to vasodilation of the cerebrovascular bed. Eight adult cats were studied to determine whether such pathological vasodilation was present in an experimental model of hepatic encephalopathy. All animals were anesthetized, ventilated, and monitored for intracranial pressure (ICP), arterial pressure, heart rate, arterial blood gases, temperature, and blood ammonia content. The regional cerebral blood flow (rCBF) was measured at three cortical sites by the hydrogen clearance technique. The intravenous infusion of ammonium acetate was used to produce blood ammonia levels comparable to those observed in severe Reyes syndrome. All experimental animals showed a significant increase in ICP as well as rCBF to a mean of 79.5 +/- 7.3 ml/100 g/minute. This represents a mean increase in %rCBF to 252% of control. The mean calculated cerebrovascular resistance (CVR) was noted to fall to 55 +/- 4.7% of control CVR values (p less than 0.001). This relative vasodilation was diffuse with no significant difference between hemispheres or lobes studied. Such a vasodilation, as shown by a marked fall in the resistance of the cerebrovascular bed, is a pathological response in light of the rising ICP. This suggests that pathological cerebral vasodilation may be an important cause of increased ICP in the brain suffering an acute generalized insult.