Christopher L. Taylor

Intraventricular infusion of vascular endothelial growth factor promotes cerebral angiogenesis with minimal brain edema.

OBJECTIVE Therapeutic cerebral angiogenesis, i.e., using angiogenic factors to enhance collateral vessel formation within the central nervous system, is a potential method for cerebral revascularization. Vascular endothelial growth factor (VEGF) is a potent endothelial cell mitogen that also increases capillary permeability, particularly in ischemic tissue. The purpose of this study was to assess the angiogenic and capillary permeability effects of chronic intraventricular infusion of exogenous VEGF in nonischemic brain tissue, because many patients with impaired cerebrovascular reserve do not exhibit chronic cerebral ischemia. METHODS Recombinant human VEGF165 was infused into the right lateral ventricle of rats at a rate of 1 &mgr;l/h for 7 days, at concentrations of 1 to 25 &mgr;g/ml, with osmotic minipumps. Control animals received vehicle only. Vessels were identified in laminin immunohistochemical analyses. Capillary permeability and brain edema were assessed with Evans blue extravasation, [3H]inulin permeability, and brain water content measurements. RESULTS Vessel density was dose-dependently increased by VEGF165 infusions, with significant increases occurring in animals treated with 5 or 25 &mgr;g/ml, compared with control animals (P < 0.01). Significant enlargement of the lateral ventricles was observed for the highest-dose group but not for animals treated with other doses. Capillary permeability was assessed in animals treated with a dose of 5 &mgr;g/ml. An increase in capillary permeability in the diencephalon was identified with Evans blue extravasation and [3H]inulin permeability assessments; however, the brain water content was not significantly increased. CONCLUSION Chronic intraventricular infusions of VEGF165 increased vascular density in a dose-dependent manner. There seems to be a therapeutic window, because infusion of VEGF165 at a concentration of 5 &mgr;g/ml resulted in a significant increase in vessel density with minimal associated brain edema and no ventriculomegaly.

Treatment of dural arteriovenous fistula using ethylene vinyl alcohol (onyx) arterial embolization as the primary modality: short-term results.

OBJECT A dural arteriovenous fistula (DAVF) typically involves meningeal feeding arteries and can cause clinical symptoms ranging from tinnitus to rupture of draining cortical or parenchymal veins. Surgical treatment may be technically demanding. Ethylene vinyl alcohol (Onyx, ev3 Neurovascular) has several properties that make it potentially useful as a primary treatment agent for DAVF. Onyx is expected to be a permanent embolic agent. It should have a decreased risk of catheter retention when compared with other permanent embolic materials. METHODS The authors report a series of six patients with symptomatic DAVF who were treated initially with transarterial Onyx embolization and other endovascular techniques. RESULTS Five patients had complete occlusion of their DAVF noted on the follow-up angiogram obtained between 2 and 4 months. One patient had residual filling via a small arterial branch that was stable on follow-up angiography. None of the patients had worsening of neurological function. One case was complicated by a retained catheter fragment. CONCLUSIONS Transarterial Onyx embolization and other endovascular methods can angiographically obliterate DAVF. In some cases, embolization allowed occlusion of multiple arterial feeding arteries from a single arterial injection. Technically, the embolization was optimized when a microcatheter position immediately adjacent to the point(s) of fistulization was achieved.

Cranial radiation exposure during cerebral catheter angiography

Background Radiation exposure to patients and personnel remains a major concern in the practice of interventional radiology, with minimal literature available on exposure to the forehead and cranium. Objective In this study, we measured cranial radiation exposure to the patient, operating interventional neuroradiologist, and circulating nurse during neuroangiographic procedures. We also report the effectiveness of wearing a 0.5 mm lead equivalent cap as protection against radiation scatter. Design 24 consecutive adult interventional neuroradiology procedures (six interventional, 18 diagnostic) were prospectively studied for cranial radiation exposures in the patient and personnel. Data were collected using electronic detectors and thermoluminescent dosimeters. Results Mean fluoroscopy time for diagnostic and interventional procedures was 8.48 (SD 2.79) min and 26.80 (SD 6.57) min, respectively. Mean radiation exposure to the operators head was 0.08 mSv, as measured on the outside of the 0.5 mm lead equivalent protective headgear. This amounts to around 150 mSv/year, far exceeding the current deterministic threshold for the lens of the eye (ie, 20 mSv/year) in high volume centers performing up to five procedures a day. When compared with doses measured on the inside of the protective skullcap, there was a statistically significant reduction in the amount of radiation received by the operators skull. Conclusions Our study suggests that a modern neurointerventional suite is safe when equipped with proper protective shields and personal gear. However, cranial exposure is not completely eliminated with existing protective devices and the addition of a protective skullcap eliminates this exposure to both the operator and support staff.

Neurosurgical practice liability: relative risk by procedure type.

BACKGROUND Neurosurgeons have the highest exposure to litigation of all medical and surgical specialties. OBJECTIVE To determine the relative risk of claims for compensation and indemnity by procedure type. The most common alleged factors and clinical outcomes are also determined. METHODS The Physician Insurers Association of America Data Sharing Project was queried for all claims involving a neurosurgeon with an incident date during the calendar year 2006. Data were compared with the American Association of Neurological Surgeons National Neurosurgical Procedural Statistics 2006 Survey. Statistical analysis was performed using the χ test and Fisher exact test as appropriate. RESULTS Claims were most common after spine surgery, followed by medical management and cranial surgery. Compared with spine surgery, cranial surgery was significantly less likely to result in a claim (P < .0001, relative risk: 0.45). However, the average indemnity for spine surgery was

Correlation between cerebral blood flow and oxygen saturation in patients with subarachnoid hemorrhage and traumatic brain injury

278,362 vs

Bilateral giant cavernous carotid artery aneurysms in a child with juvenile Paget's disease.

423,539 for medical management and

Delayed rebleeding of a spontaneously thrombosed aneurysm after subarachnoid hemorrhage

438,183 for cranial surgery. The most common alleged factors in spine surgery were improper performance, wrong level operated on, and unindicated procedure. The most common alleged factors in medical management were errors in diagnosis and failure to monitor a patient. The most common alleged factors in cranial surgery were errors in diagnosis and improper performance. For all claims, the most common clinical outcomes were paraplegia, infection, other unspecified complications, and cauda equina syndrome. CONCLUSION Claims are statistically less likely to occur after cranial surgery. However, indemnity is higher in cranial and medical management cases than in spine surgery cases. Nonsurgical treatment is a common source of liability in neurosurgical practice.

Acute Respiratory Distress Syndrome after Onyx Embolization of Arteriovenous Malformation

The INVOS cerebral oximeter and portable xenon enhanced CT (Xe/CT) scan are two commonly used diagnostic devices in patients who have experienced neurologic insults such as traumatic brain injury and subarachnoid hemorrhage. While the INVOS device is a relatively inexpensive, non-invasive measure of cerebral blood oxygen saturation, Xe/CT is a more complex costly diagnostic test that is the current gold standard for assessing cerebral perfusion in patients in the neurosciences intensive care unit (NSI) at the University of New Mexico Hospital. The purpose of this research was to investigate a possible relationship between these two diagnostic devices that might enable clinicians to better determine the appropriate timing and necessity of Xe/CT scans by evaluating trends in cerebral oximetry. The research was conducted in the University of New Mexico Hospital NSI over 18 months, with 25 imaging studies being collected from among 22 patients. Computer generated cortical segments obtained from the Xe/CT scans were correlated to INVOS cerebral oximeter pad placement on each patients forehead, and the values were then compared using Spearman correlation coefficients. In this study, no statistically significant relationship between the devices was found although expansion of the study to a greater number of patients may uncover such a relationship.

A novel single twist-drill access device for multimodal intracranial monitoring: a 5-year single-institution experience.

BACKGROUND Juvenile Paget disease (JPD) is a rare genetic bone disorder, also affecting the immune and vascular systems. We describe the first ever case of JPD associated with bilateral giant cavernous carotid artery aneurysms in a child. CASE DESCRIPTION A child with known JPD presented with left abducens nerve palsy and a computed tomographic angiogram revealed bilateral giant cavernous carotid artery aneurysms. He underwent a left-sided superficial temporal artery to middle cerebral artery bypass and endovascular carotid artery occlusion, followed by an identical procedure on the right side 3 months later and made an event-free recovery without any new neurological deficits. CONCLUSIONS This previously unreported association poses the question of determining the optimal management strategy for such cases. The pathophysiology and clinical features of JPD are discussed, with special emphasis on the management of giant cavernous carotid aneurysms in this subgroup of individuals.

The Use of Clinical Practice Guidelines in Determining Standard of Care

Background: This report provides a rare documentation of spontaneous thrombosis of a ruptured aneurysm followed by delayed recanalization and subsequent rerupture. Case Description: A 47-year-old female presented with spontaneous subarachnoid hemorrhage (SAH). Four aneurysms were identified on CT angiogram including a basilar apex aneurysm, considered source of bleeding. Cerebral angiogram on postbleed day (PBD) #1 showed spontaneous thrombosis of basilar apex aneurysm. The patient was discharged to a nursing home on PBD #18 after two subsequent studies showed no recanalization of the basilar aneurysm. The patient returned on PBD #26 with a second episode of spontaneous SAH. The previously thrombosed basilar aneurysm had recanalized and reruptured, which was now treated with coil embolization. Conclusion: We are not aware of a previous report of saccular cerebral aneurysm documenting spontaneous thrombosis after SAH and recanalization with second hemorrhage. This occurrence presents a dilemma regarding the timing and frequency of subsequent cerebrovascular imaging and treatment.