Stereotactic radiosurgery for motor cortex region arteriovenous malformations.

OBJECTIVE: The optimal management of arteriovenous malformations (AVMs) in critical brain locations remains controversial. To reduce the risk of an AVM hemorrhage and to enhance the possibility of preserving neurological function, stereotactic radiosurgery was performed in 33 patients with newly diagnosed or residual AVMs located within the motor cortex. The role of embolization also was examined. METHODS: During a 9-year study period, 33 patients with AVMs located primarily in the motor cortex region were treated with stereotactic radiosurgery. These patients were followed up radiographically for a minimum of 36 months, or less if obliteration was documented before 36 months had elapsed. Of the 33 patients, 9 underwent embolization and 1 underwent microsurgery before radiosurgery. Nine patients required a second radiosurgery. The mean AVM target volume was 4.35 cc, and the average radiation dose to the AVM margin was 20 Gy. The median follow-up was 36 months (range, 10-91 mo), and angiographic follow-up of eligible patients was performed 24 or 36 months after radiosurgery. RESULTS: Results were stratified by radiosurgical target volumes: less than 3 cc (Group 1), 3 to 10 cc (Group 2), and greater than 10 cc (Group 3). Overall (including second radiosurgery), 13 (87%) of 15 patients in Group 1 had complete obliteration confirmed by angiography. Nine (64%) of 14 patients in Group 2 exhibited nidus obliteration, and one (25%) of four patients in Group 3 demonstrated obliteration on a magnetic resonance imaging scan. Eight patients (24%) underwent second-stage radiosurgery after angiography revealed a persistent AVM nidus; three patients demonstrated complete obliteration on follow-up angiography. The obliteration rate was higher (87%) for AVMs with less than 3 cc target volume and lower (56%) for those with target volumes larger than 3 cc. One patient experienced worsening neurological function after radiosurgery, and one died from delayed AVM hemorrhage during the latency period. No patient bled after angiographically confirmed AVM obliteration. CONCLUSION: Stereotactic radiosurgery is a successful and safe management option for patients with motor cortex AVMs. The obliteration of AVMs and the attendant low morbidity rates indicate a primary role for radiosurgery in these patients. Staged radiosurgery may be necessary to increase obliteration rates for larger AVMs or for those that are not obliterated after the first procedure.

Hyperthermia in the neurosurgical intensive care unit.

OBJECTIVE: In patients with traumatic or ischemic brain injury, hyperthermia is thought to worsen the neurological injury. We studied fever in the neurosurgical intensive care unit (ICU) population using a definition common to surgical practice (rectal temperature >38.5 degrees C). We sought to determine fever incidence, fever duration, and peak temperature and to quantify the use of antipyretic therapy. We also attempted to determine the patient subgroups that are at highest risk for development of fever. METHODS: In a retrospective chart review of a 6-month period, all febrile episodes that occurred in a consecutive series of neurosurgical ICU patients in a university hospital setting were studied. A febrile episode was defined as a rectal temperature of at least 38.5 degrees C; an episode lasted until the temperature fell below this threshold. RESULTS: The 428 patients studied had 946 febrile episodes. Fever occurred in 47% of patients, with a mean of 4.7 febrile episodes in each febrile patient. Fevers occurred in more than 50% of patients who were admitted to the ICU for subarachnoid hemorrhage, a central nervous system infection, seizure control, or hemorrhagic stroke, but they occurred in only 27% of patients admitted for spinal disorders. Fevers occurred in 15% of the patients who stayed in the ICU less than 24 hours, but in 93% of those who remained longer than 14 days. Despite the use of antipyretic therapy for 86% of the febrile episodes, 57% lasted longer than 4 hours and 5% lasted longer than 12 hours. CONCLUSION: Fever is common in critically ill neurosurgical patients, especially those with a prolonged length of stay in the ICU or a cranial disease. If hyperthermia worsens the functional outcome after a primary ischemic or traumatic injury, as has been suggested by several studies of stroke patients, treatment of fever is a clinical issue that requires better management.

The neurosurgeon as innovator and entrepreneur.

INNOVATION IS THE driving force behind progress in neurosurgery. Most significant innovations require commercialization to ensure appropriate development and ultimate distribution to patients. There are several key factors that determine whether a particular innovation is likely to be commercially successful. Relationships between academic neurosurgeons and industry are likely to increase in the future. Stronger and more productive relationships between academic neurosurgeons and commercial ventures will provide new opportunities for neurosurgeons to bring innovations to patients more effectively and efficiently. The transfer of innovation from the academic environment to the commercial setting is consistent with the academic mission and can increase funding for basic and clinical neuroscience research.

Relationship between cerebral blood flow and clinical outcome in acute stroke.

OBJECTIVE: The purpose of this study was to determine the relationship between cerebral blood flow (CBF) measurements in acute stroke and early clinical outcome. MATERIAL AND METHODS: The xenon-enhanced computed tomography (XeCT) CBF studies performed in 50 patients in the acute stage (within 8 h) of a hemispheric stroke were retrospectively analyzed. The mean CBF of the symptomatic vascular territory was compared to the corresponding territory in the contralateral hemisphere. Clinical assessment on admission and discharge was performed using the National Institutes of Health stroke scale (NIHSS). RESULTS: Three groups were defined according to the degree of CBF asymmetry between the symptomatic and the contralateral asymptomatic vascular region. The CBF asymmetry was mild in group A (< or =20%), moderate in group B (>20% and <60%) and severe in group C (> or =60%). Patients in group A (n = 18) had a good outcome with a mean NIHSS score of 2 +/- 2 at discharge. In group B, the patients (n = 22) had intermediate but variable outcomes: 2 patients died and the mean NIHSS score for the survivors was variable (mean NIHSS score: 9 +/- 6). The patients in group C (n = 10) had a very poor outcome: 4 patients died and the survivors had a mean NIHSS score of 15 +/- 1. CONCLUSIONS: Quantitative XeCT CBF measurements may be useful for selecting subgroups of stroke patients with different clinical outcomes. The possibility of predicting patient prognosis as early as in the first hours after the ischemic event may help to identify the appropriate target population that will benefit from aggressive stroke therapy.

The utility of XeCT cerebral blood flow in the management of acute stroke.

The fundamental pathophysiologic event underlying acute ischemic stroke is a reduction in cerebral blood flow (CBF). Over 100 patients with acute stroke have been studied with xenon-enhanced computed tomography (XeCT) during the past three years. A retrospective analysis of these patients has revealed several important observations. XeCT is very sensitive in detecting acute ischemia. The pattern and depth of ischemia can be correlated with the physical examination, CT findings, and angiographic results. Patients with large volumes of severely ischemic tissue are more likely to suffer herniation, hemorrhagic conversion, and death than patients with small volumes of less ischemic tissue. Patients with normal CBF studies are more likely to have their deficits resolved within 24 hours that patients with abnormal CBF maps. It is likely that future prospective studies will better define the precise utility of XeCT in the acute management of cerebral ischemia.

Xenon-enhanced computed tomography in the management of cerebral vasospasm following aneurysmal subarachnoid hemorrhage.

At the University of Pittsburgh, xenon-enhanced computed tomography (XeCT) serves numerous critical roles in the management of patients following aneurysmal subarachnoid hemorrhage (SAH). Routine baseline XeCT studies are obtained within 24 hours of surgery and are used for comparison to later studies. In the setting of a delayed neurological deficit, XeCT is used emergently to distinguish vasospasm from other possible causes and to triage patients to appropriate non-invasive or invasive therapies. In cases of a delayed neurologic deficit without CBF changes, regardless of transcranial doppler results which can be unreliable, XeCT can prevent unnecessary angiography and potentially harmful invasive treatments. For patients demonstrating territorial ischemia diagnostic of symptomatic vasospasm, XeCT is used to monitor the efficacy of both invasive and non-invasive interventions. This paper summarizes the results and significance of clinical studies of XeCT in the management of patients after SAH at our institution.

Remote effects of acute ischemic stroke: A xenon CT cerebral blood flow study.

OBJECTIVE: The purpose of this study was to verify transhemispheric diaschisis in the early hours after an ischemic event. METHODS: XeCT cerebral blood flow (CBF) studies within 8 h of stroke were studied in 23 patients. Mean CBF was evaluated in the ischemic area, contralateral hemisphere and ipsilateral cerebellum. RESULTS: A severe CBF reduction was found in the ischemic area (mean 9 +/- 3 ml/100 g/min). The mean CBF in the unaffected hemisphere (33 +/- 10 ml/100 g/min) was 35% less compared to the normal mean value. CBF was decreased in the cerebellum ipsilateral to the stroke (mean 31 +/- 12 ml/100 g/min) suggesting a blood flow depression of the whole brain. CONCLUSIONS: During the initial hours of cerebral ischemia, the asymptomatic hemisphere demonstrated CBF depression that was part of the global flow reduction.

Factors affecting survival rates for acute vertebrobasilar artery occlusions treated with intra-arterial thrombolytic therapy: a meta-analytical approach.

OBJECTIVE: To determine whether recanalization, coma at presentation, or clot location in the basilar artery influences the relative mortality risk after intra-arterial thrombolytic therapy for acute vertebrobasilar artery occlusions. METHODS: Studies were identified using the MEDLINE database for January 1987 to November 1997. Series were included if they involved 10 or more patients with basilar or vertebrobasilar artery occlusions, used urokinase and/or recombinant tissue plasminogen activator, and were written in English. A fixed-effect meta-analysis approach was used to estimate the risk of death with the aforementioned risk factors. Each study was weighted according to sample size. Relative risks were calculated with 95% confidence intervals. RESULTS: As calculated from peer-reviewed published data, the relative mortality risk for patients for whom recanalization was attempted but not achieved was 2.34 (95% confidence interval, 1.48-3.71; n = 126). Coma at presentation was associated with a relative mortality risk of 1.95 (95% confidence interval, 1.26-2.99; n = 145). Clot locations in the distal one-third of the basilar artery were shown to favor survival, compared with clots located in the proximal and/or middle portions of the basilar artery (relative risk, 0.52; 95% confidence interval, 0.31-0.86; n = 126). CONCLUSION: The combined data suggest that coma at presentation has an independent and adverse effect on survival rates. Complete recanalization, distal clot location, and responsiveness at the time of presentation are statistically significant factors for increased patient survival rates.

Development of obstructive hydrocephalus with lumboperitoneal shunting following subarachnoid hemorrhage.

Hydrocephalus is a frequent complication of subarachnoid hemorrhage (SAH). The optimum method of treating hydrocephalus in this setting has not been determined. We review our experience with patients developing communicating hydrocephalus secondary to SAH and subsequently treated with lumboperitoneal (LP) shunts. Following hospitalization for the treatment of SAH, patients who developed clinical symptoms and radiologic signs of hydrocephalus were treated with (ventriculoperitoneal) VP or LP shunting. Eighteen patients received an LP shunt, of which seven (28%) developed a non-communicating or obstructive hydrocephalus. These seven patients underwent replacement with a VP shunt and have not had further complications. In the setting of post-SAH communicating hydrocephalus, obstructive hydrocephalus may develop after LP shunt placement. Patients who develop this complication and have their LP shunts converted to VP shunts have a favorable prognosis.

Advanced CT imaging (functional CT).

Computed tomography can provide anatomic and functional information about the brain. The conventional CT of the brain can be coupled with a cerebral blood flow examination using the stable xenon CT technique and with a CT angiography. Distinct subgroups of patients based on variations in cerebral blood flow and vascular pathology have been demonstrated. The addition of the functional information has become extremely important in triaging and determining the appropriate intervention in the patient with an acute neurological deficit.

Intra-arterial papaverine for the treatment of cerebral vasospasm following aneurysmal subarachnoid hemorrhage.

BACKGROUND: Intra-arterial papaverine (IAP) has been described as a treatment for cerebral vasospasm refractory to standard therapy. METHODS: We report a series of 15 consecutive patients with aneurysmal subarachnoid hemorrhage in which IAP was employed for the treatment of symptomatic vasospasm. All patients exhibited delayed ischemic neurologic deficits, focal cerebral hypoperfusion on stable xenon-enhanced computerized tomography cerebral blood flow studies, and angiographically defined arterial narrowing. Papaverine was infused into 32 arteries on 23 occasions. Six patients required multiple treatments between 1 and 8 days apart. In five instances, IAP was combined with angioplasty. RESULTS: Angiographically defined vasospasm was at least partially reversed immediately following treatment on 18 of 23 occasions. The associated clinical improvement was major on 6 occasions, and either minor or none on 17. Post-treatment cerebral blood flow was assessed on 13 occasions and showed improvement in previously ischemic areas on six occasions and no improvement on seven. Complications were encountered on four occasions. Systemic hypotension and transient brain-stem depression were seen with vertebral artery infusions; a generalized seizure and paradoxical aggravation of vasospasm resulting in hemispheric infarction occurred with internal carotid artery infusions. CONCLUSIONS: Intra-arterial papaverine resulted in reversal of arterial narrowing in the majority of cases (78%). However, this angiographic improvement was associated with cerebral blood flow augmentation in only 46% of cases analyzed, and major clinical improvement in 26%.

The peer-review process of the Journal of Neurosurgery.

Peer review is the process by which scientific articles are evaluated and selected for publication. To clarify this procedure for readers and writers, the authors present a detailed description of peer review at the Journal of Neurosurgery (JNS) in the context of other journals. They discuss the unique characteristics of JNS's peer-review process and how it contributes to the quality of the JNS.

Ischemic core and penumbra in human stroke.

BACKGROUND AND PURPOSE: The ischemic core and penumbra have not been thoroughly characterized after acute cerebral thromboembolic occlusion in humans. Differentiation between areas of potentially viable and irreversibly injured ischemic tissue may facilitate assessment and treatment of stroke patients. METHODS: Cerebral blood flow (CBF) was measured in 20 patients with acute middle cerebral artery (MCA) occlusion between 60 and 360 minutes after stroke onset, with the stable xenon computerized tomography (CT) technique. Threshold displays were generated at a single level, and the percentages of hemisphere with CBF 30 cm3. 100 g-1. min-1 were measured. The corresponding images on 12 available follow-up CT scans were similarly assessed to determine the area of final infarct. Comparisons were analyzed with a paired Student's t test and Pearson's correlation coefficient. RESULTS: Discrete and confluent areas of CBF

The effect of reperfusion therapy on cerebral blood flow in acute stroke.

The effect of reperfusion therapy on cerebral blood flow (CBF) in acute cerebral ischemia was studied using xenon-enhanced computed tomography (XeCT). The XeCT CBF studies of 10 patients were evaluated before and after thrombolytic therapy. CBF evidence of reperfusion was evaluated in relation to the angiographic results and the clinical outcomes. Six patients had occlusions of the middle cerebral artery and four of the internal carotid artery. The mean CBF of the ischemic areas before attempted reperfusion was 9 +/- 3 mL/100g/min compared with 34 +/- 9 mL/100g/min in the contralateral asymptomatic region (P<.001). Intra-arterial-thrombolysis was performed in nine patients, and in one patient the intravenous route was used. Reperfusion of the ischemic region was shown in 9 of 10 patients, both angiographically and with the XeCT CBF studies (the mean CBF increased from 9 +/- 3 mL/100g/min to 32 +/- 10 mL/100g/min, P<.001). Among the nine successfully reperfused patients, seven were neurologically improved, one was unchanged, and one died. The mean National Institutes of Health stroke scale in the eight reperfused survivors was 12 on admission and decreased to 6 on discharge. XeCT CBF measurements are correlated with the angiographic results and can assist in the understanding of the effects of thrombolytic therapy on CBF in acute stroke. Re-establishment of CBF is associated with an improved clinical outcome but exceptions can be found. Reperfusion can occur in ischemic brain regions even with very low CBF (approaching 0 mL/100g/min) although it is not associated with prevention of infarction.

Aneurysmal intracerebral hemorrhage: clinical outcome after emergent surgical treatment.

BACKGROUND: Management guidelines and recovery potentials for individuals presenting with poor clinical condition owing to an aneurysmal intracerebral hemorrhage are not well established. METHODS: We assessed the outcome of a consecutive series of 6 patients with aneurysmal intracerebral hemorrhages presenting with Hunt and Hess clinical grade IV or V selected to undergo emergent hematoma evacuation and aneurysm clip obliteration. Their presenting clinical condition and neuroradiology were assessed, as well as early surgical results and follow-up outcome. RESULTS: The 2 women and 4 men were 30 to 59 years old. All 6 patients had profound neurological deficits on admission, with Glasgow Coma Scale scores of 4 to 9. Aneurysmal intracerebral hemorrhage diameters measured from 6 to 8 cm and were associated with 5 to 15 mm of midline shift. Surgical intervention was initiated within 3 hours of ictus in 5 patients and within 7 hours in one patient. All 6 patients survived, demonstrated clinical improvement postoperatively, and were transferred to rehabilitation centers 19 to 30 days after presentation. The Glasgow Outcome Scores were 2 to 3 with a minimum follow-up interval of 12 months. Four patients returned home and resumed independent activities of daily living; one required partial supervision. One patient remained in a chronic care facility. CONCLUSION: An acute management protocol, including aggressive neurosurgical intervention, with craniotomy for hematoma evacuation and aneurysm clip obliteration, can result in good neurological outcome in carefully selected, poor-grade patients with aneurysmal intracerebral hemorrhage.

Xenon-enhanced computed tomography cerebral blood flow measurements in acute cerebral ischemia: Review of 56 cases.

OBJECTIVE: Ischemic stroke must be diagnosed promptly if patients are to be treated with thrombolytic therapy. The diagnosis of acute cerebral ischemia, however, is usually based on clinical and computed tomography (CT) scan findings. CT scans are often normal in the first few hours after stroke. The purpose of this study was to determine whether Xenon-enhanced CT (XeCT) cerebral blood flow (CBF) studies could increase the sensitivity of stroke detection in the acute stage. METHODS: CBF studies performed within 8 hours of symptom onset were evaluated in 56 patients who presented with hemispheric stroke symptoms. Mean CBF in the symptomatic vascular territory was calculated and compared with the corresponding contralateral area. CBF values below 18 mL/100g/min on 2 adjacent regions of interest were considered ischemic lesions. CT scans and angiograms were compared with the XeCt findings. Neurological condition on admission and discharge was evaluated by using National Institutes of Health Stroke Scale (NIHSS) scores. RESULTS: The mean NIHSS score on admission was 12+/-5. Early CT scans were abnormal in 28 (50%) patients. There were 9 (16%) patients who had normal XeCT scans because of spontaneous reperfusion of the ischemic area. XeCT studies showed an ischemic lesion in 47 (84%) patients. In these patients, the mean CBF in the affected vascular territory was 16+/-8 mL/100g/min compared with 35+/-13 mL/100g/min in the contralateral specular territory (P<0.001). There were no false positive or negative XeCT studies, and the location of the perfusion defect corresponded with the CT and/or angiographic findings in all cases. Eight patients died (14%), and the 48 survivors (86%) had a mean NIHSS score of 9+/-6 on discharge. CONCLUSIONS: CBF measurements were correlated with the CT and angiographic results and greatly assisted in the diagnosis of acute ischemic stroke. XeCT studies used for estimating the location and extent of cerebral ischemia may be important in the triage of patients for acute stroke therapy.

Staged volume radiosurgery followed by microsurgical resection: a novel treatment for giant cerebral arteriovenous malformations: technical case report.

OBJECTIVE AND IMPORTANCE: We describe the successful treatment of symptomatic giant arteriovenous malformations (AVMs) using staged volume radiosurgery followed by microsurgical resection. CLINICAL PRESENTATION: A 57-year-old man presented with Spetzler-Martin Grade 5 AVMs, with persistent headaches and seizures. He had previously undergone eight attempts at AVM embolization and a craniotomy for attempted AVM resection; he had suffered four episodes of brain hemorrhaging but had made a good neurological recovery. INTERVENTION: Because of the persistent symptoms of the patient and his history of hemorrhaging, a treatment plan based on staged radiosurgical treatments of different portions of the AVMs (three sessions, spaced 6 mo apart), followed by delayed microsurgical removal of the much-reduced residual AVMs (3 years later), was undertaken. The patient did not suffer any additional hemorrhaging episodes, his AVMs were completely removed, and he has made a good recovery. CONCLUSION: Staged volume radiosurgery followed by microsurgical resection of the residual AVMs represents a novel treatment strategy for the management of Grade 5 AVMs that might be untreatable by any single treatment method used alone.