Andrew D. Firlik

Hyperthermia in the Neurosurgical Intensive Care Unit

OBJECTIVEIn 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°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. METHODSIn 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°C; an episode lasted until the temperature fell below this threshold. RESULTSThe 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. CONCLUSIONFever 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.

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 ≤6, ≤10, 11 to 20, 21 to 30, and >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 ≤20 cm3 · 100 g−1 · min−1 were identified in all patients, ips...

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.

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%.

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.

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.

Relation between cerebral blood flow and neurologic deficit resolution in acute ischemic stroke

Background and objective: Early intervention remains the key to acute ischemic stroke therapy. Many patients whose deficits would later resolve without intervention are exposed to the risks of stroke treatment without benefit. The purpose of this study was to determine whether patients with transient deficits could be distinguished from patients with evolving strokes on the basis of acute cerebral blood flow (CBF) measurements before any clinical distinction could be made. Methods: Fifty-three patients who presented with acute hemispheric stroke symptoms and who underwent xenon-enhanced CT (XeCT) CBF studies within 8 hours of onset of symptoms (and before any clinical improvement) were studied. Results: Eight patients (15%) had a complete resolution of their symptoms within 24 hours (not related to treatment). All eight patients with deficits that resolved had normal CBF in the symptomatic vascular territories (mean time to XeCT = 3 hours, 51 min). Mean CBF in the regions of interest of the symptomatic vascular territories of patients who had deficits that resolved was 35.4 ± 8.1 mL · 100 g-1 · min-1 compared with 17.3 ± 9.3 patients with evolving strokes (p= 0.00058). Conclusions: Patients with ischemic neurologic deficits that will later resolve can be acutely distinguished from patients with evolving cortical infarctions using XeCT CBF measurements. CBF measurements may assist in the triage of patients for acute stroke therapy by selecting patients with a favorable prognosis and may not benefit from therapy but would still be exposed to the potential risks and expense of treatment.

Quantitative Cerebral Blood Flow Determinations in Acute Ischemic Stroke Relationship to Computed Tomography and Angiography

BACKGROUND AND PURPOSE The advent of new modalities to treat acute ischemic stroke presents the need for accurate, early diagnosis. In acute ischemic stroke, CT scans are frequently normal or reveal only subtle hypodense changes. This study explored the utility and increased sensitivity of xenonenhanced CT (XeCT) in the diagnosis of acute cerebral ischemia and investigated the relationship between cerebral blood flow (CBF) measurements and early CT and angiographic findings in acute stroke. METHODS The CT scans, XeCT scans, and angiograms of 20 patients who presented within 6 hours of acute anterior circulation ischemic strokes were analyzed. RESULTS CT scans were abnormal in 11 (55%) of 20 patients. XeCT scans were abnormal in all 20 (100%) patients, showing regions of interest with CBF < 20 (mL/100 g per minute) in the symptomatic middle cerebral artery (MCA) territories. The mean CBF in the symptomatic MCA territories was significantly lower than than of the asymptomatic MCA territories (P < .0005). In patients with basal ganglia hypodensities, the mean symptomatic MCA territory CBF was significantly lower than that of patients who did not exhibit these early CT findings (P < .05). The mean symptomatic MCA territory CBF in patients with angiographic M1 occlusions was significantly lower than that of patients whose infarcts were caused by MCA branch occlusions (P < .01). CONCLUSIONS These results show that XeCT is more sensitive than CT in detecting acute strokes and that CBF measurements correlate with early CT and angiographic findings. XeCT may allow for the hyperacute identification of subsets of patients with acute ischemic events who are less likely to benefit and more likely to derive complications from aggressive stroke therapy.

COMPLICATIONS OF STEREOTACTIC BRAIN SURGERY

The authors review iatrogenic complications of stereotactic surgery, including tumor biopsy, cyst or abscess aspiration, movement disorder surgery, and radiosurgery. The expected morbidities and steps taken to reduce complications are also discussed.

Physiological diagnosis and surgical treatment of recurrent limb shaking : Case report

OBJECTIVE AND IMPORTANCE Although recurrent limb shaking has been observed in patients with carotid occlusion, its cause, method of diagnosis, and definitive treatment have yet to be fully elucidated. This report examines the cerebrovascular physiology of a patient with recurrent limb shaking by means of xenon-enhanced computed tomographic (XeCT) scanning. By measuring cerebral blood flow (CBF) and cerebrovascular reserve capacity, we were able to confirm both the clinical diagnosis and the response to treatment on physiological grounds. CLINICAL PRESENTATION The patient is a 49-year-old man who presented with frequent brief attacks of left arm and leg shaking that occurred at standing or coughing. After cervical radiation therapy for a laryngeal carcinoma, he was found to have bilateral carotid occlusion with minimal collateral development. XeCT scans revealed borderline ischemic perfusion and lack of cerebrovascular reserve in response to an acetazolamide vasodilatory challenge. INTERVENTION The patient underwent a right superficial temporal artery to middle cerebral artery bypass to augment cerebral perfusion. CONCLUSION After the procedure, the patients limb shaking attacks ceased. The postoperative XeCT scan showed improved CBF and a return of cerebrovascular reserve capacity. Recurrent limb shaking is a manifestation of decreased CBF. Quantitative XeCT CBF studies coupled with vasodilatory challenge is an important way to assess patients with cerebrovascular disorders and thus identify individuals who will benefit from cerebral revascularization.