Rapid monitoring of intraoperative cerebral blood flow using 133Xe.

This study examined the feasibility of rapid rCBF monitoring using 133Xe as a tracer during operative procedures. We compared the initial slope index derived from two bicompartmental and one monocompartmental physiological models. The single-compartment model requires only 3 min of monitoring, whereas the bicompartmental models, thought to be more reliable, require 11 min of clearance. Data were collected from 26 patients undergoing carotid endarterectomy. Approximately 20 mCi of 133Xe in saline was injected i.v. for up to five measurements per patient, for a total of 117 measurements. The robustness of the regression for the three parameters (r = 0.781-0.99, p less than 0.0001) suggests that the three parameters are closely related. This is supported by similarity of the slopes of the regression lines (between 0.944 and 1.25) and the mean +/- SD of the three rCBF models (24.9-27.5 +/- 12.0-14.3 ml 100 g-1 min-1). Similar results were obtained for individual detectors, despite the expected higher variability. For intraoperative use in surgical procedures in which physiological conditions may change rapidly and i.v. injections of tracer must be used, a rCBF index that quickly and accurately reflects flow conditions is useful. Our data suggest that the single-compartmental Wyper index may be used to provide information about cerebral perfusion that is as accurate and robust as bicompartmental models, but requires only one-quarter of the data collection time.

Reduced hypercapnic vasoreactivity in moyamoya disease.

We measured cerebral perfusion at rest and in response to CO2 in eight patients with moyamoya disease (MMD), using the 133xenon inhalation method to determine the effect of large-vessel occlusive disease on vasoreactivity. We studied three other groups for comparison, including four with bilateral internal carotid artery occlusions (BICAO), 11 with unilateral carotid occlusion (UICAO), and six with unilateral middle cerebral artery stem occlusion (UMCAO). Resting flows appeared to correlate with the severity of occlusive disease overall. Normocapnic perfusion was lowest in the group with BICAO and decreased in proportion to the degree of contralateral stenosis in the group with UICAO. Hypercapnic perfusion correlated with the apparent adequacy of angiographic collaterals. Reactivity was lowest in the MMD group (0.79%/mm Hg) whose collateral supply was limited to leptomeningeal anastomosis from the posterior cerebral artery, but highest in the patients with BICAO (2.72%/mm Hg), each of whom showed excellent posterior communicating artery flow. The clinical course of the MMD group was compatible with the syndrome of perfusion insufficiency with repeated ischemic attacks or a saltatory progression of an ischemic deficit; CT showed infarction in the borderzone territory. These results suggest that a severely reduced hypercapnic response may help to identify patients with ischemic syndromes due to perfusion failure in the borderzones, as in MMD.

Carotid endarterectomy: what is its current status?

The plethora of recent articles regarding carotid endarterectomy has tended to confuse rather than clarify its indications, efficacy, and acceptability. The National Institutes of Health has recently funded two large multicenter controlled clinical trials, one including asymptomatic persons with carotid stenoses, and the other, patients having transient ischemic episodes or minor strokes. Eight academic professors of neurology (four), neurosurgery (two), and vascular surgery (two) with a long and abiding interest in cerebrovascular disease prepared a statement delineating acceptable levels of mortality and morbidity from this procedure. These might serve as guidelines until the large trials have been completed.

Basal arterial occlusive disease.

Seventeen patients with basal occlusive disease have been seen over the past 4 years. Nine of these had a classical moyamoya appearance on angiography. Of these nine, seven were adults and two were children. Eight had ischemic episodes, and one had a hemorrhage. One had neurofibromatosis with a chiasmal glioma and had received radiotherapy. Eight patients underwent superficial temporal-middle cerebral artery (STA-MCA) bypass, and one refused operation. Six patients improved, one had a stroke on the opposite side, and one died. Eight patients had unilateral basal arterial occlusive disease. Of these, three had ischemic episodes, four had hemorrhages, and one had only headaches. Four were adults, and four were children. Five underwent STA-MCA bypass with improvement, one with headaches had an aneurysm treated, and two were not operated upon. Considerations regarding the cause, therapeutic options, and disease course in these patients are discussed.

Computerized electroencephalogram monitoring and carotid artery shunting.

During carotid artery surgery, ischemic electroencephalogram (EEG) changes were detected by computerized analysis in 27 of 225 carotid clamping intervals. All but 7 of these changes resolved spontaneously before the restoration of blood flow. Restored flow was associated, after variable delay, with an improved EEG pattern in 6 of 7 cases. Of 27 EEG episodes, there were 5 cases in which the EEG event persisted for 10 minutes or longer. All 5 patients developed new neurological deficits; none of the other patients did. It is suggested that all patients undergoing carotid artery surgery be monitored with EEG and that a shunt be placed if a persistent EEG change is noted.

Persistent hypoglossal artery and persistent trigeminal artery presenting with posterior fossa transient ischemic attacks. Report of two cases.

Two patients, one with a persistent hypoglossal artery and the other with a persistent trigeminal artery, presented with transient ischemic attacks in the distribution of the posterior fossa. Both had stenosis and ulcerative plaques at the carotid bifurcation. Their symptoms were successfully relieved after carotid endarterectomy.

Management of extracranial carotid stenosis and intracranial aneurysms.

Twenty patients with extracranial carotid stenosis and intracranial aneurysms are reviewed. Fifteen of these patients had transient ischemic attacks (TIA's) and incidental aneurysms. The other five presented with symptoms referrable to an aneurysm, and angiography revealed significant carotid stenosis. None of the patients who presented with TIA's and underwent endarterectomy suffered subarachnoid hemorrhage. However, those patients who presented with symptoms referrable to an aneurysm and underwent endarterectomy seem to be at greater risk for subarachnoid hemorrhage.

Incidence and etiology of intracerebral hemorrhage following carotid endarterectomy.

In a consecutive series of 1930 carotid endarterectomies there were eight cases of postoperative intracerebral hemorrhage. One of these patients was operated on 2 weeks following cerebral infarction and had severe uncontrollable hypertension after surgery. A second patient had an intraoperative embolus and bled while fully heparinized on the 3rd postoperative day. Only one patient in the series bled into an area of documented cerebral infarction. The remainder of the cases represented hemorrhage into essentially normal brain. Seven of the eight patients with intracerebral hemorrhage had high-grade internal carotid artery stenosis preoperatively. Although several factors have contributed to the brain hemorrhages in this series of patients, postoperative cerebral hyperperfusion which often follows endarterectomy may have played an important role. Defective cerebrovascular autoregulation in chronically ischemic brain regions may predispose patients to intracerebral hemorrhage after removal of a high-grade stenosis of the internal carotid artery.

Thiopental effect on cerebral blood flow during carotid endarterectomy.

To investigate the effect of thiopental on cerebral blood flow (CBF) during carotid endarterectomy, five patients receiving isoflurane-N2O anesthesia were studied. During the period of temporary bypass shunting, a baseline CBF was measured using i.v. Xe washout, and global CBF was calculated from the mean of 10 detectors. Thiopental was given in a dose sufficient (mean 4.5, range 2.6-5.8 mg/kg) to result in burst-suppression on the electroencephalogram (EEG) of approximately 1:1 duration and CBF was measured again. Data were compared using repeated measures analysis of variance. Thiopental significantly reduced mean (+/-SE) CBF (ml/100 g/min) from 37 +/- 6 to 18 +/- 2 (p <0.02). Corresponding PaCO2 (mm Hg) values were 42.8 +/- 1.2 and 41.2 +/- 1.6 and mean systemic blood pressure (mm Hg) was 101 +/- 3 and 100 +/- 6, respectively (NS). Mean % change in CBF was 48 +/- 5 (range 32-62%). There was no relationship between the dose administered and the change in CBF. During steady-state anesthesia, a small dose of thiopental capable of suppressing EEG resulted in a profound reduction in CBF.

Rupture of a previously documented asymptomatic aneurysm enhances the argument for prophylactic surgical intervention.

A case is presented of an incidentally discovered 6-mm aneurysm that was left untreated and subsequently produced a subarachnoid hemorrhage. The patient had no previous history of intracranial hemorrhage from any other source. A case of this type has not been previously documented in the literature. This experience points out the potential for catastrophe in small unruptured aneurysms found in patients without previous subarachnoid hemorrhage. The extremely low operative morbidity for repair of these types of lesions in otherwise healthy individuals would argue strongly for prophylactic surgery in properly selected patients.

Cerebral emboli from intracranial aneurysms.

Cerebral vasospasm has been implicated as the major pathophysiologic mechanism responsible for the cerebral ischemia and infarction that sometimes follows the rupture of intracranial aneurysms. Two cases are reported in which aneurysms of the internal carotid arteries were the source of emboli resulting in infarctions. Embolic phenomena should be considered as a possible cause of the morbidity associated with intracranial aneurysms.

Spinal extradural meningiomas.

Spinal meningiomas may be primarily extradural, leading to errors in diagnosis and management. Myelographic findings and the microscopic examination of fresh tissue at the time of operation often lead to the conclusion that the tumor is metastatic. Three patients with this type of meningioma have been encountered. Although extensive removal of the tumor was accomplished in each case, the correct diagnosis was difficult to establish at the time of the operation. A second operation was necessary in one patient because the true nature of the tumor was not recognized initially.

Reproductive function in temporal lobe epilepsy: the effect of temporal lobectomy.

We have examined sexual and reproductive changes in 25 patients (11 men and 14 women; mean follow-up 13 years) with temporal lobe epilepsy who underwent temporal lobectomy. Five men and two women had sexual dysfunction preoperatively, in particular, decreased libido. This improved after temporal lobectomy in three of these patients. One woman developed a partial Klüver-Bucy syndrome. Reproductive dysfunction was present in one man (oligospermia) and in ten women (four had the onset of seizures either at pregnancy or menarche; four had increased frequency of seizures during menarche or pregnancy, and two had amenorrhea). The man fathered two children post-operatively, and an appreciable improvement in both the seizure activity and the reproductive dysfunction was noted in the majority of the women.

Outcome after carotid endarterectomy for asymptomatic carotid stenosis.

OBJECTIVE: To compare the long-term outcome in patients with asymptomatic carotid stenosis (ACS) among those treated with carotid endarterectomy (CE) or medical therapy. BACKGROUND: Until randomized trials are completed, treatment of ACS will depend on identification of subgroups likely to benefit from CE. METHODS: A retrospective cohort study was done on 215 patients with ACS: 107 underwent CE, and 108 were treated medically (MED). A neurologist reviewed medical records and performed a telephone interview to detect outcome (stroke and death). Mean follow-up was 3.8 years; only 4% were lost to follow-up. RESULTS: Among CE patients, there was a 4.7% risk of postoperative ipsilateral stroke within 30 days. Four of five postoperative strokes occurred among patients with prior contralateral symptoms. There was no significant difference between CE and MED in the cumulative life-table 5-year risk of ipsilateral stroke, any stroke, or survival free of any stroke. Among diabetics, however, there were no ipsilateral strokes at 5 years after CE compared to 20% in MED (p = 0.03). Excluding postoperative complications, the 5-year risk of ipsilateral stroke was reduced among CE patients who "ever smoked" (CE 1%, MED 8%, p = 0.03) and the 5-year risk of any stroke was reduced among CE patients who had no prior myocardial infarction (CE 6%, MED 16%, p = 0.02). Among those with prior contralateral carotid territory symptoms, the 5-year risk of any stroke was worse in the MED patients (CE 5% MED 32%, p = 0.004). Among CE patients, a Cox proportional hazards model determined that the independent predictors of worse long-term outcome were: a history of myocardial infarction; admission systolic blood pressure greater than 160 mm Hg; and age greater than 65. CONCLUSION: The approach to patients with ACS will await completion of large, randomized clinical trials, now in progress. Even if these studies are negative, there may remain specific subgroups of patients who show clear benefit from carotid endarterectomy.