Neuropsychological course after surgery for intracranial aneurysms. A prospective study and a critical review.

Previously, only three studies with representative samples of patients with ruptured intracranial aneurysms have provided detailed results of prospective, repeated, neuropsychological assessments after surgery. These studies apparently disagree with regard to occurrence of cognitive deficits and to degree of improvement between early and delayed follow-ups. The present paper attempts to analyze the conditions underlying these differences in results. As a first step in this analysis we present a comprehensive, prospective, neuropsychological investigation of a consecutive sample of 41 patients with rupture of a supratentorial aneurysm, assessed 4 and 12 months after surgery. It is concluded that a prorated course of improvement of a wide specter of psychological functions may be revealed, but that sensitive tests and large samples are needed to establish the range of deficits and improvements with time. Differences in patient selection with respect to severity of the acute clinical state and delayed deterioration apparently contribute importantly to the discrepance in previously reported outcome.

Prospective neuropsychological investigation of patients with supratentorial arteriovenous malformations.

Thirty-one patients subjected to direct radical excision of a supratentorial arteriovenous malformation (AVM) participated in a comprehensive neuropsychological assessment both pre-operatively and at 4 and 12 months after surgery. The sample constitutes a consecutive series of patients who could complete the neuropsychological assessment before surgery. At the pre-operative assessment the mean results of all the tests fell very close to the average performance of age-equivalent normative samples. Postoperatively, the mean results showed a mild to moderate deterioration of performance on most cognitive and perceptual tasks by 4 months after surgery and a return approximately to the premorbid level by 12 months. Twelve of 15 patients with pre-operative epileptic seizures remained seizure free on medication during this first postoperative year, while two developed seizures de novo. Headache was cured or markedly reduced in all 16 patients incapacitated by headache prior to surgery. No definite emotional or affective changes after surgery were reported by the patients or their relatives. Comparison of pre-operative test results of patients with right-sided and left-sided AVM showed significant differences on five of 24 test parameters. Postoperatively, the number of statistically significant differences increased to nine test parameters at 4 months and ten at the 12-month assessment. The increase in number of statistically significant differences appears to reflect a moderate focal impact of the surgical intervention on cognitive functions in six of the 31 patients (19%). Postoperative improvement of test performance exceeding what may be ascribed to practice effects and chance fluctuations was only encountered in one patient. The present results therefore lend little empirical support to the so-called 'cerebral steal' hypothesis.

Emotional responses during unilateral amobarbital anesthesia: differential hemispheric contributions?

OBJECTIVES: To explore (1) effects of test and subject variables in determining euphoric and dysphoric responses during unilateral amobarbital anesthesia and (2) which cerebral areas contribute to the emotional responses. METHOD: Incidence of euphoric and dysphoric reactions during left- and right-sided amobarbital anesthesia of the internal carotid artery (ICA) and selective anesthesia of the middle cerebral (MCA) and the posterior cerebral (PCA) artery was recorded. The sample comprised 270 Norwegians (6-61 years), and a total of 562 injections were performed under conditions endeavoring to calm down the patients. RESULTS: The overall incidence of observed emotional responses during ICA anesthesia was 21.5%, euphoric reactions being about 10 times more frequent than dysphoric. The incidence of euphoric reactions, however, was not significantly higher under right- than under left-sided anesthesia, and dysphoric reactions were not more frequent under left- than under right-sided anesthesia. Indeed, 13 patients showed elevated mood under both right- and left-sided anesthesia. Anesthesia of the territories of ICA and MCA gave rise to similar results, while no cases of mood change were observed under selective PCA anesthesia. CONCLUSION: It is concluded that unilateral amobarbital anesthesia as such, irrespective of side, may trigger both euphoric and dysphoric responses. The relative frequency obtained is influenced importantly both by the emotional responsiveness of the subjects and the emotional climate of the test situation. Finally, it is suggested that brain regions supplied by the PCA contribute less to modulation of euphoric and dysphoric responses than those supplied by the MCA or the ICA.