PROSPECTIVE NEUROPSYCHOLOGICAL INVESTIGATION OF PATIENTS WITH SUPRATENTORIAL ARTERIOVENOUS-MALFORMATIONS

Thirty-one patients subjected to direct radical excision of a supraten torial arteriovenous malformation (AVM) participated in a comprehensiv e neuropsychological assessment both pre-operatively and al 4 and 12 m onths after surgery. The sample constitutes a consecutive series of pa tients who could complete the neuropsychological assessment before sur gery. At the pre-operative assessment the mean results of all the test s fell very close to the average performance of age-equivalent normati ve samples. Postoperatively, the mean results showed a mild to moderat e 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 postop erative year, while two developed seizures de novo. Headache was cured or markedly reduced in all 16 patients incapacitated by headache prio r to surgery. No definite emotional or affective changes after surgery were reported by the patients or their relatives. Comparison of pre-o perative test results of patients with right-sided and left-sided AVM showed significant differences on five of 24 test parameters. Postoper atively, the number of statistically significant differences increased to nine test parameters at 4 months and ten at the 12-month assessmen t. The increase in number of statistically significant differences app ears to reflect a moderate focal impact of the surgical intervention o n cognitive functions in six of the 31 patients (19%). Postoperative i mprovement of test performance exceeding what may be ascribed to pract ice effects and chance fluctuations was only encountered in one patien t. The present results therefore lend little empirical support to the so-called 'cerebral steal' hypothesis.