Delayed neurological deterioration following resection of arteriovenous malformations of the brain

Object. The aim of this study was to analyze delayed neurological deficits following surgical resection of arteriovenous malformations (AVMs). Methods. The authors report on a consecutive series of 200 patients with an giographically proven AVMs of the brain that were surgically resected betwe en January 1989 and June 1998. The 30-day mortality rate for patients in th is series was 1%, with one death caused by AVM resection and one death attr ibuted to basilar artery aneurysm repair following successful AVM resection . The Spetzler-Martin grading system correlated well with the difficulty of surgery. No permanent incidence of morbidity resulted from resection of Gr ade I or II AVMs; the percentage of patients with a significant neurologica l deficit due to resection was 7.8% for those with Grade III lesions and 33 .3% for those with Grade IV or V AVMs. However, this grading system did not accurately predict the development of delayed neurological deficits. Ten patients (5%) developed delayed neurological deficits after recovering from anesthesia and surgery. The delayed deficit was due to hemorrhage in f our of the 10 patients and all four had undergone resection of AVMs measuri ng at least 4 cm in diameter. An increase in blood pressure during the firs t 8 postoperative days precipitated hemorrhage in these patients. Edema ari sing as a consequence of propagated venous thrombosis (two patients) was as sociated with extensive venous drainage networks rather than large AVM nidu ses. Both hemorrhagic and edematous complications can be included under the umbrella term of "arterial-capillary-venous hypertensive syndrome" to desc ribe the common underlying pathogenesis accurately. An additional four pati ents developed a delayed deficit as a result of vasospasm. Vasospasm occurr ed when resection had involved extensive dissection of proximal anterior an d middle cerebral arteries; in such cases the incidence of vasospasm was 27 %. Conclusions. On the basis of their analysis of these complications, the aut hors recommend strict blood pressure control for patients with lesions meas uring 4 cm or more in diameter (particularly those with a deep arterial sup ply). Thromboprophylaxis with aspirin and heparin is prescribed for patient s with extensive venous drainage networks, and prophylactic nimodipine ther apy and angiographic surveillance for vasospasm are suggested for patients in whom extensive dissection of proximal anterior or middle cerebral arteri es has been necessary.