Arteriovenous malformations (Fig 3) are congenital vascular anomalies in which an abnormal communication exists between an artery and a vein. Hemorrhage associated with arteriovenous malformations is usually more benign than that associated with aneurysms, and the risk of rebleeding is much less (6 per cent in the first year and 2-3 per cent per year thereafter) (Wilkins . . . 1985). However, as they usually present in younger patients (even children), the lifetime risk of re-hemorrhage can be substantial.
The type and timing of surgical intervention for arteriovenous malformations is dictated more by their size, position, and nature than by the clinical condition of the patient. Complete excision may be possible by craniotomy alone, or complete obliteration by embolization alone. Often, however, a combination of the above techniques is necessary. With many large lesions treatment can be carried out in stages. In those arteriovenous malformations that are unsuitable for the above approach (too deep-seated, in an eloquent area of brain, feeding artery, also end artery) treatment with stereotactic radiosurgery may be possible.
Preoperative preparation of these patients may be in the acute post-hemorrhage period or some time later. Again, an assessment of the general medical condition of the patient and routine laboratory investigations are necessary. Nimodipine has been used following hemorrhage, and in some cases antiepileptic treatment and steroids are prescribed prophylatically.
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