Diagnosis and Treatment of Brain Stem Hemorrhage Caused by Angiographically Occult Vascular Malformation(AOVM)

ABSTRACT

In cases of symptomatic AOVM of the brainstem, there is a great risk of progressive morbidity caused by repetitive hemorrhage, and the condition can even be fatal. To establish the optimum method of management of this condition, we investigated 15 patients treated between January 1991 and January 1996. Seven lesions were located in the pons, three in the medulla, three in the midbrain, and one each at the pontomedullary and pontomesencephalic junction. Surgery was performed in six cases in which the lesions were close to the dorsal pial surface of the brainstem ; the histological diagnosis was five cases of cavernous angioma and one of arteriovenous malformation. Nine patients with surgically inaccessible lesions, deep seated or located in the midbrain, were treated by gamma knife radiosurgery. All patients who underwent surgery showed neurologic improvement, and among those who underwent radiosurgery, the outcome was favorable. For symptomatic lesions located in the dorsal pial surface of the pons or medulla, surgical resection is the treatment of choice, and prevents further neurological disability and rehemorrhage. For the best possible outcome, intraoperative sonography and electrophysiologic monitoring are mandatory. Gamma knife radiosurgery can be employed in selected cases in which lesions are deep-seated and inaccessible and associated with repeated hemorrhage and progressive neurologic deficit.