Vascular Malformations

For these reasons, it is imperative that patients with cerebellar hemorrhage are assessed at presentation with the specific purpose of determining whether they should be subjected to surgical intervention in the early course of their illness, before neurologic deterioration. These considerations are based on the correlation between preoperative level of consciousness and surgical result: patients who are alert or obtunded preoperatively have a surgical mortality of approximately 15%, while those who have reached the stage of lethargy or coma have a surgical mortality of at least 75%. Once the decision has been made to subject the patient to surgery, an initial consideration is to whether an emergency ventriculostomy is required before performing the more definitive suboccipital craniectomy for hematoma evacuation. This procedure is indicated in patients with massive hydrocephalus whose level of consciousness has suddenly deteriorated and is used as an emergency temporizing procedure while arrangements are being made for the patient’s transfer to the operating room for the more definite suboccipital craniectomy. Also in favor of this type of management of cerebellar hemorrhage is the fact that, despite an initially severely compromised neurologic condition, the successful removal of the cerebellar hematoma is generally followed by adequate functional outcomes because the initially severe ipsilateral limb ataxia and gait ataxia tend to gradually improve, at times leaving no long-term motor disability.

Hemorrhage into the cerebellar vermis is one variety of cerebellar hemorrhage that differs from the classic unilateral hemispheric type described above. This type of hemorrhage tends to be more severe in its initial manifestations and has less potential for benefit from surgery because of the generally early and bilateral compression of the tegmentum of the pons. This often results in severe compromise in the level of consciousness, with bilateral oculomotor deficits at presentation, at times with coma and bilateral ophthalmoplegia with miosis, a presentation that is clinically difficult to separate from primary pontine hemorrhage. Because of this early and bilateral compromise of the pontine tegmentum, and the localization of the hemorrhage in the midline of the cerebellum, the surgical option of hematoma evacuation is generally less successful than in the hemispheric variety of cerebellar hemorrhage, and most patients are only treated with ventriculostomy because they frequently have prominent supratentorial hydrocephalus as a result of fourth ventricular compression.

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