Vessels in the Brain

I recently had two cases of craniotomies for resection of vascular lesions in the brain; one was an arteriovenous malformation, and the second was clipping of an aneurysm. The image above shows a cross-section of the brain with an extraordinarily large AVM in the parietal lobe. In an arteriovenous malformation, the artery connects directly to a vein without an intervening capillary network. They present with strokes, seizures, headaches, and focal neurologic deficits.

An aneurysm in the brain is a weakening or abnormality of an arterial blood vessel that creates a so-called "ticking time-bomb." Abrupt increases in blood pressure can cause the aneurysm to burst, leading to a devastating hemorrhagic stroke. A tenth of patients die before reaching the hospital, and only a third have a "good outcome" after treatment.

The anesthesia for both these cases is incredibly delicate. Resections of AVMs can be a bloodbath. Not only do we have to be ready for a large-volume resuscitation, but we also have to consider various tricks to rescue the patient: for example, if the surgeon simply cannot control the bleeding, we can consider adenosine, which stops the heart for thirty seconds. Hopefully the surgeon can get physical hemostasis while the heart stops beating. For the cerebral aneurysm, we do everything we can to avoid spikes in blood pressure. An inadvertent increase in blood pressure can burst the aneurysm and stroke or kill the patient. We induce anesthesia with a generous dose of pain medication so that intubation and placement of lines do not disturb the blood pressure. We pay extra vigilance when the neurosurgeons place the head in pins to avoid a sympathetic surge. We tolerate more hypotension because that is less risky. And we tiptoe around the patient superstitiously.

In the next few months, I expect to do more and more neurosurgical anesthesia, and here, I realize, the details in anesthesia can make the difference between life and death.

Both images are in the public domain, from Wikipedia.