Awake Crani II

This is a continuation of the last post.

The most important aspect of anesthesia for an awake brain surgery is the psychological preparation. We talked to this patient for over an hour the day before surgery. Along with the routine pre-operative evaluation focusing on heart disease, breathing problems, allergies, and medications, we wanted to build rapport and confidence. We got to know the patient as a person, not only to develop the patient-doctor relationship, but also to get to know details about the patient's life. If, during the surgery, we ask the patient the name of her first husband to test memory and speech fluency, we want to be able to verify her answer. Furthermore, we want a detailed neurologic exam; we test how accurate she can touch her finger to her nose, examine the way she walks, note her muscle strength. Most importantly, however, is the psychological prepation to be under surgery fully awake. We walk her through each step, what to expect, what we'll say, what she will see and hear.

For the beginning of the surgery, we sedate the patient until the brain is open and tumor exposed. The choice of anesthetic has to allow spontaneous breathing and have a quick offset (or be reversible); for this, we chose dexmedetomidine, midazolam, and low dose propofol. The patient comfortably snoring, we place additional IVs, an arterial line, and a subclavian central venous catheter. Then I begin the scalp block. As anyone who has hit their head knows well, the scalp is densely innervated. I inject bupivicaine, catching the nerves as they exit the skull above the eye, around the ear, and near the upper neck. We have to be generous as this is most of the pain control while the patient is awake during the surgery. Meanwhile, the neurologists place electrodes to monitor various nerves. Then, I numb up the pin sites generously. The surgeons place the skull in pins to immobilize it, then position the head to access the tumor. The patient remains sedated as the surgeons dissect through the scalp, drill through bone, and expose the tumor. Then, I run in some IV tylenol but turn all other anesthesia off, and within 10 minutes, the patient wakes up.

Immediately, the patient is oriented so she does not move while her head is in pins. The scalp block seems to work well; she has mild tolerable head discomfort, but complains more of an itch by her eye. The neurologists examine her continuously, asking her to wiggle her fingers and toes, do coordinated motions, answer questions, stick out her tongue, and test her vision (we used an iPhone app). The surgeons debulk the glioblastoma, but when they near the motor strip, they stimulate the tissue prior to resecting it. If the tissue they stimulate is responsible for movement, we will notice twitching or jerking of the arms or legs, and the surgeons know they cannot remove it without consequences. Unfortunately, such stimulation can generalize into a seizure, requiring the surgeons to pour cold saline onto the brain or me to give a touch of propofol. This can be tricky because both a seizure and propofol can cause the patient to stop breathing, and if we were to need a breathing tube, placing one in a draped, pinned patient will not be easy (we had a flexible fiberoptic bronchoscope ready). The procedure went smoothly, and at the end, we even had the patient call her husband from the operating room. The nerve blocks worked so well that the patient didn't need anything during the closure as the surgeons replaced the bone and sutured the skin. She talked all the way through it, telling us about her young adulthood in New York City. When we brought the patient to the intensive care unit for postoperative monitoring, we didn't even need to give her supplemental oxygen. She was wide awake, comfortable, and chatty and the only pain medication she received during the entire thing was local anesthesia and tylenol. I returned to see her the following day to check her neurologic exam and see how she was doing. It was an incredibly satisfying anesthetic.