Oct. 24, 2017
Awake craniotomy, which allows for maximal tumor resection while preserving functional tissue, has become an established approach for the removal of tumors in the cortical speech area of the brain. Mayo Clinic neurosurgeons are expanding their use of awake craniotomy to resecting tumors in eloquent motor and sensory tissue.
Typically, awake craniotomy is avoided in those areas, due to the risk of intraoperative seizures. However, Mayo Clinic neurosurgeons have demonstrated expertise with this approach, offering better outcomes for patients and lower costs than tumor resection performed under general anesthesia.
"As a tertiary referral center, Mayo Clinic can invest in the multidisciplinary teams that allow us to perform these complex procedures," says Alfredo Quinones-Hinojosa, M.D., chair of Neurosurgery at Mayo Clinic in Jacksonville, Florida. "What separates us from any other center is the Mayo system of care — a multidisciplinary approach, with strong investment in people and technology that ensures patient safety is at the forefront."
Mayo Clinic's awake craniotomy protocol seeks to minimize the intensity of current used for cortical and subcortical stimulation, while not compromising the reliability of stimulation mapping. In surgery involving eloquent motor tissue, the primary motor region is targeted to determine a minimum current intensity necessary to elicit a clinical response.
Reported rates of stimulation-induced intraoperative seizures during an awake craniotomy range from 2.2 to 21.9 percent, with 70 to 86 percent of those seizures occurring during resections of tumors involving the frontal lobe perirolandic region.
A neurosurgical wand is used for electrocortical stimulation and functional mapping of the brain
Alfredo Quinones-Hinojosa, M.D., chair of Neurosurgery at Mayo Clinic in Jacksonville, Florida, holds a neurosurgical wand used for electrocortical stimulation and functional mapping of the brain during awake craniotomy.
However, a study published in Neurosurgery reported that intraoperative seizures occurred in just two of 27 (7.4 percent) awake craniotomy surgeries performed by Dr. Quinones-Hinojosa to treat perirolandic gliomas. In both cases, the seizures were rapidly controlled, and the surgeries continued.
"Successful surgery of this type requires a very large team — neurosurgeons with expertise in awake craniotomy, neurologists, neuroanesthesiologists, neuroradiologists and experienced nurses," Dr. Quinones-Hinojosa says.
This depth of subspecialized expertise facilitates rapid identification of impending intraoperative seizure. "We take an active approach to intraoperative monitoring of brain function at Mayo Clinic in an attempt to identify patterns on the electrocorticogram that may portend a greater risk of impending seizures when superficial or deep brain stimulation is performed," says William Tatum, D.O., a consultant in Neurology at Mayo Clinic's campus in Florida.
"Any seizure that occurs in the operating room is immediately treated to rapidly terminate it and prevent it from recurring," he adds. "Having a prearranged protocol for neurophysiological monitoring, together with open communication in the OR, ensures the best possible care for patients. Coordination and combined expertise during the surgical procedure is critical not only to optimize the extent of resection and limit morbidity but also to avert potential risk of intraoperative seizures."
The Neurosurgery study also documented improved outcomes in the patients who had awake craniotomy compared with 31 matched case-control patients who had perirolandic glioma resection under general anesthesia:
- Total resection achieved in seven patients (25.9 percent) in the awake craniotomy group versus two (6.5 percent) in the general anesthesia group
- Mean delayed Karnofsky performance scale (KPS) score of 93.3 for the awake craniotomy group (mean follow-up time of 28 months)
- Mean delayed KPS score of 81.1 for the general anesthesia group (mean follow-up of 3.9 months)
A separate study by Dr. Quinones-Hinojosa and colleagues published in Neurosurgery comparing cost associated with awake craniotomy versus general anesthesia during resection of perirolandic region tumors found that the total inpatient expense per patient was $34,804 for the awake craniotomy group and $46,798 for the general anesthesia group. The study concluded that the costs of additional personnel and equipment for awake craniotomy were offset by better postoperative status and shorter hospitalization — a mean length of stay of 4.12 days compared with 7.61 days for the general anesthesia group.
"Our studies show that with awake craniotomy, you resect more tumor, the patients do better, and the overall health bill is less," Dr. Quinones-Hinojosa says.
Another potential advantage of awake craniotomy may be avoidance of cancer cell migration during surgery. "Just recently we have begun to realize that anesthesia might have a deleterious effect on this cell migration, possibly by inhibiting the immune system," Dr. Quinones-Hinojosa says.
To enhance guidance during brain tumor resection, Mayo Clinic has pioneered combining awake surgeries with high-field intraoperative MRI. "This gives us the best possible functional guidance — motor and speech mapping — and image guidance, allowing us to safely resect tumors that would be difficult to remove without causing harm otherwise," says Ian F. Parney, M.D., Ph.D., a consultant in Neurosurgery at Mayo Clinic in Rochester, Minnesota.
In addition to tumor resection, treatment for cavernomas, small arteriovenous malformations (AVMs) and select patients with moyamoya disease is often performed at Mayo Clinic with awake surgery.
"It allows us to map white matter around cavernous vascular malformations and AVMs, and to resect epileptogenic tissue that would have been left behind otherwise," says Bernard R. Bendok, M.D., chair of Neurosurgery at Mayo Clinic's campus in Phoenix/Scottsdale, Arizona. "For moyamoya disease, awake surgery may lower the risk of ischemic complications by reducing hemodynamic compromise and giving the anesthesia and surgical teams immediate feedback that can prompt hemodynamic interventions."
Patient selection is key to successful awake craniotomy in areas of eloquent tissue. Contraindications for awake craniotomy include communication problems, developmental delay, age under 12 years, uncontrolled coughing, severe dysphagia, hemiplegia and less than antigravity motor function.
Dr. Quinones-Hinojosa stresses the importance of building a relationship of trust with the patient. "Patients put their lives in my hands. So before I take them to the operating room, I always explain exactly what I'm going to do," he says. "If you develop these relationships, patients have faith in the team. Our anesthesiologists also do a beautiful job with nerve blocks in the scalp, so patients are comfortable and have no pain.
"We used to say not all parts of the brain are eloquent. It turns out that there are many more eloquent parts than what we thought," Dr. Quinones-Hinojosa adds. "One day, awake surgery will be done for all gliomas. That's the way we're moving."
For more information
Eseonu CI, et al. Awake craniotomy vs craniotomy under general anesthesia for perirolandic gliomas: Evaluating perioperative complications and extent of resection. Neurosurgery. 2017;81:481.
Eseonu CI, et al. The cost of brain surgery: Awake vs asleep craniotomy for perirolandic region tumors. Neurosurgery. 2017;81:307.