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ASA NEWSLETTER
 
 
May 2001
Volume 65
Number 5
 
SUBSPECIALTY NEWS

Neurologic Surgery: A Logical Choice for Anesthesiologists

Michael E. Mahla, M.D.
Society of Neurosurgical Anesthesia and Critical Care


Much like other subspecialty societies, the Society of Neurosurgical Anesthesia and Critical Care (SNACC) is beginning to tackle the questions surrounding the definition of a consultant in neurosurgical anesthesiology. This process initially involved defining the curricular content of the required primary rotation in neuroanesthesia in the core residency program. It is now focusing on fellowship training curriculum and content. What unique and special competencies and services can a neuroanesthesiologist provide to patients having surgery that risks the structure and function of the central and peripheral nervous systems?

Neuroanesthesiologists are becoming recognized as the logical choice to head medical direction for neurologic monitoring services to patients undergoing surgery that places the nervous system at risk, such as scoliosis repair or thoracic aneurysm repair. This concept regarding the role of anesthesiologists in nonanesthesia monitoring is similarly embraced by the Society of Cardiovascular Anesthesiologists with respect to transesophageal echocardiography. Currently, there are several SNACC members in the United States and internationally who are entirely responsible for the provision of neurologic monitoring at their respective institutions. Indeed, these same SNACC members are performing much of the current and important research in neurologic monitoring.

This initiative will require significant changes in neuroanesthesia training programs. Fellows training in neuroanesthesia will need significant exposure (at least six months) to neurologic monitoring modalities including auditory and somatosensory-evoked responses, motor-evoked responses, evoked and spontaneous electromyography, electroencephalography, transcranial Doppler ultrasound and other methods for cerebral blood flow measurement. They will also need training in basic neuroanatomy and neurophysiology to provide a solid basic science foundation necessary for understanding and interpreting these responses. Also, current practitioners, if interested in gaining skills in this area, will need equivalent exposure and training.

As the specialty of neurologic surgery continues to advance, requirements for intensive neurologic monitoring both in the operating room and the intensive care unit will likely expand. Complex spinal surgery and intracranial neurovascular surgery already utilize extensive monitoring at many centers. 1, 2 Recently, a patient at the University of Florida was spared a major neurologic deficit following clipping of a basilar apex aneurysm. During surgery, one of several clips placed to control this complex, multilobed aneurysm put pressure on a small atheroma in one of the exiting posterior cerebral arteries. The problem was not visible under the operating microscope, but a persistent unilateral loss of the cortical somatosensory evoked a response following temporary occlusion of the basilar artery, which alerted the surgeon and anesthesiologist to the problem and prompted re-exploration and induced hypertension that would not have otherwise occurred. Even less complex cases performed in community hospitals are increasingly using neurologic monitoring. Within the next decade, clinical intraoperative monitoring of motor pathways, with its incumbent anesthetic requirements, is likely to become much more common, especially at larger private and university hospitals.

Currently, neurologic monitoring is provided for the most part by nonanesthesiologists. 3 While these models work well, I believe that anesthesiologists could do a better job. Many of these physician providers rely on technicians to perform the monitoring and are not physically present in the operating room. In this case, when a change in a monitored response occurs, the technologist must contact the medical director who must then verify the change. The medical director must then determine what has happened surgically to make certain that the change makes sense. He or she can then interact with the surgeon and anesthesiologist to determine what is best to do at that point in time. Having the anesthesiologist actually responsible for the monitoring reduces the clinical response time to a change in the monitored response to near zero. He or she can then in real time discuss work with the surgeon to immediately implement appropriate surgical and medical therapy.

The prospect for anesthesiologists becoming more involved with neurologic monitoring is obviously very exciting, but there is a potential problem that could defeat this initiative before it even gets started. Anesthesiology reimbursement, particularly from Medicare, has been undergoing many changes in recent years. One of the most important issues to emerge from these changes involves concurrent care. Can the anesthesiologist provide nonanesthesia services at the same time he or she is supervising anesthesia care by other providers (residents or nurse anesthetists)? Obviously, if the anesthesiologist is providing direct care to a patient, it would not be appropriate to supervise a neurologic monitoring technologist in another location. That would be no better than most current models. However, based on my nearly 20 years of experience, I strongly feel that neuroanesthesiologists in the operating room supervising two anesthetizing locations can readily supervise neurologic monitoring without compromising care to either his or her anesthetized patients or to the patient being monitored. As more anesthesiologists become trained in neurologic monitoring, it would be readily possible for the anesthesiologist to only supervise monitoring in rooms where he /she is providing supervision of the anesthetic.

SNACC is working hard with ASA to address issues relating to neuroanesthesia. However, the importance of these issue extend far beyond neurosurgical anesthesiology. Indeed, it extends to the very definition of an anesthesiologist as a perioperative medicine specialist. As anesthesiology moves into the 21st century, neurologic monitoring, transesophageal echocardiography or those skills involved with management of acute or chronic pain will define the anesthesiologist's role. It will make him or her different from other providers of anesthesia care, both in fact and in the eyes of the public. The support of ASA in this issue is greatly appreciated by all in SNACC.

References:

1. Nuwer MR, Dawson EG, Carlson LG, et al. Somatosensory evoked potential spinal cord monitoring reduces neurologic deficits after scoliosis surgery: Results of a large multicenter survery. Electroencephalogr Clin Neurophysiol. 1995; 96(1):6-11.

2. Burke D, Nuwer MR, Daube J, et al. Intraoperative monitoring. The International Federation of Clinical Neurophysiology. Electroencephalogr Clin Neurophysiol Suppl. 1999; 52:133-148.

3. Nuwer JM, Nuwer MR. Neurophysiologic surgical monitoring staffing patterns in the USA. Electroencephalogr Clin Neurophysiol. 1997; 103(6):616-620.



    Michael E. Mahla, M.D., is Associate Professor of Anesthesiology and Neurosurgery, and Residency Program Director, University of Florida College of Medicine, Gainesville, Florida.


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