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Best Way to Monitor Neurologic Function During Cervical Spine Surgery

Spine surgery can result in permanent damage to the spinal cord or spinal nerves. To avoid this, intraoperative monitoring (IOM) is used. Special devices are used to alert the surgeon to any problems. There are several ways to do this including somatosensory evoked potential (SSEP), motor evoked potential (MEP), and electromyography (EMG).

None of these methods is 100 per cent accurate. As a result, many surgery centers use multimodal monitoring in all spinal operations. This means they use more than one monitoring device at the same time. Using these together improves the precision and accuracy of early warnings. The surgeon can then avoid causing further harm to the neural tissue.

In this study, neurosurgeons look back over 1,055 cervical spine patients treated at a university-based neurosurgical unit between the years 2001 and 2005. The data collected from each monitoring method was compared later to the kinds of postoperative results patients had.

Any new deficits were noted compared to the baseline. Then they compared the methods used to see which one worked best. They also calculated the rate of incidence for new sensory or motor deficits. Patients were followed for up 10 19 months to see if the problems resolved.

Two cases studies were presented to show how the monitoring helped the surgeon. The authors presented how the procedure was adapted due to the problems that occurred. For example, one patient had a tumor inside the spinal cord. As soon as a decline in the SSEP was noted, the surgeon stopped trying to cut the tumor out. The operation continued in a start-and-stop fashion. The surgeon used the SSEP to show how much the tumor and spinal cord could be moved around.

The second patient was suspected of having spinal cord injury during the surgery. The surgeon stopped the operation right away. Drugs were given to raise the blood pressure and reduce swelling in the spinal cord area. The surgery was finished after the patient was stabilized.

The results showed that patients with the worst results had a major problem before the operation. Pressure on the spinal cord was significant. For these patients, they couldn't even get a baseline measurement of neurologic function using IOM.

A number of cord injuries did not show up with SSEPs alone. For this reason, the authors advise against using this method alone in high-risk cases. Using SSEP with EMG was not as good as monitoring with MEP. Combining MEP and SSEP gave the best results and should be used to improve spinal cord monitoring. This is especially true for high-risk patients.

References: Michael O. Kelleher, FRCS, MD, et al. Predictive Value of Intraoperative Neurophysiological Monitoring During Cervical Spine Surgery: A Prospective Analysis of 1055 Consecutive Patients. In Journal of Neurosurgery: Spine. March 2008. Vol. 8. No. 3. Pp. 215-221.

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