» Neurologic Safety of Spinal Deformity Surgery
Neurologic Safety of Spinal Deformity Surgery

Any time surgery is done on the spine, there is a risk of neurologic problems. Best case scenario is a mild loss of motor or sensory function that only lasts a short time. The patient has a full recovery back to normal. In a worst case scenario, the patient is paralyzed and stays that way. Understandably, surgeons do everything they can to avoid neurologic complications, especially serious ones that lead to loss of function and disability.

When presented with the possibilities of complications associated with the spinal surgery, patients want to know a few things. Like how often do such problems develop? And what's the usual prognosis? What are my chances of such a problem developing? Am I at risk and if so, why? What can I do to decrease my risk for neurologic complications? This study attempts to answer some of those questions.

A committee of fellowship-trained spine surgeons from many practice settings provided data on over 100,000 cases of spine surgery. The group is referred to as the Scoliosis Research Society Morbidity and Mortality Committee. The information gathered was analyzed in several different ways to get different perspectives on the problem of neurologic complications associated with spinal surgery. Types of information collected included patient age, main diagnosis, type of surgery, type of complication, and amount of recovery.

Both adults and children were included. Children were defined as anyone under the age of 21 years. Most of the adults were treated for degenerative spine conditions or idiopathic problems affecting the spine. Idiopathic means the surgeon does not know why the problem developed in the first place. Degenerative spine conditions ranged from disc herniation, spinal stenosis, and disc degeneration in the cervical (neck) area and the lumbar (low back) area. A smaller number of patients had similar problems in the thoracic (mid-spine) region.

Among the children, neuromuscular causes of scoliosis was the most common problem leading to surgical correction. Congenital and idiopathic causes were also reported many times in this age group. A much smaller number of cases were the result of trauma. Children were 59 per cent more likely to experience new neurologic problems associated with spine surgery compared with adults. The reason for this may have to do with the use of instrumentation (metal plates, screws, rods, and pins to hold the spine steady until fusion takes place).

One other risk factor for neurologic problems developing after spinal surgery was the need for revision (a second) surgery. Results showed a 41 per cent increase in risk of new neurologic problems developing when the case was a revision procedure. Overall, the study showed only a one per cent chance of new neurologic problems among the 100,000 plus patients. That low figure is considered pretty darn good.

One area of controversy in spinal surgery is the use of neuromonitoring. This is a way of detecting whether or not the patient is in immediate risk of damage being done to the spinal cord or spinal nerve roots. The surgeon can either wake the patient up and test him or her for normal sensation and movement or use a special device that monitors the patient's neurologic status. The wake-up test isn't very practical because it doesn't measure what's going on from moment-to-moment.

On the other hand, the use of tests such as electromyography, somatosensory evoked potentials (SSEP), and motor-evoked potentials (MEPs) can produce false negatives (test is negative indicating no problem when the patient is really compromised and in danger of paralysis). False negatives can be very serious.

In summary, this study is the largest reported on the number and causes of new neurologic problems occurring after spine surgery in adults and children. The information gathered can be used to warn patients planning to have spinal surgery what to expect in terms of a worst case scenario.

Analysis of the data also provided some idea of prognosis (likelihood of no recovery, partial recovery, full recovery) for patients who experienced paralysis. An equal number of patients had partial or complete recovery (around 46 to 47 per cent). Only a small number (4.7 per cent) had no recovery at all.

Reference: D. Kojo Hamilton, MD, et al. Rates of New Neurological Deficit Associated with Spine Surgery Based on 108,419 Procedures. In Spine. July 1, 2011. Vol. 36. No. 15. Pp. 1218-1228.