Neurologic risk in growing rod spine surgery in early onset scoliosis: is neuromonitoring necessary for all cases?

STUDY DESIGN Retrospective case series from a multicenter database. OBJECTIVE To evaluate the risk of neurologic injury during growing rod surgeries and to determine whether intraoperative neuromonitoring is necessary for all growing rod procedures. SUMMARY OF BACKGROUND DATA Although the use of growing rod constructs for early-onset spinal deformity has become a commonly accepted treatment, the incidence of neurologic events during growing rod surgeries remains unknown. METHODS We reviewed data from a multicenter database on 782 growing rod surgeries performed in 252 patients. VEPTR devices and any constructs with rib attachments were excluded. A questionnaire was sent to all surgeons contributing cases requesting detailed information about all neurologic events associated with any growing rod surgery. RESULTS There were 782 growing rod surgeries performed on 252 patients including 252 primary growing rod implantations, 168 implant exchanges, and 362 lengthenings. Five hundred sixty-nine of 782 (73%) cases were performed with neuromonitoring. Only one clinical injury occurred in the series, resulting in an injury rate of 0.1% (1/782). This deficit occurred during an implant exchange while attempting pedicle screw placement, and resolved within 3 months. There were 2 cases with neuromonitoring changes during primary implant surgeries (0.9%, 2/231), 1 change during implant exchanges (0.9%, 1/116), and 1 neuromonitoring change during lengthenings (0.5%, 1/222). The single monitoring change that occurred during a lengthening was in a child with an intracanal tumor who also had a monitoring change during the primary surgery. There are anecdotal cases (outside this study group series) of neuromonitoring changes during simple lengthenings in children with uneventful primary implantations. CONCLUSION Based on our study, the largest reported series of growing rod surgeries, the rate of neuromonitoring changes during primary growing rod implantation (0.9%) and exchange (0.9%) justifies the use of intraoperative neuromonitoring during these surgeries. As there were no neurologic events in 361 lengthenings in patients with no previous neurologic events, the question may be raised as to whether intraoperative neuromonitoring is necessary for simple lengthenings in these patients. However, caution should be maintained when interpreting our results as anecdotal cases of neurologic changes from simple lengthenings do exist outside of this series.