Medical Student Johns Hopkins University School of Medicine Johns Hopkins School of Medicine
Disclosure(s):
Ritvik R. Jillala, BSE: No financial relationships to disclose
Introduction: Posterior vertebral column subtraction osteotomy (PVSCO) has emerged as a viable option for managing recurrent tethered cord syndrome. Real-time intraoperative neuromonitoring (IONM) provides crucial feedback during neurological surgeries. Quantitative analysis of IONM could lead to substantiated real-time feedback during PVSCO, potentially providing a metric for the degree of decompression and detethering. This study aims to quantitatively analyze changes in IONM signals during PVSCO for recurrent tethered cord syndrome.
Methods: This single-center retrospective review analyzed 10 patients undergoing PVSCO. Motor evoked potentials (MEPs) were recorded from bilateral anterior tibialis (ATib), abductor hallucis (AH), abductor pollicis brevis (APB), and deltoid (Delt) muscles. Train-of-four (TOF) stimulations were acquired from APB and AH. Waveforms were divided into pre-shortening, mid-shortening, and post-shortening subsets. MEPs were adjusted for TOF amplitude. Amplitudes, areas under the curve (AUCs), and latencies were calculated for each subset and compared using paired Wilcoxon signed-rank tests (p < 0.05 considered significant).
Results: The majority (6/10 patients, 60%) exhibited significant MEP amplitude increases, averaging 49% ± 19% (p < 0.001). The remaining participants showed a decrease in amplitude, averaging -25% ± 28% (p < 0.05). Similarly, MEP area under the curve (AUC) increased in 60% of patients, with a mean enhancement of 46% ± 17% (p < 0.001), while the non-responding group showed a reduction of -35% ± 22% (p < 0.01). MEP latency remained stable, with no significant changes observed between pre- and post-intervention measurements (0.1% ± 7%, p=0.53).
Conclusion : Increased amplitude and AUC in IONM during PVSCO suggest improved neural conduction post-shortening. These quantitative changes may help surgeons optimize the extent of shortening during the procedure, potentially improving surgical outcomes for recurrent tethered cord syndrome.