gms | German Medical Science

Objective: Closed spinal dysraphism warrants primary or secondary surgical intervention. Surgery nowadays is expected to cause no neurological deterioration, regardless of the existence or absence of pre-operative deficits. Extended intraoperative monitoring (eIOM) is often used to reduce the risk of intraoperative injury. However, there is limited evidence that IOM is feasible, helps to reduce morbidity and carries predictive value for functional outcome. The present study reviews changes in IOM metrics in pediatric patients undergoing surgery for closed spinal dysraphism.

Method: 41 consecutive patients (4,9±5,1 years, 23 female) with spinal dysraphism and primary or secondary surgery were enrolled. eIOM included motor-evoked potentials (MEP) to the M. quadriceps (qMEP), M. gastrocnemius (gMEP), M. tibialis anterior (taMEP), plantar foot muscles (fMEP) and external anal sphincter muscles (sMEP) and somatosensory-evoked potentials after electrical stimulation of the Tibial nerve (tSEP). Latencies and amplitudes of the potentials at the beginning and at the end of the surgery were analyzed. Statistical significant relative changes were determined by Wilcoxon signed rank test (p<0.05).

Results: Baseline somatosensory and motor evoked potentials of all muscles could not be obtained in all patients (qMEP/gMEP/taMEP/fMEP/sMEP: n=23/27/29/26/20/22). During surgery EP vanished in a few cases despite prompt surgical reaction policy to IOM changes (qMEP/gMEP/taMEP/fMEP/sMEP: n=2/0/2/1/3/8). In contrast, in more patients EPs were evocable at the end of surgery despite of their absence at the beginning of surgery (qMEP/gMEP/taMEP/fMEP/sMEP: n=2/3/2/3/4/2). A significant overall increase of EP amplitudes was found for gMEP, taMEP and fMEP. Concurrently the latencies of gMEP and fMEP significantly decreased. A detectable postoperative clinical deterioration of motor and bladder symptoms at the time of neuropediatric discharge examination was present in one patient only.

Conclusions: The use of eIOM is feasible in elective pediatric spinal dysraphism surgery. It contributes to the safety of surgical action, with a peri-operative neurological deterioration rate of <3% in this series. Furthermore, surgery improved motor-evoked potentials significantly. The exact predictive value of EP deterioration during TC surgery remains unclear, since some patients lost motor EP without post-operative deficits. IOM should be mandatory for all spinal dysraphism procedures in pediatric cases of all age.