Intraoperative neurophysiological monitoring during separation of conjoined caudal spinal cords in pygopagus twins

We describe the intraoperative neurophysiological monitoring that was performed in the separation of 11-month-old pygopagus conjoined twins with fused spinal cords. The spines of the patients were fused below S2 level and they shared their thecal sac and spinal cord below that level. They also shared a common anal opening and closely placed urethral and vaginal opening. Transcranial motor evoked potentials (MEPs), electromyography (EMG), and triggered EMG (T-EMG) were recorded throughout the neuroseperation. Baseline MEP in one of the twins was suboptimal and continued to be suboptimal throughout the procedure. The other twin continued to show good MEP responses. T-EMG and EMG are guided during the successful separation and detethering of the cord. There was no fresh sensory or motor neurological deficit postoperatively. Both the patients recovered from their preoperative status as evaluated 4 months after the surgery. Monitoring two spinal cords at the same time is a challenging job. However, good monitoring systems, communication with the operating team and choice of monitoring, and utmost vigilance at crucial times helps getting the fruitful results.