Delayed neuromonitoring alarm after scoliosis correction in Lenke type 4 adolescent idiopathic scoliosis.

A 12-year-old girl underwent surgery for Lenke type 4 adolescent idiopathic scoliosis. After scoliosis correction, the transcranial motor-evoked potential (Tc-MEP) showed no alarm. However, the Tc-MEP amplitude had declined ~10 min after correction, with a normal blood pressure (BP) and body temperature and without any technical monitoring errors. Therefore, we suspected indirect spinal cord ischaemia because of the delayed true-positive Tc-MEP alarm. All the strong corrections made loss of Tc-MEP and all the correction releases made recovers of waveform. Finally, a weak correction was performed, and the Tc-MEP amplitude was recovered. Because transient spinal cord ischaemia due to correction of triple curves may cause a delayed monitoring alarm, the monitoring team should frequently check Tc-MEP after these manoeuvres. This patient had no neurological deficits and was considered to be a rescue case.