Letters

摘要

We read with interest the paper by Hsu and colleagues. For many years spinal deformity surgery was monitored with only somatosensory-evoked potentials (SSEPs). The introduction of transcranial motor-evoked potentials (TcMEPs) was a significant step forward in patient safety during these procedures. The 2 techniques are complimentary, but not interchangeable. TcMEPs provide information about the major descending motor pathway, which is supplied vascularly by the anterior spinal artery, which supplies around 2/3 of the spinal cord and lies hidden from the surgical field of view in posterior approach surgery. SSEPs assess dorsal column function, which lies more superiorly in the surgical field. Although unusual, either structure can be injured independently of the other.