The rare case of Siamese twin separation produces interesting challenges: here the two 15 month old female patients, based in Indonesia, were joined at the sacrum with fused spinal cords, and a single anus. The local neuro-monitorists required assistance, which was provided remotely by Inomed Neurocare Ltd from London due to the Covid travel restrictions.
Though local equipment had limited capacity, bilateral posterior tibial SEP’s and transcranial MEP’s were recorded in both twins, along with free running and triggered EMG, from bilateral tibialis anterior (TA), gastrocnemius (MG), abductor hallucis (AH). Unfortunately, the external anal sphincter was not available for monitoring due to earlier stages of the procedure.
Free running EMG showed activation during separation of the spinal cords, whilst triggered EMG using a bipolar concentric probe aided nerve identification and preservation in both twins. MEPs from twin 1 had poor amplitude on the left: unstable responses from the right - both sides becoming stable, with improved amplitudes, by closure. Twin 2 had no detectable responses from TA or MG, but small unstable responses were seen bilaterally from AH: by closure these responses all became stable and recordable, with increased amplitudes.  SEP’s in both twins were small and initially unstable, but though still small, more replicable by closure.
Findings demonstrate the ability of standard multi-modal IOM techniques to assist surgeons in identifying structures in these unusual patients: though remote assistance of local monitoring only was possible due to covid, both twins are doing well with no complications.

Acknowledgements: Significant contribution to this work  also from Indonesian Neurologists Dr. R A Tjandrajani; Dr. C Raditha; Dr. R C Lestari: Inomed surgical neurophysiologist N. Pereira