Heterogeneous effect of increasing spinal cord perfusion pressure on sensory evoked potentials recorded from acutely injured human spinal cord
Mathew J Gallagher, David Martín López, Helen V Sheen, Florence R A Hogg, Argyro Zoumprouli, Marios C Papadopoulos, Samira Saadoun
Purpose: To investigate the effect of increasing spinal cord perfusion pressure (SCPP) on sensory evoked potentials (SEPs) and injury site metabolism in patients with severe traumatic spinal cord injury TSCI.
Materials and methods: In 12 TSCI patients we placed a pressure probe, a microdialysis catheter and a strip electrode with 8 contacts on the surface of the injured cord. We monitored SCPP, lactate-to-pyruvate ratio (LPR) and SEPs (after median or posterior tibial nerve stimulation).
Results: Increase in SCPP by ~20 mmHg produced a heterogeneous response in SEPs and injury site metabolism. In some patients, SEP amplitudes increased and the LPR decreased indicating improved tissue metab olism. In others, SEP amplitudes decreased and the LPR increased indicating more impaired metabolism. Compared with patients who did not improve at follow-up, those who improved had significantly more electrode contacts with SEP amplitude increase in response to increasing SCPP.
Conclusions: Increasing SCPP after acute, severe TSCI may be beneficial (if associated with increase in SEP amplitude) or detrimental (if associated with decrease in SEP amplitude). Our findings support individualized management of patients with acute, severe TSCI guided by monitoring from the injury site rather than applying universal blood pressure targets as is current clinical practice.
Keywords: Blood pressure; Critical care; Microdialysis; Monitoring; Somatosensory evoked potential; Spinal cord injury; Subdural electrode.