Object: In contrast to intracranial pressure (ICP) in traumatic brain injury (TBI), intraspinal pressure (ISP) after traumatic spinal cord injury (TSCI) has not received the same attention in terms of waveform analysis. Based on a recently introduced technique for continuous monitoring of ISP, here the morphological characteristics of ISP are observationally described. It was hypothesized that the waveform analysis method used to assess ICP could be similarly applied to ISP.
Methods: Data included continuous recordings of ISP and arterial blood pressure (ABP) in 18 patients with severe TSCI.
Results: The morphology of the ISP pulse waveform resembled the ICP waveform shape and was composed of 3 peaks representing percussion, tidal, and dicrotic waves. Spectral analysis demonstrated the presence of slow, respiratory, and pulse waves at different frequencies. The pulse amplitude of ISP was proportional to the mean ISP, suggesting a similar exponential pressure-volume relationship as in the intracerebral space. The interaction between the slow waves of ISP and ABP is capable of characterizing the spinal autoregulatory capacity.
Conclusions: This preliminary observational study confirms morphological and spectral similarities between ISP in TSCI and ICP. Therefore, the known methods used for ICP waveform analysis could be transferred to ISP analysis and, upon verification, potentially used for monitoring TSCI patients.
Keywords: ABP = arterial blood pressure; CPP = cerebral perfusion pressure; ICP = intracranial pressure; ISCoPE = Injured Spinal Cord Pressure Evaluation; ISP = intraspinal pressure; PRx = pressure reactivity index; SCPP = spinal cord perfusion pressure; TBI = traumatic brain injury; TSCI = traumatic spinal cord injury; biophysics; intraspinal pressure; observation; sPRx = spinal PRx; spinal cord injury.