Predictors of Intraspinal Pressure and Optimal Cord Perfusion Pressure After Traumatic Spinal Cord Injury

Abstract

Background/objectives: We recently developed techniques to monitor intraspinal pressure (ISP) and spinal cord perfusion pressure (SCPP) from the injury site to compute the optimum SCPP (SCPPopt) in patients with acute traumatic spinal cord injury (TSCI). We hypothesized that ISP and SCPPopt can be predicted using clinical factors instead of ISP monitoring.

Methods: Sixty-four TSCI patients, grades A-C (American spinal injuries association Impairment Scale, AIS), were analyzed. For 24 h after surgery, we monitored ISP and SCPP and computed SCPPopt (SCPP that optimizes pressure reactivity). We studied how well 28 factors correlate with mean ISP or SCPPopt including 7 patient-related, 3 injury-related, 6 management-related, and 12 preoperative MRI-related factors.

Results: All patients underwent surgery to restore normal spinal alignment within 72 h of injury. Fifty-one percentage had U-shaped sPRx versus SCPP curves, thus allowing SCPPopt to be computed. Thirteen percentage, all AIS grade A or B, had no U-shaped sPRx versus SCPP curves. Thirty-six percentage (22/64) had U-shaped sPRx versus SCPP curves, but the SCPP did not reach the minimum of the curve, and thus, an exact SCPPopt could not be calculated. In total 5/28 factors were associated with lower ISP: older age, excess alcohol consumption, nonconus medullaris injury, expansion duroplasty, and less intraoperative bleeding. In a multivariate logistic regression model, these 5 factors predicted ISP as normal or high with 73% accuracy. Only 2/28 factors correlated with lower SCPPopt: higher mean ISP and conus medullaris injury. In an ordinal multivariate logistic regression model, these 2 factors predicted SCPPopt as low, medium-low, medium-high, or high with only 42% accuracy. No MRI factors correlated with ISP or SCPPopt.

Conclusions: Elevated ISP can be predicted by clinical factors. Modifiable factors that may lower ISP are: reducing surgical bleeding and performing expansion duroplasty. No factors accurately predict SCPPopt; thus, invasive monitoring remains the only way to estimate SCPPopt.

Keywords: Blood pressure; Perfusion pressure; Spinal cord injury; Trauma.

Conflict of interest statement

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical Approval

All procedures performed here were in accordance with the ethical standards of the institutional and national research committees and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Figures

Fig. 1

ISP monitoring technique. a Preoperative MRI of a 37-year-old male patient with TSCI AIS grade C at C3/4. b Postoperative CT of same patient showing C3/4 anterior cervical cage, posterior C3/4 laminectomies, and ISP probe (circled). c MAP, ISP SCPP signals. d sPRx versus SCPP plot. Minimum is SCPPopt

Fig. 2

Factors that correlate with mean ISP. a Level of spinal cord injury (cervical, thoracic, conus). b Age group in years (< 30, 30 – 40, 40 – 50, 50 – 60, > 60). c Extent of decompression (Spinal Alignment, Spinal Alignment + Laminectomy, Spinal Alignment + Laminectomy + Duroplasty). d Intraoperative blood loss as  % of total blood volume (< 15%, 15 – 30%, 30 – 40%, > 40%). e Excess alcohol consumption. Box plots show median, upper and lower quartiles, minimum and maximum. Gray trend line. P < 0.05*, 0.005#

Fig. 3

Factors that correlate with SCPPopt. a Mean ISP group (< 10, 10–20, 20–30, > 30 mmHg). b Level of spinal cord injury (cervical, thoracic, conus). SCPPopt grouped as < 60, 60–70, 70–80, > 80 mmHg. P < 0.05*, 0.01**