Intraspinal pressure and spinal cord perfusion pressure predict neurological outcome after traumatic spinal cord injury

Abstract

Surgery Following bony realignment and posterior fixation, the ISP probe (Codman, Depuy Synthes, Leeds, UK) was tunnelled through skin into the wound cavity. Under the operating microscope, the dura was opened one level below the injury. The ISP probe was inserted through the durotomy and placed on the spinal cord surface (Fig. 1A) Data collection Neurological examinations were done pre-operatively (day of injury) and at 9-12 months. Whole spine CT and MRI were done on admission and another CT within 48hours of surgery to check probe and screw position. We collected the following: patient age, AIS grade pre-operatively and at 9-12 months, level of injury, ISP and SCPP.Statistics Data were analysed using exact asymptotic logistic regression (LogXact 11, Cytel, Cambridge MA, USA). Neurological outcome was AIS grade at follow-up vs. pre-operative, binarised as improved vs. non-improved. We first assessed each factor individually. A forward stepwise method was then used to construct multi-variate models. RESULTSThere were 45 patients with average age 41 years (range 19-70) and male:female ratio 4:1.53% patients had cervical (C2-C7), 22% upper thoracic (T1-T6), 7% lower thoracic (T7-T10) and 18% conus medullaris (T11-L2) injuries. Pre-operative AIS grade was A in 67%patients, B in 20 % and C in 13%. For details see Supplementary Multivariate analysis was used to determine whether AIS grade on admission, injury level, patient age, mean ISP and mean SCPP are independent predictors of improvement by at least one AIS grade. We produced two models. In one model, age, AIS grade on admission and ISP were independent predictors of AIS improvement (P<0.05). Increase in ISP by 10 mmHg reduced the chance of AIS grade improvement about five times. In the other model, age, AIS grade on admission and SCPP were independent predictors of AIS improvement (P<0.05). Increase in SCPP by 10mmHg increased the chance of AIS grade improvement about 2.7 times. Due to collinearity, ISP and SCPP were not predictors in the same model.For details see Supplementary Table 3. DISCUSSIONOur key finding is that injury site ISP and SCPP, monitored during the first few days after TSCI, predict neurological improvement at 9-12 months. Mean ISP <10 mmHg and mean SCPP >90 mmHg are associated with the best recovery. In multivariate analysis, elevated ISP or low SCPP is a significant risk factor independent of AIS grade on admission and patient age. Limitations of the study include the small number of patients and use of the AIS as the only outcome measure. Ultimately, a randomised, controlled trial is required to determine whether interventions that reduce ISP or increase SCPP improve neurological outcome after TSCI. ACKNOWLEDGMENTS

Targeted Perfusion Therapy in Spinal Cord Trauma

“…The chance of AIS grade conversion at 9-12 months after the TSCI negatively correlates with the mean ISP on admission and positively correlates with the mean SCPP on admission (Fig. 3) [43]. Increasing SCPP presumably reduces ischemia at the injury site.…”

Method of Decompression by durotomy and duroplasty for cervical spinal cord injury in patients without fracture or dislocation

“…It was of belief that bony decompression with laminectomy released the spinal epidural veins which had become congested and had inhibited the free flow of CSF, and dural decompression can be used in the prevention of high ISP [17]. Papadopoulos also demonstrated that high ISP and low SCPP are associated with injury site ischaemia, which likely causes secondary damage [18]. In patients with extensive swelling from spinal cord injury, durotomy can relieve the blockage of spinal epidural veins and arterioles of the cord, as well as relieve secondary injury [19].…”

Visibility Graph Analysis of Intraspinal Pressure Signal Predicts Functional Outcome in Spinal Cord Injured Patients

“…Time series are also used to identify correlations with biological meaning e.g. higher ISP correlates with worse neurological outcome 13 , when ISP increases then sPRx increases (impaired autoregulation) 1,8 and tissue lactate to pyruvate ratio also increases (increased tissue ischemia) 12 Unlike ISP monitoring for TSCI, ICP monitoring for severe TBI has been the standard of care in developed countries for many years 21,22 . The early management of patients with TBI is focused on limiting secondary injury by reducing ICP below 25 mmHg and increasing CPP above 60 mmHg.…”

“…Second, intervention to increase SCPP in TSCI patients improves neurological status in some patients 1 . Third, lower mean ISP and higher mean SCPP correlate with improved long-term neurological outcome 13 . Fourth, intervening to increase SCPP increases the amplitude of motor evoked responses monitored from below the injury site in some patients 1 .…”