Acute Spinal Cord Injury: Monitoring Lumbar Cerebrospinal Fluid Provides Limited Information about the Injury Site

Critical Care of Spinal Cord Injury

PURPOSE OF REVIEW

Spinal cord injury (SCI) is a major cause of morbidity and mortality, posing a significant financial burden on patients and the healthcare system. While little can be done to reverse the primary mechanical insult, minimizing secondary injury due to ischemia and inflammation and avoiding complications that adversely affect neurologic outcome represent major goals of management. This article reviews important considerations in the acute critical care management of SCI to improve outcomes.

RECENT FINDINGS

Neuroprotective agents, such as riluzole, may allow for improved neurologic recovery but require further investigation at this time. Various forms of neuromodulation, such as transcranial magnetic stimulation, are currently under investigation. Early decompression and stabilization of SCI is recommended within 24 h of injury when indicated. Spinal cord perfusion may be optimized with a mean arterial pressure goal from a lower limit of 75-80 to an upper limit of 90-95 mmHg for 3-7 days after injury. The use of corticosteroids remains controversial; however, initiation of a 24-h infusion of methylprednisolone 5.4 mg/kg/hour within 8 h of injury has been found to improve motor scores. Attentive pulmonary and urologic care along with early mobilization can reduce in-hospital complications.

Neurocritical care and neuromonitoring considerations in acute pediatric spinal cord injury

Management of pediatric spinal cord injury (SCI) is an essential skill for all pediatric neurocritical care physicians. In this review, we focus on the evaluation and management of pediatric SCI, highlight a novel framework for the monitoring of such patients in the intensive care unit (ICU), and introduce advancements in critical care techniques in monitoring and management. The initial evaluation and characterization of SCI is crucial for improving outcomes as well as prognostication. While physical examination and imaging are the main stays of the work-up, we propose the use of somatosensory evoked potentials (SSEPs) and transcranial magnetic stimulation (TMS) for challenging clinical scenarios. SSEPs allow for functional evaluation of the dorsal columns consisting of tracts associated with hand function, ambulation, and bladder function. Meanwhile, TMS has the potential for informing prognostication as well as response to rehabilitation. Spine stabilization, and in some cases surgical decompression, along with respiratory and hemodynamic management are essential. Emerging research suggests that targeted spinal cerebral perfusion pressure may provide potential benefits. This review aims to increase the pediatric neurocritical care physician's comfort with SCI while providing a novel algorithm for monitoring spinal cord function in the ICU.

A Clinical Practice Guideline for the Management of Patients With Acute Spinal Cord Injury: Recommendations on Hemodynamic Management

STUDY DESIGN

Clinical practice guideline development following the GRADE process.

OBJECTIVES

Hemodynamic management is one of the only available treatment options that likely improves neurologic outcomes in patients with acute traumatic spinal cord injury (SCI). Augmenting mean arterial pressure (MAP) aims to improve blood perfusion and oxygen delivery to the injured spinal cord in order to minimize secondary ischemic damage to neural tissue. The objective of this guideline was to update the 2013 AANS/CNS recommendations on the hemodynamic management of patients with acute traumatic SCI, acknowledging that much has been published in this area since its publication. Specifically, we sought to make recommendations on 1. The range of mean arterial pressure (MAP) to be maintained by identifying an upper and lower MAP limit; 2. The duration of such MAP augmentation; and 3. The choice of vasopressor. Additionally, we sought to make a recommendation on spinal cord perfusion pressure (SCPP) targets.

METHODS

A multidisciplinary guideline development group (GDG) was formed that included health care professionals from a wide range of clinical specialities, patient advocates, and individuals living with SCI. The GDG reviewed the 2013 AANS/CNS guidelines and voted on whether each recommendation should be endorsed or updated. A systematic review of the literature, following PRISMA standards and registered in PROSPERO, was conducted to inform the guideline development process and address the following key questions: (i) what are the effects of goal-directed interventions to optimize spinal cord perfusion on extent of neurological recovery and rates of adverse events at any time point of follow-up? and (ii) what are the effects of particular monitoring techniques, perfusion ranges, pharmacological agents, and durations of treatment on extent of neurological recovery and rates of adverse events at any time point of follow-up? The GDG combined the information from this systematic review with their clinical expertise in order to develop recommendations on a MAP target range (specifically an upper and lower limit to target), the optimal duration for MAP augmentation, and the use of vasopressors or inotropes. Using methods outlined by the GRADE working group, recommendations were formulated that considered the balance of benefits and harms, financial impact, acceptability, feasibility and patient preferences.

RESULTS

The GDG suggested that MAP should be augmented to at least 75-80 mmHg as the "lower limit," but not actively augmented beyond an "upper limit" of 90-95 mmHg in order to optimize spinal cord perfusion in acute traumatic SCI. The quality of the evidence around the "target MAP" was very low, and thus the strength of this recommendation is weak. For duration of hemodynamic management, the GDG "suggested" that MAP be augmented for a duration of 3-7 days. Again, the quality of the evidence around the duration of MAP support was very low, and thus the strength of this recommendation is also weak. The GDG felt that a recommendation on the choice of vasopressor or the use of SCPP targets was not warranted, given the dearth of available evidence.

CONCLUSION

We provide new recommendations for blood pressure management after acute SCI that acknowledge the limitations of the current evidence on the relationship between MAP and neurologic recovery. It was felt that the low quality of existing evidence and uncertainty around the relationship between MAP and neurologic recovery justified a greater range of MAP to target, and for a broader range of days post-injury than recommended in previous guidelines. While important knowledge gaps still remain regarding hemodynamic management, these recommendations represent current perspectives on the role of MAP augmentation for acute SCI.

Interventions to Optimize Spinal Cord Perfusion in Patients With Acute Traumatic Spinal Cord Injury: An Updated Systematic Review

STUDY DESIGN

Systematic review update.

OBJECTIVES

Interventions that aim to optimize spinal cord perfusion are thought to play an important role in minimizing secondary ischemic damage and improving outcomes in patients with acute traumatic spinal cord injuries (SCIs). However, exactly how to optimize spinal cord perfusion and enhance neurologic recovery remains controversial. We performed an update of a recent systematic review (Evaniew et al, J. Neurotrauma 2020) to evaluate the effects of Mean Arterial Pressure (MAP) support or Spinal Cord Perfusion Pressure (SCPP) support on neurological recovery and rates of adverse events among patients with acute traumatic SCI.

METHODS

We searched PubMed/MEDLINE, EMBASE and ClinicalTrials.gov for new published reports. Two reviewers independently screened articles, extracted data, and evaluated risk of bias. We implemented the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) approach to rate confidence in the quality of the evidence.

RESULTS

From 569 potentially relevant new citations since 2019, we identified 9 new studies for inclusion, which were combined with 19 studies from a prior review to give a total of 28 studies. According to low or very low quality evidence, the effect of MAP support on neurological recovery is uncertain, and increased SCPP may be associated with improved neurological recovery. Both approaches may involve risks for specific adverse events, but the importance of these adverse events to patients remains unclear. Very low quality evidence failed to yield reliable guidance about particular monitoring techniques, perfusion ranges, pharmacological agents, or durations of treatment.

CONCLUSIONS

This update provides an evidence base to support the development of a new clinical practice guideline for the hemodynamic management of patients with acute traumatic SCI. While avoidance of hypotension and maintenance of spinal cord perfusion are important principles in the management of an acute SCI, the literature does not provide high quality evidence in support of a particular protocol. Further prospective, controlled research studies with objective validated outcome assessments are required to examine interventions to optimize spinal cord perfusion in this setting.

The 2023 AO Spine-Praxis Guidelines in Acute Spinal Cord Injury: What Have We Learned? What Are the Critical Knowledge Gaps and Barriers to Implementation?

STUDY DESIGN

Narrative summary of the 2023 AO Spine-Praxis clinical practice guidelines for management in acute spinal cord injury (SCI).

OBJECTIVES

The objective of this article is to summarize the key findings of the clinical practice guidelines for the optimal management of traumatic and intraoperative SCI (ISCI). This article will also highlight potential knowledge translation opportunities for each recommendation and discuss important knowledge gaps and areas of future research.

METHODS

Systematic reviews were conducted according to accepted methodological standards to evaluate the current body of evidence and inform the guideline development process. The summarized evidence was reviewed by a multidisciplinary guidelines development group that consisted of international multidisciplinary stakeholders. The Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) approach was used to rate the certainty of the evidence for each critical outcome and the "evidence to recommendation" framework was used to formulate the final recommendations.

RESULTS

The key recommendations regarding the timing of surgical decompression, hemodynamic management, and the prevention, diagnosis, and management of ISCI are summarized. While a strong recommendation was made for early surgery, further prospective research is required to define what constitutes sufficient surgical decompression, examine the role of ultra-early surgery, and assess the impact of early surgery in different SCI phenotypes, including central cord syndrome. Furthermore, additional investigation is required to evaluate the impact of mean arterial blood pressure targets on neurological recovery and to determine the utility of spinal cord perfusion pressure measurements. Finally, there is a need to examine the role of neuroprotective agents for the treatment of ISCI and to prospectively validate the new AO Spine-Praxis care pathway for the prevention, diagnosis, and management of ISCI. To optimize the translation of these guidelines into practice, important barriers to their implementation, particularly in underserved areas, need to be explored. Ultimately, these recommendations will help to establish more personalized approaches to care for SCI patients.

CONCLUSIONS

The recommendations from the 2023 AO Spine-Praxis guidelines not only highlight the current best practice in the management of SCI, but reveal critical knowledge gaps and barriers to implementation that will help to guide further research efforts in SCI.

Updates in the Early Management of Acute Spinal Cord Injury

Spinal cord injury (SCI) is a leading cause of disability worldwide, and effective management is necessary to improve clinical outcomes. Many long-standing therapies including early reduction and spinal cord decompression, methylprednisolone administration, and optimization of spinal cord perfusion have been around for decades; however, their efficacy has remained controversial because of limited high-quality data. This review article highlights studies surrounding the role of early surgical decompression and its role in relieving mechanical pressure on the microvascular circulation thereby reducing intraspinal pressure. Furthermore, the article touches on the current role of methylprednisolone and identifies promising studies evaluating neuroprotective and neuroregenerative agents. Finally, this article outlines the expanding body of literature evaluating mean arterial pressure goals, cerebrospinal fluid drainage, and expansive duroplasty to further optimize vascularization to the spinal cord. Overall, this review aims to highlight evidence for SCI treatments and ongoing trials that may markedly affect SCI care in the near future.

Cerebrospinal Fluid Pressure Dynamics as a Bedside Test in Traumatic Spinal Cord Injury to Assess Surgical Spinal Cord Decompression: Safety, Feasibility, and Proof-of-Concept

BACKGROUND

Sufficient and timely spinal cord decompression is a critical surgical objective for neurological recovery in spinal cord injury (SCI). Residual cord compression may be associated with disturbed cerebrospinal fluid pressure (CSFP) dynamics.

OBJECTIVES

This study aims to assess whether intrathecal CSFP dynamics in SCI following surgical decompression are feasible and safe, and to explore the diagnostic utility.

METHODS

Prospective cohort study. Bedside lumbar CSFP dynamics and cervical MRI were obtained following surgical decompression in N = 9 with mostly cervical acute-subacute SCI and N = 2 patients with non-traumatic SCI. CSFP measurements included mean CSFP, cardiac-driven CSFP peak-to-valley amplitudes (CSFPp), Valsalva maneuver, and Queckenstedt's test (firm pressure on jugular veins, QT). From QT, proxies for cerebrospinal fluid pulsatility curve were calculated (ie, relative pulse pressure coefficient; RPPC-Q). CSFP metrics were compared to spine-healthy patients. computer tomography (CT)-myelography was done in 3/8 simultaneous to CSFP measurements.

RESULTS

Mean age was 45 ± 9 years (range 17-67; 3F), SCI was complete (AIS A, N = 5) or incomplete (AIS B-D, N = 6). No adverse events related to CSFP assessments. CSFP rise during QT was induced in all patients [range 9.6-26.6 mmHg]. However, CSFPp was reduced in 3/11 (0.1-0.3 mmHg), and in 3/11 RPPC-Q was abnormal (0.01-0.05). Valsalva response was reduced in 8/11 (2.6-23.4 mmHg). CSFP dynamics corresponded to CT-myelography.

CONCLUSIONS

Comprehensive bedside lumbar CSFP dynamics in SCI following decompression are safe, feasible, and can reveal distinct patterns of residual spinal cord compression. Longitudinal studies are required to define critical thresholds of impaired CSFP dynamics that may impact neurological recovery and requiring surgical revisions.

Case report: Continuous spinal cord physiologic monitoring following traumatic spinal cord injury-A report from the Winnipeg Intraspinal Pressure Study (WISP)

Introduction

Acute traumatic spinal cord injury is routinely managed by surgical decompression and instrumentation of the spine. Guidelines also suggest elevating mean arterial pressure to 85 mmHg to mitigate secondary injury. However, the evidence for these recommendations remains very limited. There is now considerable interest in measuring spinal cord perfusion pressure by monitoring mean arterial pressure and intraspinal pressure. Here, we present our first institutional experience of using a strain gauge pressure transducer monitor to measure intraspinal pressure and subsequent derivation of spinal cord perfusion pressure.

Case presentation

The patient presented to medical attention after a fall off of scaffolding. A trauma assessment was completed at a local emergency room. He did not have any motor strength or sensation to the lower extremities. A computed tomography (CT) scan of the thoracolumbar spine confirmed a T12 burst fracture with retropulsion of bone fragments into the spinal canal. He was taken to surgery for urgent decompression of the spinal cord and instrumentation of the spine. A subdural strain gauge pressure monitor was placed at the site of injury through a small dural incision. Mean arterial pressure and intraspinal pressure were then monitored for 5 days after surgery. Spinal cord perfusion pressure was derived. The procedure was performed without complication and the patient underwent rehabilitation for 3 months where he regained some motor and sensory function in his lower extremities.

Conclusion

The first North American attempt at insertion of a strain gauge pressure monitor into the subdural space at the site of injury following acute traumatic spinal cord injury was performed successfully and without complication. Spinal cord perfusion pressure was derived successfully using this physiological monitoring. Further research efforts to validate this technique are required.

Proposal of a Management Algorithm to Predict the Need for Expansion Duraplasty in American Spinal Injury Association Impairment Scale Grades A-C Traumatic Cervical Spinal Cord Injury Patients

Expansion duraplasty to reopen effaced subarachnoid space and improve spinal cord perfusion, autoregulation, and spinal pressure reactivity index (sPRX) has been advocated in patients with traumatic cervical spinal cord injury (tCSCI). We designed this study to identify candidates for expansion duraplasty, based on the absence of cerebrospinal fluid (CSF) interface around the spinal cord on magnetic resonance imaging (MRI), in the setting of otherwise adequate bony decompression. Over a 61-month period, 104 consecutive American Spinal Injury Association Impairment Scale (AIS) grades A-C patients with tCSCI had post-operative MRI to assess the adequacy of surgical decompression. Their mean age was 53.4 years, and 89% were male. Sixty-one patients had falls, 31 motor vehicle collisions, 11 sport injuries, and one an assault. The AIS grade was A in 56, B in 18, and C in 30 patients. Fifty-four patients had fracture dislocations; there was no evidence of skeletal injury in 50 patients. Mean intramedullary lesion length (IMLL) was 46.9 (standard deviation = 19.4) mm. Median time from injury to decompression was 17 h (interquartile range 15.2 h). After surgery, 94 patients had adequate decompression as judged by the presence of CSF anterior and posterior to the spinal cord, whereas 10 patients had effacement of the subarachnoid space at the injury epicenter. In two patients whose decompression was not definitive and post-operative MRI indicated inadequate decompression, expansion duraplasty was performed. Candidates for expansion duraplasty (i.e., those with inadequate decompression) were significantly younger (p < 0.0001), were AIS grade A (p < 0.0016), had either sport injuries (six patients) or motor vehicle collisions (three patients) (p < 0.0001), had fracture dislocation (p = 0.00016), and had longer IMLL (p = 0.0097). In regression models, patients with sport injuries and inadequate decompression were suitable candidates for expansion duraplasty (p = 0.03). Further, 9.6% of patients failed bony decompression alone and either did (2) or would have (8) benefited from expansion duraplasty.

Significance of spinal cord perfusion pressure following spinal cord injury: A systematic scoping review

This scoping review systematically reviewed relevant research to summarize the literature addressing the significance of monitoring spinal cord perfusion pressure (SCPP) in acute traumatic spinal cord injury (SCI). The objectives of the review were to (1) examine the nature of research in the field of SCPP monitoring in SCI, (2) summarize the key research findings in the field, and (3) identify research gaps in the existing literature and future research priorities. Primary literature searches were conducted using databases (Medline and Embase) and expanded searches were conducted by reviewing the references of eligible articles and searches of Scopus, Web of Science core collection, Google Scholar, and conference abstracts. Relevant data were extracted from the studies and synthesis of findings was guided by the identification of patterns across studies to identify key themes and research gaps within the literature. Following primary and expanded searches, a total of 883 articles were screened. Seventy-three articles met the review inclusion criteria, including 34 original research articles. Other articles were categorized as conference abstracts, literature reviews, systematic reviews, letters to the editor, perspective articles, and editorials. Key themes relevant to the research question that emerged from the review included the relationship between SCPP and neurological recovery, the safety of monitoring pressures within the intrathecal space, and methods of intervention to enhance SCPP in the setting of acute traumatic SCI. Original research that aims to enhance SCPP by targeting increases in mean arterial pressure or reducing pressure in the intrathecal space is reviewed. Further discussion regarding where pressure within the intrathecal space should be measured is provided. Finally, we highlight research gaps in the literature such as determining the feasibility of invasive monitoring at smaller centers, the need for a better understanding of cerebrospinal fluid physiology following SCI, and novel pharmacological interventions to enhance SCPP in the setting of acute traumatic SCI. Ultimately, despite a growing body of literature on the significance of SCPP monitoring following SCI, there are still a number of important knowledge gaps that will require further investigation.

Advances in monitoring for acute spinal cord injury: a narrative review of current literature

Spinal cord injury (SCI) is a devastating condition that affects about 17,000 individuals every year in the United States, with approximately 294,000 people living with the ramifications of the initial injury. After the initial primary injury, SCI has a secondary phase during which the spinal cord sustains further injury due to ischemia, excitotoxicity, immune-mediated damage, mitochondrial dysfunction, apoptosis, and oxidative stress. The multifaceted injury progression process requires a sophisticated injury-monitoring technique for an accurate assessment of SCI patients. In this narrative review, we discuss SCI monitoring modalities, including pressure probes and catheters, micro dialysis, electrophysiologic measures, biomarkers, and imaging studies. The optimal next-generation injury monitoring setup should include multiple modalities and should integrate the data to produce a final simplified assessment of the injury and determine markers of intervention to improve patient outcomes.

Monitoring Spinal Cord Tissue Oxygen in Patients With Acute, Severe Traumatic Spinal Cord Injuries

Objectives

To determine the feasibility of monitoring tissue oxygen tension from the injury site (psctO2) in patients with acute, severe traumatic spinal cord injuries.

Design

We inserted at the injury site a pressure probe, a microdialysis catheter, and an oxygen electrode to monitor for up to a week intraspinal pressure (ISP), spinal cord perfusion pressure (SCPP), tissue glucose, lactate/pyruvate ratio (LPR), and psctO2. We analyzed 2,213 hours of such data. Follow-up was 6-28 months postinjury.

Setting

Single-center neurosurgical and neurocritical care units.

Subjects

Twenty-six patients with traumatic spinal cord injuries, American spinal injury association Impairment Scale A-C. Probes were inserted within 72 hours of injury.

Interventions

Insertion of subarachnoid oxygen electrode (Licox; Integra LifeSciences, Sophia-Antipolis, France), pressure probe, and microdialysis catheter.

Measurements and Main Results

psctO2 was significantly influenced by ISP (psctO2 26.7 +/- 0.3 mm Hg at ISP > 10 mmHg vs psctO2 22.7 +/- 0.8 mm Hg at ISP <= 10 mm Hg), SCPP (psctO2 26.8 +/- 0.3 mm Hg at SCPP < 90 mm Hg vs psctO2 32.1 +/- 0.7 mm Hg at SCPP >= 90 mm Hg), tissue glucose (psctO2 26.8 +/- 0.4 mm Hg at glucose < 6 mM vs 32.9 +/- 0.5 mm Hg at glucose >= 6 mM), tissue LPR (psctO2 25.3 +/- 0.4 mm Hg at LPR > 30 vs psctO2 31.3 +/- 0.3 mm Hg at LPR <= 30), and fever (psctO2 28.8 +/- 0.5 mm Hg at cord temperature 37-38[degrees]C vs psctO2 28.7 +/- 0.8 mm Hg at cord temperature >= 39[degrees]C). Tissue hypoxia also occurred independent of these factors. Increasing the FIO2 by 0.48 increases psctO2 by 71.8% above baseline within 8.4 minutes. In patients with motor-incomplete injuries, fluctuations in psctO2 correlated with fluctuations in limb motor score. The injured cord spent 11% (39%) hours at psctO2 less than 5 mm Hg (< 20 mm Hg) in patients with motor-complete outcomes, compared with 1% (30%) hours at psctO2 less than 5 mm Hg (< 20 mm Hg) in patients with motor-incomplete outcomes. Complications were cerebrospinal fluid leak (5/26) and wound infection (1/26).

Conclusions

This study lays the foundation for measuring and altering spinal cord oxygen at the injury site. Future studies are required to investigate whether this is an effective new therapy.

Intraoperative monitoring of CSF pressure in patients with degenerative cervical myelopathy (COMP-CORD Study): a prospective cohort study

Degenerative cervical myelopathy (DCM) is hallmarked by spinal canal narrowing and related cord compression and myelopathy. CSF pressure dynamics are likely disturbed due to spinal canal stenosis. The study aims to investigate the diagnostic value of continuous intraoperative CSF pressure monitoring during surgical decompression. Prospective single center study (NCT02170155) with enrolment of DCM patients that underwent surgical decompression between December 2019 and May 2021. Data from N=17 patients were analyzed, symptom severity graded with the modified Japanese Orthopedic Score (mJOA). CSF pulsations were continuously monitored with a lumbar intrathecal catheter during surgical decompression. Mean patient age was 62±9 years (range 38-73; 8F), symptoms were mild-moderate in most patients (mean mJOA 14±2, range 10-18). Measurements were well tolerated without safety concerns. In 15/16 (94%) CSF pulsations increased at the time of surgical decompression. In one case, responsiveness could not be evaluated for technical reasons. Unexpected CSF pulsation decrease was related to adverse events (i.e., CSF leakage). Median CSF pulsation amplitudes increased from pre-decompression (0.52 mmHg [IQR 0.71]) to post-decompression (0.72 mmHg [IQR 0.96]) (P=0.001). Mean baseline CSF pressure increased with lower magnitude than pulsations, from 9.5±3.5 to 10.3±3.8 mmHg (P=0.003). Systematic relations of CSF pulsations were confined to surgical decompression, independent of arterial blood pressure (P=0.927) or heart rate (P=0.102). Intraoperative CSF pulsation monitoring was sensitive, timely, and specifically related to surgical decompression while in addition adverse events could be discerned. Further investigation of the clinical value of intraoperative guidance for decompression in complex DCM surgery is promising.

Acute, severe traumatic spinal cord injury: improving urinary bladder function by optimizing spinal cord perfusion

OBJECTIVE

The authors sought to investigate the effect of acute, severe traumatic spinal cord injury on the urinary bladder and the hypothesis that increasing the spinal cord perfusion pressure improves bladder function.

METHODS

In 13 adults with traumatic spinal cord injury (American Spinal Injury Association Impairment Scale grades A-C), a pressure probe and a microdialysis catheter were placed intradurally at the injury site. We varied the spinal cord perfusion pressure and performed filling cystometry. Patients were followed up for 12 months on average.

RESULTS

The 13 patients had 63 fill cycles; 38 cycles had unfavorable urodynamics, i.e., dangerously low compliance (< 20 mL/cmH2O), detrusor overactivity, or dangerously high end-fill pressure (> 40 cmH2O). Unfavorable urodynamics correlated with periods of injury site hypoperfusion (spinal cord perfusion pressure < 60 mm Hg), hyperperfusion (spinal cord perfusion pressure > 100 mm Hg), tissue glucose < 3 mM, and tissue lactate to pyruvate ratio > 30. Increasing spinal cord perfusion pressure from 67.0 ± 2.3 mm Hg (average ± SE) to 92.1 ± 3.0 mm Hg significantly reduced, from 534 to 365 mL, the median bladder volume at which the desire to void was first experienced. All patients with dangerously low average initial bladder compliance (< 20 mL/cmH2O) maintained low compliance at follow-up, whereas all patients with high average initial bladder compliance (> 100 mL/cmH2O) maintained high compliance at follow-up.

CONCLUSIONS

We conclude that unfavorable urodynamics develop within days of traumatic spinal cord injury, thus challenging the prevailing notion that the detrusor is initially acontractile. Urodynamic studies performed acutely identify patients with dangerously low bladder compliance likely to benefit from early intervention. At this early stage, bladder function is dynamic and is influenced by fluctuations in the physiology and metabolism at the injury site; therefore, optimizing spinal cord perfusion is likely to improve urological outcome in patients with acute severe traumatic spinal cord injury.

A review of spinal cord perfusion pressure guided interventions in traumatic spinal cord injury

PURPOSE

To evaluate the causality between interventions on spinal cord perfusion pressure and neurological outcome in traumatic spinal cord injury.

METHODS

A systematic review was conducted in concordance with PRISMA guidelines. The literature was found in the EMBASE, PUBMED, SCOPUS, and WEB OF SCIENCE. Eligible studies included those that reported measurements and interventions on the spinal cord perfusion pressure in either animals or patients suffering from spinal cord injury. Only studies that reported a clinical or relevant clinical outcome measure (i.e., neurophysiology) were included.

RESULTS

The search yielded 795 unique records, and six studies were included after careful review. These studies suggested a positive correlation between spinal cord perfusion pressure and neurological outcome, but conclusions on causality could not be made.

CONCLUSION

In spite of growing indications that neurological outcomes are related to the spinal cord perfusion pressure in traumatic spinal cord injuries, a solid conclusion cannot be made due to the limited literature available. Additional well-designed studies are needed to address this issue.

Spinal Cord Perfusion Pressure Correlates with Anal Sphincter Function in a Cohort of Patients with Acute, Severe Traumatic Spinal Cord Injuries

Background

Acute, severe traumatic spinal cord injury often causes fecal incontinence. Currently, there are no treatments to improve anal function after traumatic spinal cord injury. Our study aims to determine whether, after traumatic spinal cord injury, anal function can be improved by interventions in the neuro-intensive care unit to alter the spinal cord perfusion pressure at the injury site.

Methods

We recruited a cohort of patients with acute, severe traumatic spinal cord injuries (American Spinal Injury Association Impairment Scale grades A–C). They underwent surgical fixation within 72 h of the injury and insertion of an intrathecal pressure probe at the injury site to monitor intraspinal pressure and compute spinal cord perfusion pressure as mean arterial pressure minus intraspinal pressure. Injury-site monitoring was performed at the neuro-intensive care unit for up to a week after injury. During monitoring, anorectal manometry was also conducted over a range of spinal cord perfusion pressures.

Results

Data were collected from 14 patients with consecutive traumatic spinal cord injury aged 22–67 years. The mean resting anal pressure was 44 cmH₂O, which is considerably lower than the average for healthy patients, previously reported at 99 cmH₂O. Mean resting anal pressure versus spinal cord perfusion pressure had an inverted U-shaped relation (Ȓ² = 0.82), with the highest resting anal pressures being at a spinal cord perfusion pressure of approximately 100 mmHg. The recto-anal inhibitory reflex (transient relaxation of the internal anal sphincter during rectal distension), which is important for maintaining fecal continence, was present in 90% of attempts at high (90 mmHg) spinal cord perfusion pressure versus 70% of attempts at low (60 mmHg) spinal cord perfusion pressure (P < 0.05). During cough, the rise in anal pressure from baseline was 51 cmH₂O at high (86 mmHg) spinal cord perfusion pressure versus 37 cmH₂O at low (62 mmHg) spinal cord perfusion pressure (P < 0.0001). During anal squeeze, higher spinal cord perfusion pressure was associated with longer endurance time and spinal cord perfusion pressure of 70–90 mmHg was associated with stronger squeeze. There were no complications associated with anorectal manometry.

Conclusions

Our data indicate that spinal cord injury causes severe disruption of anal sphincter function. Several key components of anal continence (resting anal pressure, recto-anal inhibitory reflex, and anal pressure during cough and squeeze) markedly improve at higher spinal cord perfusion pressure. Maintaining too high of spinal cord perfusion pressure may worsen anal continence.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12028-021-01232-1.

Acute, Severe Traumatic Spinal Cord Injury: Monitoring from the Injury Site and Expansion Duraplasty

We discuss 2 evolving management options for acute spinal cord injury that hold promise to further improve outcome: pressure monitoring from the injured cord and expansion duraplasty. Probes surgically implanted at the injury site can transduce intraspinal pressure, spinal cord perfusion pressure, and cord metabolism. Intraspinal pressure is not adequately reduced by bony decompression alone because the swollen, injured cord is compressed against the dura. Expansion duraplasty may be necessary to effectively decompress the injured cord. A randomized controlled trial called DISCUS is investigating expansion duraplasty as a novel treatment for acute, severe traumatic cervical spinal cord injury.

Efficacy of Early (≤ 24 Hours), Late (25-72 Hours), and Delayed (>72 Hours) Surgery with Magnetic Resonance Imaging-Confirmed Decompression in American Spinal Injury Association Impairment Scale Grades C and D Acute Traumatic Central Cord Syndrome Caused by Spinal Stenosis

The therapeutic significance of timing of decompression in acute traumatic central cord syndrome (ATCCS) caused by spinal stenosis remains unsettled. We retrospectively examined a homogenous cohort of patients with ATCCS and magnetic resonance imaging (MRI) evidence of post-treatment spinal cord decompression to determine whether timing of decompression played a significant role in American Spinal Injury Association (ASIA) motor score (AMS) 6 months following trauma. We used the t test, analysis of variance, Pearson correlation coefficient, and multiple regression for statistical analysis. During a 19-year period, 101 patients with ATCCS, admission ASIA Impairment Scale (AIS) grades C and D, and an admission AMS of ≤95 were surgically decompressed. Twenty-four of 101 patients had an AIS grade C injury. Eighty-two patients were males, the mean age of patients was 57.9 years, and 69 patients had had a fall. AMS at admission was 68.3 (standard deviation [SD] 23.4); upper extremities (UE) 28.6 (SD 14.7), and lower extremities (LE) 41.0 (SD 12.7). AMS at the latest follow-up was 93.1 (SD 12.8), UE 45.4 (SD 7.6), and LE 47.9 (SD 6.6). Mean number of stenotic segments was 2.8, mean canal compromise was 38.6% (SD 8.7%), and mean intramedullary lesion length (IMLL) was 23 mm (SD 11). Thirty-six of 101 patients had decompression within 24 h, 38 patients had decompression between 25 and 72 h, and 27 patients had decompression >72 h after injury. Demographics, etiology, AMS, AIS grade, morphometry, lesion length, surgical technique, steroid protocol, and follow-up AMS were not statistically different between groups treated at different times. We analyzed the effect size of timing of decompression categorically and in a continuous fashion. There was no significant effect of the timing of decompression on follow-up AMS. Only AMS at admission determined AMS at follow-up (coefficient = 0.31; 95% confidence interval [CI]:0.21; p = 0.001). We conclude that timing of decompression in ATCCS caused by spinal stenosis has little bearing on ultimate AMS at follow-up.

Acute Traumatic Spinal Cord Injury in Humans, Dogs, and Other Mammals: The Under-appreciated Role of the Dura

We review human and animal studies to determine whether, after severe spinal cord injury (SCI), the cord swells against the inelastic dura. Evidence from rodent models suggests that the cord swells because of edema and intraparenchymal hemorrhage and because the pia becomes damaged and does not restrict cord expansion. Human cohort studies based on serial MRIs and measurements of elevated intraspinal pressure at the injury site also suggest that the swollen cord is compressed against dura. In dogs, SCI commonly results from intervertebral disc herniation with evidence that durotomy provides additional functional benefit to conventional (extradural) decompressive surgery. Investigations utilizing rodent and pig models of SCI report that the cord swells after injury and that durotomy is beneficial by reducing cord pressure, cord inflammation, and syrinx formation. A human MRI study concluded that, after extensive bony decompression, cord compression against the dura may only occur in a small number of patients. We conclude that the benefit of routinely opening the dura after SCI is only supported by animal and level III human studies. Two randomized, controlled trials, one in humans and one in dogs, are being set up to provide Level I evidence.

Effects of local hypothermia-rewarming on physiology, metabolism and inflammation of acutely injured human spinal cord

In five patients with acute, severe thoracic traumatic spinal cord injuries (TSCIs), American spinal injuries association Impairment Scale (AIS) grades A-C, we induced cord hypothermia (33 °C) then rewarming (37 °C). A pressure probe and a microdialysis catheter were placed intradurally at the injury site to monitor intraspinal pressure (ISP), spinal cord perfusion pressure (SCPP), tissue metabolism and inflammation. Cord hypothermia-rewarming, applied to awake patients, did not cause discomfort or neurological deterioration. Cooling did not affect cord physiology (ISP, SCPP), but markedly altered cord metabolism (increased glucose, lactate, lactate/pyruvate ratio (LPR), glutamate; decreased glycerol) and markedly reduced cord inflammation (reduced IL1β, IL8, MCP, MIP1α, MIP1β). Compared with pre-cooling baseline, rewarming was associated with significantly worse cord physiology (increased ICP, decreased SCPP), cord metabolism (increased lactate, LPR; decreased glucose, glycerol) and cord inflammation (increased IL1β, IL8, IL4, IL10, MCP, MIP1α). The study was terminated because three patients developed delayed wound infections. At 18-months, two patients improved and three stayed the same. We conclude that, after TSCI, hypothermia is potentially beneficial by reducing cord inflammation, though after rewarming these benefits are lost due to increases in cord swelling, ischemia and inflammation. We thus urge caution when using hypothermia-rewarming therapeutically in TSCI.

Targeted Perfusion Therapy in Spinal Cord Trauma

We review state-of-the-art monitoring techniques for acute, severe traumatic spinal cord injury (TSCI) to facilitate targeted perfusion of the injured cord rather than applying universal mean arterial pressure targets. Key concepts are discussed such as intraspinal pressure and spinal cord perfusion pressure (SCPP) at the injury site, respectively, analogous to intracranial pressure and cerebral perfusion pressure for traumatic brain injury. The concept of spinal cord autoregulation is introduced and quantified using spinal pressure reactivity index (sPRx), which is analogous to pressure reactivity index for traumatic brain injury. The U-shaped relationship between sPRx and SCPP defines the optimum SCPP as the SCPP that minimizes sPRx (i.e., maximizes autoregulation), and suggests that not only ischemia but also hyperemia at the injury site may be detrimental. The observation that optimum SCPP varies between patients and temporally in each patient supports individualized management. We discuss multimodality monitoring, which revealed strong correlations between SCPP and injury site metabolism (tissue glucose, lactate, pyruvate, glutamate, glycerol), monitored by surface microdialysis. Evidence is presented that the dura is a major, but unappreciated, cause of spinal cord compression after TSCI; we thus propose expansion duroplasty as a novel treatment. Monitoring spinal cord blood flow at the injury site has revealed novel phenomena, e.g., 3 distinct blood flow patterns, local steal, and diastolic ischemia. We conclude that monitoring from the injured spinal cord in the intensive care unit is a safe technique that appears to enable optimized and individualized spinal cord perfusion.