Surgical Decompression of Traumatic Cervical Spinal Cord Injury: A Pilot Study Comparing Real-Time Intraoperative Ultrasound After Laminectomy With Postoperative MRI and CT Myelography

Time is spine: critical updates for the intensivist

PURPOSE OF REVIEW

The concept of 'time is spine' emphasizes early or ultra-early surgical decompression within 24 or 12 h, respectively, after spinal cord injury (SCI) to maximize recovery. This review updates the latest findings on the timing of surgical decompression and hemodynamic management in acute SCI, focusing on neurological outcomes and complications.

RECENT FINDINGS

While early decompression may improve neurological outcomes, factors like injury severity, comorbidities, and system resources affect surgical timing. Recent studies question the benefits of ultra-early decompression, finding no significant improvement at 12 months, suggesting earlier analyses may have overstated its benefits. Current recommendations include tailoring decompression timing to individual cases, considering patient-specific and systemic factors. New techniques like spinal cord pressure monitoring, intraoperative ultrasound, and advanced imaging are advancing targeted intervention and hemodynamic management in SCI.

SUMMARY

The timing of spinal decompression and hemodynamic management may impact neurological function, however, because of the deficiencies of current studies, individualized, patient-tailored decision-making is critical. A multidisciplinary approach that considers injury severity and patient characteristics is essential for optimal management. Further research is required to refine the timing of surgical intervention and explore additional factors influencing recovery.

The feasibility and utility of intraoperative ultrasound in spinal cord injury patients: an international survey of AO spine members

STUDY DESIGN

Survey.

OBJECTIVES

Intraoperative ultrasound (IOUS) is an emerging tool for assessing the injured spinal cord during surgical intervention and particularly after traumatic spinal cord injury (SCI). The extent of utilization of this technique is unknown. To assess whether a knowledge gap exists regarding IOUS in managing SCI patients, an international survey of spine surgeons was performed.

SETTING

International Survey.

METHODS

Members of the AO Spine international community were surveyed using a web-based questionnaire developed by an SCI expert commission. The categorical data were analyzed descriptively.

RESULTS

Of the 276 completed surveys, 22% (n = 61/276) indicated IOUS was utilized during spine surgery, with most responses coming from Europe (38% n = 24/61) and North America (30% n = 18/61). Only 41% (n = 25/61) had received formal IOUS training. There were 59% (n = 36/61) of respondents who indicated they use IOUS on patients with acute SCI, mainly to assess adequate decompression. Of those not using IOUS, 50% (n = 107/215) did not have access to an ultrasound machine available. Overall, 92% (n = 254/276) indicated that an IOUS training course would be beneficial to improve understanding and patient care.

CONCLUSIONS

This international survey of spine surgeons demonstrated that currently, there is limited use of IOUS in the surgical management of acute SCI. Understanding the needs of spine surgeons and tailoring educational opportunities may increase the role of IOUS. Given the importance of surgical decompression in enhancing outcomes after acute SCI coupled with the ability of IOUS to assess decompression, greater adoption of IOUS could further enhance the efficacy of decompressive surgery.

Evolution of Spinal Cord Swelling in Acute Traumatic Spinal Cord Injury

We hypothesized that the Monro-Kellie doctrine, a key principle in traumatic brain injury (TBI), also applies in traumatic spinal cord injury (TSCI). By analyzing 9986 h of intraspinal pressure (ISP) monitoring data from 79 TSCI patients, we show that concepts developed to quantify compensatory reserve in TBI may be analogously defined in TSCI, termed ISP pulse amplitude (sAMP), spinal compensatory reserve index (sRAP), and ISP waveform shape. As ISP increases beyond 15 mmHg, compensatory reserve becomes impaired (sAMP rises and sRAP becomes positive). As ISP increases beyond 20 mmHg, the morphology of the ISP waveform changes from three peaks (P1, P2, P3) with P1 dominant, to three peaks with P2 dominant, to a rounded signal. Key differences in TSCI, compared with TBI, are no plateau ISP waves, and no critical ISP beyond which sAMP decreases and sRAP becomes negative. Four factors were associated with increased spinal cord swelling or reduced spinal cord compliance: thoracic level of injury, no laminectomy, delayed surgery, and more severe injury. We also hypothesized that, as in TBI, the spinal cord maximally swells a few days after injury. Serial ultrasound scans of the injured spinal cords in 9 patients and plots of change from baseline in ISP, sAMP, and sRAP versus time in 79 patients revealed delayed maximal cord swelling within 5 days of surgery. We conclude that the spinal Monro-Kellie concept allows the spinal compensatory reserve to be quantified. Our data show that spinal compensatory reserve becomes exhausted as ISP increases above 15-20 mmHg and that there is delayed cord swelling after injury, which implies that adequate cord decompression confirmed during surgery by ultrasound may not persist postoperatively.

The concepts of Intra Spinal Pressure (ISP), Intra Thecal Pressure (ITP), and Spinal Cord Perfusion Pressure (SCPP) in acute, severe traumatic spinal cord injury: Narrative review

There is increasing interest in monitoring pressure from the injured spinal cord to guide the management of patients with acute, severe traumatic spinal cord injuries (TSCI). This is analogous to monitoring intracranial pressure and cerebral perfusion pressure in traumatic brain injury (TBI). Here, we explore key concepts in this field and novel therapies that are emerging from these ideas. We argue that the Monro-Kellie doctrine, a fundamental principle in TBI, may also apply to TSCI as follows: The injured cord swells, initially displacing surrounding cerebrospinal fluid (CSF) that prevents a rise in spinal cord pressure; once the CSF space is exhausted, the spinal cord pressure at the injury site rises. The spinal Monro-Kellie doctrine allows us to define novel concepts to guide the management of TSCI based on principles employed in the management of TBI such as intraspinal pressure (ISP), intrathecal pressure (ITP), spinal cord perfusion pressure (SCPP), spinal pressure reactivity index (sPRx), and optimum SCPP (SCPPopt). Draining lumbar CSF and expansion duroplasty are currently undergoing clinical trials as novel therapies for TSCI. We conclude that there is acknowledgement that blood pressure targets applied to all TSCI patients are inadequate. Current research aims to develop individualised management based on ISP/ITP and SCPP monitoring. These techniques are experimental. A key controversy is whether the spinal cord pressure is best measured from the injury site (ISP) or from the lumbar cerebrospinal fluid (ITP).

Invasive devices to monitor the intraspinal perfusion pressure in the hemodynamic management of acute spinal cord injury: A systematic scoping review

BACKGROUND

Various methods for measuring intrathecal pressure (ITP) after spinal cord injury (SCI) to guide hemodynamic management have been investigated. To synthesize the current literature, this current study conducted a scoping review of the use of intrathecal devices to monitor ITP during acute management of SCI with the aim of understanding the association between ITP monitoring with physiological and clinical outcomes.

METHODS

A systematic review of literature following the Cochrane Handbook for Systematic Reviews of Interventions and Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement. All eligible studies were screened for inclusion and exclusion criteria. Data extracted included number of patients included, severity of injury, characteristics of the intervention-intrathecal device used to record the ITP, outcomes -hemodynamic parameters observed, changes in the American Spinal Injury Association (ASIA) Impairment Scale (AIS), total motor scores, association of ITP with other physiological variables.

RESULTS

The search yielded a total of 1,698 articles, of which 30 observational studies and 2 randomized clinical trials were deemed eligible based on their use of an intrathecal invasive device to monitor spinal cord perfusion pressure (SCPP) in patients with SCI. Of these, 9 studies used a lumbar drain, 23 a Codman pressure probe and 1 study that used both. These studies underscore the crucial interplay between ITP, the SCPP and physiological variables, with neurological outcome. It is still unclear whether monitoring from a lumbar drain is accurate enough to highlight what is occurring at the site of SCI, which is the main advantage of Codman Probe, however, the latter requires specialized personnel that may not be available in most settings. Minor adverse effects were associated with lumbar drain catheters, while cerebrospinal fluid leak requiring repair (~ 7%) is the main concern with Codman Probes.

CONCLUSION

Future investigation of SCPP protocols via lumbar drains and Codman probes ought to involve multi-centered randomized controlled trials and continued translational investigation with animal models.

Real-Time Intraoperative Ultrasound Using a Minimally Invasive Transducer During Anterior Cervical Spine Surgery

BACKGROUND AND OBJECTIVES

Intraoperative ultrasound (IOUS) during anterior cervical surgery is hindered by large transducer size and small operative corridor. We hypothesized that a linear (minimally invasive) transducer designed for transsphenoidal surgery can visualize the spinal cord, nerve roots, and surrounding structures during anterior cervical approaches, facilitating intraoperative assessment of central and foraminal decompression.

METHODS

IOUS was used to evaluate 26 levels in 17 patients (15 anterior cervical discectomy and fusion, 1 corpectomy, 1 arthroplasty) with a linear probe (7 × 6-mm end-fire transducer, 150-mm length, 12-15 MHz). After pin-based distraction, discectomy, and posterior longitudinal ligament resection, IOUS assessed adequacy of cord decompression and, following proximal foraminotomy or uncinectomy, nerve root decompression. If indicated, additional decompression was completed. Criteria for adequate central and foraminal decompression were visualization of subarachnoid space around the cord and cerebrospinal fluid pulsatility along the root sleeve/absence of nerve root compression distal to the root sleeve, respectively.

RESULTS

IOUS successfully visualized the cord, nerve roots, and surrounding structures in all 26 levels and influenced management in 11 levels (42.3%). IOUS indicated persistent cord and nerve root compression in 2 and 7 levels, respectively. Planned uncinectomy was aborted in 2 levels after IOUS demonstrated adequate nerve root decompression with intervertebral distraction/proximal foraminotomy alone. IOUS identified persistent nerve root compression after initial proximal foraminotomy in 4 levels and uncinectomy in 2 levels. An unplanned uncinectomy was performed in 1 level after IOUS showed persistent nerve root compression after multiple iterations of proximal foraminotomy. At follow-up (mean 3.1 months), the mean improvement in Numeric Rating Scale neck and arm pain, Neck Disability Index, and modified Japanese Orthopedic Association was 4.0%, 3.2%, 3.7%, and 0.7%, respectively.

CONCLUSION

The neural elements and their relationships to surrounding bone/soft tissue can be visualized using a minimally invasive IOUS transducer during anterior cervical surgery without having to remove pin-based distraction. This allows surgeons to intraoperatively verify the extent of central and foraminal decompression.

Spinal Cord Injury: Emerging Technologies

The mainstay of treatment for spinal cord injury includes decompressive laminectomy and elevation of mean arterial pressure. However, outcomes often remain poor. Extensive research and ongoing clinical trials seek to design new treatment options for spinal cord injury, including stem cell therapy, scaffolds, brain-spine interfaces, exoskeletons, epidural electrical stimulation, ultrasound, and cerebrospinal fluid drainage. Some of these treatments are targeted at the initial acute window of injury, during which secondary damage occurs; others are designed to help patients living with chronic injuries.

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.

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.

Evolving trends in the surgical, anaesthetic, and intensive care management of acute spinal cord injuries in the UK

PURPOSE

We surveyed the treatment of acute spinal cord injuries in the UK and compared current practices with 10 years ago.

METHODS

A questionnaire survey was conducted amongst neurosurgeons, neuroanaesthetists, and neurointensivists that manage patients with acute spinal cord injuries. The survey gave two scenarios (complete and incomplete cervical spinal cord injuries). We obtained opinions on the speed of transfer, timing and aim of surgery, choice of anaesthetic, intraoperative monitoring, targets for physiological parameters, and drug treatments.

RESULTS

We received responses from 78.6% of UK units that manage acute spinal cord injuries (33 neurosurgeons, 56 neuroanaesthetists/neurointensivists). Most neurosurgeons operate within 12 h for incomplete (82%) and complete (64%) injuries. There is a significant shift from 10 years ago, when only 61% (incomplete) and 30% (complete) of neurosurgeons operated within 12 h. The preferred anaesthetic technique in 2022 is total intravenous anaesthesia (TIVA), used by 69% of neuroanaesthetists. Significantly more intraoperative monitoring is now used at least sometimes, including bispectral index (91%), non-invasive cardiac output (62%), and neurophysiology (73-77%). Methylprednisolone is no longer used by surgeons. Achieving at least 80 mmHg mean arterial blood pressure is recommended by 70% neurosurgeons, 62% neuroanaesthetists, and 75% neurointensivists.

CONCLUSIONS

Between 2012 and 2022, there was a paradigm shift in managing acute spinal cord injuries in the UK with earlier surgery and more intraoperative monitoring. Variability in practice persists due to lack of high-quality evidence and consensus guidelines.

Visibility of Prevertebral Soft Tissues in the Neck Using Ultrasonography: A Feasibility Study

OBJECTIVE

To aid emergent diagnosis of postoperative retropharyngeal hematoma in anterior cervical spine surgery patients, this study investigates ultrasonography's potential role by evaluating the visibility of retropharyngeal and prevertebral soft tissues in the neck using ultrasound and potential correlations with body habitus.

METHODS

The visibility of the anterior vertebral bodies and the prevertebral soft tissues in both sides of the neck was recorded and analyzed with 95% CI using the Wilson method. Body mass index, neck circumference, and neck length were measured. A point-biserial correlation was performed to compare body habitus with visibility of vertebrae and prevertebral tissues.

RESULTS

Longus colli muscle and C3 to C6 were successfully visualized in all 10 (100%) cases on both sides. C2 was only visible in 6 (60%) on both sides. C7 was visible in 9 (90%) on the right and 7 (70%) on the left. The esophagus was visible in 7 (70%) on the right and 10 (100%) on the left. There was a significant negative correlation with neck circumference and C2 visibility on the right side, r(8) = -0.76, P = 0.011.

CONCLUSIONS

Ultrasonography was successful in visualizing prevertebral tissues, with a trend of obstructed visibility with wider and longer necks.

CLINICAL RELEVANCE

Ultrasonography has potential to aid early detection of postoperative retropharyngeal hematoma after cervical spine surgery.

LEVEL OF EVIDENCE: 4

Current insights into the management of spinal cord injury

Background

Traumatic spinal cord injury (SCI) is a serious disorder that results in severe impairment of neurological function as well as disability, ultimately reducing a patient's quality of life. The pathophysiology of SCI involves a primary and secondary phase, which causes neurological injury.

Methods

Narrative review on current clinical management of spinal cord injury and emerging therapies.

Results

This review explores the management of SCI through early decompressive surgery, optimizing mean arterial pressure, steroid therapy and focused rehabilitation. These management strategies reduce secondary injury mechanisms to prevent the propagation of further neurological damage. The literature regarding emerging research is also explored in cell-based, gene, pharmacological and neuromodulation therapies, which aim to repair the spinal cord following the primary injury mechanism.

Conclusions

Outcomes for patients with SCI can be enhanced and improved if primary and secondary phases of SCI can be addressed.