Meta-Analysis of Pre-Clinical Studies of Early Decompression in Acute Spinal Cord Injury: A Battle of Time and Pressure

Abstract

BackgroundThe use of early decompression in the management of acute spinal cord injury (SCI) remains contentious despite many pre-clinical studies demonstrating benefits and a small number of supportive clinical studies. Although the pre-clinical literature favours the concept of early decompression, translation is hindered by uncertainties regarding overall treatment efficacy and timing of decompression.MethodsWe performed meta-analysis to examine the pre-clinical literature on acute decompression of the injured spinal cord. Three databases were utilised; PubMed, ISI Web of Science and Embase. Our inclusion criteria consisted of (i) the reporting of efficacy of decompression at various time intervals (ii) number of animals and (iii) the mean outcome and variance in each group. Random effects meta-analysis was used and the impact of study design characteristics assessed with meta-regression.ResultsOverall, decompression improved behavioural outcome by 35.1% (95%CI 27.4-42.8; I2=94%, p<0.001). Measures to minimise bias were not routinely reported with blinding associated with a smaller but still significant benefit. Publication bias likely also contributed to an overestimation of efficacy. Meta-regression demonstrated a number of factors affecting outcome, notably compressive pressure and duration (adjusted r2=0.204, p<0.002), with increased pressure and longer durations of compression associated with smaller treatment effects. Plotting the compressive pressure against the duration of compression resulting in paraplegia in individual studies revealed a power law relationship; high compressive forces quickly resulted in paraplegia, while low compressive forces accompanying canal narrowing resulted in paresis over many hours.ConclusionThese data suggest early decompression improves neurobehavioural deficits in animal models of SCI. Although much of the literature had limited internal validity, benefit was maintained across high quality studies. The close relationship of compressive pressure to the rate of development of severe neurological injury suggests that pressure local to the site of injury might be a useful parameter determining the urgency of decompression.

Does surgical treatment within 4 hours after trauma have an influence on neurological remission in patients with acute spinal cord injury?

“…Because damage in the primary phase cannot be prevented, all approaches focus on restricting damage in the secondary phase of the injury. Some animal models have suggested that surgical decompression of the spinal cord is accompanied by a reduction of secondary damage, as well as an improvement in motor function 9. Clear evidence for a positive neuroprotective effect of spinal cord decompression and improved clinical outcome is still absent.…”

“…Clear evidence for a positive neuroprotective effect of spinal cord decompression and improved clinical outcome is still absent. Also, the proper timing for decompression remains controversial; however, most studies indicate an enhanced neuroprotective effect after early spinal cord decompression 9–12…”

Intubation Biomechanics

“…58 In the absence of prior injury, brief periods (seconds-minutes) of moderate cord compression are relatively well tolerated 59,60 whereas, with pre-existing cord injury/compression, the amount and duration of “tolerable” compression is likely to be much less. 61 Consequently, our general conclusion regarding the clinical utility/safety of either the Macintosh or Airtraq in the setting of a Type II odontoid fracture may not apply in the setting of pre-existing bony displacement and/or cervical cord injury.…”

Traumatic Spinal Cord Injury

“…Preclinical studies show patterns of primary and secondary injury mechanisms and provide reasoning toward surgical decompression (7). For one, many of these core concepts have been the basis of care of patients with spinal cord injuries (SCIs).…”