Surgical management of acute spinal cord injury in emergency setting

Introduction

Historically, closed reduction with external immobilization was the milestone of treatment for acute SCI and only few cases were reserved for surgical management. However, in the last 2 decades, spine surgeons emphasized early surgical management of SCI ( ; ; ).

Preclinical studies suggested that persistent compression of spinal cord after primary injury is responsible for an additional secondary damage which might be avoided reducing tissue damage as soon as possible and improving outcomes ( ; ).

SDSF allows stabilization of vertebral column and decompression of spinal cord. Moreover, stabilization prevents any further trauma on spinal cord and allows early rehabilitation ( ).

Since vascular mechanisms of secondary injury after SCI were already discovered in the past, the practice of ESD has now biological support ( ; ).

Removing spinal cord compression and restoring blood supply should reduce the biochemical process induced by ischemia due to local compression ( ; ; ).

Despite the increasing literature, there are still some unanswered questions about the optimal methods for ESD. We still don’t know if all patients are going to benefit from ESD or if there are subgroups which are more likely to benefit than others ( Table 1 ). We still don’t know the appropriate time for surgical intervention balancing key priorities of efficacy and clinical feasibility.

In this narrative review, we will highlight the situation of last 20 years literature about ESD in patients with acute SCI focusing to which subgroups of SCI will benefit from ESD and the time of surgical intervention.

Natural history of patients with acute cervical SCI

Approximately, one third of patients with cervical SCI has a complete injury. However, the incidence is double in patients with associated polytrauma ( ).

At 1 year from injury, 70% of patients with an initial ASIA ( Table 2 ) score A injury will remain A, while about 30% of them will show some signs of improvement. Around 14% will improve to B, 9.5% to C, 6.5% to D, while none will improve to ASIA E ( ; ). On the other hand, patients with incomplete SCI have a much higher spontaneous recovery ( ).

Unfortunately, at 1 year after time of injury, patients with complete cervical SCI had a mean recovery ranging from 9.0 to 14 motor score points( ), calculating as motor score (ranging from 0 to 5 per muscle group), the strength for each muscle group below the lesion level ( ).

Neurological improvement will typically show within the first 3 months and then it will enter a steady state ( ); even if in a little percentage of patients (about 9%) some little improvement can be showed even 5 years after injury ( ).

Natural history of patients with thoracic or thoracolumbar SCI

A complete neurological injury is reported ranging from 16.2% to 73.0% of patients with acute thoracic SCI ( ) and it is more frequent in patients with polytrauma ( ) ( Fig. 1 ).

At 1 year from injury, about 85% of patients with initial ASIA A will not improve, while about 15% of them will show 1 or more ASIA grade improvement. In patients with initial ASIA B, more than 80% of them will show some improvement ( ; ).

Substantially, acute thoracic SCI will improve less than cervical or thoracolumbar SCI ( ). In only 3.6% of patients with ASIA A grade at 1 year after injury, some minor neurological recovery can be recorded up till 5 years ( ).

Thoracolumbar fractures can be associated with conus medullary injury (fractures from T8-L2) and cauda equina injury (fractures below L1-L2) ( ).

Both syndromes are difficult to be distinguished one by the other. CMS is often characterized by a symmetric sensory deficits, bladder and bowel disfunction, and mild lower extremity weakness. CES is often defined by asymmetric sensory and motor deficits. In 20% of patients a complete lack of sensory and motor function will be present below the level of injury ( ).

Thoracolumbar SCI will show the same rate of neurological recovery of complete cervical SCI ( ) After 1 year from trauma, patients will experience a mean recovery of 4.5 motor score points below injury level ( ).

Surgical procedures

SCI are a wide spectrum of injuries, ranging from less to more severe spinal cord damage. For this reason, a singular approach to the spine is not correct and surgical choice should be individualized to each patient ( ; ). The main goals of treatment are fixation of instability and decompression of the spinal cord ( Fig. 2 ) and the choice of the correct surgical procedure is based on severity, level and mechanism of injury; location and extension of compression and surgeon preference.

Surgical approaches to the spine are classified as anterior or posterior. With both approaches stabilization and decompression can be achieved, but in more severe cases where a circumferential arthrodesis is needed, both approaches are combined together (staged or in single setting) ( ).

In cervical SCI, anterior approach is the most widely used allowing easily a ventral decompression and corpectomy, while a posterior approach is more appropriate for the thoracolumbar spine, where chest and abdomen represent an anatomical barrier.

In most cases, due to complex injury with disruption of anterior and posterior elements, anterior and posterior approach where combined together to perform a 360° arthrodesis.

Most common instrumentation devices used are pedicle screws with or without cement augmentation for thoracolumbar spine and pedicle or lateral masses screws for cervical spine. Usually, in acute traumatic SCI only one or two vertebral segments are involved and short segment stabilization is always preferred if possible. In flexion type injuries, posterior approach is usually preferred in the most of thoracolumbar injuries. In most cases, laminectomy, assure quick spinal decompression and also reduction with ligamentotaxis for thoracolumbar fractures ( ; ) ( Fig. 3 ).

How to define early versus late surgery post SCI?

Several articles have examined a different post injury range of time thresholds to define early versus late surgery. However, how much time can be considered “early” in not already clearly established. To recommend one of these thresholds and to choose the most favorable moment, two main principles must be considered ( ; ):

• (1)

  efficacy (the extent of time in which surgery results in better outcomes).

• (2)

  feasibility (the extent of time in which it is possible to perform surgery before the said limit taking into account the practical realities of the prehospital and hospital environment).

Which is the most efficacious threshold?

The theoretical objective of surgery is to begin a neuroprotective therapy performing a post injury treatment as soon as possible, preventing a secondary injury and favoring better recovery.

According to literature ( ), three common time thresholds can be found:

• (1)

  ultra-early threshold (8–12 h post SCI).

• (2)

  early threshold (24 h post SCI).

• (3)

  late threshold (48–72 h post SCI).