Acute cervical spinal cord injury (SCI) is one of the most devastating conditions, and can lead to paralysis, sensory impairment and bowel, bladder and sexual dysfunction. Individuals with cervical canal stenosis are known at high risk to develop cervical SCI. Among cervical SCI patients with cervical stenosis, extensional injury is the most common injury mechanism, not a few of them radiologically presented no fracture or dislocation(SCIWORA). This injury should be classified into distractive extension type according to Allen’s report[19] or included into the B3 type according AO classification, and need surgery intervention. Distractive extension injuries are characterized by progressive failure of the motion segment in an anterior to posterior direction, which consists of failure of the anterior longitudinal ligament and annulus fibrosus. Widening of the disc space could be seen on x-ray under extention. There may be a small avulsion fracture at the anterior margin of the disc space in some cases. If extensional force continued, posterior subluxation could be seen. And this is also not uncommon that the magnitude of posterior displacement could often be vanished by followed flexion of head. Distractive extension injuries often were the result of a fall on the face. So if patients with face injury, who are diagnosed with spinal cord injury but without fracture or dislocation, need be paid attention to the extensional cervical SCIWORA. In this study, we advocated that cervical laminoplasty combined with transpedicular screw fixation is preferred in treating extensional cervical SCIWORA in patients with stenosis.
Early decompression surgery for extensional cervical SCIWORA had an excellent outcome. Controversies exist with regard to the time of surgery intervention for traumatic CSCI. La RosaG[20]reported that early decompression surgery within 24 h of trauma had a significantly better outcome, compared with late surgical management. Guest et al also reported that early surgery (within 24 hours of injury) bring about an improved overall motor recovery in patients whose traumatic central cord syndrome was related to acute disc herniation or fracture [21].On the contrary, another study reported that surgical treatment was not found to be superior to conservative treatment for traumatic CSCI without major fracture or dislocation with spinal cord compression in the acute phase[22]. The patients in this cohort received early decompression, and the obvious improvement of postsurgical neurological scores indicate that patients benefit from early decompressive surgery. We considered the injured cord will be more severely squeezed in patients with a preconditioned stenotic canal under the rapid development edema in the early stage after spinal cord trauma. Therefore, the patients in this cohort may be benefit from the early decompression.
In patients with cervical canal stenosis, sufficient decompression for extensional cervical SCIWORA was critical. Some previous studies recommended surgical treatment for traumatic CSCI without major fracture or dislocation with cervical cord compression at the injured segment [20,23,24]. However, we considered these patients have already had pathological stenotic precondition, in which MRI frequently reveals long hematoma and edema intramedullarily, so multi-segmental decompression could be more sufficient. Several options for multi-segmental decompression are available including anterior corpectomy and posterior laminoplasty [25–28]. But the multiple cervical vertebrae fusion with a large bone graft through anterior route could lead to severe disability of cervical mobility or poor fusion and severe complications, such as dysphagia and dyspnea[29–31]. Posterior laminoplasty is a relatively simple operation, which could preserve cervical mobility with fewer postoperative complications. Therefore, posterior laminoplasty has become one of the superior approaches for multilevel CSCS[32]. We also advocate to apply laminoplasty not only to fulfill complete decompression, but also to avoid anterior approach associated-complication as compared to corpectomy in this cohort. Extra anterior approach associated- complication such as dysphagia were observed in group B compared with no analogical complications occurred in group A. Patients in both groups obtained sufficient decompression that was verified by postoperative MRI. Laminoplasty decompression conducted in all patients may explain the neurofunction recovery that there is no significant difference between two groups according to postoperative ASIA grades and JOA scores.
Immediately postoperative cervical stabilization is another indispensable factor for avoiding secondary injury in extensional cervical SCIWORA patients. Laminoplasty could decompress sufficiently for stenotic canal, on the other hand, it could aggravate the stability of a cervical spine with a preexisting anterior vertebral destruction by hyperextensional stress. Masaki[17]reported a hypermobility of vertebrae at the cord compression level is a risk factor for poor surgical outcome after laminoplasty. Therefore, stabilization intervention need be committed in this cohort with options of extra anterior fusion or posterior instrumentation. Studies indicated that the posterior transpedicle screw internal fixation had been shown to convey better stability for unstable spine than anterior fixation and fusion[33,34], and the transpedicle screw instrumentation, of its three-column stabilization property, had superior biomechanical advantages, like anti-pullout ability, compared with lateral mass screws fixation [35]. The strategy of short-segmental fixation was for preserving as much as mobile cervical segments, which would decrease the stiffness of cervical spine, retard the probability of cervical degeneration and keep more postoperative cervical range of motion. We found there were no instruments failures in group A, but 2 instrument dislodges occurred in group B. One postoperative fixation displacement occurred with the reason that the intervertebral cage was too much high, which resulted in a focal hyperlordosis of involved segment. Anther postoperative dislodge also happened in the condition of hyperextensional cervical spine.
In this study, compared with laminoplasty combined with anterior fusion procedure, Laminoplasty associated with transpedicular screw instrumentation definitely decreased intraoperative blood loss, surgery time and hospital stay. This was not difficult to understand due to only one surgery approach conducted in group A associated with less surgical trauma, from which patients benefitted more and recovered much fast. Xu[36]reported laminoplasty in combination with posterior fixation brought about several advantages of minimal surgical trauma, less intraoperative blood loss and satisfactory stable effect in treating multilevel CSS and spinal cord injury in the trauma population. Our results were consistent with Xu’s report.
There are some limitations in the study. First, in this retrospective multicenter study, the surgical techniques for decompression and fixation were not controlled and were different in different institutions. Second, the admitted time of patients was different and optimal time for surgery was different. These may influent the treatment results in some respects.