The biomechanical effect of preexisting different types of disc herniation in cervical hyperextension injury

Effects of two posterior procedures for treatment of cervical hyperextension injury with multilevel spinal stenosis: A retrospective study

BACKGROUND

Cervical hyperextension injuries (CHI), commonly resulting in central cord syndrome and spinal instability, often affect the elderly with preexisting degenerative spinal changes, leading to a need for surgical interventions that address both the compression and stability of the cervical spine. This study compares the clinical outcomes of two posterior decompression and fixation procedures for treating cervical hyperextension injury in patients with preexisting multilevel spinal canal stenosis.

METHODS

Patients suffering from cervical hyperextension injury combined with multilevel spinal stenosis were divided into two groups. They received laminoplasty combined with selective unilateral pedicle screw fixation or laminectomy combined with bilateral lateral mass screw fixation. The clinical records including demographic data, operation time, length of hospital stay, estimated blood loss and surgical complications were collected, and clinical outcomes were evaluated using the American Spinal Injury Association (ASIA) impairment scale. Preoperative and postoperative cervical lordosis were measured.

RESULTS

Postoperative AISA scores were significantly increased compared with that before surgery in both groups, there was no significant differences between groups. The intraoperative blood loss in the laminoplasty group was significantly less than that in the laminectomy group and there were no significant differences in operation time and length of hospital stay between the two groups. No significant difference was found in the incidence of overall surgical complications between the two groups. There was no significant difference in the cervical lordosis after surgery compared with that before surgery in both groups.

CONCLUSIONS

For patients suffering from cervical hyperextension injury combined with preexisting multilevel spinal stenosis, both cervical laminoplasty with selective unilateral pedicle screw fixation and laminectomy with bilateral lateral mass screw fixation could achieve satisfactory clinical outcomes.

Finite element modeling and analysis of effect of preexisting cervical degenerative disease on the spinal cord during flexion and extension

Recent studies have emphasized the importance of dynamic activity in the development of myelopathy. However, current knowledge of how degenerative factors affect the spinal cord during motion is still limited. This study aimed to investigate the effect of various types of preexisting herniated cervical disc and the ligamentum flavum ossification on the spinal cord during cervical flexion and extension. A detailed dynamic fluid-structure interaction finite element model of the cervical spine with the spinal cord was developed and validated. The changes of von Mises stress and maximum principal strain within the spinal cord in the period of normal, hyperflexion, and hyperextension were investigated, considering various types and grades of disc herniation and ossification of the ligamentum flavum. The flexion and extension of the cervical spine with spinal canal encroachment induced high stress and strain inside the spinal cord, and this effect was also amplified by increased canal encroachments and cervical hypermobility. The spinal cord might evade lateral encroachment, leading to a reduction in the maximum stress and principal strain within the spinal cord in local-type herniation. Although the impact was limited in the case of diffuse type, the maximum stress tended to appear in the white matter near the encroachment site while compression from both ventral and dorsal was essential to make maximum stress appear in the grey matter. The existence of canal encroachment can reduce the safe range for spinal cord activities, and hypermobility activities may induce spinal cord injury. Besides, the ligamentum flavum plays an important role in the development of central canal syndrome.Significance. This model will enable researchers to have a better understanding of the influence of cervical degenerative diseases on the spinal cord during extension and flexion.

Benefits of Early Surgical Treatment for Patients with Multilevel Cervical Canal Stenosis of Acute Traumatic Central Cord Syndrome

INTRODUCTION

Currently, there exists considerable debate surrounding the optimal treatment approaches for different subtypes of patients with spinal cord injury (SCI). The purpose of this study was to conduct a comparative analysis of the benefits associated with conservative treatment and treatments with different surgical periods for patients diagnosed with acute traumatic central cord syndrome (ATCCS) and multilevel cervical canal stenosis (CCS).

METHODS

A retrospective cohort study was conducted, and 93 patients who met inclusion and exclusion criteria in our hospital between 2015 and 2020 were followed for a minimum duration of 2 years. Among them, 30 patients (Group A) received conservative treatment, 18 patients (Group B) received early surgery (≤7 days), and 45 patients (Group C) received late surgery (>7 days). The American Spinal Injury Association (ASIA) grade, Japanese Orthopedic Association (JOA) score, and recovery rate (RR) were evaluated. Multivariate linear regression was used to analyze prognostic determinants. Cost-utility analysis was performed based on the EQ-5D scale.

RESULTS

The ASIA grade, JOA score, and RR of all three groups improved compared with the previous evaluation (P < 0.05). During follow-up, the ASIA grade, JOA score, and RR of Group B were all better than for Group A and Group C (P < 0.05), while there was no significant difference between Group A and C (P > 0.05). The EQ-5D scale in Group B was optimal at the last follow-up. The incremental cost-utility ratio (ICUR) of Group A was the lowest, while that of Group B compared to Group A was less than the threshold of patients' willingness to pay. Age, initial ASIA grade, and treatment types significantly affected the outcomes.

CONCLUSIONS

Both conservative and surgical treatments yield good results. Compared with patients who received conservative treatment and late surgery, patients who received early surgery had better clinical function and living quality. Despite the higher cost, early surgery is cost-effective when compared to conservative treatment. Younger age, initial better ASIA grade, and earlier surgery were associated with better prognosis.

Cerebrospinal fluid pressure dynamics reveal signs of effective spinal canal narrowing in ambiguous spine conditions

Spinal canal narrowing with consecutive spinal cord compression is considered a key mechanism in degenerative cervical myelopathy (DCM). DCM is a common spine condition associated with progressive neurological disability, and timely decompressive surgery is recommended. However, the clinical and radiological diagnostic workup is often ambiguous, challenging confident proactive treatment recommendations. Cerebrospinal fluid pressure dynamics (CSFP) are altered by spinal canal narrowing. Therefore, we aim to explore the potential value of bedside CSFP assessments for qualitative and quantitative assessment of spinal canal narrowing in DCM. In this prospective case series, seven patients with DCM underwent bedside lumbar puncture with measurement of CSFP dynamics and routine CSF analysis (NCT02170155). The patients were enrolled when standard diagnostic algorithms did not permit a clear treatment decision. Measurements include baseline CSFP, cardiac-driven CSFP peak-to-trough amplitude (CSFPp), and the Queckenstedt's test (firm pressure on jugular veins) in neutral and reclined head position. From the Queckenstedt's test, proxies for craniospinal elastance (i.e., relative pulse pressure coefficient; RPPC-Q) were calculated analogously to infusion testing. CSFP metrics were deemed suspicious of canal narrowing when numbers were lower than the minimum value from a previously tested elderly spine-healthy cohort (N = 14). Mean age was 56 ± 13 years (range, 38–75; 2F); symptom severity was mostly mild to moderate (mean mJOA, 13.5 ± 2.6; range, 9–17). All the patients showed some extent of cervical stenosis in the MRI of unclear significance (5/7 following decompressive cervical spine surgery with an adjacent level or residual stenosis). Baseline CSFP was normal except for one patient (range, 4.7–17.4 mmHg). Normal values were found for CSFPp (0.4–1.3 mmHg) and the Queckenstedt's test in normal head positioning (9.-25.3 mmHg). During reclination, the Queckenstedt's test significantly decreased in one, and CSFPp in another case (>50% compared to normal position). RPPC-Q (0.07–0.19) aligned with lower values from spine-healthy (0.10–0.44). Routine CSF examinations showed mild total protein elevation (mean, 522 ± 108 mg/ml) without further evidence for the disturbed blood brain barrier. Intrathecal CSFP measurements allow discerning disturbed from normal CSFP dynamics in this population. Prospective longitudinal studies should further evaluate the diagnostic utility of CSFP assessments in DCM.