Cervical Rotatory Manipulation Decreases Uniaxial Tensile Properties of Rabbit Atherosclerotic Internal Carotid Artery

Effects of cervical rotatory manipulation on the cervical spinal cord complex with ossification of the posterior longitudinal ligament in the vertebral canal: A finite element study

Background: There are few studies focusing on biomechanism of spinal cord injury according to the ossification of the posterior longitudinal ligament (OPLL) during cervical rotatory manipulation (CRM). This study aimed to explore the biomechanical effects of CRM on the spinal cord, dura matter and nerve roots with OPLL in the cervical vertebral canal. Methods: Three validated FE models of the craniocervical spine and spinal cord complex were constructed by adding mild, moderate, and severe OPLL to the healthy FE model, respectively. We simulated the static compression of the spinal cord by OPLL and the dynamic compression during CRM in the flexion position. The stress distribution of the spinal cord complex was investigated. Results: The cervical spinal cord experienced higher von Mises stress under static compression by the severe OPLL. A higher von Mises stress was observed on the spinal cord in the moderate and severe OPLL models during CRM. The dura matter and nerve roots had a higher von Mises stress in all three models during CRM. Conclusion: The results show a high risk in performing CRM in the flexion position on patients with OPLL, in that different occupying ratios in the vertebral canal due to OPLL could significantly increase the stress on the spinal cord complex.

Effects of cervical rotatory manipulation on the cervical spinal cord: a finite element study

BACKGROUND

Little information is available concerning the biomechanism involved in the spinal cord injury after cervical rotatory manipulation (CRM). The primary purpose of this study was to explore the biomechanical and kinematic effects of CRM on a healthy spinal cord.

METHODS

A finite element (FE) model of the basilaris cranii, C1-C7 vertebral bodies, nerve root complex and vertebral canal contents was constructed and validated against in vivo and in vitro published data. The FE model simulated CRM in the flexion, extension and neutral positions. The stress distribution, forma and relative position of the spinal cord were observed.

RESULTS

Lower von Mises stress was observed on the spinal cord after CRM in the flexion position. The spinal cord in CRM in the flexion and neutral positions had a lower sagittal diameter and cross-sectional area. In addition, the spinal cord was anteriorly positioned after CRM in the flexion position, while the spinal cord was posteriorly positioned after CRM in the extension and neutral positions.

CONCLUSION

CRM in the flexion position is less likely to injure the spinal cord, but caution is warranted when posterior vertebral osteophytes or disc herniations exist.

Bilateral medial medullary syndrome following anterior screw fixation of type 2 odontoid fracture, a case report of two patients

INTRODUCTION

Medial medullary syndrome (MMS) has not been reported after anterior screw fixation of an odontoid type 2 fracture.

CASE PRESENTATION

We report on two cases who suffered from an unstable type 2 odontoid fracture following a skiing and a domestic fall accident. Prior to anterior screw fixation surgery both patients presented without neurologic deficits but postoperatively developed a bilateral MMS, including an incomplete tetraparesis, impaired sensation of position and movement as well as tactile discrimination and paralysis of the tongue muscle with deviation to the paralyzed side. MRI showed a typical heart-shaped ischaemic lesion in the medial medulla bilaterally. The search for aetiologic factors was uneventful in both patients except for severe atherosclerosis.

DISCUSSION

Due to the close proximity of the ischaemic area to the surgical site, we here propose the perioperative mechanical manipulation of the upper cervical spine during surgery of patients with atherosclerosis as a new aetiology for MMS.

Effects of Cervical Rotatory Manipulation on Internal Carotid Artery in Hemodynamics Using an Animal Model of Carotid Atherosclerosis: A Safety Study

BACKGROUND Spinal manipulation, particularly in cervical rotatory manipulation (CRM), has become increasingly popular in physical therapies, with satisfying effect. However, it is still unclear whether CRM affects internal carotid arteries (ICA) with mild carotid atherosclerosis (CAS), especially in hemodynamics. MATERIAL AND METHODS Nine cynomolgus monkeys were randomly divided into 3 groups: the CAS-CRM, the CAS, and the blank control groups. CAS models were developed in the left ICA in the CAS-CRM and the CAS groups. The monkeys in the CAS-CRM group underwent CRM intervention for 3 weeks. Histology and hemodynamics were measured, including peak systolic velocity (PSV), end-diastolic velocity (EDV), time average velocity (TAV), resistance index (RI), and pulsatility index (PI). Measurements were made separately at 3 different rotation angles (0°, 45°, and 90°). RESULTS In the 3 groups, with the increase of rotation angle, the decreasing tendency of PSV, EDV, and TAV and the increasing tendency of RI and PI were statistically significant. At each angle, the monkeys in the CAS-CRM and the CAS groups had lower levels of PSV, EDV, and TAV and higher levels of RI and PI compared with the blank control group. No significant difference in hemodynamics was found between the CAS-CRM and the CAS groups. CONCLUSIONS Both the rotational angle and the atherosclerotic disease can affect the blood flow of the ICA. However, CRM does not cause adverse effects on hemodynamics in cynomolgus monkeys with mild CAS, and appears to be a relatively safe technique.

Effects of Cervical Rotatory Manipulation (CRM) on Carotid Atherosclerosis Plaque in Vulnerability: A Histological and Immunohistochemical Study Using Animal Model

Background

The safety of cervical rotatory manipulation (CRM) is still controversial, especially in patients with carotid artery atherosclerosis (CAS). The study aimed to investigate the effects of CRM on carotid plaques in vulnerability.

Methods

50 rabbits were randomly divided into four groups: model rabbits with CRM [CAS-CRM (n=15)]; model rabbits without CRM [CAS (n=15)]; normal rabbits with CRM [Normal-CRM (n=10)]; and Blank-control group (n=10). CAS disease models were induced by carotid artery balloon injury combined with a high-fat diet for 12 weeks. Then, CRM technique was performed in CAS-CRM and Normal-CRM groups for 3 weeks. In the end, determination of serum level of hs-CRP and Lp-PLA2, histological analysis under HE and Masson trichromic staining, and immunohistochemical analysis with CD34 and CD68 antibody were completed in order.

Results

Carotid stenosis rates on successful model rabbits ranged from 70% to 98%. The CAS-CRM group had an increased level of hs-CRP (P<0.05), in comparison with the CAS group, whereas effects were not significant between the Normal-CRM group and Blank-control group. In comparison with the CAS group, the positive expression of CD34 and CD68 in the CAS-CRM group increased significantly (P<0.05).

Conclusion

CRM therapy may increase the vulnerability of carotid plaque in rabbits with severe CAS.