The relationship between the cervical spinal canal diameter and the pathological changes in the cervical spine

Abstract

A congenitally narrow cervical spinal canal has been established as an important risk factor for the development of cervical spondylotic myelopathy. However, few reports have described the mechanism underlying this risk. In this study, we investigate the relationship between cervical spinal canal narrowing and pathological changes in the cervical spine using positional magnetic resonance imaging (MRI). Two hundred and ninety-five symptomatic patients underwent cervical MRI in the weight-bearing position with dynamic motion (flexion, neutral, and extension) of the cervical spine. The sagittal cervical spinal canal diameter and cervical segmental angular motion were measured and calculated. Each segment was assessed for the extent of intervertebral disc degeneration and cervical cord compression. Based on the sagittal canal diameter, the subjects were classified into three groups: A, subjects with a congenitally narrow canal, diameter of less than 13 mm; B, subjects with a normal canal, diameter of 13–15 mm; C, subjects with a wide canal, diameter of more than 15 mm. When compared with Groups A and B, the disc degeneration grades at the C3-4, C5-6, and C6-7 segments and the cervical cord compression scores at the C3-4 and C5-6 segments showed significant differences. Additionally, when compare with Groups A and C, the disc degeneration grades at all segments, except C2-3, and the cervical cord compression scores at all segments, except C2-3, showed significant differences. With respect to the cervical kinematics, few differences in the kinematics were observed between Groups B and C, however, the kinematics in Group A was different with other two groups. In Group A, the segmental mobility at the C4-5 and C6-7 segments were significantly higher than those observed in Group B, and the segmental mobility at the C3-4 segment was significantly lower than that observed in Groups B or C. We demonstrated the unique pathological and kinematic traits of cervical spine that exist in a congenitally narrow canal. We hypothesize that kinematic trait associated with a congenitally narrow canal may greatly contribute to pathological changes in the cervical spine. Our results suggest that cervical spinal canal diameter of less than 13 mm may be associated with an increased risk for development of pathological changes in cervical intervertebral discs. Subsequently, the presence of a congenitally narrow canal can expose individuals to a greater risk of developing cervical spinal stenosis.

Cervical canal stenosis and adjacent segment degeneration after anterior cervical arthrodesis

“…To better understand the development of ASD after anterior cervical arthrodesis and the overall prevalence of this problem, we focused our attention on the size of the cervical spinal canal and determined whether preoperative congenital stenosis predicted ASD at a minimum follow-up of 6 years. Morishita et al [31] found that a congenitally narrow canal had different effects on cervical kinematics. In other words, subjects with a congenitally narrow cervical canal may be exposed to a large mechanical loading at the cervical spine.…”

Clinical relationship between cervical spinal canal stenosis and traumatic cervical spinal cord injury without major fracture or dislocation

“…We defined the sagittal diameter of the CSF column at a given pedicle level as the sagittal cervical canal diameter [10][11][12][13]. The sagittal diameter of the spinal cord is nearly constant in adults, averaging approximately 8 mm from C3 to C7 [14].…”

Cervical Spondylotic Myelopathy: Pathophysiology, Clinical Presentation, and Treatment

“…Unique pathologic and kinematic traits may exist in the patient with a developmentally narrow canal. Dynamic MRI studies have shown that patients with a congenitally narrow cervical canal (<13 mm) have increased segmental mobility in the cervical spine which may in turn predispose to the development of radiographic dynamic cord compression and potentially clinical myelopathy [36].…”