Measurement of cervical spinal canal diameter by radiographs to study the degree of cervical spinal canal stenosis in an Indian population; Predictive value of Torgs ratio to assess cervical spinal canal stenosis

Cervical myelopathy a debilitating degenerative condition occurs due to cervical spinal canal stenosis, the incidence of which increases significantly with age and is more common above the age of 50 years. Imaging of the spinal canal is an indispensable procedure for evaluation of cervical myelopathy and standard lateral radiographs remain the recommended initial imaging study of choice. The present study was undertaken to measure the cervical spinal canal diameter by lateral radiographs of the cervical spine and to study the degree of cervical spinal canal stenosis in symptomatic patients and asymptomatic cases. The canal body ratio and its reliability to assess cervical spinal canal stenosis and risk of cervical myelopathy was evaluated. In this study 200 cases who presented to the radiology department for radiographs of cervical spine, were divided into symptomatic and asymptomatic cases and were grouped age wise. Measurements of the cervical vertebral body and cervical spinal canal were taken. Torg ratio was assessed. The measurements were analyzed statistically and results tabulated. Cervical spinal canal diameter was lower in symptomatic cases as compared to asymptomatic cases across all age groups and the lowest value was measured at C3 level. All the symptomatic cases had Torg ratio of less than 0.82, and that of C3 was lowest. The data analysis showed the sensitivity of the Torg ratio as 100%. 40% of patients above 50 years were symptomatic and had cervical spinal canal stenosis on lateral radiographs. Our results suggest that plain films can estimate the cervical spinal canal midsagittal diameter and be used as a first step examination for the evaluation of cervical spinal stenosis. The importance of canal body ratio in lateral cervical radiographs for determining the stenosis of cervical spinal canal is confirmed.