Variation of C1 spinolaminar line and prevalence of C1 stenosis in normal population.

BACKGROUND

The variation of C1 spinolaminar line in normal population is not fully understood. The relative position of C1 lamina to C3-C2 spinolaminar line is reported as good screening tool for determination of C1 canal stenosis.

OBJECTIVE

To determine the variation of C1 spinolaminar line and find the prevalence of C1 canal stenosis in normal population using C3-C2 spinolaminar test.

MATERIALS AND

METHODS

Three hundred and fifteen lateral cervical radiographs from 315 volunteers without neurological symptoms were analyzed. The relative position of C1 spinolaminar line was determined by C3-C2 spinolaminar and considered positive if C1 lamina lay ventral to C3-C2 line. C1 space available for cord (SAC) was measured from posterior border of dens to the C1 lamina to determine the sagittal diameter.

RESULTS

The mean sagittal spinal canal diameter of C1 was 22.2 mm (13-26 mm). Of 315, 14 (4.4%) had positive, 184 (58.4%) had neutral, and 117 (37.1%) had negative C1 spinolaminar line in relation to C3-C2 line. The mean SAC among positive group was 14.9 mm compared to neutral and negative groups which were 22.2 and 23.3 mm, respectively. 21.4% of positive group had SAC of less than 12 mm. The 92.8% of positive C1 spinolaminar line was found in age ≥ 60 years.

CONCLUSION

In a normal population, 4.4% has positive C1 spinolaminar line. The C1 stenosis is more prevalent in positive C1 spinolaminar line group.