Prevalence of cervical spine stenosis. Anatomic study in cadavers.

BACKGROUND The sagittal diameter of the cervical spinal canal is of clinical importance in traumatic, degenerative, and inflammatory conditions. A small canal diameter has been associated with an increased risk of injury; however, there is a lack of reliable normative data on spinal canal diameters in different age groups in the United States population. The purpose of this study was to use direct measurement of skeletal specimens to determine the spectrum of the sagittal diameters of the cervical spinal canal, the frequency of cervical stenosis in the general population, and the prevalence of cervical stenosis for different age groups, races, and sexes. METHODS Four hundred and sixty-nine adult skeletal specimens of the cervical spine were obtained from the Hamann-Todd Collection in the Cleveland Museum of Natural History. With use of digital calipers, the distance from the posteriormost aspect of the vertebral body to the anteriormost aspect of the spinolaminar structure was measured and recorded for each specimen at every level from C3 to C7. Cervical stenosis was defined as a canal diameter of <12 mm. We analyzed the direct measurements and then assessed those data after correcting for size increases in the current population compared with the Hamann-Todd Collection. Finally, we analyzed the data after both that size correction and adjustment for radiographic magnification. RESULTS The average anterior-posterior canal diameter (and standard deviation) in all specimens at all levels was 14.1 +/- 1.6 mm. The canal diameters ranged from 9.0 to 20.9 mm, with a median diameter of 14.4 mm. Men had significantly larger cervical spinal canals than women at all of the levels that were evaluated. Specimens from donors who were sixty years of age or more at the time of death had significantly narrower canals than specimens from younger donors. There were no significant differences, with the numbers available, between black and white groups. After correcting for increased body size and adjusting for radiographic magnification, we estimated that cervical stenosis was present in 4.9% of the adult population, 6.8% of the population fifty years of age or older, and 9% of the population seventy years of age or older. CONCLUSIONS Cervical spine stenosis appears to be very common. The radiographic finding of cervical stenosis should therefore be correlated with the clinical presentation prior to decision-making regarding treatment.