[Roentgenological study of antero-posterior diameter in developmental canal stenosis of cervical spine].

Developmental canal stenosis of the cervical spine is an important underlying condition of cervical spondylotic myelopathy. However, the criteria of the degree of narrowing is different among investigators and their rationales are unclear. To clarify this point, the antero-posterior diameter of the cervical spinal canal was measured in groups of normal subjects, patients with neck-shoulder-arm syndrome and cervical spondylosis. The measured values were analyzed statistically. The antero-posterior diameter was the widest in normal individuals and the narrowest in patients with the cervical spondylotic myelopathy. The point of differentiation of developmental canal stenosis was determined as 14 mm for males and 13 mm for females using the mean +/- 2SD of the values in normal subjects. Patients with values lower than this criteria comprised 82% of those with the cervical spondylotic myelopathy. These patients could be further classified into those that also showed clear cervical spondylotic changes and those that did not.