In this study, we measured the intervertebral foramina on the plain radiographs of cervical spine of fifty three patients who were over forty-year-old, and with single or multiple unilateral cervical radiculopathies on EMG. In order to determine if the foraminal stenosis on plain radiographs can determine the presense of radiculopathy, four parameters such as vertical diameter, mid-transverse diameter, inferior transverse diameter, and area were measured by a digital caliberator(CD-15C, Mitutoyo, Japan) and an image analyzer(VIDAS 2.0, Kontron, Germany) in 194 foramina of both sides(affected and unaffected groups). Another 80 foramina were also measured as control group in ten age-matched patients who did not show any abnormality on EMG.

In control group, C4/5 intervertebral foramen showed maximal values of the parameters among foramina, with vertical diameter of 10.55⁑0.35 mm(mean⁑S.D.), mid-transverse diameter of 6.22⁑0.33 mm, inferior transverse diameter of 5.09⁑0.19 mm and area of 0.77⁑0.05 cm². The minimal values were noted in C6/7 foramen except those of the vertical diameter which were noted in C4/5 foramen. The mid-transverse diameter and area of C7/T1 intervertebral foramen of affected group were significantly smaller than those of control and unaffected groups(p＜0.05). The other values in affected group were also smaller among the groups but they did not reach statistical significance.

In conclusion, the mid-transverse diameter and area of intervertebral foramen on plain cervical radiographs are somewhat useful to determine the encroachment of nerve root within the intervertebral foramen, especially in the lower cervical spine, in patients with cervical radiculopathy.