Establishment of parameters for congenital stenosis of the cervical spine: an anatomic descriptive analysis of 1,066 cadaveric specimens.

Purpose: Congenital cervical stenosis (CCS) occurs when the bony anatomy of the cervical canal is smaller than expected in the general population predisposing an individual to symptomatic neural compression. No studies have defined CCS based on the normal population. The diagnosis is currently made based on clinical impression from radiographic studies. The aim of this study is to establish parameters that are associated with CCS, based on anatomic measurements on a large sample of skeletal specimens.

Methods: From the Hamann-Todd collection at the Cleveland Museum of Natural History, 1,066 skeletal specimens were selected. Digital calipers were used to measure the sagittal canal diameter (SCD), interpedicular distance (IPD), and pedicle length. Canal area at each level was calculated using a geometric formula. A standard distribution was created and values that were 2 SD below mean were considered as congenitally stenotic. An analysis of deviance was performed to identify parameters that were associated with CCS. Regression analysis was used to determine odds ratios (OR) for CCS using these parameters.

Results: CCS was defined at each level as: C3/4 = 1.82 cm(2), C4/5 = 1.80 cm(2), C5/6 = 1.84 cm(2), C6/7 = 1.89 cm(2), C7/T1 = 1.88 cm(2). Values of SCD < 13 mm and IPD < 22.5 mm were associated with CCS and yielded sensitivities and specificities of 88-100 % at each level. Logistic regression demonstrated a significant association between these parameters and presence of CCS with OR > 18 at each level.

Conclusions: Based on our study of a large population of adult skeletal specimens, we have defined CCS at each level. Values of SCD < 13 mm and IPD < 23 mm are strongly associated with the presence of CCS at all levels.