O-C2 angle as a predictor of dyspnea and/or dysphagia after occipitocervical fusion

A retrospective clinical study.

To confirm the impact of the O-C2 angle on dyspnea and dysphagia after posterior occipitocervical (O-C) fusion.

Dyspnea and dysphagia are complications of posterior O-C fusion with malalignment, and may be prolonged or occasionally serious. However, it is difficult to select a safe alignment during surgery, and no indicators of the appropriate alignment have been available to preclude these complications.

The authors retrospectively reviewed 29 consecutive patients who had undergone O-C or occipitocervicothoracic fusion between 2003 and 2008. Data were analyzed for O-C2 angles on plain radiographs and the axial computed tomographic cross-sectional areas of the oropharynx just cranial to the epiglottis before and after surgery. The patients were grouped according to whether they developed postoperative dyspnea and/or dysphagia (group A) or not (group B).

After surgery, 4 patients complained of dysphagia, and 1 patient had dyspnea and dysphagia, although they had all undergone short O-C fusions. The difference in the O-C2 angle (dOC2A = postoperative O-C2 angle--preoperative O-C2 angle) and the percentage change in the cross-sectional area of the oropharynx (S) before and after surgery (% dS) were linearly correlated. Both dOC2A and % dS were significantly lower in group A than in group B. All patients with dOC2A of less than -10 degrees showed % dS of less than -40%, and developed dyspnea and/or dysphagia after surgery. Conversely, no patients with positive dOC2A developed these complications.

The O-C2 angle has considerable impact on dyspnea and/or dysphagia after O-C fusion. The O-C2 angle is easily measured during surgery and can be a practical index with which to avoid postoperative dyspnea and dysphagia.