The Role of C2–C7 and O–C2 Angle in the Development of Dysphagia After Cervical Spine Surgery

Abstract

Dysphagia is a known complication of cervical surgery and may be prolonged or occasionally serious. A previous study showed that dysphagia after occipitocervical fusion was caused by oropharyngeal stenosis resulting from O-C2 (upper cervical lordosis) fixation in a flexed position. However, there have been few reports analyzing the association between the C2-C7 angle (middle-lower cervical lordosis) and postoperative dysphagia. The aim of this study was to analyze the relationship between cervical lordosis and the development of dysphagia after anterior and posterior cervical spine surgery (AC and PC). Three hundred fifty-four patients were reviewed in this retrospective clinical study, including 172 patients who underwent the AC procedure and 182 patients who had the PC procedure between June 2007 and May 2010. The presence and duration of postoperative dysphagia were recorded via face-to-face questioning or telephone interview performed at least 1 year after the procedure. Plain cervical radiographs before and after surgery were collected. The O-C2 angle and the C2-C7 angle were measured. Changes in the O-C2 angle and the C2-C7 angle were defined as dO-C2 angle = postoperative O-C2 angle - preoperative O-C2 angle and dC2-C7 angle = postoperative C2-C7 angle - preoperative C2-C7 angle. The association between postoperative dysphagia with dO-C2 angle and dC2-C7 angle was studied. Results showed that 12.8 % of AC and 9.4 % of PC patients reported dysphagia after cervical surgery. The dC2-C7 angle has considerable impact on postoperative dysphagia. When the dC2-C7 angle is greater than 5°, the chance of developing postoperative dysphagia is significantly greater. The dO-C2 angle, age, gender, BMI, operative time, blood loss, procedure type, revision surgery, most cephalic operative level, and number of operative levels did not significantly influence the incidence of postoperative dysphagia. No relationship was found between the dC2-C7 angle and the degree of dysphagia. We conclude that postoperative dysphagia is common after cervical surgery. The dC2-C7 angle may play an important role in the development of dysphagia in both anterior and posterior cervical spine surgery. Intraoperative measurement of the dC2-C7 angle is practical and essential in avoiding inadvertent postoperative dysphagia.

Dysphagia following combined anterior-posterior cervical spine surgeries

“…This finding is consistent with the report from Tian et al, 32 in which they reported that increasing change in C2-7 lordosis was significantly associated with increased risk for the development of postoperative dysphagia, and all patients in their series with long-term dysphagia had correction of the C2-7 angle that was greater than 5°. However, their study may have been limited by recall bias, since they relied on interviews at 1 year postoperatively to assess dysphagia.…”

“…Ota et al 18 also found a strong positive linear correlation between the 2 parameters in a different sample of 40 healthy volunteers (Spearman r = 0.839, p < 0.001). However, we did not find any significant difference in the change of occiput-C2 angle between the dysphagia and the no-dysphagia groups (p = 0.711), which is consistent with a report by Tian et al 32 It is certainly possible that the lack of association between change in the occiput-C2 angle and development of dysphagia observed in the present study may be due to the lack of cases in which fusion included the occiput.…”

“…Preoperative and postoperative anteroposterior and lateral cervical spine radiographs were routinely obtained. Radiographic measures were performed as previously described by Tian et al 32 The occiput-C2 angle was defined as the angle of intersection of the McGregor line and a line drawn parallel to the inferior endplate of the C-2 vertebral body. The C2-7 angle was defined as the angle subtended by the intersection of lines parallel to the inferior endplates of the C-2 and C-7 vertebral bodies.…”

“…2,5,6,9,10,12,16,18,21,22,[27][28][29]31,32 However, the associations are not consistent among studies.…”

Voice and swallowing outcomes following reoperative anterior cervical discectomy and fusion with a 2-team surgical approach

“…VCP may be due to sectioning or retraction injury of the RLN, retraction of the esophagus with reduced perfusion, 21 direct pharyngeal or esophageal pressure, 22 hypoglossal nerve injury, 35 or alteration in C2-7 angle. 36,47 Injury to the superior laryngeal nerve (particularly in high approaches) is also a cited cause, and although not well documented in the ACDF literature, is a well-known cause of dysphagia following oncological surgery of the neck. During reoperative ACDF, the presence of scar tissue after prior ACDF often distorts the normal anatomy, makes exposure and retraction more difficult, and increases the risk of RLN injury during revision.…”