BACKGROUND CONTEXT
Dysphagia is one of the postoperative complications of cervical degenerative disorders. However, few studies have evaluated the pre- and postoperative swallowing function in detail.

PURPOSE
To analyze pre- and postoperative swallowing dynamics kinetically and investigate factors associated with postoperative dysphagia in patients with cervical degenerative disorders.

STUDY DESIGN
Retrospective review of prospectively collected data.

PATIENT SAMPLE
A total of 41 consecutive patients who underwent an anterior approach (anterior cervical discectomy/corpectomy and fusion (ACDF, ACCF), hybrid surgery (ACDF+ACCF) and total disc replacement) and 44 consecutive patients who underwent a posterior approach (laminoplasty and laminoplasty/laminectomy with fusion).

OUTCOME MEASURES
We compared the pre- and postoperative functional oral intake scale (FOIS), dysphagia severity scale (DSS), esophageal dysphagia, anterior/superior hyoid movement, upper esophageal sphincter (UES) opening, pharyngeal transit time, bolus residue scale (BRS), and the number of swallows.

METHODS
Videofluoroscopy was performed on the day before surgery and within two weeks after surgery. Data related to age, gender, disease, surgical procedure, surgical site, operative time, and blood loss were collected from the medical records. Pre- and postoperative data were compared for each item in the anterior and posterior approaches. The odds ratio of dysphagia after an anterior approach was also calculated.

RESULTS
In the anterior approach, DSS, FOIS, the anterior and superior hyoid movements, maximum UES opening, BRS, and number of swallows worsened postoperatively (p<.05, respectively). In the posterior approach, DSS, FOIS, the anterior hyoid movement, and BRS worsened postoperatively (p<.05, respectively). The factors associated with dysphagia were a proximal surgical site above C3 (OR: 14.40, CI: 2.84−73.02), blood loss >100 mL (OR: 9.60, CI: 2.06−44.74), an operative time >200 minutes (OR: 8.18, CI: 1.51−44.49), and an extensive surgical field of more than three intervertebral levels (OR: 6.72, CI: 1.50−30.07). The decline in swallowing function after the posterior approach was related to aging (p=.045).

CONCLUSIONS
Each approach may decrease swallowing function, especially because of the limitation on the anterior hyoid movement. Dysphagia after anterior approaches was associated with the operative site, operative time, and blood loss.

1. Haruka Tohara, Professor
   
   Department of Dysphagia Rehabilitation,
   Graduate School of Medical and Dental Sciences,
   Tokyo Medical and Dental University (TMDU)
   E-mail: h.tohara.swal(at) tmd.ac.jp
   
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