Dysphagia is a well-known complication following cervical spine surgery, including anterior or posterior approach. However, which muscle at oropharyngeal region weakness and the recovery course of these patients are still unknown.

The high resolution impedance manometry (HRIM) could be used to measure the postoperative recovery esophageal function.

Dysphagia is a well-known complication following cervical spine surgery, including anterior or posterior approach. However, which muscle at oropharyngeal region weakness and the recovery course of these patients are still unknown.

The high resolution impedance manometry (HRIM) could be used to measure the postoperative recovery esophageal function.

In this study, using the high resolution impedance manometry to determine (1) whether the occurrence of dysphagia in the postoperative 1 or 7 days and 1 month in the patients receiving anterior vs posterior approach of cervical spine surgery (2) which muscle in the pharyngeal region would be destroyed Consecutive patients who will fulfill the criteria of cervical spine surgery patients under general anesthesia and aged >= 20 will be enrolled. The patients would receive the dysphagia questionnaire. All subjects would receive the swallowing function by HRIM before the surgeries. The cough test was also measured. After the surgery, the patient would be followed the swallowing function in the postoperative one day, and 1 week by HRIM and questionnaire.

This study would expect (1) that the posterior cervical spine surgery would result in dysphagia greater than baseline, but less than that of anterior cervical procedures; (2) decreasing upper esophageal sphincter (UES) pressure may be the reason of postoperative dysphagia in the anterior cervical spine surgery, resulted from the intraoperative traction; (3) decreasing hypopharyngeal muscle pressure may be the reason of postoperative dysphagia in the posterior spine surgery, resulted from the prone and flexion positioning.

Inclusion Criteria:1. Patients who fulfill the criteria of cervical spine surgery under general anesthesia 2. Aged from 20-80 years old -

Exclusion Criteria:

- 1. Major systemic disease, such as congestive heart failure, liver cirrhosis, end stage renal disease and malignancy.

2. Patients who have the risk of difficult ventilation or intubation. 3. pregnant women 4. coagulopathy

The patients recieved elective cervical spine surgery