## 2 Material and Methods
### Clinical Presentations  
Case 1: A 76-year-old man presented to otorhinolaryngology and gastroenterology departments 3 years ago because he had little difficulty in swallowing food. Endoscopy demonstrated compression of the dorsal side of the pharynx and esophagus. The patient was seen by an orthopedic surgeon, who diagnosed C-OALL and performed follow-up. Gradually, numbness and dyslexia in the upper limbs developed, and dysphagia was felt to have been exacerbated. The patient's ability to walk was preserved. The patient was treated conservatively, but he fell and hit his head at home after drinking. He became paraplegic and was hospitalized for surgery due to the diagnosis of cervical spinal cord injury without bone injury. Assessment on admission: hypovolemia and leakage. A urethral balloon was placed. Sensory disturbance: both shoulders, inguinal and subparesthesia, tendon reflexes; decreased biceps tendon reflexes, bilateral enhancement below the triceps tendon, Hoffmann's reflex; \(-/+\) Babinski, foot clonus \(-/-\), manual muscle test of upper and lower extremities; deltoid 4/4, biceps 4/4, triceps 5/5, wrist dorsiflexion 3/3, palmar flexion 3/3, finger extension 3/3, lower limbs all 4/4. A physical therapist (PT), occupational therapist (OT), and speech language hearing therapist (ST) intervened from the day after admission. The patient wore a cervical collar and was not restricted to bed rest. He could not hold a spoon but could eat regular meals with assistance after approximately 1 h of noting the difficulty in swallowing. The oral function was expected, and the jaw opened to a width of 3 fingers. There was slight tooth loss. Tongue movement did not differ between the left and right sides, and coughing was possible. On the 30 mL water swallowing test, 5 and 10 mL were ingested from a syringe, and swallowing was possible without swelling or hoarseness (LEVEL II). For safety reasons, his postoperative soup and water were thickened. Moreover, VE was conducted, but VF was not conducted for bed rest to spinal cord injury (Figure 2). His swallowing function was as follows: Food Intake LEVEL Scale: 8, and dysphagia severity scale: 6. Radiological evaluation: the ossification size of C-OALL at C3/4 was 16.8 mm. Intervertebral mobility was noted at C3/4 and 5/6. C3/4 had 5\({}^{\circ}\) of intervertebral mobility with 4\({}^{\circ}\) of extension in retroflexion and \(-1^{\circ}\) in flexion. The O-C2 angle was 25\({}^{\circ}\). The pharyngeal inlet angle (PIA) was 76\({}^{\circ}\). The S-line was negative. The C2-7 angle was 16\({}^{\circ}\) (Figure 2). Posthospitalization day 4: Posterior decompression fixation of the 3 rd and 6 th cervical vertebrae was performed. Intraoperatively, the patient was immobilized in the intermediate position using a Mayfield holder. The postoperative ossification size was unchanged; the C3/4 intervertebral angle was fixed at 4\({}^{\circ}\) lordosis; the O-C2 angle, PIA angle, and S-line were negative; and the C2-7 angle was unchanged (Figure 3). Postoperative day 1: resumption of eating; postoperative day 2: getting out of bed. On postoperative day 4, the patient was able to eat staple food, whole porridge, and side dishes in a sitting position, and he was able to eat on his own using a spoon. There was no subjective difficulty in swallowing when meat was previously served with soft greens in bite-size pieces. The 30 mL water swallowing test was improved LEVEL I. His swallowing function was as follows: Food Intake LEVEL Scale: 9, and dysphagia severity scale: 6. Three weeks postoperatively, he was able to walk with a Lofstrand crutch cane and ascend and descend stairs with light assistance, although he was unsteady on his feet. He was transferred to another hospital for 3 weeks and 5 days postoperatively. Figure 2: Case 1. **(a)** Functional cervical spine X-ray (figures from left to right show middle, extension, and flexion).