## 3 Discussion  
Dysphagia is a significant risk factor for the development of choking and aspiration pneumonia [1]. The pathogenesis of dysphagia in C-OALL includes physical compression of the swallowing organs, inflammation of the larynx and esophagus, edema and degeneration, restriction of movement due to friction between the ossification and the cirothyroid cartilage, obstruction of the collapsing epiglottis due to ossification, degeneration of the surrounding nerves, and swelling of the posterior pharyngeal wall [21,22]. Dysphagia is diagnosed by questionnaires, such as the Eating Assessment Tool [23], screening tests, the 30 mL water swallowing test [17], clinical assessment by VE, and VF. In case 1, the patient was evaluated using the 30 mL water drinking test and VE only due to cervical spinal cord injury. Pressure drainage of the pharynx was noted. In case 2, the 30 mL water swallow test results were expected, but he was diagnosed with compression and dysphagia by both VE and VF. In the report on the relationship between dysphagia and the thickness of C-OALL, the average thickness was more significant than 10.0-13.5 mm, and the morphology was often globular type [24,25]. On the other hand, there did not appear to be a direct correlation between the size and the severity of dysphagia [26]. The relationship between dysphagia and radiographic alignment in other cervical spine diseases has also been reported to assess dysphagia in OALL [16]. [PERSON] et al. found the O-C2 angle irrelevant in cervical spine surgery because dysphagia in C-OALL occurs below the C2 vertebrae. On the other hand, they reported a 5\({}^{\circ}\) decrease in the C2-7 angle associated with the exacerbation of postoperative dysphagia [27]. However, there were patients with a greater extent of C-OALL without dysphagia, and the cutoff of the thickness of OALL and the alignment of  
Figure 4: Case 2. C3/4 OALL increased from 6.8 mm (**a**) to 11.6 mm (**b**) since the first X-ray and CT 6 years ago. (**c**) No evidence of spinal cord compression on MRI. (**d**) VF showed narrowing of the pharyngeal cavity in the area of ossification, which was further exacerbated by flexion (arrow). (**e**) The S-line was negative. VE: the pharyngeal cavity was compressed and narrowed anteriorly due to ossification, which was further exacerbated by flexion. Figure 5: Postoperatively, the ossification was reduced by resection (arrow). the surgical procedure for C-OALL with dysplasia is unclear. The S-line in the two cases was negative, and we may need to consider a new index that takes alignment, thickness or morphology of C-OALL, and intervertebral mobility into account. Regarding the treatment of C-OALL, there are reports of improvement by conservative treatment [8; 9; 28]. Aspiration pneumonia, depression due to loss of appetite, and weight loss for dysplasia require surgical treatment, although there have been reports of dysphagia occurring in 5.6%, hoarseness in 5.2%, transient sore throat in 4.8%, worsening of pre-existing myelopathy in 3%, and graft extrusion in 1.7% [29]. On the other hand, successful relief of dysphagia was obtained in 89% of patients after comparatively early surgery. Failure to relieve dysphagia was associated with an increased length of symptoms preoperatively [13]. [PERSON] et al. reported that especially in the elderly, timely bone resection appeared crucial, even with mild dysphagia, in the presence of a long-lasting clinical history [10]. As an operation method, anterior cervical osteophytectomy (resection of C-OALL) is highly effective. The most common type of surgery is surgical resection of the ossification layer [10; 25; 30; 31; 32]. Reports of additional posterior fixation seem to be limited to cases with [PERSON]'s disease and maintaining alignment [33]. Recurrence is a problem after resectioning the ossification layer alone, with recurrence in two out of seven cases reported at 10 years [34]. [PERSON] et al.