Spinal osteophytosis is a common disease in the elderly population. More than 75% of people over 65 years old have age-related changes in cervical vertebra anatomy [1]. There are various causes for the development of anterior cervical osteophytes (ACOs). The majority of cervical osteophytes occur due to degenerative diseases. Other causes for the development of anterior osteophytes include diffuse idiopathic skeletal hyperostosis (DISH), failure of surgery, adjacent segmental instabilities after fusion, heterotopic ossification after cervical disc arthroplasty, and posttraumatic instabilities [2,3]. Most of the time, an ACO does not present with any accompanying symptoms. However, prominent ACOs can cause dysphonia, dyspnea, dysphagia, and pain [4]. Dysphagia is the most common presentation of symptomatic ACOs [3]. According to Granville et al. [5], 10.6% of people presenting with dysphagia have cervical osteophytes. According to Utsinger et al. [6], 17% of patients with cervical osteophytosis develop dysphagia.

ACOs could be isolated or diffuse. They are most often idiopathic as a part of the disease entity called DISH [1]. DISH is characterized radiologically by flowing calcification along anterolateral sides of contiguous vertebrae of the spine [7]. Secondary dysphagia due to DISH has been frequently described in case reports [2]. There are no treatment guidelines for dysphagia induced by ACOs. Several cases have described the effect of surgical management on symptomatic osteophytes [3]. However, evidence for surgical approach remains insufficient.

The aim of this study was to analyze swallowing characteristics of dysphagic patients with ACOs and compare clinical courses according to different treatment options.

In this study, 22 of 23 patients (96%) were males. Their mean age was 78.7 years. A meta-analysis study of 204 cases by Verlaan et al. [13] has reported that the maleto-female ratio of ACO incidence is 6.1:1 and the average age is 68.9 years. Kim et al. [14] have reported that ACOs occur more frequently in men and that the average age at onset is 66 years. This is generally consistent with our study demographics. ACOs were reported in 2.9% to 4.1% of adults in Korea [14]. Its prevalence is known to increase with age [14]. Seidler et al. [15] have found that the dysphagic symptom severity increases with age. Because life expectancy is increasing, the prevalence of dysphagia due to ACOs may also increase in the coming decades [14].

Spondylosis is a common finding in the aging cervical spine [16]. ACOs can be a result of such degenerative disorders of the cervical spine. Indeed, in this study, all participants had arthritis. Symptomatic degenerative changes of the cervical spine affect approximately 75% of the population aged more than 60 years [16]. Therefore, older male patients with unexplained dysphagia may need to evaluate cervical spine for possible ACOs.

The main findings of this study were that swallowing characteristics of dysphagic patients with ACOs showed pharyngeal phase dysphagia including penetration, decreased laryngeal elevation, and reduced epiglottis inversion. The surgical group had a significant higher pharyngeal phase score of VDS than the other groups. Moreover, in the surgical group, the thickest and most affected level of ACO were at higher level of the cervical spine and their ACOs were significantly thicker than the other two groups.

Although some studies have suggested various mechanisms to account for ACO-induced dysphagia, the exact mechanisms remain unclear. Dysphagia due to ACO is most commonly associated with anterior osteophyte formation at C3-5 levels. This might be due to the fact that the normal epiglottic tilt lies over the laryngeal inlet at these levels [13]. In this study, all patients in group A had ACOs at C3-5 levels and showed reduced epiglottis inversion, decreased laryngeal elevation, and penetration on VFSS findings. According to Di Vito [17], bolus deflects off directly into the open larynx because of the shelf formed by an anterior osteophyte at C3-5 levels. This has been reported to cause direct aspiration [17]. Seidler et al. [15] have reported that osteophytes at C3-4 and C4-5 levels are associated with aspiration during swallowing due to restriction of the epiglottic closure. This type of aspiration was more common in patients of group A who had ACOs at higher cervical spine levels. In contrast, residue retention with possible post-swallow aspiration is often found in patients with osteophytes in lower cervical spine levels (C5-6, C6-7) [15]. Osteophytes at the C6-7 level can cause esophageal impingement or obstruction [17]. Group C had more osteophytes at C6-7 level. However, esophageal impingement or obstruction was not detected on VFSS. This suggests that osteophytes might not be thick enough to cause such conditions.

According to Strasser et al. [18], aspiration is rare in patients with osteophytes <10 mm. They found that clinically relevant obstruction of the pharynx occurred from about 12 to 15 mm osteophyte thickness. Seidler et al. [15] have reported that osteophytes >10 mm in the anteriorposterior length could lead to symptoms related to dysphagia. In our study, osteophyte thickness in group A was 13.13±2.26 mm, which was significantly thicker than that in other groups. The mean osteophyte thickness was 9.07±3.84 mm (range, 3–18 mm). These findings were consistent with results of other studies. The thickness of the osteophyte can affect the epiglottic tilt or direct aspiration into the larynx. It can also cause physical obstruction of the esophageal lumen. In addition, increased thickness may increase the incidence and severity of symptoms such as choking and aspiration. In the present study, the surgical group showed significantly higher scores in pharyngeal phase of VDS than the other groups. This suggests that laryngeal dysfunction along with aspiration may influence the decision to undergo surgical treatment.

There is no consensus about proper ACO treatments at this time. Most case reports and studies have reported improvements in dysphagia symptoms within 6 weeks after surgical treatment. von der Hoeh et al. [2] have reported improvements in VFSS findings and dysphagia symptoms in all their six patients after surgery. Flynn [19] have reported improvement of dysphagia symptoms in 28 of 30 patients after surgical resection of ACOs. In our study, the surgical group showed significant improvements in their dysphagia severity compared to the other treatment groups. The swallowing rehabilitation group did not show significant improvement in dysphagia severity. This might be due to the small sample size, short follow-up duration after swallowing rehabilitation, and difficult structural changes in osteophytes. However, swallowing rehabilitation has been suggested as a treatment option because neuromuscular strengthening and diet modification can help improve patients’ symptoms [20-22].

Based on EMR review, patients with thick ACO and definite aspiration were recommended to undergo surgery. In the surgical group, 3 out of 4 patients were referred to a neurosurgeon after VFSS in the rehabilitation department while the other patient underwent orthopedic surgery recommended by the otolaryngologist. In the swallowing rehabilitation group, 2 out of 9 patients refused surgery but underwent rehabilitation and 2 patients were unable to undergo an operation due to the presence of comorbidities. The remaining 5 patients were determined to conduct swallowing rehabilitation by an internist. Moreover, we compared VDS total score (40.50±6.47, 39.30±10.30) and VDS pharyngeal phase score (32.75±7.96, 33.90±8.32) of patients who were recommended for surgical treatment and those who were determined to initially undergo rehabilitation. There was no statistically significant difference (p=1.0 and p=0.905, respectively). In the conservative treatment group, 1 of 10 patients refused the recommended surgical treatment and 7 patients refused the swallowing rehabilitation. Two patients were isolated. Hence, rehabilitation was not performed. For patients with dysphagia caused by ACO, surgical indication or treatment method has not been established yet. Therefore, selection of treatment option by patient might have influenced the final decision of the treatment method.

Characteristics associated with treatment options in dysphagic patients with ACOs were analyzed. ACOs at C3 level had positive correlations with treatment options. Those in the more active treatment groups such as patients who underwent surgery and swallow rehabilitation had frequent alterations on the upper cervical spine, especially at the C3 level. A systematic review of 204 cases by Verlaan et al. [13] has elucidated that the most affected vertebrae are C3, C4, and C5 known to be associated with epiglottic tilt. Based on the study by Bartalena et al. [23], VFSS shows epiglottis impingement at C3–C4 level which alters the pharyngeal phase of swallowing and leads to laryngeal penetration. von der Hoeh et al. [2] have also reported that most surgeries are performed at C3–C4 level. Osteophytes at the C3–C5 level may cause inflammation of the anterior spinal soft tissue at the cricopharyngeal opening, thus inhibiting the opening of the UES [17]. It has been reported that the upper esophageal sphincter opening width is significantly increased, along with an improvement of hyoid movement after surgical treatment of ACOs [3]. Consistent with other studies, all patients in the surgical group of the present study had ACOs at C3–C5 level and showed laryngeal penetration, decreased laryngeal elevation, reduced epiglottis inversion, and incomplete UES opening. Moreover, ACO was significantly thicker in the surgical group. Therefore, upper cervical spine alterations, severity of the pharyngeal dysphagia, and ACO thickness might need to be considered when deciding for appropriate treatment options.

Although beneficial effects of surgical removal have been reported, surgical management of ACOs in dysphagia patients is still being debated. Post-surgical soft tissue edema and laryngeal nerve damage can occur. Therefore, there is a chance that surgery can actually degrade swallowing [24]. If there are long-term progressive bone formation and irreversible surrounding tissue changes, it is impossible to completely resolve dysphagia through surgery [25]. Therefore, it is important to establish a proper surgical indication. In an attempt to assist with decisionmaking, correlations between treatment options and various factors were analyzed. If patients’ pharyngeal dysphagia and incomplete UES opening are severe, they are more likely to undergo active treatment such as surgery and swallow rehabilitation rather than with conservative treatment.

This study has several limitations. First, it was conducted retrospectively using EMR of subjects. For this reason, selection bias could not be ruled out. Second, the number of subjects was small which limited the study’s validity. Third, VFSS follow-up was not performed for all patients after treatment. Therefore, it could not fully evaluate changes of VFSS findings.

In conclusion, the main swallowing characteristics in patients with ACOs were dysphagia features of pharyngeal phase including inappropriate airway protection, decreased laryngeal elevation, and reduced epiglottis inversion. When deciding on a treatment option, considering the severity of dysphagia, specifically at the pharyngeal phase, and the overall osteophyte thickness might be helpful.