Ossification of the Anterior Longitudinal Ligament with Dysphagia as the First Symptom: Rehabilitation of Two Cases

Round 1

Reviewer 1 Report

Abstract of the manuscript is focused on examination of the mechanical properties of the ligamentum flavum using tensile test.

But, manuscript contains two cases of C-OALL with dysphagia, one in which posterior fixation incidentally improved dysphagia and one in which dysphagia improved after ossification layer excision.

 

I don't think the abstract belongs to the article.

Author Response

 

We are grateful to reviewer #1 for their critical comments and useful suggestions that have helped us to improve our paper. As outlined in the responses below, we have taken all reviewer comments and suggestions into account in the revised version of our manuscript.

 

Comment #1: Abstract of the manuscript is focused on examination of the mechanical properties of the ligamentum flavum using tensile test. But, manuscript contains two cases of C-OALL with dysphagia, one in which posterior fixation incidentally improved dysphagia and one in which dysphagia improved after ossification layer excision. I don't think the abstract belongs to the article.

 

Response #1: It is our mistake to check. We had corrected the problem, but you did not receive the correction.

“Dysphagia is associated with a poor quality of life, and pneumonia due to aspiration is life-threatening. Cervical ossification of the anterior longitudinal ligament (C-OALL) is one of the causes of dysphagia, and we report two cases in which dysphagia improved after surgery. Case 1: A 76-year-old man had C-OALL of greater than 16 mm and dysphagia, and developed myelopathy. A fall resulted in upper and lower limb insufficiency paralysis, and posterior decompression fixation was performed; pressure on the pharynx by C-OALL remained, but dysphagia improved. Improvement in this case was considered to be due to the loss of intervertebral mobility. Case 2: A 62-year-old man developed dysphagia 6 years ago. It gradually exacerbated and the C-OALL increased. Laryngeal fiberscope and swallowing angiography revealed that the pharyngeal cavity was compressed and narrowed anteriorly due to ossification. Resection of the ossification was performed and the patient's symptoms improved. Direct decompression was successful in this case. Several evaluation methods for dysphagia have been reported, including screening tests, endoscopy, contrast studies, and radiological evaluation. In Case 1, extensive ossification was improved by posterior fixation, albeit incidentally, whereas in Case 2, a patient with extensive ossification exhibited symptoms. It is necessary to examine the cervical mobility, extent and morphology of ossification, and stenosis to determine the risk factors and treatment options including rehabilitation.”

Reviewer 2 Report

The biggest concern to me is there is no methods section. I understand this is a case report but there are some methodical questions that need to be addressed in a methods section.

1. Move definition of s-line to the methods section. Describe the importance of the s-line, how it is measured, what a normal s-line is.
2. Please include a figure showing how the s-line is measure, where it is located on x-ray, etc.
3. The methods section also needs to include how these two cases were obtained, what criteria made you choose these two patients. Why were these 2 cases important.
4. Further describe what standard dysphagia related tests were done to make these two cases comparable.
5. In case 1: what was the food intake level and dysphagia severity scale score post-operative? The manuscript says the patient was able to eat food and no trouble swallowing, however was there a VFSS or some other measurable test to determine the dysphagia was improved?
6. In Case 2: you describe difficulty swallowing but do not indicate any quantifiable swallow studies/diagnosis to denote dysphagia in this case. It is indicated that the patient was able to eat 80% of main meals post-operative but what is this compared to before?

Author Response

We are grateful to reviewer #2 for critical comments and useful suggestions that have helped us to improve our paper. As outlined in the responses below, we have taken all reviewer comments and suggestions into account in the revised version of our manuscript.

 

Specific comments

Comment #1: The biggest concern to me is there is no methods section. I understand this is a case report but there are some methodical questions that need to be addressed in a methods section.

 

Response #1: I added the Material and Methods section. The first section describes the measured assessments, and then I changed the structure to a Case presentation.

 

Comment #2: Move definition of s-line to the methods section. Describe the importance of the s-line, how it is measured, what a normal s-line is.

 

Response #2: I moved the definition of S-line to the methods section, mentioned the importance of the S-line, how it is measured and what a regular and cut-off of S-line is.

 

Comment #3: Please include a figure showing how the s-line is measure, where it is located on x-ray, etc.

 

Response #3: I changed Figure 1 to explain S-line.

Figure 1. (a) the occipito-C2 angle (O-C2A: angle between McGregor’s line and lower end plate of C2) (b) pharyngeal inlet angle (PIA) is defined as the angle between McGregor’s line and the line that links the center of the C1 anterior arch and the apex of cervical sagittal curvature. the Swallow-line (S-line) (-) is PIA <90°, (c) the Swallow-line (S-line) (+) is PIA >90°.

 

Comment #4: The methods section also needs to include how these two cases were obtained, what criteria made you choose these two patients. Why were these 2 cases important.

 

Response #4: The reasons for choosing these two cases are described in the Introduction, including the contents of this study, considering the opinions of other reviewers.

“In this study, we experienced two cases in which the dysphagia improved with a different technique despite similar swallowing evaluation including x-rays. Case 1, different from regular reports, posterior fixation incidentally improved dysphagia without anterior resection, and Case 2, in which dysphagia improved after ossification layer resection. The difference between the two cases is the presence of intervertebral mobility and trauma. There is still controversial research area reporting intervertebral mobility, and we report these cases with a review of the literature.”

 

Comment #5: Further describe what standard dysphagia related tests were done to make these two cases comparable.

 

Response #5: We have added a description of the tests performed before the pre-and post-operation to be compared.

 

Comment #6: In case 1: what was the food intake level and dysphagia severity scale score post-operative? The manuscript says the patient was able to eat food and no trouble swallowing, however was there a VFSS or some other measurable test to determine the dysphagia was improved?

 

Response #6: I added to the Methods section about the food intake level and dysphagia severity scale score.

“We used the Food Intake LEVEL Scale [18], a 10-point observer-rating scale to measure the severity of dysphagia. Dysphagia outcome and severity scale[19] [20], a simple, easy-to-use, 7-point scale developed to systematically rate the functional severity of dysphasia based on objective assessment and make recommendations for diet level, independence level, and type of nutrition.”

 

I added the result of Screening Test and Practical assessment tool in the postoperative sentence.

Case 1: “The 30-ml water swallowing test was improved LEVELⅠ. His swallowing function was as follows: Food Intake LEVEL scale: 9 and dysphagia severity scale: 6.”

 

Case 2: “The patient was able to get out of bed the day after surgery, and the ST intervened. The patient had an inducible swallowing reflex, and an ice massage was performed with no swelling or wet hoarseness. Postoperative day 3: He was able to eat 80% (compared with preoperative days) of main meals and side dishes in 15 minutes. He continued oral intake after that. On the fifth postoperative day, he was able to eat regular food without discomfort in the pharynx. He was discharged on the 10th postoperative day. Food type-based dysphagia disappeared after one month postoperatively. The 30-ml water swallowing test was LEVELⅠ. His swallowing function was as follows: Food Intake LEVEL scale: 10 and dysphagia severity scale: 7.”

 

In the postoperative period for both cases, Covid-19 was instructed by the otorhinolaryngological not to perform VE except in cases of high necessity, and VF in case1was refused by the otorhinolaryngological physician because of the opinion that it should not be performed except in cases of repeated aspiration.

 

Comment #7: In Case 2: you describe difficulty swallowing but do not indicate any quantifiable swallow studies/diagnosis to denote dysphagia in this case. It is indicated that the patient was able to eat 80% of main meals post-operative but what is this compared to before?

 

Response #7: Thank you for your comments.

I added the Radiological evaluation of the Screening Test, Practical assessment tool, and Figures in Pre- and Post-operation.

“Evaluation on admission: no symptoms of nerve disturbance. There were no complaints other than dysphagia. The oral function was expected, and the jaw opened to a width of 3 fingers. The tooth was intact. Tongue movement did not differ between the left and right sides, and coughing was possible. On the 30-ml water swallowing test, drinking water successfully without interruption or coughing (LEVELⅠ). His swallowing function was as follows: Food Intake LEVEL scale: 8 and dysphagia severity scale: 6.”

 

I corrected Post-operative describe.

“The patient was able to get out of bed the day after surgery, and the ST intervened. The patient had an inducible swallowing reflex, and an ice massage was performed with no swelling or wet hoarseness. Postoperative day 3: He was able to eat 80% (compared with preoperative days) of main meals and side dishes in 15 minutes. He continued oral intake after that. On the fifth postoperative day, he was able to eat regular food without discomfort in the pharynx. He was discharged on the 10th postoperative day. Food type-based dysphagia disappeared after one month postoperatively. The 30-ml water swallowing test was LEVELⅠ. His swallowing function was as follows: Food Intake LEVEL scale: 10 and dysphagia severity scale: 7.”

 

Author Response File: Author Response.docx

Reviewer 3 Report

The paper is well written, but some concepts should be better discussed.

Since there’s no literature review, the related sentence in the introduction should be removed and maybe substituted with another one better focused on the real message of the paper: both anterior and posterior surgery can lead to an improvement of dysphagia.

Case 1: the cervical spine MRI documents a C3-C4 post-traumatic myelopathy basically sustained by an anterior ostephyte. Therefore, why a C3-C6 posterior approach (decompression and fixation) was preferred to an anterior decompression (even of the bony spurs compressing the pharynx) and fusion?  The imaging doesn’t show clearly the traumatic fracture/lesion, so please integrate with better images or at least provide a description of the injury according to the AOSpine classification.

As in your case usually the compression determining a spinal cord injury is mainly due to osteophytes especially in a patient with DISH. In this sense, although rare, a DISH discovered through a traumatic injury is usually approached from anterior, in order to provide with a single surgery both a spinal cord and a pharyngo-esophageal decompression, removing osteophytes and prevertebral bony spurs. Then an anterior fixation is usually performed. Did the patient undergo video endoscopy both pre- and post-operatively? It would be of great importance providing such images since, without any decompression of prevertebral ossification, a post-operative improvement of dysphagia was noted with resumption of eating. How the authors justify such a benefit obtained through a posterior surgery? I do believe that the hypothetic reduced friction due to the posterior immobilization may have played a role, but probably only in reducing the chronic inflammation sustaining the dysphagia. Therefore, I would have expected an advantage, but not in the immediate post-operative course. Since this is the real take home message and novelty of the paper, I suggest developing this concept more extensively with solid argumentations. In this sense in discussion should be mentioned even a relevant concept documented by a recent study (PMID: 33590802, doi: 10.1177/2192568220988272) on the largest pool of patients operated for DISH of the cervical spine: time to surgery calculated from the onset of symptoms has an impact on outcome in terms of dysphagia more than other factors such as the patient age or the extension of bony spurs resection. So maybe in case 1 a short waiting time to surgery significantly helped in determining a prompt post-operative improvement.

Literature regarding other patients with DISH of the cervical spine treated from posterior should be cited and adequately discussed.         

Author Response

We are grateful to reviewer #3 for critical comments and useful suggestions that have helped us to improve our paper. As outlined in the responses below, we have taken all reviewer comments and suggestions into account in the revised version of our manuscript. 

Specific comments

Comment #1: Since there’s no literature review, the related sentence in the introduction should be removed and maybe substituted with another one better focused on the real message of the paper: both anterior and posterior surgery can lead to an improvement of dysphagia.

 

Response #1: Thank you for your comments.

We have corrected the Introduction and Discussion from general information about dysphasia by DISH and C-OALL to surgical information about why we need to compare the two cases.

 

Comment #2: Case 1: the cervical spine MRI documents a C3-C4 post-traumatic myelopathy basically sustained by an anterior ostephyte. Therefore, why a C3-C6 posterior approach (decompression and fixation) was preferred to an anterior decompression (even of the bony spurs compressing the pharynx) and fusion?  The imaging doesn’t show clearly the traumatic fracture/lesion, so please integrate with better images or at least provide a description of the injury according to the AO Spine classification.

 

Response #2: In Case 1, there was intervertebral mobility in C3-C4 (probably because the caudal spine was stabilized by DISH). Due to the mobility, the ligamentum flavum was thickened due to mechanical stress, and compression of the spinal cord was observed. We diagnosed that this injury was the diagnosis of cervical spinal cord injury without bone injury and that the instability was caused by the ALL and intervertebral disc injury at C3-C4. The first reason we performed the posterior decompression and fusion was for spinal decompression. The anterior approach alone would have placed too much stress on the bone graft and plate, and decompression of the ligamentum flavum would have been more beneficial to the spinal cord. In the preoperative informed consent, I explained that if the dysphasia worsened postoperatively, I would perform resection of C-OALL. Considering the possibility of bleeding from soft tissue damage, we prioritized decompression first.

Comment #3: As in your case usually the compression determining a spinal cord injury is mainly due to osteophytes especially in a patient with DISH. In this sense, although rare, a DISH discovered through a traumatic injury is usually approached from anterior, in order to provide with a single surgery both a spinal cord and a pharyngo-esophageal decompression, removing osteophytes and prevertebral bony spurs. Then an anterior fixation is usually performed. Did the patient undergo video endoscopy both pre- and post-operatively? It would be of great importance providing such images since, without any decompression of prevertebral ossification, a post-operative improvement of dysphagia was noted with resumption of eating. How the authors justify such a benefit obtained through a posterior surgery? I do believe that the hypothetic reduced friction due to the posterior immobilization may have played a role, but probably only in reducing the chronic inflammation sustaining the dysphagia. Therefore, I would have expected an advantage, but not in the immediate post-operative course. Since this is the real take home message and novelty of the paper, I suggest developing this concept more extensively with solid argumentations. In this sense in discussion should be mentioned even a relevant concept documented by a recent study (PMID: 33590802, doi: 10.1177/2192568220988272) on the largest pool of patients operated for DISH of the cervical spine: time to surgery calculated from the onset of symptoms has an impact on outcome in terms of dysphagia more than other factors such as the patient age or the extension of bony spurs resection. So maybe in case 1 a short waiting time to surgery significantly helped in determining a prompt post-operative improvement. Literature regarding other patients with DISH of the cervical spine treated from posterior should be cited and adequately discussed.

 

Response #3: I corrected the overall flow of the manuscripts, Discussion, and Conclusion.

 First, I would like to answer about postoperative VE.

I ask the otorhinolaryngology physician to perform VE in the postoperative period for both cases. However, Covid-19 affected the otorhinolaryngology physician not to perform VE except in cases of high necessity. Moreover, VF in case1was refused by the otorhinolaryngological physician because it should not be performed except in cases of repeated aspiration. I added the result of the Screening Test and Practical assessment tool in the postoperative sentence.

Case 1: “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.”

Case 2: “The patient was able to get out of bed the day after surgery and the ST intervened. The patient had an inducible swallowing reflex and ice massage was performed, with no swelling or wet hoarseness. Postoperative day 3: He was able to eat 80% (compared with preoperative days) of main meals and side dishes in 15 minutes. He continued oral intake thereafter. On the fifth postoperative day, he was able to eat regular food without discomfort in the pharynx. He was discharged on the 10th postoperative day. Food type-based dysphagia disappeared after one month postoperatively. The 30-ml water swallowing test was LEVELⅠ. His swallowing function was as follows: Food Intake LEVEL scale: 10 and dysphagia severity scale: 7.”

 

As you said, in Case 1, we think the improvement is due to reduced friction. Both Cases were operated on relatively early after the onset of symptoms (Case 2 was less inclined...) I think Case 1 would have been an anterior operation if dysphagia was the main problem, but for the reasons in Response#2, the posterior was done first. This may have resulted in a decrease in friction. In addition, the improvement in swallowing ability was surprised to me, but it may have been due to the early surgical fixation. Unfortunately, there were no reports of posterior fixation with ossification in place. Based on these results, I rewrote the Discussion.

Round 2

Reviewer 2 Report

Thank You for making all of the suggested changes. This paper has improved significantly and reads much smoother. I have no further suggestions/concerns.

Author Response

Thank you for your reviewing and precious opinions.

Reviewer 3 Report

The manuscript improved, but there are still some minor issues to be overcome.

Introduction: the authors still declare among the purposes to have provided a “review of the literature”, but this is a pure case report format, and the discussion of what literature describes on this topic doesn’t mean that the paper can be considered a review, therefore that sentence should be removed.

Materials and methods: the sentence “the occipito-C2 angle is that the decrease of the O-C2A has been thought to be…” should be amended, since is not understandable in its sense.

Case reports: although in conclusion section the authors recognize the short-term follow-up as a limitation of their manuscript, they should however mention the length of follow-up at the end of each case report. This is particularly important in DISH patients who typically may continue suffering from dysphagia despite the surgical treatment and may incur in recurrences even decades after surgery.

Author Response

We are grateful to reviewer #3 for critical comments and useful suggestions that have helped us to improve our paper. As outlined in the responses below, we have taken all reviewer comments and suggestions into account in the revised version of our manuscript.

 

Specific comments

Comment #1: The manuscript improved, but there are still some minor issues to be overcome.

Introduction: the authors still declare among the purposes to have provided a “review of the literature”, but this is a pure case report format, and the discussion of what literature describes on this topic doesn’t mean that the paper can be considered a review, therefore that sentence should be removed.

 

 

Response #1: Thank you for your comments.

I deleted and changed sentences “There is still a controversial research area reporting intervertebral mobility and timing of surgery, and we report these cases with a review of the literature.”.

Comment #2: Materials and methods: the sentence “the occipito-C2 angle is that the decrease of the O-C2A has been thought to be…” should be amended, since is not understandable in its sense. 

Response #2: Thank you for your point out.

I corrected the sentence.

“We measured radiological parameters on the lateral cervical radiograph as follows; the thick of C-OALL, the occipito-C2 angle (O-C2A: angle between McGregor’s line and lower endplate of C2) [14] [15], and the pharyngeal inlet angle (PIA) between McGregor's line and the line that links the center of the C1 anterior arch and the apex of the cervical sagittal curvature[16]. A significant reduction in O-C2A was correlated with a decrease in oropharyngeal space and postoperative dysphagia[14] [15]. Keneyama et al. considered that the dysphagia should be predicted at the condition of PIA <90°, where the apex of midcervical sagittal curvature protruded anterior to the Swallow-line (S-line): S-line (-). However, no patients experienced dysphagia as long as PIA was 90°, where the apex of mid-cervical curvature stays posterior to the S-line: S-line (+)[16] (Figure 1).  ”

 

Comment #3: Case reports: although in conclusion section the authors recognize the short-term follow-up as a limitation of their manuscript, they should however mention the length of follow-up at the end of each case report. This is particularly important in DISH patients who typically may continue suffering from dysphagia despite the surgical treatment and may incur in recurrences even decades after surgery.

 Response #3: Thank you for your valuable input.

I corrected the relevant Discussion.

“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 dysphasia require surgical treatment, although there have been reports of dysphagia occurred in 5.6%, hoarseness in 5.2%, transient sore throat in 4.8%, worsening of pre-existing myelopathy in 3%, 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]. Lofrese 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]. The reports of additional posterior fixation seem to be limited to cases with Parkinson's disease and maintaining alignment [33]. Recurrence is a problem after resectioning the ossification layer alone, with recurrence in 2 out of 7 cases reported at ten years [34]. Lofrese et al. reported that one and two recurrences respectively at clinical and radiological follow-up were registered 18-30 months after surgery in elderly patients and short-range [10]. Kaur reported that the patient was 63 years old and had a recurrence two years after osteophytectomy. On the other hand, some papers have shown that dysphagia did not recur for a long time. Hoeh et al. reported that at the final follow-up (23 ± 8 months) for six patients, the radiographic examinations showed no pathological regrowth, and the patients reported no recurrence of dysphagia [30]. Urrutia reported that postoperative radiographs demonstrated complete removal of osteophytes for five patients. At final follow-up, ranging from 1 to 9 years (average 59.8 months, median 53 months), no patients reported recurrence of dysphagia. Final radiographic examination demonstrated minimal regrowth of the osteophytes [31]. Further investigation is needed to determine what may be a factor in recurrence.”