Eur Spine J DOI 10.1007/s00586-014-3281-3
ORIGINAL ARTICLE
The association between psychiatric factors and the development of chronic dysphagia after anterior cervical spine surgery Sung Shik Kang • Jung Sub Lee • Jong Ki Shin Jae Myung Lee • Bu Hyun Youn
•
Received: 7 August 2013 / Revised: 30 December 2013 / Accepted: 15 March 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose Little data are available regarding the influence of psychiatric factors on chronic dysphagia after anterior cervical spine surgery. The purpose of this study was to identify associations between psychiatric factors and the development of chronic dysphagia in patients after anterior cervical spine surgery. Methods The authors prospectively examined 72 patients with degenerative disc disease of the cervical spine who were treated by single-level anterior cervical discectomy and fusion. Demographic data including age, gender, body mass index, and smoking status were collected. Short form36, mental component scores (MCS), physical component scores (PCS), Neck Disability Indices (NDI), and the Neck Pain and Disability Scale (NPDS) were assessed before surgery and at final follow-up. Psychiatric conditions were evaluated using the Zung depression scale and the Zung anxiety scale. At 1 year postoperatively, patients were contacted by telephone to determine the presence and S. S. Kang Department of Orthopaedic Surgery, Medical Research Institute, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea J. S. Lee (&) J. K. Shin Department of Orthopaedic Surgery, Medical Research Institute, Pusan National University School of Medicine, 1-10 Ami-Dong, Seo-Gu, Busan 602-739, Republic of Korea e-mail: [email protected]
severity of dysphagia. For statistical analyses, patients were divided into two groups: group I, those with No or Mild dysphagia; and group II, those with Moderate or Severe dysphagia at 1 year after surgery. Potential risk factors of chronic dysphagia were evaluated by multivariate logistic regression analysis. Results The patients included 22 women and 50 men of overall average age 47.1 ± 7.8 years. The prevalences of No/Mild (group I) and Moderate/Severe (group II) dysphagia were 69.4 % (50 patients) and 30.6 % (22 patients), respectively. Mean preoperative NDI, NPDS, PCS, and MCS scores of 34.2, 44.8, 33.7, and 46.2 in the 72 study subject improved to 9.9, 16.1, 55.1, and 56.2, respectively, at 1 year after surgery. The mean preoperative ZDS and ZAS scores were 35.2 and 34.2, respectively. The two study groups were significantly different in terms of the presence of a psychiatric problem, preoperative NDIs, and MCS scores. However, multivariate logistic regression showed that the presence of a psychiatric problem prior to surgery (P = 0.005) was the only significant predictor of chronic dysphagia. Conclusions The presence of a psychiatric problem seems to be an important risk factor of chronic dysphagia in patients with cervical disc herniation. The study shows that psychiatric factors should be evaluated prior to surgery to determine the risk of chronic dysphagia. Keywords Cervical disc herniation Chronic dysphagia Psychiatric factor
J. M. Lee Department of Naval Architecture and Ocean Engineering, Pusan National University, Busan, Republic of Korea
Introduction
B. H. Youn Department of Biologic Sciences, College of Natural Sciences, Pusan National University, Busan, Republic of Korea
Dysphagia is a well-known complication of anterior cervical spine surgery, and is defined as difficulty swallowing
123
Eur Spine J
solids and liquids, which can lead to an inability to protect the airway from aspiration. Because of the diversity of diagnostic criteria, reported prevalences of dysphagia range widely (1–79 %) [1]. Most patients are asymptomatic or develop only mild symptoms, but severe impairment of swallowing can lead to severe complications. Improved understanding of the causes of dysphagia and its risk factors could help minimize this postoperative complication of anterior cervical spine surgery, and various factors have been considered in this context. Investigators have attempted to correlate demographic factors (age, sex, use of alcohol/tobacco, hypertension, diabetes) [2–6] and surgical factors (length of surgery, use of a plate, thickness and design of plates, extent of intraoperative retraction, endotracheal tube cuff pressure, use of steroids, number of levels, and revision versus primary surgery) [3, 4, 6–9] with the occurrence of postoperative dysphagia. However, little information is available on the influence of preoperative psychiatric factors on chronic dysphagia after anterior cervical spine surgery. The purpose of this study was to evaluate the association between psychiatric factors and development of chronic dysphagia in patients after anterior cervical spine surgery.
Materials and methods Between March 2006 and December 2010, we prospectively examined 85 consecutive patients with degenerative disc disease of the cervical spine treated by single-level anterior cervical discectomy and fusion (ACDF). Thirteen patients were lost to follow-up and excluded. In total, 72 patients with a minimum follow-up of 1 year were enrolled in this study, which was approved by our Institutional Clinical Research Ethics Committee. All patients were operated on for cervical radiculopathy. A typical Smith–Robinson left-sided anterior approach to the cervical spine was performed in all patients. Graft materials were allogeneic fibular cortical bone and 1 cc of demineralized bone matrix in all patients. In addition, plate and screw fixation was performed. Patients with radiculopathy requiring two-level ACDF, a foraminal type of herniated disc, cervical trauma, and those requiring corpectomy were excluded. Patients with cervical myelopathy with one or more upper motor neuron signs (e.g., spasticity, hyperreflexia, a positive Babinski’s sign) by neurological examination were excluded. Litigious cases, such as, traffic accidents and worker’s compensation cases, were also excluded. Clinical outcomes were evaluated using Short form-36 (SF-36) [10], mental component scores (MCS), physical component scores (PCS), Neck Disability Indices
123
(NDI) [11], and the Neck Pain and Disability Scale (NPDS) [12] before surgery and at 1 year after surgery (final follow-up). At final follow-up, all patients were contacted by telephone to complete a questionnaire designed to determine the presence and severity of dysphagia based on the Bazaz– Yoo scale [2]. This system defines four grades, that is, None, Mild, Moderate, or Severe dysphagia based on subjective symptoms. ‘‘None’’ was defined no episode of swallowing difficulty. Patients who experienced rare episodes of dysphagia were graded as ‘‘Mild’’; these patients did not feel that dysphagia was a significant problem. Patients that experienced an occasional swallowing difficulty with specific foods were graded as ‘‘Moderate’’, whereas ‘‘Severe’’ dysphagia was defined as frequent swallowing difficulties with most foods. Respondents could report only one of these pre-coded response options. For statistical analyses, patients were divided into two groups: group I, No or Mild dysphagia; and group II, Moderate or Severe dysphagia. Psychiatric conditions were evaluated using the Zung depression scale (ZDS) [13] and the Zung anxiety scale (ZAS) [14]. The score of the ZDS ranges from 20 ‘‘no depression’’ to 80 ‘‘major depression’’, with a cut-off value [49 indicating significant depressive symptoms. The score of the ZAS also ranges from 20 ‘‘no anxiety’’ to 80 ‘‘extreme anxiety’’, with a cut-off value [44 indicating significant anxious symptoms. Patients were divided into two different cohorts (with or without a psychiatric problem) based on their baseline ZDS and ZAS scores. In this study, no psychiatric problem was defined as a ZDS score \50 and/or a ZAS score of \45. The possible risk factors of chronic dysphagia evaluated were: age, sex, body mass index (BMI), smoking history, duration of symptoms, and level of herniated nucleus pulposus (HNP). Chronic dysphagia was defined as dysphagia persisting at final follow-up. Symptom duration was defined as time elapsed between onset of neurologic symptoms (shoulder, arm, and/or hand pain; numbness; and/or motor weakness) and surgery. Statistical analysis was performed using SPSS ver. 11.5 for Windows (SPSS, Chicago, IL, USA). Results are expressed as mean ± standard deviations. Logistic regression analysis was performed to identify predictors of motor deficit. Initially, univariate logistic regression was used to test for associations between variables, and then forward stepwise multiple logistic regression analysis was used to develop a prediction model. The significances of differences between the two study groups were assessed using the t test or the Chi-square test. Statistical significance was accepted for p values \0.05.
Eur Spine J
Results
Discussion
The patients comprised 22 women and 50 men of overall average age 47.1 ± 7.8 years. The prevalences of No/Mild (group I) and Moderate/Severe (group II) dysphagia were 69.4 % (50 patients) and 30.6 % (22 patients), respectively. Mean preoperative NDI, NPDS, PCS, and MCS scores of 34.2, 44.8, 33.7, and 46.2 improved to 9.9, 16.1, 55.1, and 56.2, respectively, at final follow-up. The mean preoperative ZDS and ZAS scores were 35.2 and 34.2, respectively. The two groups did not differ statistically in terms of age, gender, BMI, smoking history, duration of symptoms, HNP level, preoperative clinical scores, or clinical scores at final follow-up (Table 1). However, significant differences were observed between the two groups in terms of the prevalence of a psychiatric problem, preoperative NDIs, and MCS scores at final follow-up. However, multivariate logistic regression showed that the presence of a psychiatric problem (P = 0.005) was the only significant predictor of the presence of chronic dysphagia (Table 2).
The anterior approach to the cervical spine has been used to treat numerous spinal disorders [15, 16]. Although the procedure is associated with low morbidity and mortality rates [17], the development of dysphagia after anterior cervical spine surgery is not uncommon. The pathophysiologic mechanism of postoperative dysphagia remains unclear, and few reports have been issued on chronic dysphagia after anterior cervical surgery. Accordingly, we sought to identify the risk factors of chronic dysphagia development after anterior cervical spine procedures. Reported prevalences of dysphagia after anterior spine surgery vary widely, but the majority of these reports were based on retrospective analysis. Furthermore, although several demographic and operative risk factors have been found to be associated with the development of postoperative dysphagia, physical and psychosocial factors have not been well studied, and thus, in the present study, we used a prospective approach to identify risk factors of chronic dysphagia development after anterior spine surgery. Previously reported rates of dysphagia after the anterior cervical approach ranged 1–79 % within 1 week of surgery, to 50–56 % after 1 month, and to plateau at 1 year at between 13 and 21 % [1, 4, 18]. In the present study, the incidence of Moderate or Severe dysphagia (30.6 %) was slightly higher than the average reported in the literature, which implies that universally accepted methods for accurately determining dysphagia are lacking and that authors have used different diagnostic criteria for dysphagia. In a previous study, female gender was found to be a risk factor of dysphagia after anterior cervical spine surgery [2]. In another, the prevalence of dysphagia was greater in women at 6 months, 1 year, and 2 years after surgery [4]. The etiology of this finding is unclear, but it may be related to the smaller anatomy of women. However, in this study no significant gender ratio differences were observed. Furthermore, it has been suggested in the literature that oropharyngeal swallowing varies with age [9], but in the present study, the average ages of symptomatic and asymptomatic patients were no different at final follow-up. And patients with cervical esophagus perforation often present dysphagia. Lu et al. [19] reported five cases of esophageal perforation with dysphagia, and presented their diagnosis and treatment strategy. Although there was no
Table 1 Details of the patients Group I (n = 50)
Group II (n = 22)
P value
Age (years)
46.8 ± 6.9
44.2 ± 7.2
0.160
Sex (F/M)
12/38
10/12
0.123
BMI (kg/m2)
24.0 ± 1.6
23.4 ± 2.0
0.155
Smoking (n)
30
11
0.595
Symptom duration (months)
8.1 ± 5.8
7.6 ± 3.9
0.851
Surgery level 4–5/5–6/6–7 (n)
7/24/19
0/12/10
0.181
Psychiatric problem (n) Preoperative NDI
7 33.1 ± 6.7
10 36.7 ± 8.1
0.009 0.044
Preoperative NPDS
44.5 ± 7.7
45.5 ± 8.7
0.628
Preoperative PCS
34.5 ± 7.5
31.8 ± 8.7
0.174
Preoperative MCS
47.0 ± 7.5
44.4 ± 9.4
0.198
Last NDI
9.4 ± 5.1
11.0 ± 4.6
0.200
Last NPDS
15.4 ± 7.0
17.7 ± 5.9
0.187
Last PCS
56.2 ± 9.5
52.5 ± 9.8
0.142
Last MCS
57.3 ± 7.5
53.6 ± 8.4
0.049
Improvement NDI
23.7 ± 7.3
25.7 ± 7.0
0.287
Improvement NPDS
29.1 ± 11.0
27.8 ± 8.1
0.623
Improvement PCS
21.7 ± 9.5
20.8 ± 8.7
0.709
Improvement MCS
10.3 ± 7.4
9.2 ± 8.6
0.599
Mean follow-up (months)
23.8 ± 8.8
22.3 ± 7.0
0.734
Table 2 Stepwise multiple logistic regression analysis for prediction of chronic dysphagia
Variables Psychiatric factor Constant
Coefficient 1.6330
Standard error
95 % CI
Odds ratio
P value
0.5911
1.6069 * 16.3071
5.1190
0.0057
-1.2763
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esophageal perforation in our cases, patients with esophagus perforation are easily overlooked or can lead to misdiagnosis as patients with simple dysphagia. Although a decrease in the prevalence of dysphagia was reported for patients that had undergone single-level surgery at C5/6 [4], this difference was not statistically significant, but given the small patient numbers analyzed this result should be interpreted cautiously. It appears likely that surgery requiring more soft tissue retraction (C3/4 and C6/7) contributes to dysphagia. Accordingly, Fengbin et al. [20] suggested that the approach should be selected in accordance with the surgery level (through the lateral edge of omohyoid approach for C3–C4, via the medial edge of omohyoid approach for C6–C7). Furthermore, it has been suggested that surgery at a higher level (C3/4), where there is a smaller soft tissue envelope, increases dysphagia rates. However, our data do not support this hypothesis. In the present study, univariate analysis showed that the presence of a psychiatric factor, a self-reported high preoperative NDI score, and a low MCS score at final followup were significantly associated with the development Moderate or Severe dysphagia. However, multivariate logistic regression analysis showed that only the presence of a psychiatric factor significantly predicted chronic dysphagia development. We do not know how the presence of a psychiatric factor predisposes patients to chronic dysphagia, and it is possible, these patients tended to overreport dysphagia. Nevertheless, our findings indicate that patients with a psychiatric factor should be counseled prior to surgery regarding the risk of chronic dysphagia development. As with any study, this study has its weaknesses. First, this study did not assess medication to psychiatric disorders and presurgical level of dysphagia. Antidepressive medicaments with anticholinergic side effects cause mouth dryness, and that could have caused dysphagia. Second, although data were obtained in a prospective manner, patients were not randomized, and because, this was an observational study, the effects of potential confounders were not controlled. Third, the data recovered were subjective, that is, patients were asked if they had dysphagia, and if they did, were further interviewed to determine the severity. Accordingly, no objective data were obtained that might be correlated with patient perceived symptoms. Future prospective studies incorporating objective measures of dysphagia may provide more insight. In conclusion, our findings suggest that the presence of a psychiatric problem before surgery is associated with the development of chronic dysphagia after anterior cervical spine surgery in patients with cervical disc herniation. Furthermore, our findings suggest that patients with a psychiatric factor should be counseled before surgery regarding the risk of developing chronic dysphagia.
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Acknowledgments This work was supported by the Convergence Research Grant funded by the Pusan National University (PNU, Convergence Research Grant) (PNU-2013-1312-0001). Conflict of interest
None.
References 1. Riley LH III, Vaccaro AR, Dettori JR, Hashimoto R (2010) Postoperative dysphagia in anterior cervical spine surgery. Spine 35:S76–S85 2. Bazaz R, Lee MJ, Yoo JU (2002) Incidence of dysphagia after anterior cervical spine surgery: a prospective study. Spine 27:2453–2458 3. Frempong-Boadu A, Houten JK, Osborn B, Opulencia J, Kells L, Guida DD, Le Roux PD (2002) Swallowing and speech dysfunction in patients undergoing anterior cervical discectomy and fusion: a prospective, objective preoperative and postoperative assessment. J Spinal Disord Tech 15:362–368 4. Lee MJ, Bazaz R, Furey CG, Yoo J (2007) Risk factors for dysphagia after anterior cervical spine surgery: a two-year prospective cohort study. Spine J 7:141–147 5. Papavero L, Heese O, Klotz-Regener V, Buchalla R, Schroder F, Westphal M (2007) The impact of esophagus retraction on early dysphagia after anterior cervical surgery: dose a correlation exist? Spine 32:1089–1093 6. Riley LH III, Skolasky RL, Albert TJ, Vaccaro AR, Heller JG (2005) Dysphagia after anterior cervical decompression and fusion: prevalence and risk factors from a longitudinal cohort study. Spine 30:2564–2569 7. Chin KR, Eiszner JR, Adams SB Jr (2007) Role of plate thickness as a cause of dysphagia after anterior cervical fusion. Spine 32:2585–2590 8. Mendoza-Lattes S, Clifford K, Bartelt R, Stewart J, Clark CR, Boezaart AP (2008) Dysphagia following anterior cervical arthrodesis is associated with continuous, strong retraction of the esophagus. J Bone Joint Surg Am 90:256–263 9. Smith-Hammond CA, New KC, Pietrobon R, Curtis DJ, Scharver CH, Turner DA (2004) Prospective analysis of incidence and risk factors of dysphagia in spine surgery patients: comparison of anterior cervical, posterior cervical, and lumbar procedures. Spine 29:1441–1446 10. Han CW, Lee EJ, Iwaya T, Kataoka H, Kohzuki M (2004) Development of the Korean version of Short-Form 36-Item Health Survey: health related QOL of healthy elderly people and elderly patients in Korea. Tohoku J Exp Med 203:189–194 11. Song KJ, Choi BW, Choi BR, Seo GB (2010) Cross-cultural adaptation and validation of the Korean version of the neck disability index. Spine 35:E1045–E1049 12. Wheeler AH, Goolkasian P, Baird AC, Darden BV 2nd (1999) Development of the Neck Pain and Disability Scale: Item analysis, face, and criterion-related validity. Spine 24:1290–1294 13. Zung WW (1965) A self-rating depression scale. Arch Gen Psychiatry 12:63–70 14. Zung WW (1971) A rating instrument for anxiety disorders. Psychosomatics 12:371–379 15. Bailey RW, Badglery CE (1960) Stabilization of the cervical spine by anterior fusion. J Bone Joint Surg Am 42:565–594 16. Cloward RB (1985) History of the anterior cervical fusion technique. J Neurosurg 63:817–819 17. Graham JJ (1989) Complications of cervical spine surgery. A five-year report on a survey of the membership of the Cervical Spine Research Society by the Morbidity and Mortality Committee. Spine 14:1046–1050
Eur Spine J 18. Kalb S, Reis MT, Cowperthwaite MC, Fox DJ, Lefevre R, Theodore N, Papadopoulos SM, Sonntag VKH (2012) Dysphagia after anterior cervical spine surgery: incidence and risk factors. World Neurosurg 77:183–187 19. Lu X, Guo Q, Ni B (2012) Esophagus perforation complicating anterior cervical spine surgery. Eur Spine J 21:172–177
20. Fengbin Y, Xinwei W, Haisong Y, Yu C, Xiaowei L, Deyu C (2013) Dysphagia after anterior cervical discectomy and fusion: a prospective study comparing two anterior surgical approaches. Eur Spine J 22:1147–1151
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ORIGINAL ARTICLE
The association between psychiatric factors and the development of chronic dysphagia after anterior cervical spine surgery Sung Shik Kang • Jung Sub Lee • Jong Ki Shin Jae Myung Lee • Bu Hyun Youn
•
Received: 7 August 2013 / Revised: 30 December 2013 / Accepted: 15 March 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose Little data are available regarding the influence of psychiatric factors on chronic dysphagia after anterior cervical spine surgery. The purpose of this study was to identify associations between psychiatric factors and the development of chronic dysphagia in patients after anterior cervical spine surgery. Methods The authors prospectively examined 72 patients with degenerative disc disease of the cervical spine who were treated by single-level anterior cervical discectomy and fusion. Demographic data including age, gender, body mass index, and smoking status were collected. Short form36, mental component scores (MCS), physical component scores (PCS), Neck Disability Indices (NDI), and the Neck Pain and Disability Scale (NPDS) were assessed before surgery and at final follow-up. Psychiatric conditions were evaluated using the Zung depression scale and the Zung anxiety scale. At 1 year postoperatively, patients were contacted by telephone to determine the presence and S. S. Kang Department of Orthopaedic Surgery, Medical Research Institute, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea J. S. Lee (&) J. K. Shin Department of Orthopaedic Surgery, Medical Research Institute, Pusan National University School of Medicine, 1-10 Ami-Dong, Seo-Gu, Busan 602-739, Republic of Korea e-mail: [email protected]
severity of dysphagia. For statistical analyses, patients were divided into two groups: group I, those with No or Mild dysphagia; and group II, those with Moderate or Severe dysphagia at 1 year after surgery. Potential risk factors of chronic dysphagia were evaluated by multivariate logistic regression analysis. Results The patients included 22 women and 50 men of overall average age 47.1 ± 7.8 years. The prevalences of No/Mild (group I) and Moderate/Severe (group II) dysphagia were 69.4 % (50 patients) and 30.6 % (22 patients), respectively. Mean preoperative NDI, NPDS, PCS, and MCS scores of 34.2, 44.8, 33.7, and 46.2 in the 72 study subject improved to 9.9, 16.1, 55.1, and 56.2, respectively, at 1 year after surgery. The mean preoperative ZDS and ZAS scores were 35.2 and 34.2, respectively. The two study groups were significantly different in terms of the presence of a psychiatric problem, preoperative NDIs, and MCS scores. However, multivariate logistic regression showed that the presence of a psychiatric problem prior to surgery (P = 0.005) was the only significant predictor of chronic dysphagia. Conclusions The presence of a psychiatric problem seems to be an important risk factor of chronic dysphagia in patients with cervical disc herniation. The study shows that psychiatric factors should be evaluated prior to surgery to determine the risk of chronic dysphagia. Keywords Cervical disc herniation Chronic dysphagia Psychiatric factor
J. M. Lee Department of Naval Architecture and Ocean Engineering, Pusan National University, Busan, Republic of Korea
Introduction
B. H. Youn Department of Biologic Sciences, College of Natural Sciences, Pusan National University, Busan, Republic of Korea
Dysphagia is a well-known complication of anterior cervical spine surgery, and is defined as difficulty swallowing
123
Eur Spine J
solids and liquids, which can lead to an inability to protect the airway from aspiration. Because of the diversity of diagnostic criteria, reported prevalences of dysphagia range widely (1–79 %) [1]. Most patients are asymptomatic or develop only mild symptoms, but severe impairment of swallowing can lead to severe complications. Improved understanding of the causes of dysphagia and its risk factors could help minimize this postoperative complication of anterior cervical spine surgery, and various factors have been considered in this context. Investigators have attempted to correlate demographic factors (age, sex, use of alcohol/tobacco, hypertension, diabetes) [2–6] and surgical factors (length of surgery, use of a plate, thickness and design of plates, extent of intraoperative retraction, endotracheal tube cuff pressure, use of steroids, number of levels, and revision versus primary surgery) [3, 4, 6–9] with the occurrence of postoperative dysphagia. However, little information is available on the influence of preoperative psychiatric factors on chronic dysphagia after anterior cervical spine surgery. The purpose of this study was to evaluate the association between psychiatric factors and development of chronic dysphagia in patients after anterior cervical spine surgery.
Materials and methods Between March 2006 and December 2010, we prospectively examined 85 consecutive patients with degenerative disc disease of the cervical spine treated by single-level anterior cervical discectomy and fusion (ACDF). Thirteen patients were lost to follow-up and excluded. In total, 72 patients with a minimum follow-up of 1 year were enrolled in this study, which was approved by our Institutional Clinical Research Ethics Committee. All patients were operated on for cervical radiculopathy. A typical Smith–Robinson left-sided anterior approach to the cervical spine was performed in all patients. Graft materials were allogeneic fibular cortical bone and 1 cc of demineralized bone matrix in all patients. In addition, plate and screw fixation was performed. Patients with radiculopathy requiring two-level ACDF, a foraminal type of herniated disc, cervical trauma, and those requiring corpectomy were excluded. Patients with cervical myelopathy with one or more upper motor neuron signs (e.g., spasticity, hyperreflexia, a positive Babinski’s sign) by neurological examination were excluded. Litigious cases, such as, traffic accidents and worker’s compensation cases, were also excluded. Clinical outcomes were evaluated using Short form-36 (SF-36) [10], mental component scores (MCS), physical component scores (PCS), Neck Disability Indices
123
(NDI) [11], and the Neck Pain and Disability Scale (NPDS) [12] before surgery and at 1 year after surgery (final follow-up). At final follow-up, all patients were contacted by telephone to complete a questionnaire designed to determine the presence and severity of dysphagia based on the Bazaz– Yoo scale [2]. This system defines four grades, that is, None, Mild, Moderate, or Severe dysphagia based on subjective symptoms. ‘‘None’’ was defined no episode of swallowing difficulty. Patients who experienced rare episodes of dysphagia were graded as ‘‘Mild’’; these patients did not feel that dysphagia was a significant problem. Patients that experienced an occasional swallowing difficulty with specific foods were graded as ‘‘Moderate’’, whereas ‘‘Severe’’ dysphagia was defined as frequent swallowing difficulties with most foods. Respondents could report only one of these pre-coded response options. For statistical analyses, patients were divided into two groups: group I, No or Mild dysphagia; and group II, Moderate or Severe dysphagia. Psychiatric conditions were evaluated using the Zung depression scale (ZDS) [13] and the Zung anxiety scale (ZAS) [14]. The score of the ZDS ranges from 20 ‘‘no depression’’ to 80 ‘‘major depression’’, with a cut-off value [49 indicating significant depressive symptoms. The score of the ZAS also ranges from 20 ‘‘no anxiety’’ to 80 ‘‘extreme anxiety’’, with a cut-off value [44 indicating significant anxious symptoms. Patients were divided into two different cohorts (with or without a psychiatric problem) based on their baseline ZDS and ZAS scores. In this study, no psychiatric problem was defined as a ZDS score \50 and/or a ZAS score of \45. The possible risk factors of chronic dysphagia evaluated were: age, sex, body mass index (BMI), smoking history, duration of symptoms, and level of herniated nucleus pulposus (HNP). Chronic dysphagia was defined as dysphagia persisting at final follow-up. Symptom duration was defined as time elapsed between onset of neurologic symptoms (shoulder, arm, and/or hand pain; numbness; and/or motor weakness) and surgery. Statistical analysis was performed using SPSS ver. 11.5 for Windows (SPSS, Chicago, IL, USA). Results are expressed as mean ± standard deviations. Logistic regression analysis was performed to identify predictors of motor deficit. Initially, univariate logistic regression was used to test for associations between variables, and then forward stepwise multiple logistic regression analysis was used to develop a prediction model. The significances of differences between the two study groups were assessed using the t test or the Chi-square test. Statistical significance was accepted for p values \0.05.
Eur Spine J
Results
Discussion
The patients comprised 22 women and 50 men of overall average age 47.1 ± 7.8 years. The prevalences of No/Mild (group I) and Moderate/Severe (group II) dysphagia were 69.4 % (50 patients) and 30.6 % (22 patients), respectively. Mean preoperative NDI, NPDS, PCS, and MCS scores of 34.2, 44.8, 33.7, and 46.2 improved to 9.9, 16.1, 55.1, and 56.2, respectively, at final follow-up. The mean preoperative ZDS and ZAS scores were 35.2 and 34.2, respectively. The two groups did not differ statistically in terms of age, gender, BMI, smoking history, duration of symptoms, HNP level, preoperative clinical scores, or clinical scores at final follow-up (Table 1). However, significant differences were observed between the two groups in terms of the prevalence of a psychiatric problem, preoperative NDIs, and MCS scores at final follow-up. However, multivariate logistic regression showed that the presence of a psychiatric problem (P = 0.005) was the only significant predictor of the presence of chronic dysphagia (Table 2).
The anterior approach to the cervical spine has been used to treat numerous spinal disorders [15, 16]. Although the procedure is associated with low morbidity and mortality rates [17], the development of dysphagia after anterior cervical spine surgery is not uncommon. The pathophysiologic mechanism of postoperative dysphagia remains unclear, and few reports have been issued on chronic dysphagia after anterior cervical surgery. Accordingly, we sought to identify the risk factors of chronic dysphagia development after anterior cervical spine procedures. Reported prevalences of dysphagia after anterior spine surgery vary widely, but the majority of these reports were based on retrospective analysis. Furthermore, although several demographic and operative risk factors have been found to be associated with the development of postoperative dysphagia, physical and psychosocial factors have not been well studied, and thus, in the present study, we used a prospective approach to identify risk factors of chronic dysphagia development after anterior spine surgery. Previously reported rates of dysphagia after the anterior cervical approach ranged 1–79 % within 1 week of surgery, to 50–56 % after 1 month, and to plateau at 1 year at between 13 and 21 % [1, 4, 18]. In the present study, the incidence of Moderate or Severe dysphagia (30.6 %) was slightly higher than the average reported in the literature, which implies that universally accepted methods for accurately determining dysphagia are lacking and that authors have used different diagnostic criteria for dysphagia. In a previous study, female gender was found to be a risk factor of dysphagia after anterior cervical spine surgery [2]. In another, the prevalence of dysphagia was greater in women at 6 months, 1 year, and 2 years after surgery [4]. The etiology of this finding is unclear, but it may be related to the smaller anatomy of women. However, in this study no significant gender ratio differences were observed. Furthermore, it has been suggested in the literature that oropharyngeal swallowing varies with age [9], but in the present study, the average ages of symptomatic and asymptomatic patients were no different at final follow-up. And patients with cervical esophagus perforation often present dysphagia. Lu et al. [19] reported five cases of esophageal perforation with dysphagia, and presented their diagnosis and treatment strategy. Although there was no
Table 1 Details of the patients Group I (n = 50)
Group II (n = 22)
P value
Age (years)
46.8 ± 6.9
44.2 ± 7.2
0.160
Sex (F/M)
12/38
10/12
0.123
BMI (kg/m2)
24.0 ± 1.6
23.4 ± 2.0
0.155
Smoking (n)
30
11
0.595
Symptom duration (months)
8.1 ± 5.8
7.6 ± 3.9
0.851
Surgery level 4–5/5–6/6–7 (n)
7/24/19
0/12/10
0.181
Psychiatric problem (n) Preoperative NDI
7 33.1 ± 6.7
10 36.7 ± 8.1
0.009 0.044
Preoperative NPDS
44.5 ± 7.7
45.5 ± 8.7
0.628
Preoperative PCS
34.5 ± 7.5
31.8 ± 8.7
0.174
Preoperative MCS
47.0 ± 7.5
44.4 ± 9.4
0.198
Last NDI
9.4 ± 5.1
11.0 ± 4.6
0.200
Last NPDS
15.4 ± 7.0
17.7 ± 5.9
0.187
Last PCS
56.2 ± 9.5
52.5 ± 9.8
0.142
Last MCS
57.3 ± 7.5
53.6 ± 8.4
0.049
Improvement NDI
23.7 ± 7.3
25.7 ± 7.0
0.287
Improvement NPDS
29.1 ± 11.0
27.8 ± 8.1
0.623
Improvement PCS
21.7 ± 9.5
20.8 ± 8.7
0.709
Improvement MCS
10.3 ± 7.4
9.2 ± 8.6
0.599
Mean follow-up (months)
23.8 ± 8.8
22.3 ± 7.0
0.734
Table 2 Stepwise multiple logistic regression analysis for prediction of chronic dysphagia
Variables Psychiatric factor Constant
Coefficient 1.6330
Standard error
95 % CI
Odds ratio
P value
0.5911
1.6069 * 16.3071
5.1190
0.0057
-1.2763
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esophageal perforation in our cases, patients with esophagus perforation are easily overlooked or can lead to misdiagnosis as patients with simple dysphagia. Although a decrease in the prevalence of dysphagia was reported for patients that had undergone single-level surgery at C5/6 [4], this difference was not statistically significant, but given the small patient numbers analyzed this result should be interpreted cautiously. It appears likely that surgery requiring more soft tissue retraction (C3/4 and C6/7) contributes to dysphagia. Accordingly, Fengbin et al. [20] suggested that the approach should be selected in accordance with the surgery level (through the lateral edge of omohyoid approach for C3–C4, via the medial edge of omohyoid approach for C6–C7). Furthermore, it has been suggested that surgery at a higher level (C3/4), where there is a smaller soft tissue envelope, increases dysphagia rates. However, our data do not support this hypothesis. In the present study, univariate analysis showed that the presence of a psychiatric factor, a self-reported high preoperative NDI score, and a low MCS score at final followup were significantly associated with the development Moderate or Severe dysphagia. However, multivariate logistic regression analysis showed that only the presence of a psychiatric factor significantly predicted chronic dysphagia development. We do not know how the presence of a psychiatric factor predisposes patients to chronic dysphagia, and it is possible, these patients tended to overreport dysphagia. Nevertheless, our findings indicate that patients with a psychiatric factor should be counseled prior to surgery regarding the risk of chronic dysphagia development. As with any study, this study has its weaknesses. First, this study did not assess medication to psychiatric disorders and presurgical level of dysphagia. Antidepressive medicaments with anticholinergic side effects cause mouth dryness, and that could have caused dysphagia. Second, although data were obtained in a prospective manner, patients were not randomized, and because, this was an observational study, the effects of potential confounders were not controlled. Third, the data recovered were subjective, that is, patients were asked if they had dysphagia, and if they did, were further interviewed to determine the severity. Accordingly, no objective data were obtained that might be correlated with patient perceived symptoms. Future prospective studies incorporating objective measures of dysphagia may provide more insight. In conclusion, our findings suggest that the presence of a psychiatric problem before surgery is associated with the development of chronic dysphagia after anterior cervical spine surgery in patients with cervical disc herniation. Furthermore, our findings suggest that patients with a psychiatric factor should be counseled before surgery regarding the risk of developing chronic dysphagia.
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Acknowledgments This work was supported by the Convergence Research Grant funded by the Pusan National University (PNU, Convergence Research Grant) (PNU-2013-1312-0001). Conflict of interest
None.
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