Dysphagia is a poorly understood and underappreciated consequence of anterior cervical (AC) spine surgery. Despite being a recognized clinical problem, there is no universally accepted definition or method of determining the presence of postoperative dysphagia. In part because of this lack of a clear definition of both the condition and its diagnosis, the incidence of dysphagia varies in the literature from 1% to 79%.1–10
A large number of risk factors for the development of postoperative dysphagia have been proposed. These include the use of plate fixation,11–13 plate prominence,3,14 sex,7,9,11,12 revision surgery,12 multiple-level fusion,11–13 recombinant human bone morphogenetic protein-2 (rhBMP-2) use,2,15 and severe pain.13
Strategies to reduce the risk of developing dysphagia have also been suggested. These include the use of perioperative methylprednisolone,8 endotracheal tube cuff pressure (ETCP) monitoring,9 and the use of a low-profile plate.3,14 With such a large variation in the reported incidence and prevalence of dysphagia, a lack of a clear definition of dysphagia and often contradictory conclusions regarding risk factors and prevention strategies, a clearer perspective on our current understanding of this important clinical problem is needed.
The purpose of this review is to attempt to answer the following 3 clinical questions:
- What is the incidence or prevalence of postoperative dysphagia in AC surgery?
- What are the risk factors for the development of postoperative dysphagia?
- Are there effective recommendations to decrease the incidence or prevalence of postoperative dysphagia in AC surgery?
Materials and Methods
Electronic Literature Database.
The literature search is outlined in detail elsewhere.14a Briefly, we conducted a systematic search in Medline, EMBASE, and the Cochrane Collaboration Library for literature published from January 1990 through December 2008 reporting on dysphagia after AC spine surgery. We limited our results to humans and to articles published in the English language. Reference lists of key articles were also systematically checked. We sought prospective studies to determine incidence and prevalence, and prospective studies or registry studies that collected data prospectively for risk factor assessment. Because there were several prospective studies available to answer our question, we excluded all retrospective studies. We also excluded studies evaluating dysphonia that did not include cases of dysphagia as well as editorials, review articles without quantitative data, and case reports (Figure 1).
Each retrieved citation was reviewed by 2 independently working reviewers. Most articles were excluded on the basis of information provided by the title or abstract. Citations that seemed to be appropriate or those that could not be excluded unequivocally from the title and abstract were identified, and the corresponding full-text reports were reviewed by the 2 reviewers. Any disagreement between them was resolved by consensus. From the included articles, the following data were extracted: study design, patient demographics, surgical procedures rendered, and potential prognostic factors identified by the authors of each article.
Level of evidence ratings were assigned to each article independently by 2 reviewers using criteria set by The Journal of Bone and Joint Surgery, American Volume (J Bone Joint Surg Am)16 for therapeutic studies and modified to delineate criteria associated with methodologic quality and described elsewhere (See Supplemental Digital Content 1, individual study ratings, tables, individual study ratings, available at: http://links.lww.com/BRS/A423).
Dysphagia was reported as the proportion of patients experiencing any level of dysphagia. Cumulative incidence was reported in those patients without dysphagia before surgery who subsequently developed dysphagia at the first postoperative evaluation. The prevalence of dysphagia is the proportion of patients with dysphagia at subsequent evaluations. Data were summarized in tables and pooled complication rates were calculated, weighted by sample size. Qualitative analysis was performed considering the following 3 domains: quality of studies (level of evidence), quantity of studies (the number of published studies similar in patient population, condition treated, and outcome assessed), and consistency of results across studies (whether the results of the different studies lead to a similar conclusion).17 We judged whether the body of literature represented a minimum standard for each of the 3 domains using the following criteria: for study quality, at least 80% of the studies reported needed to be rated as a level of evidence I or II; for study quantity, at least 3 published studies were needed which were adequately powered to answer the study question; for study consistency, at least 70% of the studies had to have consistent results. The overall strength of the body of literature was expressed in terms of the impact that further research may have on the results. An overall strength of “high” means that further research is very unlikely to change our confidence in the estimate of effect. The overall strength of “moderate” is interpreted as further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. A grade of “low” means that further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate, whereas “very low” means that any estimate of effect is very uncertain.14a
We identified 126 articles from our literature search potentially evaluating dysphagia after AC spine surgery. From these potential articles, we judged 28 to undergo full-text review. After full-text review, we excluded 13 of the articles for the following reason: 6 articles were retrospective studies, 3 articles reported on dysphonia as the outcome, 1 article did not include dysphagia as a major outcome, 1 article studied the association between patient complaints and surgeon records concerning dysphagia, 1 used an administrative database, and 1 article discussed the treatment of dysphagia by removing cervical plates. Of the remaining 15 articles, 14 are prospective cohort studies1–12,14,18 graded as level of evidence I through III, and 1 is a registry study13 graded as level of evidence II (reference methods paper; Supplemental Digital Content, available at: http://links.lww.com/BRS/A423; details with respect to level of evidence for each study; Table 2).
Question 1. What Is the Incidence or Prevalence of Postoperative Dysphagia in AC Surgery?
The reported incidence or prevalence of postoperative dysphagia varies, depending, in part, on how studies defined dysphagia. There seems to be no universally accepted method of determining dysphagia after AC spine surgery. For example, among the studies evaluated for this review, 3 did not describe their method of determining dysphagia,2,6,18 9 used 1 of the 5 patient-reported dysphagia outcomes measures,3,5,7,9–14 1 study used a clinician-based outcomes measure,1 and 1 determined dysphagia through the use of a barium swallow4 (Table 1). In general, a patient-reported outcome that has been shown to be reliable and valid is preferred over a clinician-reported outcome or a physiologic study.19,20 Among the 15 studies included in this report, only 2 used patient-reported outcomes that were found to be reliable and valid.5,13 A summary of the outcomes measures used in the included studies, their scale, interpretation, and whether they have validity or reproducibility is found in Table 2.
The prevalence rate of dysphagia is higher, in general, in the first postoperative month and progressively decreases over time. The overall mean incidence of dysphagia within the first week after AC discectomy and fusion (ACDF) with or without instrumentation was 33.1% (range, 1%–79%).1–10 The mean prevalence of dysphagia was 53.2% (range, 50%–56%) in 3 studies 1 month after ACDF,11,12,14 19.8% (range, 8%–22%) in 5 studies 6 months after surgery,11–14,18 16.8% (range, 13%–21%) in 4 studies 12 months after surgery,11–14 and 12.9% (range, 11%–14%) in 2 studies 24 months after fusion (Table 3).12,14 Two studies reported on ACDF with rhBMP-2 and noted a 50% incidence of dysphagia within 1 week of surgery and 54.5% prevalence rate 6 months after surgery. The incidence of dysphagia within 1 week after artificial disc replacement (ADR) was 5.2% (range, 0%–11%) as reported by 2 studies.
Dysphagia and ACDF
Bazaz et al11 assessed the incidence and severity of dysphagia in 249 consecutive patients who underwent AC spine procedures, including ACDF (n = 123), AC corpectomy and fusion (n = 97), combined ACDF and AC corpectomy and fusion (n = 1), fibular strut graft revision (n = 1), and AC plate revisions (n = 2). The presence of dysphagia was determined by telephone interview using a nonvalidated scale developed by the authors (Bazaz dysphagia score). At 1 month after the procedure, only 197 patients were available for follow-up, of which 50.3% experienced some level of dysphagia; mild in 27.9% (n = 55), moderate in 16.8% (n = 33), and severe in 5.6% (n = 11). Two months after the surgery, 32.2% of the available patients had symptoms of dysphagia; mild in 21.0% (n = 45), moderate in 10.3% (n = 22), and severe in 0.9% (n = 2). At 6 months follow-up, 17.8% of available patients still had symptoms of dysphagia; mild in 13.0% (n = 27), moderate in 4.3% (n = 9), and severe in 0.5% (n = 1). Twelve months after surgery, 12.5% (19 of 152) of available patients continued to experience dysphagia; mild in 11.8% and severe in 0.7%.
Frempong-Boadu et al4 reported outcomes from a small swallow study of 23 consecutive patients who had undergone up to 3-level ACDF. The presence of dysphagia was determined using a modified barium swallow study followed by videolaryngoendoscopy. Although no patients had symptoms of dysphagia before surgery, the swallowing study identified abnormal swallowing in 47.8% (n = 11) patients (group B). Of the 12 patients who did not have preoperative swallowing dysfunctions (group A), 66% (8 of 12) had radiographic evidence of abnormal swallowing 1 week after surgery; all cases had resolved by 1 month after ACDF. Of the 11 patients who did have preoperative swallowing dysfunctions (group B), 1 week postoperative swallowing function had not improved in 63.6% (7 of 11), improved in 27.2% (3 of 11), and worsened in 9.1% (1 of 11). Results at 1 month were not reported. At 1 year, the patient with postoperative worsening of swallowing function had no significant improvement. The authors concluded that although it is common for a patient to have radiographic evidence of swallowing dysfunction the first week after ACDF, most patients remained asymptomatic, and most cases had resolved by 1 month after the procedure.
Lee et al12 conducted a study aimed at determining the risk of dysphagia in 348 patients after ACDF with or without instrumentation. Dysphagia was graded using the Bazaz Scoring System via telephone interviews. A total of 310 patients were available for follow-up. The prevalence and severity of dysphagia at 1 month was 54.0% (mild: 27.5%, moderate: 19.9%, and severe: 7.0%) and decreased over time to 33.6% at 2 months (mild: 22.6%, moderate: 9.5%, and severe: 1.6%), 18.6% at 6 months (mild: 12.3%, moderate: 5.0%, and severe: 1.3%), 15.2% at 1 year (mild: 12.5%, moderate: 2.0%, and severe, 0.7%), and 13.6% at 2 years (mild: 13.0%, moderate: 0.3%, and severe: 0.3%).
Mendoza-Lattes et al5 assessed the incidence of dysphagia after AC decompression and arthrodesis in 17 patients. During the procedure, 1 surgeon used dynamic (handheld) retractors (n = 11), whereas the other used static (self-retaining) retractors (n = 6); both were positioned bilaterally for deep retraction. Dysphagia was scored using the M. D. Anderson Dysphagia Inventory. Postoperative dysphagia occurred in 52.9% (9 of 17) of patients. In patients with dysphagia, the mean postoperative M. D. Anderson Dysphagia Inventory score was significantly lower than the preoperative score (67.7 ± 11.4 vs. 93.8 ± 12.1; P < 0.001); this difference was not seen in those without any swallowing difficulties (postoperative score of 92.3 ± 4.9 vs. preoperative score of 94.7 ± 4.7; P = 0.18). The authors did not report dysphagia rates separately for the dynamic and static retractor groups.
Papavero et al7 evaluated dysphagia rates in 92 patients after ACDF at up to 3 cervical levels. The frequency and severity of swallowing difficulty was graded 0, 1, 3, and 5 days after surgery using the questionnaire and point system developed by Bazaz; dysphagia was defined by cumulative point totals of 12 or more. The postoperative dysphagia rate was 49.3%.
Riley et al13 conducted a prospective observational study to evaluate dysphagia rates in 454 patients 3, 6, and 24 months after ACDF. The presence of dysphagia was determined via telephone interviews using the standardized Cervical Spine Outcomes Questionnaire, which evaluates swallowing impairment. Three months after surgery, 28.2% (128 of 454) of patients experienced symptoms of dysphagia, and 21.5% (85 of 395) and 21.3% (66 of 310) continued to have swallowing dysfunction at 6 and 24 months, respectively.
Smith-Hammond et al10 assessed the frequency of and risk factors associated with dysphagia after 1- or 2-level anterior (N = 38) or posterior (N = 26) cervical spinal surgery in a total of 57 patients. No patients were operated on at the C2-C3 level. The presence of dysphagia was evaluated subjectively by the dysphagia disability index and objectively using a video fluoroscopic swallow evaluation (VSE). A speech pathologist interpreted the results of the radiographic study to determine whether a patient had clinically significant dysphagia. The mean postoperative dysphagia disability index score was significantly higher than the preoperative score in AC patients (23.0 ± 21.3 vs. 6.6 ± 6.9; P = 0.001); this difference was not significant in posterior cervical (PC) patients (18.1 ± 20.2 vs. 11.3 ± 10.2; P = 0.06). VSE imaging results suggested that 47.4% (18 of 38) of AC and 21.1% (4 of 19) of PC patients had dysphagia. Interestingly, 16.7% (3 of 18) of the AC and 50% (2 of 4) of the PC patients with VSE-diagnosed dysphagia had no clinical symptoms, which included throat clearing, reflexive cough after swallowing, and “wet voice” after swallowing. Treatment for patients found to have dysphagia after VSE included dietary modifications (39.5% of AC and 21.1% of PC patients), no oral intake by mouth (11.1% of AC patients), thickened liquids and solid food because of aspiration (72.2% of AC and 100% of PC patients), postural change (11.1% of AC patients), and clearing the throat after swallowing (5.6% of AC patients). The majority of AC patients regained the ability to tolerate a normal diet with or without these treatments (71% (12 of 17) within 1 month; 94% (16 of 17) within 1 year); the 2 PC patients who were available for follow-up had both similarly recovered by the end of the first month.
Dysphagia and rhBMP-2
Two studies evaluated dysphagia rates after ACDF with or without the use of rhBMP-2. In a small pilot study, Buttermann2 compared outcomes after up to 3-level ACDF using either autogenous iliac crest bone graft (ICBG) or rhBMP-2 allograft in 30 patients. Patients received 0.9 mg per level rhBMP-2 applied to an absorbable collagen sponge, which was placed both within and posterior to the allograft in the interbody space. The use of rhBMP-2 for ACDF is considered off-label. After hospital discharge, a low-dose oral steroid (methylprednisolone) was prescribed to all patients who received rhBMP-2 after hospital discharge. Dysphagia occurred in 13.9% (5 of 36) of patients in the ICBG group and in 30.0% (15 of 50) of patients in the bone morphogenetic protein (BMP) group. Of the patients who received 2-level fusion, 16% (3 of 19) in the ICBG group and 63% (10 of 16) in the BMP group developed dysphagia. Few details were given regarding dysphagia in the ICBG group, except that that the swelling resolved in these patients. In the BMP group, dysphagia occurred at 4 (±3) days after ACDF, and all symptoms had resolved 21 (±16) days later. The severity of symptoms was noted to be considerably greater in rhBMP-2-treated patients; 20% of these patients were readmitted to the intensive care unit for intravenous steroid treatment, although surgery was not required.
Vaidya et al15 conducted a small study in which 23 patients underwent ACDF with allograft and either rhBMP-2 (1 mg per level) or demineralized bone matrix on a total of 40 cervical levels. The method by which dysphagia was determined was not reported. “Prolonged” dysphagia occurred in 55% of patients in the BMP group (6 of 11) after ACDF, all of whom had postoperative prevertebral swelling. No patients in the control group developed dysphagia (0 of 12). The authors noted that the cases of dysphagia were more severe than those they had previously seen in their practice; however, they did not discuss whether patients required steroids or other treatment such as intensive care unit admission or reintubation.
Dysphagia and Artificial Disc Replacement
Two studies reported the rate of dysphagia after ACDF versus ADR. Anderson et al1 evaluated adverse events in 463 patients with symptomatic single-level cervical DDD after ACDF or ADR using the Bryan artificial cervical disc. Dysphagia occurred in 7.2% (16 of 221) of the ACDF patients and in 10.7% (26 of 242) of the ADR group (P = NR). No details regarding when dysphagia occurred, how long it persisted, and how it was treated were reported, although follow-up was performed at intervals between 6 weeks and 2 years. The severity of each adverse event was graded using the World Health Organization scale. Mummaneni et al6 reported patient outcomes after either ACDF using cortical allograft spacers and the Atlantis Cervical Plate System or ADR using the Prestige ST cervical disc prosthesis. All patients were being treated for symptomatic single-level DDD (N = 541). Dysphagia occurred during the perioperative period in 0.8% (2 of 265) of ACDF and 0.4% (1 of 276) of ADR patients. No other details, including the severity of the dysphagia and patient outcomes, were reported.
Question 2. What Are the Risk Factors for the Development of Postoperative Dysphagia?
Most studies evaluated 1 or more variables as risk factors for dysphagia. These are summarized in Table 4.
Seven studies evaluated whether sex affected postoperative dysphagia rates and reported mixed results. Four found an association with women being at higher risk. Bazaz et al11 found that the incidence of dysphagia was significantly greater in women compared with men at 6 months after the procedure (24.7% compared with 11.7%, P = 0.023), although there was no difference in the rate of dysphagia between sexes at 1 or 2 months. Lee et al12 also determined that women were nearly twice as likely to develop dysphagia at 6 months (23.6% vs. 14.1%, P < 0.03), at 1 year (20.1% vs. 10.5%, P < 0.02), and at 2 years (18.3% vs. 9.9%, P < 0.02). Papavero et al7 reported that women had a significantly higher incidence of dysphagia within the first 5 days after the procedure (67.4% vs.36.2%; P = 0.03). Finally, Ratnaraj et al9 noted that women had a significantly higher rate of dysphagia at 1 week compared with men (44.8% vs. 19.0%, P < 0.05) that was independent of treatment group, weight, and height. Conversely, Riley et al,13 from his registry study, reported that gender was not a significant risk factor for dysphagia after AC spine surgery as did 2 other smaller studies.3,5
Revision Versus Primary.
Two studies with differing results assessed whether there was a difference in postoperative dysphagia rates in patients who underwent revision versus primary surgery. One reported that at 1 and 2 years of follow-up, patients who had undergone revision surgery were more than twice as likely to develop dysphagia than those who had received primary surgery; at 1 year follow-up, 29.7% compared with 12.9%, and at 2 years, 27.7% compared with 11.3% (P < 0.01 for both).12 In contrast, Bazaz et al11 did not find a significantly higher risk of dysphagia at 1 or 6 months after surgery in patients who underwent revision versus primary surgery.
Plate Versus No Plate.
Four studies reported no statistical association between the use of instrumentation and the development of postoperative dysphagia.10–13
Number of Cervical Levels Fused.
Seven studies evaluated whether the number of cervical levels fused was associated with postoperative dysphagia; 3 provided risk estimates. Bazaz et al11 reported that compared with patients who received surgical intervention at 1 cervical level, those who underwent surgery at 2 cervical levels had a significantly higher risk of dysphagia at 1 month follow-up; those who underwent surgery at 3 or more cervical levels similarly had a significantly higher risk of dysphagia 1 month after the procedure (58% vs. 44%, P = 0.031). Lee et al12 determined that the risk of dysphagia increased with the number of surgical levels, and surgery on 3 or more levels posed a significantly higher risk 2 years after surgery compared with surgery on <3 levels (prevalence ratio = 1.99, P < 0.03). Riley et al13 found that dysphagia rates were significantly higher in patients who had 2- or 3-level ACDF compared with those who underwent single-level ACDF (2- vs. 1-level: OR = 1.99; 95% CI, 1.23–3.21; 3-level vs. 1-level: OR = 4.62; 95% CI, 2.57–8.31) and used multivariate analysis to show that the risk of developing postoperative dysphagia is significantly higher with fusion of 3 or more cervical levels compared with single-level fusion (OR = 4.21; 95% CI, 2.05–8.62). Among the 4 studies not reporting risk estimates, Frempong-Boadu et al4 noted that although patients who had undergone ACDF on >1 level had a higher rate of postoperative swallowing dysfunction compared with those who had undergone single-level ACDF, the difference was not statistically significant (P = 0.07). Smith-Hammond et al,10 Chin et al,3 and Vaidya et al18 all reported no significant association between the number of spinal level fused and postoperative swallowing difficulties.
Riley et al13 reported that patients with more severe neck pain had a significantly higher risk of dysphagia than those with lower neck pain scores (OR = 1.27; 95% CI, 1.05–1.54). Patients who presented with headaches had lower rates of postoperative dysphagia than those without headaches (OR = 0.49; 95% CI, 0.31–0.78). Multivariate analysis also showed that the risk of developing postoperative dysphagia increases with time since the first episode of pain (OR = 1.03; 95% CI. 1.00–1.06).
No association was found in 2 or more studies between postoperative dysphagia and the following: age,4,7,11–13 diabetes,4,10 hypertension,4,10 tobacco use,4,10 ACDF and AC discectomy alone,11,12 operative time,3–5,7,10,13 intraoperative retraction (dynamic vs. static5 or amount of intraoperative retraction7), or surgical level.3,4,10–13
Question 3. Are There Effective Recommendations to Decrease the Incidence or Prevalence of Postoperative Dysphagia in AC Surgery?
Three studies evaluated specific measures aimed at decreasing postoperative dysphagia; 1 looked at the administration of methylprednisolone, 1 at maintaining baseline endotracheal cuff pressure during neck retraction, and 1 at plate design.
One study evaluated the effect of methylprednisolone on postoperative dysphagia rates in a study of 236 patients who received AC corpectomy, discectomy, or discectomy with bone grafting and plate fixation.8 Patients were divided into 2 groups based on their history of gastroduodenal disorders, abdominal pain, and digestive intolerance of anti-inflammatory medications. Those with no history of these problems were given 3 intravenous injections of methylprednisolone (1 mg/kg body weight) starting at the end of the surgery and twice more at 12-hour intervals (n = 78). Patients with a history of these symptoms constituted the control group and did not receive methylprednisolone (n = 158). All patients were evaluated for the presence of inflammatory pharyngeal lesions during an ear, nose, and throat fiberoptic examination performed within 24 to 36 hours after surgery. Pharyngeal lesions occurred more frequently in patients who did not receive methylprednisolone compared with those who did (92.4% vs. 59.0%; relative risk = 1.57; 95% CI, 1.3–1.9, P < 0.0001). However, there was no statistical difference in the rate of these subjective symptoms in patients treated with versus without methylprednisolone (82.3% vs. 71.8%).
Endotrachael Tube Cuff Pressure.
One study evaluated whether maintaining a baseline ETCP was associated with decreased dysphagia rates after AC spine surgery.9 The control group (n = 24) had no ETCP adjustment, and the ETCP group had ETCP pressure maintained at 20 mm Hg during neck retraction (n = 27). The mean ETCP in the control group was 32.9 ± 9 mm Hg, which was significantly higher than the baseline pressure of 20 mm Hg (P < 0.05). Patients in the experimental group had a significantly higher mean retraction time than those in the control group (133 ± 65 vs. 97 ± 51 minutes; P < 0.05). Dysphagia discomfort was subjectively assessed on an analog scale of 1 to 10, and scores of 3 or more indicated dysphagia. One hour after surgery, ∼48% of both groups were experiencing symptoms of dysphagia. Twenty-four hours after surgery, 56.5% (13 of 23) of patients in the control group and 48.1% (13 of 27) of those in the treatment group had similar swallowing difficulties, which decreased to 39.1% (9 of 23) in the control group and 25.9% (7 of 27) in the treatment group 1 week after the procedure (P > 0.05).
One study reported the outcomes of 156 consecutive patients after AC discectomy with plate fixation using either the Atlantis plate, which is thicker and wider, or the Zephir plate, which is smaller and smoother.14 Dysphagia was evaluated via telephone interviews only, using the system defined by Bazaz et al.11 Six months after surgery, patients who received Atlantis cervical plates had a higher prevalence of dysphagia compared with those who received the Zephir plate (22.5% vs. 14%). This difference continued at 1 year and became statistically significant at 2 years after surgery as 14.2% (16 of 113) of those with Atlantis plating versus none of the Zephir plating patients (0 of 27) had difficulty swallowing (P < 0.041). When patients who had undergone revision procedures were excluded, results were similar: dysphagia was present in 16.8% of patients who had received Atlantis plates (17 of 101) compared with 0% (0 of 21) of those who had received Zephir plates at 1 year (P < 0.04). Regression analysis was used to predict the risk of permanent dysphagia to be 13.6% for patients in the Atlantis group and 3.6% for those in the Zephir group. The authors concluded that plate design may affect postoperative dysphagia rates, with an increased risk associated with the use of a larger, less smooth plate. In contrast, Chin et al3 evaluated whether the development of dysphagia was correlated with excessive protrusion or thickness of cervical plates after ACDF using 2-mm AC plates in 64 patients. Disc and plate measurements were determined using plain radiographs. The incidence of postoperative dysphagia was lower in patients in whom the cervical plate protruded less than that of the tallest preoperative osteophyte (30%) compared with those in whom the plate similarly protruded more (38.2%). However, there was no significant difference in the rates of dysphagia between the groups (P > 0.05), and the authors concluded that plate prominence between 3 and 7 mm did not increase a patient's risk of developing dysphagia. The prevalence of long-term dysphagia (i.e., more than 4 weeks) were similar in both groups, 16.7% versus 17.6%. The authors of the 3 plate studies declared an absence of conflict regarding development or consulting agreements in their publications.11,13,14 No other studies were designed to evaluate specific measures aimed at decreasing postoperative dysphagia rates.
The overall strength of evidence with respect to incidence or prevalence of dysphagia after AC surgery is “moderate”, that is, further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. The strength of evidence for risk factors for plate design is “very low” (any estimate of effect is very uncertain), whereas female sex and multilevel surgery as a risk factor for increased risk is “moderate”. The overall strength of evidence for effective recommendations is “very low” (Table 5).
This review is limited by the different methods that were used by various studies to determine dysphagia. Some of those methods included modified barium swallow,4 cinefluoroscopy,8 nonvalidated questions attempting to determine magnitude and frequency of swallowing difficulty,7,11,12,14 whether additional treatment for the dysphagia was required,1 and validated patient-reported questionnaires that sought to determine the effect of swallowing difficulty on quality of life.5,13 Although physiologic measures, such as a barium swallow, are valuable in determining the extent of mechanical disability, their results do not closely correlate with patients' symptoms of dysphagia. Frempong-Boadu et al4 noted that 48% of patients had radiographic evidence of a functional swallowing abnormality before AC surgery, though no patients were symptomatic. After surgery, two thirds of those who had a normal swallow before surgery demonstrated radiographic evidence of a functional swallowing abnormality 1 week after AC surgery, yet these patients did not describe clinical complaints of dysphagia. It has been shown that the use of surgeon office notes to retrieve information on dysphagia has been shown to markedly underestimate the prevalence of this complication compared with patient surveys.21 We sought to minimize this source of bias by only including prospective studies in which the reliance on surgeon office notes would be minimized. The spine community would benefit from adopting a common patient-reported dysphagia outcomes measure that has been shown to be reliable and valid. Using a common measure would facilitate comparisons among studies.
Despite the current limitations in our understanding of dysphagia, our systematic review found moderate evidence that rates of dysphagia declined over time after surgery and plateaued at 1 year to a rate of 13% to 21%. Moderate evidence suggests that patients undergoing multilevel procedures and female patients were at increased risk for the development of postoperative dysphagia.
Our systematic review of the literature highlights our rudimentary understanding of the problem of dysphagia after AC surgery. This review underscores the need for a more sensitive, specific, and valid outcome tool to allow a better understanding of the incidence and prevalence of postoperative dysphagia, and to characterize the spectrum of symptoms, their impact on outcome, and effective treatment measures. Ideally, an assessment tool would be patient self-reported and would include global, functional, psychosocial, and physical domains. Such an assessment tool would provide a more comprehensive assessment of the impact of dysphagia.
Postoperative dysphagia can be operationally defined as patient self-reported difficulty with swallowing. There is moderate evidence that the incidence and prevalence of dysphagia decline steadily after surgery. There is moderate evidence that multiple-level surgery and female sex are risk factors for dysphagia. There is very low evidence that the intraoperative reduction of ETCP, the use of steroids, and plate design characteristics have any effect on the rate of postoperative dysphagia.
All patients undergoing AC surgery should be counseled about the risk of postoperative dysphagia. All patients undergoing AC surgery should be queried for dysphagia after surgery. Further evaluation and treatment should be performed when deemed appropriate.
- Postoperative dysphagia can be operationally defined as patient self-reported difficulty with swallowing.
- The rates of dysphagia after ACDF range from 1% to 79% within 1 week of surgery, 50% to 56% 1 month after surgery, 8% to 22% 6 months after surgery, and 13% to 21% 1 year after surgery.
- All patients undergoing AC surgery should be counseled regarding the risk of postoperative dysphagia.
- All patients undergoing AC surgery should be queried for dysphagia after surgery.
Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (www.spinejournal.com).
The authors thank Ms. Nancy Holmes, RN, for her administrative assistance, and Ms. Erika Ecker, BS, for her assistance in searching the literature, abstracting data, and proofing.
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