The incidence of dysphagia following anterior cervical discectomy and fusion (ACDF) reported in the literature varies due to differences in measures and time intervals applied, ranging from nearly 3/4 at 2 weeks to 13% at 12 months. The most commonly used dysphagia scales remain subjective, non-validated, and do not capture functional impact. Various risk factors have been identified, though few consistently reproduced and none studied in an Australasian context. The aims of this study were to use objective and validated measures, assess both traditional and novel risk factors, and determine the impact of dysphagia on dietary status, length of stay and complications. METHODS: Twenty-nine adults undergoing ACDF for degenerative pathologies were enrolled between March and November 2015 in an Australian institution. Bazaz dysphagia scale, Dysphagia short questionnaire, 3-ounce swallow test and dietary status were assessed preoperatively, and 2 days and 6 weeks postoperatively. Descriptive statistics were used to characterise the study sample and logistic regression modelling performed on risk factors. RESULTS: Dysphagia incidence ranged from 85% on day-2 Dysphagia short questionnaire to zero on 6-week 3-ounce swallow. All measures increased at 2 days and fell by 6 weeks. Failing day-2 3-ounce swallow was the only measure associated with modifications in solids (P = 0.06), showing significant linear correlation (P = 0.02). Respiratory comorbidity increased risk of failing day-2 3-ounce swallow by more than 32-fold (OR: 32.4; 95% CI: 1.8 - 587.7; P = 0.019) and scoring moderate or severe on Bazaz by almost 10-times (OR: 9.3; 95% CI: 0.9 - 95.95; P = 0.061). Psychiatric history also increased risk of failing day-2 3-ounce swallow by more than 10-fold (OR: 10.9; 95% CI: 1 - 123.7; P = 0.054). Failing 3-ounce swallow increased length of stay (5 versus 7 days; P = 0.013). CONCLUSIONS: Incidence of dysphagia following ACDF was dependent on the measure used, though all improved over time. The 3-ounce swallow test correlated with dietary modification and length of stay, while respiratory comorbidity posed the most significant risk. This may identify a group of patients who may benefit from early intervention.
Anterior cervical discectomy and fusion (ACDF) is one of the most commonly performed operations on the spine. While complication rates are relatively low, ACDF can be associated with specific risks, including dysphagia, leading to aspiration risk, dietary modification, and even nasogastric feeds or gastrostomy in the severest of cases. Furthermore, postoperative dysphagia has been associated with increased length of stay (LOS), readmission rate, in-hospital costs and mortality [
The most commonly used scale in the literature, the Bazaz dysphagia score [
Multiple demographic, comorbid and surgical risk factors have been identified in the literature, though most derived from retrospective studies, few consistently reproduced, and none studied in an Australasian context. Demographic risk factors include increasing age, female gender, high body-mass index (BMI), and smoking [
Preoperative tracheal traction exercises have been identified as potentially protective, while there is conflicting evidence regarding reducing endotracheal cuff pressure following retractor placement [
The objectives of our study were to assess the incidence, severity and natural history of postoperative dysphagia in a prospective Australasian patient cohort using validated measurement tools, determine its impact on dietary modification, length of stay and complication rate, and identify risk factors and potential targets for intervention.
This was a prospective study. All patients undergoing ACDF for degenerative cervical spine disease between March and November 2015 were enrolled. Patients undergoing corpectomy, revision surgery or surgery for traumatic, infectious or malignant pathologies were excluded, as were patients who reported significant preoperative dysphagia. Baseline characteristics including age, gender, smoking status, BMI and specific comorbidities were recorded. Operative details including mode of presentation (emergency versus elective, myelopathy versus radiculopathy), surgical level(s), implant used and duration of surgery were assessed. Postoperatively, hospital LOS and specific complications were also recorded.
All patients at our institution underwent a right-sided approach, with the use of self-retaining retractors and distraction pins, and cage-plate system (Atlantis plate, thickness 2.5 mm, Medtronic Sofamor Danek, Memphis, TN, USA, and Blue Ridge plate, thickness 2.4 - 2.65 mm, K2M Group Holdings, Leesberg, VA, USA) filled with a combination of local bone and tricalcium phosphate. Bone morphogenetic protein was not used. Endotracheal cuffs were not routinely deflated and reinflated following retractor placement. Drains were routinely placed in the prevertebral space and removed the day after surgery. All patients underwent postoperative CT on day-1.
The Bazaz dysphagia score, Dysphagia short questionnaire, and standardised Australian food texture and fluid viscosity scales, and the 3-ounce swallow test were administered at pre-admissions clinic, on inpatient postoperative day-2, and at 6-week follow-up. The Bazaz dysphagia score [
The study protocol was approved by the institutional ethics committee. All subjects gave informed consent to participation.
Descriptive statistics were used to characterise the study sample for demographic details, comorbidities, dysphagia incidence and severity, as well as operative and postoperative details. For all data normality of distribution was evaluated using the Kolmogorov-Smirnov test with Lilliefors significance correction. Continuous data is presented as median and interquartile range (IQR, range from the 25th to the 75th percentile). Comparisons were made using the Mann Whitney U test for continuous data and the chi-square or Fisher’s exact tests for proportions. A multiple regression model with backward stepwise (likelihood ratio) variable selection was used for dysphagia risk. Where possible odds ratios (OR) and 95% confidence intervals (CI) are presented. All analyses were performed using IBM SPSS version 22.0 (SPSS Inc., Chicago, IL, USA). All tests were two tailed and statistically significant differences were considered at the P < 0.05 level.
Twenty-nine consecutive patients planned for ACDF were enrolled. Three patients were excluded; two underwent non-ACDF procedures following review of their clinical status and imaging (one cervical laminectomy and lateral mass fusion, the other cervical arthroplasty), the third failed to complete the questionnaires, leaving 26 patients available for day-2 analysis. A further 5 patients were excluded from 6-week evaluation; 4 returned interstate or rurally and were lost to follow-up, the fifth was followed up privately, leaving 21 patients available for 6-week analysis.
Median age was 54 years (IQR: 43 - 63). 62% of patients were female. Median BMI was 30 kg/m2 (IQR: 27.8 - 35.3) and 35% of patients were active smokers. Cardiovascular comorbidities were present in 38% of patients, most commonly hypertension and ischaemic heart disease. Psychiatric history was present in 38%, with depression and anxiety most common. In total, 23% suffered respiratory disease, most commonly asthma and obstructive sleep apnoea, and 19% of patients had diabetes. Overall, 88% of patients were treated electively and 12% as emergencies. Half of the patients presented with radiculopathy while the other 50% suffered myelopathy.
In total, 54% were multilevel surgeries. C5/6 + 6/7 ACDF was the most common level operated on (35%), followed by C3/4 (15%), C4/5 + 5/6 (15%), and C6/7 (15%). The median operative duration was 195 min (IQR: 158.8 - 243.3). The median distance between plate and vertebral body was 1.5 mm (IQR: 1 - 2.6).
The median hospital LOS was 5 days (IQR: 3 - 7). Approximately 4% of patients had wound complications (1 seroma), 8% respiratory complications (1 atelectasis, 1 pneumonia), and 12% urinary tract infections.
On day-2, dysphagia incidence ranged from as low as 31% on modified solids or liquids to 85% on Dysphagia short questionnaire. At 6 weeks, dysphagia ranged from zero on 3-ounce swallow test to 67% on Dysphagia short questionnaire. Similarly, day-2 dysphagia severity ranged from 8% on pureed diet to 31% scoring severe on Bazaz, falling at 6 weeks to zero on pureed diet while 38% remained moderately dysphagic on Bazaz. Trends in Bazaz dysphagia scores were closely mirrored by Dysphagia short questionnaire, while dietary status was mirrored by 3-ounce swallow.
Failing day-2 3-ounce swallow test was the only measure associated with solid
modification to soft, minced or puree (P = 0.06, linear correlation P = 0.02). There was a linear trend towards increasing number of patients on modified solid diets with increasing day-2 Bazaz severity (r = 0.95, P = 0.017) and Dysphagia short questionnaire score (r = 0.29, P = 0.049) only when the solid diet categories were combined. There was no correlation between the different measures and solid modification at 6 weeks or liquid modification at any time interval. Only 8% of patients were on a modified liquid (day-2).
Respiratory comorbidity increased the risk of failing day-2 3-ounce swallow by 32-fold (OR: 32.4; 95% CI: 1.8 - 587.7; P = 0.019) and scoring moderate or severe on Bazaz by nearly 10-fold (OR: 9.3; 95% CI: 0.09 - 95.95; P = 0.061). Psychiatric history also increased the risk of failing day-2 3-ounce swallow by 10-fold (OR 10.9; 95% CI: 1.0 - 123.7; p = 0.054). Demographic factors such as age, gender, BMI and smoking status did not correlate with dysphagia risk, nor did cardiovascular disease or diabetes. Surgical factors such as mode of presentation, high-level or multilevel surgery, operative time and plate apposition were also not associated with dysphagia risk.
Failing day-2 3-ounce swallow test was the only dysphagia measure associated with increased length of stay (5 versus 7 days; P = 0.013), as did suffering a postoperative complication (4.5 versus 7.5 days; P = 0.006). Cardiovascular comorbidity (40 versus 13%; P = 0.041) and emergency presentation (67 versus 17%; P = 0.017) were associated with increased complication rate, however, the four different dysphagia measures were not.
Our study findings confirm that the incidence and severity of dysphagia following ACDF depends on the measurement tool used and time interval applied. Knowledge of the incidence, severity and natural history of postoperative dysphagia in an Australasian cohort of patients allows clinicians to better educate, counsel and reassure patients of their expected swallowing outcomes, including in the immediate postoperative period. In our study, dysphagia rate peaked at 85% on day-2 Dysphagia short questionnaire, with 31% scoring severe on Bazaz dysphagia scale. Both incidence and severity fell over time, often to near baseline by 6 weeks. We demonstrated that while reports of dysphagia are common, particularly in the immediate postoperative period, this for the most part did not translate into dietary modification. We showed that not only is the novel 3-ounce swallow test a feasible bedside tool, it is also the tool most predictive of dietary modification and increased length of stay following ACDF. The 3-ounce swallow test could therefore potentially stratify at-risk patients, obviate the need for more invasive tests such as videofluoroscopy and fibreoptic endoscopy, and significantly impact discharge planning.
In this prospective study, the most powerful predictor of postoperative dysphagia was respiratory comorbidity, followed by psychiatric history. While psychiatric history has previously been shown to be a risk factor for dysphagia [
The maim limitation to our study was the small sample size. This may partly explain why no significant correlations were demonstrated between traditional risk factors such as high-level and multilevel surgery and postoperative dysphagia. Furthermore, our study was performed in a single institution with relatively short follow-up, although most instances of dysphagia had resolved during follow-up. Despite these shortcomings, we were able to demonstrate statistically significant results in a prospective Australasian cohort of patients, adding to the existing dysphagia literature.
Dysphagia incidence and severity are highest during the immediate postoperative period, improves in the majority of cases by 6 weeks, and varies according to the measure used, with the 3-ounce swallow test most predictive of dietary modification and length of stay, independent of postoperative complication. Respiratory comorbidity posed the most significant dysphagia risk, followed by psychiatric history. The presence of either of these comorbidities, particularly if associated with failing the 3-ounce swallow test while an inpatient, may identify an at-risk group of patients who require early intervention and close follow-up.
The authors wish to acknowledge the work of the residents, registrars and speech pathologists who assisted in the collection of patient questionnaires and administration of swallow tests.
Li, Y., Hitos, K. Mon, S.-T., Knight, N. and Vrodos, N. (2018) Incidence and Predictors of Dysphagia Following Anterior Cervical Discectomy and Fusion: Prospective Observational Study. Open Journal of Modern Neurosurgery, 8, 132-141. https://doi.org/10.4236/ojmn.2018.81011