the dysphagia short questionnaire -...

HEALTH SERVICES RESEARCH

SPINE Volume 37, Number 11, pp 996–1002©2012, Lippincott Williams & Wilkins

996 www.spinejournal.com May 2012

The Dysphagia Short Questionnaire An Instrument for Evaluation of Dysphagia: A Validation Study With 12 Months’ Follow-up After Anterior Cervical Spine Surgery

Martin Skeppholm , MD , * Catarina Ingebro , SLP , † Therese Engström , SLP , † and Claes Olerud , MD, PhD ‡

Study Design. Prospective clinical validation study of question-naire to assess dysphagia. Objective. To test validity and reliability of Dysphagia Short Questionnaire (DSQ), and also to determine levels of dysphagia over time after anterior cervical spine surgery (ACSS). Summary of Background Data. Dysphagia is common after ACSS but reports on the incidence vary widely between 1% and 79%, indicating an evaluation problem. Several tools for evaluation of dysphagia exist but common features are that they are cumbersome to use and usually are designed for patients with neurological or malignant diseases in the neck region. Others are not validated, for example, the Bazaz score. There is, thus, a need for a more adapted tool to evaluate dysphagia in patients undergoing ACSS. Methods. The DSQ was constructed in collaboration with a group of ear-nose-and-throat specialists. In a fi rst validation study, 45 patients with stationary dysphagia for various reasons completed the DSQ twice 2 weeks apart, the M.D. Anderson Dysphagia Inventory (MDADI), the Bazaz score, and a quality-of-life score, the EQ-5D. To evaluate the utility of the DSQ, a second validation study was performed, where 111 subjects undergoing ACSS for degenerative disk disease completed the form preoperatively and at 4 weeks, 3 months, and 1 year after surgery. Results. In the fi rst study, the DSQ correlated to MDADI ( r = 0.59) and showed good reproducibility. The Bazaz score did not correlate to the DSQ, the MDADI, or the EQ-5 D. In the second study, dysphagia was present in a few patients already preoperatively. At

A common complication to anterior cervical spine sur-gery (ACSS) is dysphagia. The mechanism is not fully understood, but reasonable explanations could be pre-

operative pressure on soft tissue structures, bulky implants, and damage to local innervation. 1 , 2 Formation of scar tissue in the area of surgery postoperatively may also play a role. 3 Reports on its incidence vary widely between 1% and 79%. 1 , 4 – 12 One reason for the wide variation may be different defi nitions and measurements of dysphagia in the various publications. Another explanation is different time intervals of evaluation after surgery because the presence of dyspha-gia decreases with time in this population. However, some studies have shown persistent dysphagia several years after surgery. 13 , 14 Furthermore, there is a tendency toward higher incidence of dysphagia when patient self-report and in pro-spective studies whereas objective methods of measurement, for example, video fl uoroscopy or manometry, may underesti-mate the problem. 8 To evaluate dysphagia from a patient-ori-ented perspective, there are some validated patient self-report questionnaires, for example, the M.D. Anderson Dysphagia Inventory (MDADI) 15 and SWAL-QOL. 16 These are relatively complex instruments and aim mostly at patients with neu-rological or malignant diseases in the neck region with sig-nifi cant swallowing problems. It can be assumed that ACSS patients experience less severe symptoms of dysphagia and therefore constitute a different subgroup. Bazaz et al 10 pre-sented in an article on dysphagia after ACSS a much-simpli-fi ed score, which later has been used in several other publica-tions on similar patients. However, the Bazaz score has, to our knowledge, never been validated. The aim of this study was to design and validate an easy-to-use patient self-report dysphagia questionnaire and to apply it to a group of patients undergoing anterior cervical disc surgery.

From the * Karolinska Institutet, Stockholm Spine Center, Löwenströmska Hospital, Upplands Väsby, Stockholm, Sweden ; † Karolinska Institutet, CLINTEC, Division of Speech and Language Pathology; and ‡ Department of Orthopedics, Uppsala University Hospital, Uppsala, Sweden .

Acknowledgment date: May 23, 2011. First revision date: August 17, 2011. Second revision date: September 14, 2011. Acceptance date: September 19, 2011.

The study was approved by the Regional Ethics Committee in Stockholm: 2006/1266-31/4 and 2007/336-31/3.

The legal regulatory status of the device(s)/drug(s) that is/are the subject of this manuscript is not applicable in my country.

Corporate/Industry funds were received in support of this work.

No benefi ts in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

Address correspondence and reprint request to Martin Skeppholm, MD, Martin Skeppholm, Stockholm Spine Center, Löwenströmska Sjukhuset, SE-19489 Upplands Väsby, Sweden; E-mail: [email protected]

4 weeks, 85% of the patients reported dysphagia. The level had dropped signifi cantly at 3 months and had returned to baseline levels at 1 year. Conclusion. We consider the DSQ to be a validated tool for the assessment of dysphagia in ACSS patients. Dysphagia after ACSS for cervical spondylosis is common but the symptoms on a group level are not very severe and are also temporary. Key words: spine surgery , dysphagia , validation , questionnaire . Spine 2012 ; 37 : 996 – 1002

DOI: 10.1097/BRS.0b013e31823a7a5b

Copyright © 2012 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.

BRS204788.indd 996BRS204788.indd 996 25/04/12 1:12 AM25/04/12 1:12 AM

HEALTH SERVICES RESEARCH The Dysphagia Short Questionnaire • Skeppholm et al

Spine www.spinejournal.com 997

DESIGN OF THE QUESTIONNAIRE The Dysphagia Short Questionnaire (DSQ) was designed

in collaboration with 4 ear-nose-and-throat specialists at the Department of Ear-Nose-and-Throat diseases, Uppsala Uni-versity Hospital, with vast experience of treating patients with dysphagia. A number of common symptoms that could be expected in patients with oropharyngeal dysphagia were listed. After discussions within the group, the symptom list was reduced to fi nally contain fi ve key questions, each cov-ering different aspects of dysphagia, with various response categories representing different grades of clinical severity. Each response category was given a weight, that is, the num-ber of points, in accordance with how serious and important this particular problem was considered to be for the patient. The questionnaire was again discussed with the group of ear-nose-and-throat physicians to get their opinion on rel-evance of the items, statements, and relative weights, and adjustments were made according to suggestions. A score was calculated by summing up the points given for each item to a maximum of 18 points, where lower scores represent milder symptoms and vice versa (see Appendix, Supplemental Digital Content 1, available at: http://links.lww.com/BRS/A660). The questionnaire was tested on 10 patients who underwent ACSS to ensure that even patients with clinically mild symptoms of dysphagia were detected. We also wanted to know that no misunderstandings would appear among the tested patients, and also the approximate time for fi lling out the question-naire, which typically took less than 1 minute.

In the validation process, we wanted to address the fol-lowing questions: Does the DSQ measure dysphagia? Does higher score represent more severe dysphagia and lower score milder? Will repeated applications result in similar scores? Is there a correlation between the DSQ and general health expressed as quality of life (QOL)? Is the DSQ usable in a cohort of patients undergoing ACSS? The MDADI was chosen for comparison as this is an already-validated scor-ing system, whereas the Bazaz score was included as this has previously been applied in several studies on cervical spine surgery. Both the applied scores were translated into Swed-ish and retranslated into English by 2 authorized translators. The study was approved by the regional ethics committee in Stockholm.

PATIENTS AND METHODS

The First Validation Study Forty-fi ve patients, including 22 women, undergoing treat-ment of dysphagia for various reasons were included after informed consent. The dysphagia should be stationary: no major change in the underlying disease could be expected dur-ing the 2 to 3 weeks the validation process lasted. Their aver-age age was 64.8 years (SD = 10.4). Their various diagnoses are listed in Table 1 . The test patients were recruited with the help of 2 speech-language pathologists (SLP) working at the unit for dysphagia, Department of Speech Pathology, Karolin-ska University Hospital, Solna. The SLPs also instructed the patients how to fi ll out the various instruments. The DSQ was

compared with the MDADI and the Bazaz scores and corre-lations between them were computed statistically. The DSQ was also submitted to a test-retest situation to test its repro-ducibility. For health-related QOL, the EQ-5D was used. 17 – 19 All patients were examined by the 2 SLPs. At the fi rst visit (T1), the patients completed our DSQ, the MDADI, and the Bazaz score. At the second visit (T2), a couple of weeks later the patients once again completed the DSQ and a health-related QOL score: EQ-5D. Five patients did not participate at T2; therefore, only 40 patients are included in the test-retest analysis and the correlation to health-related QOL.

The Second Validation Study One hundred eleven patients undergoing surgery for degen-erative disk disease were included after informed consent. Inclusion criteria were as follows: at least 3 months of radicular pain not responding to conservative therapy and corresponding fi ndings on magnetic resonance imaging at 1 or 2 levels, aged 25 to 60 years. Exclusion criteria were congenital malformation, severe degeneration, previous surgery for degenerative disk disease, infl ammatory spine disease, and drug or alcohol abuse. Average age was 46.9 years (SD = 6.7), 56 (50%) were women, and 35 (32%) were smokers. They were evaluated with DSQ preopera-tively and at 4 weeks, 3 months, and 1 year after surgery.

Statistics All analyses were done using the Statistica 9.0 software (StatSoft Inc., Tulsa, OK). For the validation test of DSQ, Spearman rank test and nonparametric Gamma test for cor-relations were used. P < 0.05 was considered as statistically signifi cant. Cronbach alpha coeffi cient was computed for the reliability test and a Bland-Altman diagram was con-structed with a 95% confi dence interval. Cronbach alpha coeffi cient was considered good if the value was higher than 0.6 and very good if it was more than 0.8. Wilcoxon signed-rank test for ordinal data was used for the second validation study.

RESULTS

The First Validation Study DSQ ranged from 2 to 13 with an average of 6.3 (SD = 2.7) and was fairly normally distributed ( Figure 1 ) as was the MDADI ( Figure 2 ), while the distribution of the Bazaz score

TABLE 1. The Various Diagnoses of the Patients in the First Validation Study Group

Diagnosis No. of Patients

Malignancy of the neck region 21

Neurological disease affecting the neck region 14

Miscellaneous 4

Xerostomia 2

Unknown 4





was more symmetrical with 17 of the patients classifi ed as “mild,” 14 as “moderate,” and 14 as “severe.” There was a signifi cant correlation ( r = 0.59, P < 0.01) between the DSQ and the MDADI as is seen in Figure 3 . There was no correla-tion between DSQ and the Bazaz scores, and nor between the MDADI and the Bazaz scores. Time between T1 and T2 ranged from 8 to 37 days. Three patients conducted T2 in less time than the median time, which was 14 days. There was a signifi cant correlation between the DSQ at T1 and T2 with a correlation coeffi cient of r = 0.61, P < 0.01. The Cronbach alpha coeffi cient was calculated to 0.82, indicating a very good intraclass correlation and reliability. The Bland-Altman diagram shows that a good agreement between DSQ at T1 and T2 with no systematic trend of lower values dif-fers more than higher values or vice versa 20 ( Figure 4 ). The average EQ-5D was 0.61 (SD = 0.36). The distribution of EQ-5D showed a biphasic appearance ( Figure 5 ). For this reason, nonparametric Gamma Correlation Test was chosen for these analyses. There was a weak, but signifi cant, correla-tion between the DSQ and the EQ-5D ( r = − 0.27, P < 0.05), whereas no correlation could be detected with the MDADI ( r = 0.18). The Bazaz score showed a paradoxical inverse cor-relation with the EQ-5D with higher QOL values associated with more dysphagia ( r = 0.31, P < 0.05).

The Second Validation Study Preoperatively the DSQ scores were low with a mean value of 1.4 (SD = 1.9), but 17 patients (15%) had a score of 4 or higher. At 4 weeks postoperatively, the mean value was 3.2 (SD = 2.5). Only 16 patients (14%) reported a DSQ value of 0, whereas 46 patients (41%) reported a DSQ value of 4 or higher. At 3 months, the average DSQ value had decreased to 1. 7 (SD = 2.0). Both the values at 4 weeks and at 3 months were signifi cantly higher than the preoperative value ( P � 0.05). At 1 year after surgery, the DSQ levels were back to baseline values with a mean score of 1.2 (SD = 1.7); however,

13 patients (12%) scored 4 or more, which indicates a per-sistent swallowing problem ( Figure 6 ). Of the 17 patients who scored 4 or more (mean = 5.5) preoperatively, 14 had improved at 1 year and scored less than 4 points (mean = 1.6), one remained the same at 4 points and 2 had deterio-rated, one from 6 to 7 points and one from 4 to 5 points. There was no correlation seen between DSQ level and smok-ing habits at any time of observation.

DISCUSSION The anterior approach is common in surgery aimed at treat-ing degenerative disease of the cervical spine. The procedure is considered to be safe and effective, but there are a num-ber of known complications, of which dysphagia is very fre-quent. 21 The incidence of dysphagia after ACSS varies with different techniques and extent of surgery, 22 – 25 and to the bulk of the implant used. 26 Objective measurements of the ability to swallow are often not enough to identify these patients because dysphagia often is a subjective sensation of distur-bance or discomfort when swallowing. Bazaz et al 10 found an incidence of 50.3% at 1 month after surgery and 12.5% at 1 year after surgery. For this study, they used a grading system in which patients were evaluated via a telephone inter-view and classifi ed on a 4-grade scale. However, the Bazaz score can be criticized from several different aspects. First, it is not self-administrated; that is, it represents an interpre-tation of the patient’s dysphagia symptoms by the therapist, which may introduce a bias. Second, as we realized after hav-ing used the score clinically, it may have too few categories and, thus, does not result in enough discrepancy between patients. Yet another problem is that diffi culties swallowing solids always score worse than liquids, while patients often actually experience quite the opposite. 27 , 28 Also, as far as we know, the Bazaz scoring scale has never been formally vali-dated despite its wide use. The MDADI is validated but may have some drawbacks in this group of patients. It is a rather

Figure 1. The fi rst validation study: The distribution of the Dysphagia Short Questionnaire (DSQ) at T1.





assigning these relevant weights, that is, “expert opinion” validation. The instrument also resulted in a fairly normal distribution in a group of patients with established dysphagia of different magnitude. The good correlation with the “gold standard” MDADI can be seen as a support for progressiv-ity: low values are generated in patients with mild forms of dysphagia and higher values in patients with more severe symptoms. In the test-retest analysis, we had a signifi cant, but not perfect, correlation. There may be several explanations to this. There may, of course, be a problem with the preci-sion of our instrument: the repeatability is poor. However, other plausible explanations may also be considered. The fi rst test was performed together with the SLPs at the clinic where the patient went through the investigation and tests for swal-lowing. After this fi rst session, the patients may have become

extensive tool with many questions that make it cumbersome to use, and it is designed and validated for patients with dys-phagia caused by a malignancy. These patients presumably have more severe dysphagia than patients after ACSS. They also represent a subgroup in which psychological factors may have an infl uence on their health-related QOL, whereas in ACSS patients the treatment aims at full cure and the progno-sis for the dysphagia is good.

Dysphagia after ACSS has been reported by several authors but with a big variation in incidence. In a previous article from Riley et al 29 with an attempt to make a meta-analysis of the literature, they concluded that better outcome tools were needed. The DSQ is a self-administered instrument, which is easy to use and interpret. The design process of our evalua-tion instrument ensured the extraction of relevant items and

Figure 2. The fi rst validation study: The distribution of the M.D. Anderson Dysphagia Inventory (MDADI) at T1.

Figure 3. The fi rst validation study: There was a signifi cant correlation between the Dysphagia Short Questionnaire (DSQ) and the M.D. Anderson Dysphagia Inventory (MDADI); r = − 0.59, P < 0.01.





scoring 0 on both tests, and thus improving the correlation coeffi cient considerably. Too many patients with zero scores would also have contributed to considerable fl oor effects. The fact that we saw a correlation within a group of individuals with various degree of dysphagia supports the validity and strength of the score.

We could see a weak correlation to the QOL outcome instrument EQ-5D in the fi rst validation study. However, the study population has chronic problems, many of which are caused by malignant diseases, and they may have many fac-tors apart from the dysphagia that may negatively affect the QOL. This was also evident with the MDADI, which, despite being constructed with the aim to measure the impact of dysphagia on QOL and emotional status, failed to correlate with EQ-5D. On the contrary, the Bazaz score is probably

more aware of their problem and therefore more focused on it at the time of retest. This hypothesis is supported by the fact that the retest values are higher than the test values. Another plausible explanation is a temporal fl uctuation of the dys-phagia symptoms. Even though the patients were supposed to have chronic stationary problems, the severity may not be exactly the same 2 weeks later. However, we only included patients with dysphagia in the fi rst validation study. If we had performed it instead on a group of patients after ACSS, we would have encountered several problems. First of all, the dysphagia would not have been stationary, which would have infl uenced the test-retest investigation as the patients could be expected to improve their symptoms during the 2-week test period, and depending on time after surgery, a varying group of patients would be entirely without dysphagia symptoms,

Figure 4. The fi rst validation study: The Bland-Altman diagram of the Dysphagia Short Questionnaire (DSQ) at T1 and T2, respectively, indicating a good agreement between the 2 occasions. There is no systematic error related to the magnitude of the score.

Figure 5. The fi rst validation study: The biphasic distri-bution of the EQ-5D indicates 2 groups of patients with different affection of their health-related quality of life.





Postoperative dysphagia is very common after ACSS, particularly during the fi rst weeks after surgery. The level of postoperative dysphagia is generally mild, and it resolves over time. At 1 year only a small fraction of patients remain with chronic problem. Whether additional improvement occurs with more time cannot be answered in the present study.

not very reliable. Apart from the criticism mentioned earlier, it not only fails to correlate with both MDADI and the DSQ, but also shows a paradoxically inverted correlation with the EQ-5D, which would indicate an improved QOL with worse dysphagia.

In the second part of the study, we found that at least 15% of the patients experienced a not negligible dysphagia before surgery, but it is unclear whether this is the expected prevalence of dysphagia in a normal population or whether it is a consequence of the degenerative disc disease. However, the fact that the majority of these patients improved after surgery would support the latter interpretation. Also, other authors have reported the possible coupling of dysphagia and cervical spondylosis; for example, sometimes patients with cervical spondylosis may develop large ventral osteo-phytes, which may cause dysphagia, 30 , 31 which was not the case in our study population as this would have rendered exclusion.

On average, the DSQ values did not signifi cantly dif-fer between preoperative levels and at 1 year after surgery, which erroneously could be interpreted that surgery does not cause chronic dysphagia. Some individuals with preoperative dysphagia improve, while others deteriorate and remained with symptoms at 1 year. In the short term, it seems clear that ACSS causes dysphagia in almost all patients, but the symptoms gradually resolve during the fi rst few months, and at 1 year only a small fraction remains. The symptoms, on a group level, were considerably milder after ACSS compared to the patients in the fi rst validation group who also had more stationary problems.

CONCLUSION As the DSQ correlates with the MD Anderson Dysphagia Inventory, a “gold standard” for dysphagia measurement, we can conclude that it measures dysphagia quantitatively. Its reproducibility is also satisfactory. We can, thus, consider the DSQ a validated tool for measuring dysphagia.

Figure 6. The second validation study: Box-and-whisker diagram of DSQ values. Center line equals the median. Box and whiskers show quartiles and range, respectively.

➢ Key Points

Dysphagia is a sensation of diffi culties with swallow-ing and cannot always be assessed with objective methods of measurement.

For assessment of postoperative dysphagia after ACSS, there is a need for an easy-to-use validated tool.

The DSQ fulfi lls these criteria. Postoperative dyspha-gia after ACSS is common but seems to be transient in most patients.

Dysphagia may be a symptom of cervical spondylosis.

Acknowledgments The authors thank Eva Gulle for excellent help with administration and handling of data. They also thank Jonathan Mair and Lars-Olov Skeppholm for help with translations and Johan Bring for statistical advice.

Supplemental digital content is available for this article. Direct URL citations appearing in the printed text are provided in the HTML and PDF version of this article on the journal’s web site (www.spinejournal.com).

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