Analysis of the
Videofluoroscopic and Fiberoptic Endoscopic
Noel Rao, MD*
Susan L. Brady, MS, CCC-SLP†
Gouri Chaudhuri, MD*
Joseph J. Donzelli, MD‡
Michele W. Wesling, MS, CCC-SLP†
of Speech-Language Pathology
Marianjoy Rehabilitation Hospital
Head & Neck Surgery, LTD
Carol Stream, Illinois
Work was completed at the Marianjoy Rehabilitation
Hospital, Wheaton, Illinois.
This work was supported by the Dr. Ralph and Marian
Falk Medical Research Foundation.
This paper was accepted for a poster presentation
at the Academy of Physical Medicine and Rehabilitation Annual Assembly,
November 21-24, 2002, Orlando, FL.
KEY WORDS: swallow, videofluoroscopy, rehabilitation,
Objective: The goal of this study was to determine sensitivity
and specificity values for laryngeal penetration, tracheal aspiration,
and pharyngeal residue for both the videofluoroscopic (VFSS) and fiberoptic
endoscopic (FEES) swallowing examinations. Sensitivity and specificity
values were calculated twice, first using the VFSS as the gold standard,
then using the FEES as the gold standard. Percentage of agreement
for laryngeal penetration, aspiration, pharyngeal residue, diet recommendations,
and compensatory strategies were also calculated.
Study Design: Prospective, consecutive design, set in
a freestanding rehabilitation hospital.
Participants: Eleven patients who underwent simultaneous
VFSS and FEES.
Interventions: Not applicable.
Main Outcome Measures: Presence or absence of laryngeal
penetration, tracheal aspiration, and/or pharyngeal residue.
Results: When the VFSS was used as the gold standard,
sensitivity of the FEES for laryngeal penetration was 0.87, aspiration
0.96, and pharyngeal residue 0.68. Specificity of the FEES for laryngeal
penetration was 1.0, aspiration 1.0, and pharyngeal residue 0.98.
When the FEES was used as the gold standard, sensitivity of the VFSS
for laryngeal penetration was 1.0, aspiration 1.0, and pharyngeal
residue 0.96. Specificity of the VFSS for laryngeal penetration was
0.58, aspiration 0.63, and pharyngeal residue 0.78. Agreement for
the presence or absence of pharyngeal residue was 84.38%, laryngeal
penetration 89.58%, and tracheal aspiration 96.69%. Diet recommendations
were in agreement 100%, and compensatory swallowing strategies were
in agreement 82%.
The sensitivity values were higher when FEES was used as the gold
standard, and the specificity values were higher when VFSS was used
as the gold standard. The one exception is that the sensitivity values
for aspiration, regardless of whether VFSS or FEES was used as the
gold standard, were similar.
Many authors have suggested the “gold” or “criterion”
standard for the instrumental assessment of the swallow as the videofluoroscopic
swallowing evaluation (VFSS).1–7 However, an evidence report by the
Agency for Health Care Policy and Research (AHCPR) branch of Health
and Human Services concluded that currently in the literature there
was no evidence to support that one instrumental assessment of the
swallow provided more useful information than another.8 They concluded
that neither the VFSS nor the fiberoptic endoscopic examination of
the swallow (FEES) could serve as a perfect “gold” standard for the
detection of aspiration because both examinations yield false-positive
and false-negative results. Furthermore, they reported that without
a third, more reference standard, the VFSS and FEES could not be compared
with each other. Although the controversy exits as to whether the
VFSS or FEES should be considered the gold standard, they remain the
two most common types of instrumental assessments of the swallow.5,9–12
have reported the advantages and disadvantages of both the VFSS and
FEES.5,13–20 Additionally, previous research has also compared the
two examinations.16,17,21,22 Some studies have compared the two examinations
on patients with dysphagia when the examinations were completed at
separate times.16,17,22 However, because individuals with dysphagia
often show variable abilities to swallow, an inherent weakness of
studies that are not conducted simultaneously is that they are actually
comparing two different behaviors.10 Furthermore, previous researchers
have conducted sensitivity and specificity analysis for the FEES using
the VFSS as the “gold” or “criterion” standard.23 According to Langmore,23
this step was important because the FEES was considered the “new”
examination; to establish its validity, it needed to be compared to
the “old” examination of the VFSS. An additional acknowledged limitation
of these studies is that when the old examination represents the “truth,”
it is very difficult to show that the “new” procedure is as valid.23
The purpose of this study was to determine sensitivity
and specificity values for laryngeal penetration, tracheal aspiration,
and pharyngeal residue for both the VFSS and FEES. Because sensitivity
and specificity values require a gold standard, the values were calculated
twice, first using the VFSS as the gold standard then using the FEES
as the gold standard. Calculating the sensitivity and specificity
twice is important to establish the validity of each examination.
The current literature shows no evidence-based indication of the “gold”
or “criterion” standard for the instrumental assessment of the swallow.
Eleven consecutive patients underwent the VFSS and FEES
procedures simultaneously. Criteria selection included subjects who
had a suspected laryngeal or pharyngeal abnormality or dysphonia and
required an evaluation of the oral, pharyngeal, and esophageal phases
Age range was from 29 to 77 years, with a mean age of
50 (standard deviation ± 18.10 years). Nine subjects were men and
two were women. See Table 1 for additional information on subject
demographics. All subjects possessed the cognitive abilities to perform
the VFSS and FEES procedures and the ability to accept food into the
The subjects underwent
simultaneous VFSS and FEES. Equipment used during the procedures included
the C-arm fluoroscopy system, the Olympus flexible endoscope, the
Olympus CKL halogen light source, and the Elmo one chip camera. All
of the examinations were recorded on videotape. The examiners were
not blinded to the results of each examination. Each bolus presentation
was evaluated for the presence of laryngeal penetration, aspiration,
and pharyngeal residue. Bolus size and consistency were not controlled.
A physiatrist and speech-language pathologist conducted
all the VFSS. The physiatrist performing the VFSS had successfully
completed a VFSS training program administered by a radiologist and
had received credentials to complete VFSS at this institution. An
otolaryngologist and speech-language pathologist performed the FEES.
For the FEES procedure, the flexible endoscope was passed transnasally
to the hypopharynx to provide a full view of the larynx. The endoscope
was initially placed in the high position to just above the tip of
the epiglottis before and during the swallow and then advanced to
the low position to just above the vocal folds after the swallow to
evaluate for the presence of laryngeal penetration or aspiration.
Three to five drops
of blue dye were added to each 4 ounces of the barium-and-food mixture
to ensure adequate visualization of the bolus. The ratio of barium
to food/liquid was controlled. A thin liquid barium mixture consisted
of one third liquid polibar barium and two thirds water, nectar-thick
liquid consisted of one half liquid polibar barium and one half nectar
liquid, and extra-thick liquid consisted of 2 teaspoons of liquid
polibar barium and 4 oz of applesauce. Each 4 oz of pureed and solid
foods were mixed with 3 teaspoons of powder barium.
An independent experienced
rater established interrater reliability for both VFSS and FEES. The
rater was blinded to the results of the examination and independently
rated each swallow for both the VFSS and FEES. The interrater agreement
for the presence of laryngeal penetration, tracheal aspiration, and
pharyngeal residue for both examinations as compared with the initial
rating was at 90% or higher for each parameter.
The sensitivity and specificity values were calculated.
To determine the sensitivity and specificity values, you need to establish
one measure as a gold standard. For the purpose of this investigation,
the sensitivity and specificity values were calculated twice, first
using the VFSS as the gold standard, then using the FEES as the gold
standard. To further evaluate the results, 2 x 2 contingency tables
were used to compare the results for laryngeal penetration, aspiration,
and pharyngeal residue during the FESS/VFSS.To correct for chance
agreement on the contingency tables, the kappa correlation and Fisher’s
exact tests were also completed. Percentage of agreement between the
two examinations for laryngeal penetration, aspiration, pharyngeal
residue, diet recommendations, and compensatory strategies were calculated.
A total of 100 boluses were presented across the 11
subjects. Four boluses were excluded from the study, as they were
unable to be evaluated by both the FEES and VFSS secondary to the
subject’s motion of the examination field.
Sensitivity and specificity values for the FEES when
the VFSS was used as the gold standard are represented in Table 2.
The sensitivity and specificity values for the VFSS when the FEES
was used as the gold standard are represented in Table 3. The sensitivity
values were higher when the FEES was used as the gold standard, and
the specificity values were higher when the VFSS was used as the gold
standard. The one exception was that the sensitivity values for aspiration
were similar, regardless of which examination was used as the gold
The results of the contingency tables for laryngeal
penetration, aspiration, and pharyngeal residue are summarized in
Table 4. The correlations indicate a moderate association between
the FEES and VFSS. The most similar agreement between the FEES and
VFSS was with aspiration and the least agreement was with pharyngeal
Percentage of agreement between the two examinations
for laryngeal penetration, aspiration, and pharyngeal residue was
calculated and is shown in Table 5. Laryngeal penetration was present
on 25% (24/96) of the boluses. The FEES and VFSS were in agreement
for the presence or absence of laryngeal penetration 89.58% (86 of
96) of the time. On the 10 boluses that were not in agreement, the
FEES detected laryngeal penetration all 10 times, whereas the VFSS
did not. Aspiration was present on 9.4% (9/96) of the boluses. Agreement
between the FEES and VFSS for the presence or absence of aspiration
was 96.69% (93/96). On the three boluses that were not in agreement,
the FEES detected aspiration all three times whereas the VFSS did
not. Pharyngeal residue was present on 69.79% (67/96) of the boluses.
Agreement between the FEES and VFSS for the presence or absence of
pharyngeal residue was 84.38% (81 of 96). On the 15 boluses that were
not in agreement, the FEES detected pharyngeal residue 14 times when
the VFSS did not and the VFSS detected pharyngeal residue 1 time when
the VEES did not.
Seven of the subjects presented with some type of laryngeal
or pharyngeal abnormality as identified by the FEES, and 3 subjects
presented with an anatomic abnormality as identified by the VFSS (Table
6). Excessive oropharyngeal secretions that had accumulated in the
hypopharynx were identified in 6 patients by the FEES procedure. Diet
recommendations were in agreement 100% of the time, and compensatory
swallowing safety strategies were in agreement 82% (9 of 11) of the
time (Table 6).
The results of this study support previous research
in showing that both FEES and VFSS are valuable procedures for evaluating
dysphagia and have been shown to be successful at the diagnosis and
management of dysphagia.5,15–20 In this current investigation, the
sensitivity values for aspiration were similar, regardless of whether
the VFSS or FEES measure was used as the gold standard. The sensitivity
value (the true-positive rate), which is the test’s sensitivity to
detecting a disorder when it is actually present, was higher when
FEES was used as the gold standard for laryngeal penetration and pharyngeal
residue. The specificity value is the true-negative rate and answers
the question of whether the test is sensitive to the construct being
measured or whether it picks up other constructs as well. The specificity
values were higher for laryngeal penetration, aspiration, and pharyngeal
residue when the VFSS was used as the gold standard.
current study also provided support that the VFSS and FEES are equally
effective, comparable, valid instrumental procedures for swallowing
and both deserve to be considered the “gold” standard. A moderate
association between the FEES and VFSS was demonstrated in this current
study, with the most similar values shown for aspiration. The choice
of which instrumental assessment should be used should be dictated
by clinical indications, equipment availability, and clinical expertise
of the evaluators. Furthermore, it is important to understand and
recognize the strengths and weaknesses of each diagnostic procedure.
From a clinical standpoint, the VFSS provides greater information
during the oral phase of swallowing, and the FEES may be uncomfortable
for young children and individuals with severe cognitive disorders
who may also be agitated.13 The FEES, however, may be able to provide
the examiner with additional information on anatomy and physiology
of the pharynx and larynx that the VFSS would be unable to provide.
We propose that the VFSS and FEES can be used to complement each other.
The results of this study suggest that patients who are referred for
an instrumental assessment of the swallow and the clinical indicators
of a dysphonia, suspected laryngeal or pharyngeal abnormality, presence
of a tracheotomy tube or difficulty managing secretions may be best
evaluated using FEES. Additionally, patients referred for an instrumental
assessment of dysphagia along with the clinical indicators of a suspected
esophageal abnormality might be best evaluated using the VFSS.
An advantage of this investigation was that VFSS and
FEES were conducted simultaneously. Previous investigators attempted
to show the sensitivity and specificity values of the FEES, using
the VFSS as the gold standard, with the examinations completed at
separate times.16,22 In this current investigation, the examiners
were allowed to evaluate the same swallow under both diagnostic tools
at the same time, rather than relying on inference from two separate
events. The results of this study suggest that the most effective
means for evaluating the validity of both the VFSS and FEES is by
conducting simultaneous examinations.
A recognized limitation of this study is that the dysphagia
evaluation team introduced appropriate swallowing strategies to minimize
the risk of laryngeal penetration, aspiration, and pharyngeal residue
to the patients. If this safety protocol was not in place, theoretically
more patients may have shown increased symptoms of dysphagia. Because
this safely protocol was in place for all patients, however, each
patient was presented with different bolus types and amounts. Direction
for future research may include replicating this study with a larger
sample size with the patients undergoing identical swallowing protocols
for bolus type and amount.
It was interesting to note that the overall recommendations
for diet level remained unchanged even though minor differences in
laryngeal penetration, aspiration, and pharyngeal residue detection
rate were present. However, for two subjects in this current study,
the recommendations for swallowing safety strategies were different.
One difference was based on the results of the VFSS and other was
based on the results of the FEES. Additionally, the FEES was able
to provide additional diagnostic information by identify laryngeal
abnormalities in six of the patients. However, it was unable to detect
esophageal abnormalities that the VFSS was able to show in two of
the patients. In only one patient could both VFSS and FEES be used
to identify the same abnormality. In this case, the abnormality was
prevertebral swelling after an anterior cervical spinal fusion surgery.
The FEES and VFSS are both valuable procedures for evaluating
dysphagia and show good agreement regarding laryngeal penetration,
aspiration, pharyngeal residue, diet recommendations, and compensatory
strategies. The sensitivity values are higher when the FEES is used
as the gold standard and the specificity values are higher when the
VFSS is used as the gold standard. The one exception is that the sensitivity
values for aspiration were similar regardless of whether which measure
was used as the gold standard. Because both examinations yield valuable
information in the assessment and clinical management of dysphagia,
their selection should be clinically mandated.
The Dr. Ralph and Marian Falk Medical Research Trust
funded this study. The authors would also like to acknowledge Barbara
Kremer, PhD, who provided statistical support for this study.
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Table 1. Subject
Subject Age (y) Gender
Diagnosis Boluses (n)
1 60 Male Anoxic encephalopathy 16
2 77 Male Anoxic encephalopathy 7
3 63 Male CVA 12
4 17 Female Closed head injury 5
5 29 Male Closed head injury 8
6 29 Male Dysphagia 6
7 49 Male Dysphagia 18
8 65 Male CVA 8
9 59 Male ACSS 7
10 50 Male Eaton-Lambert syndrome 1
11 51 Female CVA 8
Table 2. VFSS
as the Gold Standard, Sensitivity and Specificity of the FEES
Laryngeal penetration 0.87 1.0
Aspiration 0.96 1.0
Table 3. FEES
as the Gold Standard, Sensitivity and Specificity of the VFSS
Aspiration 1.0 0.63
Table 4. Results
of Contingency Tables for Laryngeal Penetration, Aspiration, and Pharyngeal
Correlation Exact Test
P = 0.000
Aspiration 0.75 P = 0.000
P = 0.000
Table 5. Agreement
of VFSS and FEES
Subject Penetration Aspiration
1 15/16 14/16 14/16
2 5/7 7/7 4/7
3 9/12 12/12 7/12
4 4/5 5/5 4/5
5 8/8 8/8 8/8
6 6/6 6/6 6/6
7 16/18 18/18 15/18
8 8/8 8/8 7/8
9 6/7 6/7 7/7
10 1/1 1/1 1/1
11 8/8 8/8 8/8
Table 6. Abnormalities
Abnormality Abnormality Agreement Compensatory
Subject Detected By VFSS Detected By FEES of Diet Level Strategy
1 None None Yes Yes
2 None Left vocal cord paresis, Yes Yes
small posterior glottal chink
3 None Right paralyzed vocal cord Yes
No; addition of
to eliminate penetration
a chin tuck
as detected by the FEES
4 None Swollen mucosa of Yes Yes
pyriform with floppy arytenoid
5 None Posterior glottal chink Yes Yes
6 T6-T7 None Yes No; addition of
a liquid wash
because of the
narrowing of the
7 Esophageal None Yes Yes
8 None Left paralyzed Yes Yes
9 Prevertebral Prevertebral Yes Yes
10 None None Yes Yes
11 None Bilateral vocal Yes Yes