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sensation as a contributing factor to aspiration.
5
Other
studies have provided evidence to support the notion
that aspiration may not be solely related to vocal fold
immobility, as demonstrated by continued dysphagia
and/or aspiration after patients underwent surgical
intervention to improve glottic closure.
6,7
There have yet
to be objective kinematic and temporal measurements
obtained from patients with subjective dysphagia as a
result of UVFI related solely to vagus nerve injury. The
purpose of this investigation was to evaluate pharyngeal
strength and upper esophageal sphincter (UES) opening
in individuals with UVFI caused by idiopathic or iatro-
genic injuries to the vagus nerve.
MATERIALS AND METHODS
A clinical swallowing database consisting of individuals
with dysphagia who underwent a dynamic videofluoroscopic
swallow study (DSS) was reviewed to identify individuals with
UVFI between January 1, 1999, and June 1, 2012. The Institu-
tional Review Board of the University of California, Davis,
approved use of this database for clinical research. All patients
with UVFI were confirmed by videolaryngoscopy and/or strobo-
videolaryngoscopy. Individuals were excluded if they were
under 18 years of age, had suspected vagus nerve injury of cen-
tral origin (e.g., cerebrovascular accident, neuromuscular dis-
ease, brain tumor, etc.), head or neck cancer (i.e., except that
isolated to the thyroid, which resulted in only surgical removal
of all or part of the thyroid), and/or anterior approach cervical
spine surgery. The purpose for excluding these populations was
the possibility of a more complex swallowing disorder not neces-
sarily limited to injury of the vagus nerve. This resulted in
patients with iatrogenic and idiopathic UVFI. None of the
patients had undergone a vocal fold medialization procedure
prior to the videofluoroscopic swallow study. The timing
between onset of UVFI and time of evaluation was not
recorded.
All swallow studies were preformed using a properly colli-
mated OEC Medical Systems 9800 Radiographic/Fluoroscopic
unit that provided a 63 kV, 1.2 mA-type output for the full field
of view mode (12-inch input phosphor diameter). In accordance
with our standard protocol, a metal ring of known diameter was
taped to the chin or neck of the patient for measurement cali-
bration purposes. Lateral views were obtained while the
patient, seated in an examination chair, was administered
liquid barium (EZpaque barium sulfate suspension, 60% w/v;
EZ-EM, Inc., Westbury, NY) boluses of 1 cc, 3 cc, and 20 cc and
a 3-cc paste bolus (EZ-paste, EZ-EM, Inc.) measured with a
syringe or graduated medicine cup. The patient was then
turned to obtain anteroposterior views and administered liquid
barium boluses of 3 cc and 20 cc. Studies were recorded on a
Sony Md-1000 DVD recorder (Sony Corp. America, New York,
NY) and were played back using Quick Time (7.7.1; Apple,
Cupertino, CA). Measures were obtained from digitized images
using ImageJ software (National Institutes of Health, Bethesda,
MD) and software tools from Iconico, Inc (New York, NY).
Specific measurement techniques have been previously
described in detail.
8,9
An experienced unblinded clinician (i.e.,
the same clinician who conducted the videofluoroscopic swallow
studies) analyzed all studies; however, because this study was
retrospectively completed, there was no information available
related to this study at the time of evaluation. All measures for
the current study were obtained from the lateral view.
The primary outcome measures were upper esophageal
sphincter opening (UESmax) and the pharyngeal constriction
ratio (PCR). The PCR is a validated surrogate measure of pha-
ryngeal strength on fluoroscopy; and an elevated PCR suggests
pharyngeal weakness.
9
The secondary outcome measures were
larynx to hyoid approximation (HLx), hyoid displacement
(Hmax), and total pharyngeal transit time (TPT) (see Table I
for definitions). The data from each variable were compared to
age and gender-matched controls with no history of dysphagia.
Discrete variables were analyzed with a chi-square test of inde-
pendence and an independent samples
t
test was used to com-
pare the control and combined UVFI groups with alpha set at
0.05. A one-way analysis of variance (ANOVA) was used to com-
pare the iatrogenic and idiopathic UVFI groups with the con-
trol group. A Bonferroni correction was applied to adjust for
multiple comparisons with alpha set at 0.01. There is a proba-
bility of 0.05 that a type I error has been made in the set of
tests.
RESULTS
A total of 137 individuals with UVFI were identified
from the clinical database. There were 25 subjects who
met strict inclusion and exclusion criteria (i.e., did not
TABLE I.
Objective Measures and Definitions for a Dynamic Videofluoroscopic Swallow Study.
Objective Measures on Dynamic
Videofluoroscopic Swallow Study (DSS)
Definition
Total pharyngeal transit time (TPT)
The time between the head of the bolus passing the posterior nasal spine to the
time the tail of the bolus passes through the UES.
Upper esophageal sphincter opening (UESmax)
UES opening. The narrowest point of opening between C3 and C6 during
maximal distention for bolus passage.
Pharyngeal constriction ratio (PCR)
A surrogate measure of pharyngeal strength. Specifically, a ratio of pharyngeal
area measured in lateral fluoroscopic view at the point of maximal pharyngeal
constriction during the swallow to the pharyngeal area measured with the
bolus held in the oral cavity.
Hyoid to larynx approximation (HLx)
The difference in distance between the anterior margin of the hyoid bone with a
1cc bolus held in the oral cavity to maximal approximation of the hyoid and
larynx during swallow and maximal hyoid to larynx approximation. A clear and
consistently visible landmark on the anterior thyroid cartilage, such as
calcification, was used as an alternative to the subglottic air column if it could
not easily be visualized. Maximal approximation usually occurred just after
maximal hyoid excursion.
Hyoid excursion (Hmax)
The distance traveled by the hyoid to the point of maximal elevation during a
swallow from its position during hold.
Laryngoscope 124: October 2014
Domer et al.: PCR and UES Opening in UVFI
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