ORIGINAL ARTICLE
Initiation and Duration of Laryngeal Closure During
the Pharyngeal Swallow in Post-Stroke Patients
Taeok Park Æ Youngsun Kim Æ Do-Heung Ko Æ
Gary McCullough
Published online: 17 September 2009
 Springer Science+Business Media, LLC 2009
Abstract As a bolus enters the pharynx during the
swallow, the airway is protected by laryngeal closure, a
process characterized by approximation of the vocal folds
plus approximation of the arytenoid cartilages to the base
of the epiglottis. The purpose of this study was to measure
initiation of laryngeal closure (ILC) and laryngeal closure
duration (LCD) in three groups of subjects: (1) ten stroke
patients who aspirated before and during the swallow
(aspirators), (2) ten stroke patients who did not aspirate
(nonaspirators), and (3) ten normal control subjects. Means
and standard deviations of ILC and LCD were analyzed for
both 5-ml and 10-ml thin-liquid boluses using a 100-ms
timer during subsequent analysis of videofluoroscopic
swallowing examinations. There were significant differ-
ences between aspirators and control subjects for both ILC
and LCD, and significant differences between aspirators
and nonaspirators for ILC. There were no significant dif-
ferences between aspirators and nonaspirators for LCD.
Both delayed ILC and reduced LCD were associated with
post-stroke aspiration. Delayed ILC is a significant indi-
cator of overall risk of aspiration. Clinical implications for
these findings are discussed.
Keywords Swallowing  Laryngeal closure  Stroke 
Aspiration  Pharynx  Deglutition  Deglutition disorders
As a bolus is propelled from the oral cavity into the pha-
ryngeal cavity, the pharyngeal stage of the swallow begins.
The physiological events of the normal pharyngeal swal-
low are characterized by anterior-superior displacement of
the hyolarynx, closure of the larynx, and downward dis-
placement of the epiglottis with concurrent approximation
of the arytenoids to the base of the epiglottis. These rapidly
executed, overlapping movements contribute to laryngeal
closure and protection of the airway [1]. Disturbances in
the initiation and duration of these physiological events
involved in laryngeal closure are likely to place individuals
at risk for aspiration during swallowing.
Aspiration associated with oropharyngeal swallowing is
defined as the entrance of food or liquid into the airway
before, during, or after the swallow and can cause aspira-
tion pneumonia, dehydration, malnutrition, and even death
[2]. Aspiration that occurs before and during the swallow is
likely to occur if the bolus passes into the pharynx before
laryngeal closure or if the duration of laryngeal closure is
too short. Delayed pharyngeal swallow, i.e., delayed lar-
yngeal closure relative to bolus position in the pharynx,
increases with age, i.e., in younger, healthy individuals,
laryngeal closure begins when the bolus reaches the ramus
of the mandible; in older, healthy individuals, laryngeal
closure begins after the bolus has passed the ramus of the
mandible [3–6]. However, older healthy individuals are not
Presented at the 16th Annual Dysphagia Research Society,
Charleston, South Carolina, 6–8 March 2008.
T. Park  D.-H. Ko
Division of Speech Pathology and Audiology,
Hallym University, 39 Hallymdaehak-gil, Chuncheon,
Gangwon-do 200-702, Korea
Y. Kim (&)
School of Hearing, Speech and Language Sciences, Ohio
University, Grover Center, Athens, OH 45701-2979, USA
e-mail: kimy2@ohio.edu
G. McCullough
Department of Speech-Language Pathology,
University of Central Arkansas, Conway, AR 72035, USA
123
Dysphagia (2010) 25:177–182
DOI 10.1007/s00455-009-9237-9

necessarily more likely to aspirate than younger, healthy
individuals because this physiological difference in initia-
tion of laryngeal closure is effectively compensated in
older individuals. In individuals with laryngeal-pharyngeal
weaknesses (e.g., stroke patients), delayed laryngeal clo-
sure before or during the swallow is associated with an
increased risk for aspiration [7–9]. In addition, delayed and
slowed airway closure is an indicator of risk of aspiration
in older dysphagia patients [10] and in neurogenic dys-
phagic patients [11]. Kim and McCullough [12] reported
that a delayed pharyngeal swallow in post-stroke patients
in the range of 0.9-1.0 s was associated with increased
aspiration before or during the swallow.
Aspiration before and during the swallow occurs
because the bolus enters the laryngeal vestibule and passes
below the true vocal folds before the larynx has fully
closed. Aspiration during the swallow occurs because the
bolus passes below the true vocal folds before laryngeal
closure is complete or because laryngeal closure duration is
too short. Other contributing factors include weakness in
the propulsive force of the tongue on the bolus and weak
contraction of the pharyngeal constrictors. The present
study focused on measurements of laryngeal closure, both
before and during the swallow.
To describe aspiration before and during the swallow,
this study employed a temporal measure developed by
Rademaker et al. [13]. Initiation of laryngeal closure (ILC)
is the time between when the bolus enters the pharynx
(operationally defined as the posterior edge of the ramus of
the mandible) and the first contact of the arytenoids and the
epiglottis. Under normal physiological conditions, lar-
yngeal movement starts before the bolus passes into the
pharynx [5, 6]. In pathological conditions, delayed initia-
tion of laryngeal closure may allow the bolus to enter the
airway.
To describe aspiration during the swallow, this study
measured laryngeal closure duration (LCD), described by
Perlman et al. [14]. LCD refers to the duration of
approximation of the arytenoid cartilages to the base of the
epiglottis. Kendall et al. [15] reported that older normal
individuals did not differ in laryngeal LCD when compared
to younger individuals. Bisch et al. [16] reported that LCD
was shorter in neurogenic dysphagic patients than in age-
matched control subjects. However, Power et al. [17] found
no differences in LCD among post-stroke patients and
normal controls did not identify the incidence of aspiration.
Since aspiration occurs when the bolus enters the laryngeal
vestibule and true vocal folds, it is necessary to have more
clinical data to determine whether reduced LCD is a sole
indicator associated with aspiration during the swallow.
The purpose of this investigation is to evaluate whether
delayed initiation or reduced duration of laryngeal closure
is different among stroke patients who aspirate and those
who do not aspirate compared to neurologically normal
participants using refined radiographic analyses.
Method
Subjects
Thirty subjects’ high-quality video clips from videofluo-
roscopic swallowing examinations (VFSEs) were exported
for analysis from a prior investigation [18]. Individuals
patients who experienced cerebrovascular events consistent
with stroke who aspirated (n = 10 aspirators) and who did
not aspirate (n = 10 nonaspirators) were examined and
compared to 10 neurologically normal volunteers who did
not aspirate (n = 10 normal controls). All aspirators were
observed during videofluoroscopic examination to aspirate
at least one thin liquid either before or during the swallow.
Among the stroke patients, seven had a left hemisphere
stroke, six had a right hemispheric stroke, and seven had
bilateral lesions.
The records of the ten age-matched normal control
subjects from a prior investigation [19] were analyzed for
comparison to aspirators and nonaspirators. Control and
stroke subjects were age-matched because the previous
temporal studies showed that older subjects had delayed
initiation and reduced duration of laryngeal closure com-
pared to younger subjects. The mean age was 69 years for
aspirators, 65 for nonaspirators, and 70 for aspirations. The
control group was screened for neurological or structural
abnormalities which would interfere with swallowing using
a comprehensive questionnaire and administering an oral
motor examination by a speech-language pathologist. The
Ohio University Institutional Review Board (IRB)
approved this study of temporal measurements, conducted
using videofluoroscopic films.
Videofluoroscopic Swallowing Examination (VFSE)
Videofluoroscopic swallowing examination (VFSE) data
were collected on stroke patients [18] and the control group
[19] using the same methodology. The fluoroscopic tube
was focused in the lateral plane on the oral cavity (the lips
anteriorly to the pharyngeal wall posteriorly) and the
nasopharynx (superiorly) to just below the UES area
(inferiorly). Each subject swallowed an array of consis-
tencies including bolus sizes from 5 ml to 3 ounces and
consistencies from thin liquid to solid. For this investiga-
tion, however, data were analyzed for only two 5-ml
boluses and two 10-ml boluses of thin liquid. This was
done because thin liquids create the primary risk for aspi-
ration. The boluses were a mixture of water and barium
sulfate powder (50/50 water and E-Z M barium sulfate
178 T. Park et al.: Laryngeal Closure During Pharyngeal Swallow
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