GASTROENTEROLOGY

1992;103:128-136

Pharyngeal Clearance During Swallowing: A Combined Manometric and Videofluoroscopic Study PETER

J. KAHRILAS,

JERILYN

A. LOGEMANN,

SHEZHANG

LIN,

and GULCHIN A. ERGUN Departments of Medicine and Communication Sciences and Disorders, Northwestern University and Veterans Administration Lakeside Medical Center. Chicago, Illinois

The deglutitive pharyngeal contraction was analyzed using simultaneous videofluoroscopic and manometric studies of eight volunteers. Anterior, posterior, and longitudinal movements of the pharyngeal surfaces, relative to the cervical vertebrae, were measured during swallows of 5 and 10 mL of liquid barium. Profound pharyngeal shortening during bolus transit through the pharynx eliminated access to the larynx and elevated the upper esophageal sphincter to within 1.5 cm of the retrolingual pharynx. Bolus head movement through the pharynx preceded the propagated pharyngeal contraction and registered manometrically as a slight intrabolus pressure before the major pressure complex. Contraction in the horizontal plane began after bolus head transit and culminated with stripping of the bolus tail through the pharynx. Prolonged upper sphincter opening with the largervolume swallows resulted from a delayed onset rather than altered propagation of the horizontal pharyngeal contraction. It is concluded that the propagated pharyngeal contraction facilitates pharyngeal clearance but has a minimal role in the process of bolus propulsion during swallowing. The propagated contraction works in concert with profound pharyngeal shortening to minimize hypopharyngeal residue after a swallow.

S

wallowing is a complex action with a simple result: transfer of ingested material from the oral cavity to the proximal esophagus. For this action to be accomplished, the pharynx must be transiently altered from its resting state as a respiratory conduit into a gustatory conduit in which the nasopharynx and laryngeal inlet are sealed and the oropharynx instead leads to an opened upper esophageal sphincter (UES). The ingesta must then be propelled through the UES into the esophagus. Finally, before the resumption of respiration, residual ingesta must be cleared from the pharynx to prevent subsequent inhalation of that residue into the trachea. Examined

in this way, the swallow response comprises several discrete elements including laryngeal closure, UES opening, nasopharyngeal closure, bolus propulsion, and pharyngeal clearance. Recent investigations have used computer-assisted analysis of videofluoroscopy, sometimes synchronized with intraluminal manometry, to examine the mechanism of UES opening,l the volitional modifiability of UES opening,’ and the mechanism of laryngeal closure.3 The present investigation used these same techniques to examine the mechanism of pharyngeal clearance during swallowing. Materials and Methods Concurrent videofluoroscopic and manometric studies of swallowing were obtained in eight fasted male volunteers, 23-32 years old, without swallowing problems. The study protocol was approved by the Northwestern University Institutional Review Board. During recording sessions, subjects sat upright in a high-backed chair with head support as lateral videofluoroscopic images including the vertebral bodies posteriorly, the hard palate superiorly, and the subglottic air column inferiorly were obtained. The fluoroscopic image was displayed on a monitor and recorded with a videocassette recorder (Sony U-matic, model VO-9800). A manometric assembly with three strain-gauge sensors spaced 1 cm apart in a 2.5-mm by 3-cm radiopaque cylindrical housing (Medical Measurements Inc., Hackensack, NJ) was passed nasally and positioned with the distal sensor facing posteriorly at the level of the valleculae. Pressure tracings were displayed on a polygraph (model R-611; Beckman Instruments, Oxnard, CA) with the sensitivity set at lo-20 mm Hg/cm and the chart speed at 50 mm/s. Manometric and videofluoroscopic records were synchronized using a modified videotimer (model VC 436; Thalner Electronics Laboratories, Ann Arbor, MI) that both encoded an analog time signal on the videotape in hundredths of a second and sent a 5-millisecond pulse to an instrumentation channel of the polygraph at whole0 1992 by the American

Gastroenterological 0016-5085/92/$3.00

Association

July 1992

second intervals. During each swallow sequence, one of the second marks was labeled from the video display to facilitate temporal correlation between fluoroscopic and manometric records. Pressure values corresponding to fractions of seconds were derived by interpolation between the second marks. Two swallows each of 5 and 10 mL of liquid barium were obtained. Test boluses were placed in the mouth with a syringe and subjects were told to hold the bolus over the tongue until the swallow command, at which time they should swallow it as a single bolus. Videofluoroscopic data were analyzed temporally relative to UES opening (either barium or air within the UES at the level 1 cm distal to the subglottic air column), which was set as time zero to allow for comparison of pharyngeal events among swallows.“4’5 Spatial analysis of the videofluoroscopic swallowing sequences was accomplished using an interactive computer program written to enable x-y coordinate determination of selected structures on each video frame.6 For each swallow, 40 sequential frames [at 1/3Oth-second intervals) were analyzed such that frame 15 was always the first frame showing UES opening. The analysis of anterior and posterior pharyngeal wall motion during swallowing was based on the construction of a subject-specific grid that served to normalize size differences among subjects and permit the same anatomic structure to be analyzed for each subject (Figure 1). The span of the pharynx analyzed was from the tongue base superiorly to the resting position of the uppermost margin of the UES inferiorly.4 Once constructed on tracing paper, the grid was placed over each digitized image of each swallow sequence for that subject and the data points shown in Figure 1 were marked using a mouse to position cross-hairs on the monitor showing the fluoroscopic image. The coordinates of the marked points were then stored as a data file. The image-based coordinate system was referenced to the anterior inferior corner of C3, which served as the anchor point (coordinate 0,O). Fluoroscopic magnification was corrected for using the known s-cm length of the manometric sensor casing positioned within the sagittal plane. Thus, data coordinates were corrected for magnification, head tilt, head movement, and different head sizes among subjects. As outlined above, the image data set was comprised of the coordinates of 29 structures at 40 different times during two swallows each of two test boluses in eight subjects. Data for each structure among swallows of a given condition were averaged and expressed as mean ? SE. The timing of events or the extent of movement among test conditions was compared by averaging values for each subject within a test condition and then comparing values between conditions using a paired Student’s t test. Manometric recordings were analyzed in conjunction with the fluoroscopy to determine the time of initial bolus contact with the most orad sensor in the bolus path and the time of luminal closure at the level of that sensor. Pressure during this interval was referred to as intrabolus pressure. After luminal closure, the major pharyngeal contraction was recorded and the timing and maximal value of this complex were noted. The accuracy of manometric tracings interpreted without the aid of fluoroscopy for determining

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Line 4

Topot UES

Vertical Axis

Figure 1. Subject-specific grid used to normalize anatomic data among subjects. The vertical axis of the grid was drawn through the anterior superior corners of C3 and C5. Lines 4 and 9 are perpendicular to the vertical axis at the levels of the valleculae and the uppermost margin of the LJES,respectively, in the first digitized image of each swallow. Lines 5-8 are evenly spaced between lines 4 and 9, and lines l-3 are spaced at the same interval above line 4. The nine grid lines maintain a constant relationship to the vertebrae from the first digitized image of each swallow to the last, in which the positions of the anterior pharyngeal wall structure, posterior wall structure, and anterior vertebral surface were marked at the intersection of each grid line. The positions of the valleculae and superior aspect of the arytenoid were marked as indicators of axial pharyngeal shortening. In instances of a closed lumen, anterior and posterior walls were marked as superimposed. The length of the manometric sensor casing was marked to use as a known s-cm length in the midline. The three posterior indentations on the manometric casing correspond to the sites of the pressure sensors; the proximal sensor is Sl, and the most distal is S3. The anterior inferior corner of C3 was used as the anchor point among frames.

the timing of the onset and offset of the intrabolus pressure was determined by comparing values obtained by blinded inspection of the manometric tracings with those obtained while cross-referencing the fluoroscopy. The two sets of values were then compared by linear regression analysis. Results

Bolus Movement Contraction

Relative to Pharyngeal

Of the three manometric sensors, only the most distal (3) was within the bolus path during most swallows as determined by playback of the videofluoroscopy. The more proximal sensors (Sl and S2) were usually behind the soft palate and thus removed from the bolus path. Relative to the grid in Figure 1, S3 was very close to the level of L2 at the time of luminal closure; repositioning relative to the rest position was a consequence of soft palate elevation early in the swallow. Figure 2 illustrates repre-

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5

GASTROENTEROLOGY Vol. 103, No. 1

ml

10

ml

c (Pmax)

and 0.14 for points a and b, respectively. However, when videofluoroscopy was used as an aid to interpret the unusual wave forms that occurred in four swallows, these correlation coefficients improved to 0.82 and 0.86, respectively. 0.46

c

120

mmHg

0 !_

Pharyngeal Conformation Bolus Passage

Av

b (lumen closed) (bolus

I

b

t:sensor)

Each axial level of the pharyngeal lumen showed a distinct pattern of closure, as illustrated in Figure 3. At the extreme ends, the retrolingual pattern was most evident at the level of line 1 (Ll) and the UES pattern at line 9 (L9). The retrolingual region was characterized by initial widening before sphincter opening, rapid sealing after time 0 with substantial contribution from both the anterior wall (tongue) and the posterior wall (pharyngeal constrictors), and then widening again late in the swallow. The sphincter zone showed the opposite activity, initially being narrow, widening at time 0, and then narrowing again late in the swallow. Understanding the dynamic behavior of the luminal dimensions between grid lines 1 and 9 requires consideration of pharyngeal shortening as discussed below. Each of the nine grid lines of Figure 1 maintained a constant relationship to the vertebrae as determined by the positions of the valleculae (line 4) and the uppermost margin of the UES (line 9) at rest. As the pharynx shortened, the points of intersection of the grid lines with pharyngeal structures shifted. Figure 4 illustrates the pattern of pharyngeal shortening observed during 5-mL liquid swallows and the effect of this shortening on the anatomic structures intersected by the grid lines. The lower line in Figure 4 depicts the axial level of the valleculae, which elevates an average of i’mm in the course of swallowing. Thus, line 4 was just above the level of the valleculae before initiation of swallowing but distal to the valleculae at the midpoint of the swallow. Lines 1-3, however, were consistently in the retrolingual space. Substantially more shortening was evident in the pharyngeal segment between the superior aspect of the arytenoid and the valleculae, as indicated in Figure 4. On average, the arytenoid and UES were elevated 22 mm by the midpoint of the swallow. Because the mean distance between grid lines was 6

i

1 second

Figure 2. Manometric tracings obtained from one of the subjects during 5- and lo-mL liquid barium swallows. In each panel, the times of arrival of the bolus head (a) and the bolus tail (b) are indicated as determined by playback of the videofluoroscopy. Time b also indicates the timing of luminal closure at the level of the sensor. Thus, the interval a-b indicates the period during which the bolus passes the sensor, and pressure recorded during that period (shaded area) is intrabolus pressure. The major pharyngeal contractile complex occurs after bolus passage; time c indicates the timing of the maximal pressure recorded.

sentative manometric tracings obtained from S3 during 5- and IO-mL swallows showing the relationship of contractile activity to bolus movement. Table 1 summarizes the values of times a, b, and c relative to time 0 as well as the peak value of the pharyngeal contraction (P,,,). Note that the a-b interval but not b-c interval was significantly prolonged during IO-mL swallows. The a-b interval reflects the delay between initial bolus movement and the onset of the pharyngeal contraction, whereas the b-c interval is a characteristic of the pharyngeal contraction wave itself. Thus, volume-dependent modulation of the period of UES opening during swallowing is associated with a delayed onset of the pharyngeal contraction wave relative to bolus propulsion, and consequently UES opening, without significant alteration of the wave form of the pharyngeal contraction itself. Inspection of Figure 2 suggests that times a and b could be estimated without reference to videofluoroscopy as the onset and offset of the intrabolus pressure, respectively. In most instances, values obtained with the aid of fluoroscopy were similar to those obtained by blinded reading of the manometry tracings, but because of a few widely discrepant data points the overall r values for this correlation were

Table 1. Bolus Position Relative to the Manometric Time 5 mL 10 mL NOTE. Times “P < 0.01.

a

-0.10 f 0.02 -0.10 + 0.02 a, b, and c and P,,,

During

Sensor and the Pharyngeal

Time b

Time

0.15 f 0.03 0.23 k 0.03O are as defined

c

0.25 f 0.02 0.33 k 0.02” in Figure

2.

Contractile

Complex

a-b Interval

b-c Interval

0.25 f 0.03 0.32 f 0.03”

0.10 f 0.01 0.10 rtr. 0.01

P,,,

(mm Hg) 103 f 7 90 f 7

PHARYNGEAL

July 1992

CLEARANCE

25 mm ‘20

25

25

20

20

15

15

15

10

10

10

5

5

5

0

0

0 a0

25

25

25

20

20

20

15

15

15

10

10

10

5

5

5

0

0

0

25

25

25

20

20

20

15

15

15

10

10

10

5

5

5

0

0 a o

bL3

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131

bL7

0

a0

a0

bL6

bL9

Figure 3. Anterior-posterior coordinates of the pharyngeal surfaces during 5-mL liquid swallows at the axial levels of grid lines 1-g. Distances are referenced to the anterior surface of the vertebral bodies, and in each tracing the upper line indicates the position of the anterior pharyngeal structure while the lower line indicates the position of the posterior pharyngeal wall. The vertical time line a indicates the timing of the arrival of the bolus head at the manometric sensor and 0 indicates the timing of UES opening. Thus, the interval from time a to 0 approximates the period of bolus head transit through the pharynx. Time b at each axial level indicates the time at which luminal closure had been achieved in half of the test swallows (median closure time). Thus, the interval from bL1 to bLg indicates the period of passage of the tail of the bolus through the pharynx. Time c indicates the timing of P,,, (Figure 2) and is shown only at the level of L2 because this was very nearly the position of the manometric sensor. Each tick on the time axis is 1/3Oth second. Although not shown for reasons of clarity, the maximal SE of data points ranged from 0.5 mm to 0.9 mm for posterior wall data points and from 0.7 mm to 1.4 mm for anterior wall data points among the nine levels.

mm among subjects, this amounts to shifting the upper margin of the UES three lines orad from its initial position (so as to include lines 6-8), thereby positioning it within 1.5 cm of the retrolingual pharynx. Thus, the initial luminal narrowing that occurred before time 0 at levels 6-8 in Figure 3 was a consequence of sphincter elevation, in essence making these lines indicators of sphincter opening and closing during the period of pharyngeal shortening. Table 2 quantifies parameters of pharyngeal shortening during 5- and lo-mL swallows. Although the extent of shortening achieved during 5- and lo-mL swallows was similar, maximal shortening was maintained significantly longer for the larger volume. Times a and b are marked on Figures 3 and 4 to show that the pharynx achieves and maintains its shortened configuration during virtually the entire period of bolus passage. The bolus head rapidly traverses the pharynx between time a and time 0, and the bolus tail traverses the pharynx from time bL1 to bL9. Note that although the pharynx has begun to lengthen by time bL9, lines 7, 8, and 9 all remain

within the white area of Figure 4 during this onset of lengthening (0.4-0.5 seconds), showing that the tail of the bolus is within or below the UES, in essence having already been engulfed by the sphincter. The period of sphincter opening for IO-mL swallows was 0.07 + 0.02 seconds longer than for 5-mL swallows, but maximal pharyngeal shortening was maintained 0.2 seconds longer. Thus, the period of near-maximal pharyngeal shortening is increased along with the a-b interval as part of the volume-dependent modulation of the timing of pharyngeal events. Wall Contributions

to Clearance

Figure 5 illustrates the dynamic behavior of the posterior pharyngeal wall, and Figure 6 shows the dynamic behavior of the anterior pharyngeal surface during 5-mL liquid barium swallows. These two figures contain the same data points as Figure 3 but are presented as surface contour graphs so that the movement patterns of the nine axial levels are more easily related to each other. Several aspects of these figures are notable. Distal propagation of the

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a I

GASTROENTEROLOGY Vol. 103, No. l

0 I

bL1 I

b L9 I L9 L8

L6

‘L4

Time In Seconds

Figure 4. Pharyngeal shortening during 5-mL liquid swallows. Times a, 0, bL1, and bL9, highlighted by vertical lines, are as indicated in the legend of Figure 3. The vertical axis indicates the average positions of grid lines l-6 on the right, converted into millimeters on the left (the mean distance between grid lines among subjects was 6 mm). The functional zones of the pharynx are indicated by shading on the graph; the very lightly shaded area on the bottom indicates the retrolingual propulsive chamber, the next darkest area indicates the region between the valleculae and the superior aspect of the arytenoid, the darkest area indicates the zone from the tip of the arytenoid to the top of the UES, and the white area on top indicates the zone within the UES. Thus, following any grid line across the graph indicates the functional zones of the pharynx encountered by that line in the course of the swallow. For example, L7 is initially between the valleculae and the tip of the arytenoid. However, in the interval from -6.15 to 0.53 seconds, L6 is within the LJESas a result of pharyngeal shortening. Applying this information to Figure 3, panel 7, it becomes apparent that the narrowing observed before time -0.15 (time a is 0.1 seconds) is a consequence of pharyngeal shortening and that the widening after 0.53 seconds (time bL7 is 0.41 seconds) is a consequence of pharyngeal lengthening. Although not shown for clarity, the maximal SE was 1.5 mm for the arytenoid data points and 1.6 mm for the valleculae data points.

posterior wall contraction coincided exactly with passage of the bolus tail through the pharynx but began superiorly after the head of the bolus had already traversed the entire pharynx as demonstrated by the positions of lines indicating times a, 0, and b in Figure 5. The aboral propagation of the contraction is evident by the rightward movement of the shaded stripes, indicating zones of equal distance from the vertebral surface, in Figure 5. Note that the posterior wall bulged 6 mm forward from its resting position in the retrolingual region, whereas distally the contraction only restored the wall to its initial position after having been first compressed against the vertebrae. The anterior pharyngeal surface, shown in Figure 6, showed marked conformational change characterized by proximal widening and distal narrowing before time a, coincident with pharyngeal shortening. Similarly, between time a and time 0, the tongue

base first moves forward and then begins its posterior thrust while the anterior wall of the sphincter is pulled forward (L6-L9). Thus, the initial horizontal motion of the anterior wall occurs before and coincident with passage of the bolus head through the pharynx whereas only the propagated posterior wall contraction coincides with movement of the bolus tail through the pharynx (pharyngeal clearance). Modulation of the period of sphincter opening is achieved by a dissociation between the early anterior wall events and the posterior wall events, as suggested by the modifiability of the a-b interval shown in Table 1. However, the characteristics of the propagated pharyngeal contraction itself are unchanged among swallow volumes, as detailed in Table 3. Although there is a systematic shift in time b with increased bolus volume, the rapidity of propagation and the maximal amount the posterior wall bulged forward are unchanged with the larger-volume swallow. In fact, a graph of the pharyngeal contraction during IO-mL swallows (not shown) appears virtually identical to Figure 5 except for slight prolongation of the a-b interval. As is evident in the Figures 3, 5, and 6, the closure pattern in the retrolingual pharynx is different from that in the more distal zones. In the retrolingual pharynx, the chamber first widens, then narrows by the combination of the posterior wall bulging forward from its resting position and the tongue thrusting back posterior to its resting position, and then widens again after bolus clearance. At the distal levels the pharynx first narrows in association with axial shortening, then widens as a result of traction via the hyoid axis,l and then narrows again as the propagated contraction pulls the pharyngeal walls together, achieving closure at very nearly the same anterior-posterior coordinates occupied in the resting state. Thus, the horizontal motion of the proximal pharynx is in essence 180’ out of phase with the distal pharynx. Discussion gitized

In this study, computer-assisted analysis of divideofluoroscopic swallowing studies was

Table 2. Pharyngeal Shortening During Swallowing 10 mL

5 mL Initial length (mm) Shortening at time 0 (%)” When shortening achieved (s) Persistence of shortening (s)~

47.5 41.4 -0.06 0.50

+ k f +

2 3.6 0.01 0.3

“Time 0 is the time of UES opening. bShortening greater than or equal to the degree “P < 0.05.

48.0 43.5 -0.04 0.70

achieved

f f f f

2 4.3 0.01 0.03”

at time 0.

July 1992

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10 9 8 7 6 5 4 3 2 1 0

Figure 5. Horizontal posterior pharyngeal wall movement during 5-mL liquid barium swallows. The data shown are the average values for 16 swallows. The distance from the pharyngeal wall to the anterior surface of the vertebral bodies at each level is shown on the z axis, the key on the right applying to the shading of the surface graph. Time is on the x axis, time 0 indicating UES opening, time a indicating bolus head contact with the sensor at the level of L2, and time b indicating the time at which luminal closure had been achieved in half of the cases (median closure time) at each axial level. Axial levels Ll-L6 correspond to the grid lines of Figure 1,and line b intersects with Ll-L6 at times bL1-bL6, respectively. Because UES opening corresponds with the arrival of the bolus head at the sphincter, the interval a-0 (0.1 seconds) approximates the period during which the holus head traverses the pharynx. The holus tail traverses the pharyngeal grid between the interval from bL1 to bL6 (0.37 seconds). Note that the period of bolus head passage precedes any significant contractile activity of the pharyngeal constrictors but that the pharyngeal constrictor contraction is intimately associated with passage of the bolus tail through the pharynx.

used to examine the mechanics of the deglutitive pharyngeal contraction with relation to UES opening, intraluminal pressure recording from within the pharynx, and bolus transport through the pharynx. The analysis emphasized that there are two components of the deglutitive pharyngeal contraction: longitudinal shortening with consequent laryngeal elevation and an aborally propagated, lumen-obliterating horizontal contraction. Although both elements of the pharyngeal contraction are tightly integrated into the swallow response, each has unique functional attributes. Pharyngeal shortening, largely attributable to stylopharyngeus contraction, is a major component of the conformational change that occurs early in the swallow as the pharynx is transformed from respiratory to gustatory conduit.7 Because the majority of pharyngeal shortening occurred in the segment between the valleculae and the superior margin of the arytenoid, shortening had the effect of closely approximating the UES to the tongue base, leaving only a 1.5-cm transition zone between them. Thus, the laryngeal vestibule and pyriform sinuses were vir-

tually obliterated during the period of bolus transit through the pharynx, “avoiding the problem” of postswallow residue in these areas. Shortening occurred as the bolus head traversed the pharynx and was maintained at a given axial level until after passage of the bolus tail at that level. The prolonged period of bolus transit through the pharynx associated with larger-volume swallows was matched by a proportionately prolonged duration of pharyngeal shortening. The period of deglutitive pharyngeal shortening is also subject to some element of volitional control, as shown by its marked prolongation during use of the “Mendelsohn maneuver.“’ Although the indicators of pharyngeal shortening used in this study (elevation of the valleculae and arytenoid relative to the vertebrae) reflect anterior wall motion, substantial evidence suggests that shortening in the anterior pharyngeal wall is paralleled in the posterior pharyngeal wall. During videofluorostopic swallowing studies obtained with radiopaque suction cups attached to the posterior pharyngeal wall, Palmer et al. observed degrees of shortening nearly identical to those measured in the present

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Figure 6. Anterior pharyngeal wall movement in the horizontal plane during 6-mL liquid barium swallows. All three axes and times a, b, and 0 are as described in the legend of Figure 5. Interpretation of the contour of the anterior pharyngeal surface is more complicated than that of the posterior surface because of the effect of pharyngeal shortening. Inspection of Figure 4 suggests that pharyngeal shortening is fully achieved shortly after time a. In conjunction with anterior tongue ramping, this results in widening of the pharynx in the retrolingual area (LI-L3) and substantial narrowing at the levels of grid lines L&L9. At the levels of L4 and L5, the luminal narrowing is a consequence of arytenoid to epiglottic approximation that has the effect of obliterating the laryngeal vestibule. The pharyngeal lumen narrows to the point of closure at L6-L9 because of the elevation of the UES. At time 0, the retrolingual pharynx is beginning its posterior thrust while the anterior surface of the UES is being pulled forward; minimal anterior wall movement is occurring at time b.

studies by Nilsson et al. have shown that the prevertebral space at the level of the larynx and hypopharynx is composed of a thin layer of fatty tissue and that a distinct slit along the prevertebral fascia through this tissue allows for the larynx, trachea, and attached UES to move up and down in unison

study (25 mm at the level of the UES).’ Detailed fluoroscopic and manometric analyses of the axial motion of the UES high-pressure zone during swallow support both the degree of elevation observed in this study and the prolongation of elevation associated with larger-volume swallows.4 Finally, cadaveric

Table 3. Timing, Position, and Propagation

ofLumina1

Closure During 5- and IO-mL Swallows

5-mL swallows Time b”

Ll L2 L3 L4 L5 L6 L7 LB L9

0.12+ 0.14* 0.22+ 0.27f 0.32+ 0.37+ 0.41+ 0.44+ 0.48f

0.01 0.01 0.02 0.01 0.01 0.01 0.02 0.02 0.02

Velocity

(cm/s) -

40 +15 13 f 2 17 f 5 15 * 2 15 + 2 21 * 7 24 k 5 22 * 5

lo-mL PW bulge”

6.5+ 5.7+ 5.2+ 4.4f 2.9f 1.9+ 1.8k 1.7* 1.5t

0.4 0.3 0.4 0.3 0.3 0.3 0.3 0.3 0.3

Time

b

0.17rtO.Olb 0.22* O.Olb 0.31f O.Olb 0.33+ O.Olb 0.39f 0.02b 0.42f 0.02b 0.46f O.OZb 0.50f 0.02b 0.55f 0.02b

swallows

Velocity

14 f 13 f 12 f 12 + 18 k 17 k 14 + 20 +

(cm/s)

1.8 1.6 1.7 2.0 2.5 2.6 2.8 5.8

PW bulge”

5.8k 5.5* 4.6f 3.1k 2.3k 1.4? 1.2+ 0.6f 0.6f

0.5 0.4 0.4 0.3 0.3 0.3 0.3 0.3 0.2

NOTE. Although time b and consequently the timing of luminal closure is systematically delayed with the 10-mL swallows, there was no difference in the local propagation velocity or in the extent of the posterior wall bulge between swallow volumes. Data are presented as means f SEM. “Maximal amount the posterior wall bulged forward during the propagated contraction.

bP i 0.05vs.5.mL values.

July 1992

during swallowing without oblique forces acting on the sphincter.g In contrast to the longitudinal pharyngeal contraction, the aborally propagated horizontal contraction began late in the swallow as the bolus tail traversed the pharynx. The corresponding position of the bolus head at the onset of the horizontal contraction is bolus volume dependent,3 but for the 5- and lo-mL volumes used in this work the bolus head had completely traversed the pharynx before its onset. Sequencing of the horizontal contraction coincided precisely with clearance of the bolus tail from the pharynx, supporting the suggestion of Cerenko et al.” that the propagated contraction is primarily a pharyngeal clearance event rather than an element of bolus propulsion. Aboral sequencing of the pharyngeal stripping wave is probably entirely a function of the posterior wall because no detectable sequencing occurs in the electromyographic activity of the tongue base,““’ and distal to the tongue the anterior pharyngeal wall is composed of cartilaginous structures (i.e., the underside of the epiglottis overlying the arytenoids superior to the UES and the cricoid plate within the sphincter itself). Our findings suggest that the propagated pharyngeal contraction is a highly stereotyped event within subjects and among swallow volumes in terms of propagation velocity, extent of contraction, and maximal contractile pressure achieved. Ekberg et al. similarly found minimal variability in propagation velocity with varied bolus volume.‘3 Recent investigations have shown that one mechanism by which larger volumes are accommodated during swallowing is prolongation of the interval of UES opening. The present study suggests that this prolongation is achieved as a result of a modifiable linkage between the events associated with the opening of the sphincter (pharyngeal shortening, laryngeal closure, and anterior distraction of the cricoid) and events leading to sphincter closure (the aborally propagated transverse pharyngeal contraction). The interval between opening and closing events (the a-b interval) increased proportionately with bolus volume, thereby increasing the period of UES opening without altering either the opening’ or closing events. A possible sensory cue modified by bolus volume is proprioceptive information from the tongue, which is deformed before swallowing in proportion to bolus volume. Bolus propulsion probably occurs as a result of the posterior oral tongue action against the palate. The description of the deglutitive pharyngeal contraction discussed above suggests two mechanisms of possible unilateral or bilateral impairment; reduced shortening or an impaired clearing wave. In either event, the consequence would be hypopharyngeal

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135

residue as suggested by clinical observations.‘“~‘4 However, impaired shortening and an impaired clearing wave have different clinical implications. In one case it is possible to train individuals to accentuate laryngeal elevation, which is subject to some volitional contro1,2”5 but in the other case present treatment is limited to compensations such as head turning to exclude the paretic side of the pharynx if unilateral or a postswallow cough to clear residue if it is bilateral.‘4~‘” It also becomes apparent that the clinical assessment of pharyngeal function must include determination of effective shortening, timing of shortening relative to bolus transit, and finally the characteristics of the propagated posterior wall contraction itself. Videofluoroscopic study is ideally suited to this task, but evaluation of pharyngeal function from manometric data alone is inadequate and can result in serious informational disparities. Pharyngeal manometry recordings reflect only the horizontal component of the pharyngeal contraction, and the most obvious feature of the manometric record, the time and value of maximal pressure, is of unclear functional significance. Maximal contractile pressure occurs after luminal closure, and the timing and effectiveness of luminal closure during pharyngeal clearance require evaluation because these are of the greatest functional significance. References Iacob P, Kahrilas ageal sphincter Gastroenterology

PJ, Logemann JA, Shah V, Ha T. Upper esophopening and modulation during swallowing. 1989:97:1469-1478.

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Received October 7,1991. Accepted January 7, 1992. Address requests for reprints to: Peter J. Kahrilas, M.D., Northwestern University Medical School, GI Section, Department of Medicine, Suite 1526, Wesley Towers, 250 East Superior Street, Chicago, Illinois 60611. Supported by grants no. 1 R01 DC00646-OlAl from the Public Health Service (P.J.K.), no. P01-CA-40007 (J.A.L.), and no. l-ROlNS28525-01 (J.A.L. and P.J.K.). Presented in part at the 1991 meeting of the American Gastroenterological Society, New Orleans, Louisiana, and published in abstract form (Gastroenterology 1991;10O:A455, Gastroenterology 1991;100:A440).

Pharyngeal clearance during swallowing: a combined manometric and videofluoroscopic study.

The deglutitive pharyngeal contraction was analyzed using simultaneous videofluoroscopic and manometric studies of eight volunteers. Anterior, posteri...
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