Showing papers in "Dysphagia in 1997"

The natural history of dysphagia following a stroke.

Abstract: To assess the frequency and natural history of swallowing problems following an acute stroke, 121 consecutive patients admitted within 24 hours of the onset of their stroke were studied prospectively. The ability to swallow was assessed repeatedly by a physician, a speech and language therapist, and by videofluoroscopy. Clinically 51% (61/121) of patients were assessed as being at risk of aspiration on admission. Many swallowing problems resolved over the first 7 days, through 28/110 (27%) were still considered at risk by the physician. Over a 6-month period, most problems had resolved, but some patients had persistent difficulties (6, 8%), and a few (2, 3% at 6 months) had developed swallowing problems. Ninety-five patients underwent videofluoroscopic examination within a median time of 2 days; 21 (22%) were aspirating. At 1 month a repeat examination showed that 12 (15%) were aspirating. Only 4 of these were persistent; the remaining 8 had not been previously identified. This study has confirmed that swallowing problems following acute stroke are common, and it has been documented that the dysphagia may persist, recur in some patients, or develop in others later in the history of their stroke.

Mealtime Difficulties in a Home for the Aged: Not Just Dysphagia

Abstract: A mealtime screening tool was administered to 349 residents of a home for the aged to determine the prevalence of mealtime difficulties including, but not limited to, dysphagia. Mealtime difficulties, as assessed during a single meal observation of each resident, were documented in 87% of these individuals. Though 68% exhibited signs of dysphagia, 46% had poor oral intake, 35% had positioning problems, and 40% exhibited challenging behaviors. An increased prevalence of mealtime difficulties was related to both the presence and degree of cognitive impairment. Oral intake was best among residents with severe cognitive impairment, many of whom received partial to total feeding assistance. In contrast, poor oral intake was associated with mild-moderate cognitive impairment, pointing to a need for more aggressive intervention with this group. The results clearly demonstrate that the prevalence of a wide range of eating-related problems far exceeds accepted estimates of dysphagia alone and support a multidisciplinary approach to mealtime interventions for the institutionalized elderly. Additionally, the magnitude of problems identified has implications for both resource and staff-training requirements in long-term care facilities.

Pharyngo-esophageal dysphagia in Parkinson's disease.

Abstract: The radiologic characteristics of pharyngoesophageal (PE) dysfunction in Parkinson's disease (PD) are not well established, partly because most previous studies have examined only small numbers of patients. We administered a dynamic videofluoroscopic swallowing function study to 71 patients with idiopathic PD. Using the Hoehn and Yahr disease severity scale, patients were subdivided into those with mild/moderate disease, subgroup I (n = 38), and advanced PD disease, subgroup II (n = 33). From pharyngeal ingestion to gastric emptying, bolus transport was normal in only 2 patients. The most common abnormalities occurring during pharyngeal ingestion included impaired motility, vallecular and pyriform sinus stasis, supraglottic and glottic aspiration, and deficient epiglottic positioning and range of motion. Esophageal abnormalities were multiple but most commonly included delayed transport, stasis, bolus redirection, and tertiary contractions. Typical aberrations of lower esophageal sphincter (LES) function included an open or delayed opening of the LES and gastro-esophageal reflux. A pathogenesis linking PE with the pathology of PD is proposed.

The Role of the Insular Cortex in Dysphagia

Abstract: Recent data indicate that dysphagia may occur following unilateral cortical stroke; however, the elucidation of specific cytoarchitectonic sites that produce deglutition disorders remains unclear. In a previous study of unilateral cortical stroke patients with dysphagia, Daniels et al. [8] proposed that the insula may be important in swallowing as it was the most common lesion site in the patients studied. Therefore, 4 unilateral stroke patients with discrete lesions of the insular cortex were studied to further facilitate understanding of the role of the insula in swallowing. Dysphagia, as confirmed by videofluoroscopy, was evident in 3 of the 4 patients; all had lesions that involved the anterior insula, whereas the only patient without dysphagia had a lesion restricted to the posterior insula. These data suggest that the anterior insula may be an important cortical substrate in swallowing. The anterior insula has connections to the primary and supplementary motor cortices, the ventroposterior medial nucleus of the thalamus, and to the nucleus tractus solitarius, all of which are important regions in the mediation of oropharyngeal swallowing. Therefore, discrete lesions of the anterior insula may disrupt these connections and, thereby, produce dysphagia.

Eating changes in mild-stage Alzheimer's disease: a pilot study.

Abstract: Eating impairment is well documented in the late stage of Alzheimer's disease (AD) but when these eating changes actually begin in the disease process is not known. Eating was defined as consisting of two components, self-feeding and swallowing. Self-feeding and swallowing of healthy elderly were compared with a group of individuals with mild AD. AD subjects received significantly more partner-initiated cues or direct assistance than controls. In addition, subject-initiated cued behaviors occurred more frequently in the AD group. AD subjects demonstrated significantly prolonged swallow durations for the oral transit duration (cookie), pharyngeal response duration (liquid), and total swallow duration (liquid). This pilot study suggests that self-feeding and swallowing changes may occur early in the course of AD.

Mechanisms involved in postdeglutition retention in the elderly.

Abstract: This study examines possible quantifiable causes of postdeglutition pharyngeal retention in the elderly. Manofluorography and computer processing of video images are performed. Retention in the valleculae and in the piriform sinuses is associated with a markedly reduced pharyngeal shortening, a low tongue driving force (TDF), and a diminished amplitude of the pharyngeal contraction. There is no relationship with the hypopharyngeal suction pump (HSP). Retention limited to the valleculae is associated with a low TDF, and retention restricted to the piriform sinuses is accompanied by a reduced pharyngeal shortening.

Dysphagia following Anterior Cervical Spine Surgery

Abstract: Although previous reports have identified dysphagia as a potential complication of anterior cervical spine surgery (ACSS), current understanding of the nature and etiologies of ACSS-related dysphagia remains limited. The present study was undertaken to describe the patterns of dysphagia that may occur following ACSS. Thirteen patients who exhibited new-onset dysphagia following ACSS were studied retrospectively by means of chart review and videofluoroscopic swallow study analysis. Results indicated that a variety of swallowing impairments occurred following ACSS. In 2 patients, prevertebral soft tissue swelling near the surgical site, deficient posterior pharyngeal wall movement, and impaired upper esophageal sphincter opening were the most salient videofluoroscopic findings. In another 5 patients, the pharyngeal phase of swallowing was absent or very weak, with resulting aspiration in 3 cases. In contrast, an additional 4 patients exhibited deficits primarily of the oral preparatory and oral stages of swallowing including deficient bolus formation and reduced tongue propulsive action. Finally, 2 patients exhibited impaired oral preparatory and oral phases, a weak pharyngeal swallow, as well as prevertebral swelling. Thus, a variety of swallowing deficits, due possibly to neurological and/or soft tissue injuries, may occur following ACSS.

Dysphagia--ingestion or deglutition?: a proposed paradigm.

Abstract: The current classifications of dysphagia are based on local structural or central nervous system pathology causing dysfunction of the aerodigestive tract. The result is a clinical science grounded in the analysis of the swallow with its lingual, pharyngeal, and esophageal stages. Adding bolus preparation to the swallowing paradigm improves but still constrains the study of dysphagia and treatment of the dysphagic patient. Those pre-oral facets of mealtime behavior that may evoke or exacerbate dysphagia remain beyond the existing classification boundaries imposed by the conceptual swallow and anatomic aerodigestive tract. We offer a more inclusive strategy for investigating dysphagia based on a five-stage process of ingestion: pre-oral (anticipatory), preparatory, lingual, pharyngeal, and esophageal. The first stage considers the interaction of pre-oral motor, cognitive, psychosocial, and somataesthetic elements engendered by the meal. The limited literature regarding the interaction of the pre-oral stage with other ingestion stages, in both normal subjects and patients with cortical, basal ganglia, and psychogenic diseases, is reviewed. The neurophysiologic and clinical justifications for embracing a pre-oral stage, and thus for the paradigm shift from deglutition to ingestion, are presented.

Surface electromyographic characteristics of swallowing in dysphagia secondary to brainstem stroke.

Abstract: Surface electromyography (SEMG) provides an noninvasive avenue for evaluating swallowing physiology. This report describes SEMG characteristics associated with swallow attempts in 6 dysphagic patients who had suffered brainstem stroke compared with 6 age and gender-matched controls. Results indicated that patients with dysphagia secondary to brainstem stroke differed in both amplitude and timing aspects of swallowing attempts from asymptomatic controls. Specifically, the results indicated that during swallow attempts, dysphagic patients produced more muscle activity over a shorter duration and with less coordination than controls. Potential physiological mechanisms of these results are discussed.

A Pilot Exploratory Study of Oral Electrical Stimulation on Swallow Function following Stroke: An Innovative Technique

Abstract: This pilot study investigated the effect of oral electrical stimulation on swallow function in stroke patients with chronic dysphagia. The purpose was to determine whether an innovative technique could make an improvement in swallow function that might be developed as a potential treatment for patients with persistent dysphagia. Four stroke patients with chronic dysphagia were recruited on the basis of videofluoroscopic findings of a delayed swallow reflex. A single case design was used. Oral electrical stimulation of swallowing was carried out using a palatal prosthesis starting at an output pulse of 0.5 mA, with a fixed duration of 200 μsec, repeated at 1-sec intervals. Barium paste (1 × 5 ml) was introduced at the level of the patient's maximum tolerance of stimulation and any effect on swallow function was recorded by videofluoroscopy. The findings from the pilot study indicated that oral electrical stimulation resulted in an improvement in swallow function in 2 of the 4 patients. The stimulation was well tolerated in all cases with no serious adverse effects. These early results are promising, but further research is needed.

A Comparison of Consistency and Taste of Five Commercial Thickeners

Abstract: This study presents the results of a blinded test of the performance of five commercial thickeners. Experimental variables considered are brand of commercial thickener, type of liquid, desired thickness, and thickening time. Success of outcome is defined by a numerical rating scale comparing the consistency and taste to actual liquid samples. The findings suggest that no one commercial thickener consistently produces a desired consistency or was consistently superior regarding taste. Success in producing certain liquid consistencies and ``good taste'' varied according to brand, type of liquid, desired thickness, and thickening time used. It is suggested that specific recipes be developed for each brand and liquid to be thickened. Flavorings should be tested to enhance taste.

Neuroleptic-induced dysphagia.

Abstract: Neuroleptic medications may result in extrapyramidal symptoms that can affect swallowing. Both oral and pharyngeal phases of swallowing may be affected. Unlike the more common causes of dysphagia, especially in the elderly, drug-induced dysphagia may be reversible. This report describes a case of neuroleptic-induced dysphagia in an elderly male with Alzheimer's disease. When the loxapine was discontinued, the dysphagia improved significantly.

Predictors of Outcome following Cricopharyngeal Disruption for Pharyngeal Dysphagia

Abstract: The indications for, and predictors of outcome following cricopharyngeal disruption in pharyngeal dysphagia are not clearly defined. Our purpose was to examine the symptomatic response to cricopharyngeal disruption, by either myotomy or dilatation, in patients with oral-pharyngeal dysphagia and to determine pretreatment manometric or radiographic predictors of outcome. Using simultaneous pharyngeal videoradiography and manometry, we studied 20 patients with pharyngeal dysphagia prior to cricopharyngeal diltation (n = 11) or myotomy (n = 8), and 23 healthy controls. We measured peak pharyngeal pressure, hypopharyngeal intrabolus pressure, upper esophageal sphincter diameter, and coordination. Response rate to sphincter disruption was 65%. The extent of sphincter opening was significantly reduced in patients compared with controls (p= 0.004), but impaired sphincter opening was not a predictor of outcome. Increased hypopharyngeal intrabolus pressures (>19 mmHg for 10 ml bolus; >31 mmHg for 20 ml bolus) was a significant predictor of outcome (p= 0.01). Neither peak pharyngeal pressure nor incoordination were predictors of outcome. In pharyngeal dysphagia, hypopharyngeal intrabolus pressure, and not peak pharyngeal pressure, is a predictor of response to cricopharyngeal disruption. The relationship between intrabolus pressure and impaired sphincter opening is an indirect measure of sphincter compliance which helps predict therapeutic response.

Videofluoroscopic evaluation of aspiration with visual examination of the gag reflex and velar movement

Abstract: The purpose of the present study was to investigate the relationship between prevalence of aspiration as determined by videofluoroscopic evaluation and prevalence of the gag reflex and velar movement as determined by direct visual examination. One hundred adult patients underwent a videofluoroscopic evaluation of aspiration with either an esophagram (n = 31), upper gastrointestinal series (n = 18), small bowel series (n = 23), or modified barium swallow procedure (n = 28), and concomitant evaluation of the gag reflex and velar movement on phonation. All studies were performed using the lateral, upright position, and all patients drank at least 5 cc of single contrast barium. Aspiration was defined as penetration of material below the level of the true vocal folds. A normal gag reflex and normal velar movement on phonation were observed in 14 of 15 (93%) patients who exhibited objective documentation of aspiration with videofluoroscopy. Conversely, 19 of 20 (95%) patients without a gag reflex were observed with videofluoroscopy to be without aspiration. Normal velar movement on phonation was observed in 99 of 100 (99%) patients. There was no significant age difference between patients with or without a gag reflex. No relationship was found between the prevalence of aspiration and the gag reflex or velar movement on phonation. It was concluded that the presence of a gag reflex does not protect against aspiration, and the absence of a gag reflex does not predict aspiration.

Comparative Review of Techniques for Recording Respiratory Events at Rest and during Deglutition

Abstract: The coordination between swallowing and respiration is essential for safe feeding, and noninvasive feeding-respiratory instrumentation has been used in feeding and dysphagia assessment. Sometimes there are differences of interpretation of the data produced by the various respiratory monitoring techniques, some of which may be inappropriate for observing the rapid respiratory events associated with deglutition. Following a review of each of the main techniques employed for recording resting, pre-feeding, feeding, and post-feeding respiration on different subject groups (infants, children, and adults), a critical comparison of the methods is illustrated by simultaneous recordings from various respiratory transducers. As a result, a minimal combination of instruments is recommended which can provide the necessary respiratory information for routine feeding assessments in a clinical environment.

Lateral Pharyngeal Wall Motion during Swallowing Using Real Time Ultrasound

Abstract: B-mode ultrasound imaging has been used primarily to detect temporal and spatial movements of the tongue during the oral preparatory and oral stages of swallowing. The purpose of this study was to investigate the application of M-mode (motion mode) ultrasound imaging as a method to quantify the duration and displacement of single regions along the lateral pharyngeal wall during swallows of two bolus volumes and during three swallow maneuvers (supraglottic, super-supraglottic and Mendelsohn maneuver). In 5 normal subjects, simultaneous B/M-mode images were captured at two regions along the lateral pharyngeal wall. Computer-assisted video analysis of each swallow sequence provided spatial coordinates and durational measures. Results indicated no significant differences in displacements of the lateral pharyngeal wall across bolus volumes, swallow maneuvers, or recording sites. Significant differences (p < 0.001) in lateral pharyngeal wall duration occurred as a function of volitional swallow maneuvers. Greater durations (p < 0.05) were found for the Mendelsohn and super-supraglottic swallow maneuvers. The data demonstrate that B/M-mode ultrasound imaging provides a simple, noninvasive method to visually examine movements of the lateral pharyngeal wall and may provide a clinical method for assessing the effects of direct swallowing therapies at the level of the mid-oropharynx.

Oral sensory discrimination of fluid viscosity.

Abstract: This study was designed to investigate the ability of normal young adult volunteers to sensorially identify Newtonian fluids of specified viscosities. Twenty subjects, 10 men and 10 women between the ages of 18 and 29 years participated. Seven stimuli, consisting of combinations of corn syrup and water, with viscosities ranging from 2 to 2,240 centipoise (cP) were prepared and characterized using a coaxial rotational viscometer. Subjects were presented with two anchor stimuli representing the extremes of the range of viscosities as a basis from which the experimental stimuli were judged. The seven experimental stimuli were randomly presented to each subject 10 times. The accuracy with which the subjects identified the viscosity of the fluid was significant at p < 0.01. The pattern of response was not significantly different across subjects nor gender. There were no differences in performance throughout the duration of the study. The repeat presentation of the anchor points did not significantly affect performance. Further research on oral perception of viscosity, and the processes that mediate changes in swallow physiology resulting from changes in viscosity is required.

Primary Biliary Cirrhosis, Sicca Complex, and Dysphagia

Abstract: We investigated symptoms suggestive of swallowing problems in patients with primary biliary cirrhosis, some of whom displayed features of sicca complex. A prospective study of 95 consecutive patients with primary biliary cirrhosis was conducted at a single teaching hospital using a questionnaire administered over the telephone. Some symptoms of sicca complex (dry mouth and/or dry eyes) were found in 65 patients (68.4%). Subjective xerostomia alone was present in 45 patients (47.4%). The questionnaire revealed an increase in incidence of dysphagia in xerostomia subjects, affecting 21 of 45 patients, compared with 6 of 50 non-xerostomia patients. Multivariate logistic regression analysis showed that confounding factors such as age, obesity, cigarette smoking, and medications associated with a dry mouth could not explain these findings. Twenty-eight patients complained of hoarseness, 23 of coughing, and 14 of wheezing, all of which were significantly more frequent than in the 50 patients without xerostomia. Heartburn affected 17 xerostomia patients and 15 non-xerostomia patients, indicating no difference in frequency between these two groups, even after age, obesity, cigarette smoking, and medications associated with heartburn were considered in the multivariate analysis. Acid regurgitation, nausea, and vomiting were also similar in frequency between patients with and without xerostomia. Swallowing problems, manifested primarily as dysphagia, are common in primary biliary cirrhosis patients who have subjective xerostomia.

Dysphagia in progressive supranuclear palsy: radiologic features.

Abstract: Progressive supranuclear palsy (PSP) is a progressive degenerative extrapyramidal disease that often masquerades as Parkinson's disease (PD). Similar to PD, dysphagia frequently complicates the course of PSP. Because there is only one published report characterizing dysphagia in PSP, we reviewed the neurologic features and dynamic videofluoroscopic swallowing function study results in 10 dysphagic PSP patients. Abnormalities during multiple stages of ingestion were recorded in each patient. Uncoordinated lingual movements, absent velar retraction or elevation, impaired posterior lingual displacement, and copious pharyngeal secretions were noted in all patients. Tongue-assisted mastication, noncohesive lingual transfer, excessive oral bolus lingual leakage to the pharynx prior to active transfer, vallecular bolus retention, abnormal epiglottic positioning, and hiatal hernias were noted in at least half of the cohort. Although ingestion abnormalities in PSP are similar to those previously reported in PD, the number of studied patients and observed differences were too few to clearly differentiate the two diseases.

Exploration of pharyngeal swallowing by audiosignal recording.

Abstract: The aims of this study were to analyze the following by audiorecording of swallows: (1) the influence on the volume and consistency of ingested substances on the audiosignal recorded during separate swallows; and (2) the characteristics of successive swallows during ingestion of 100 ml of the same substances to define deglutitive behaviors. Volunteers followed two protocols. Protocol (P) 1 comprised ingestion of 100 ml of water or yoghurt in successive swallows and Protocol 2 comprised separate swallows of different volumes of the same substances. Audiosignal recordings were made with a dynamic microphone. The following parameters were measured in P1: total time of ingestion (TT), number of swallows necessary for ingestion (N), and spontaneous swallowing intervals (SI). In P2 the duration (d) of each signal was measured according to consistency and volume. Mean (m) values were then calculated (TTm, Nm, SIm, and dm). During P1, TTm for yoghurt was significantly longer than for water (23.1 vs. 6.5 sec (men) and 21.8 vs. 7.8 sec (women). Nm was also greater for yoghurt (10.1 vs. 4.3 (men) and 10.0 vs. 4.8 (women). Three types of swallowing behavior were defined according to SI: swallowing at regular intervals (Reg) with increasing intervals during ingestion (Prog) and swallowing at variable intervals (Irreg). These patterns did not differ significantly according to sex. In P2 the increase in volume swallowed increased the duration (dm) of the signal for water (600 msec for 5 ml and 960 msec for 15 ml). The dm for yoghurt was significantly less than for water (580 msec for 5 ml and 920 msec for 15 ml). Our technique of recording sounds of pharyngeal swallowing is simple, reproducible, and not expensive. It permitted the analysis of each swallow according to volume and consistency and the determination of three swallowing patterns (Reg, Prog, and Irreg), taking into account the spontaneous swallowing interval. Ingestion by successive swallows could be used to characterize certain pharyngoesophageal motor dysfunctioning in relation to this reference population and to integrate this into a deglutition rehabilitation program.

Gradual onset of dysphagia: a study of patients with oculopharyngeal muscular dystrophy.

Abstract: This study describes five patients with slowly developing dysphagia secondary to oculopharyngeal muscular dystrophy (OPMD), a progressive neurological disorder characterized by gradual onset of dysphagia, ptosis, and facial and trunk limb weakness. OPMD is a genetic disorder that affects formerly healthy adults who typically begin to experience symptoms in the fourth or fifth decade of life. Despite the debilitating nature of the disease, it is common for affected individuals to live to old age. Because of the gradual progression of dysphagia, as well as the deterioration of articulation, resonance, and breath support, patients with OPMD may come to the attention of physicians, nurses, and speech pathologists before a diagnosis is made. We hope to heighten awareness of how these subjects developed strategies to cope with their swallowing problems without medical intervention until the disease was producing marked symptoms. Patients with suspected dysphagia should be questioned about overt problems with eating and swallowing, but also about their adaptations and compensatory strategies. A Clinical Interview Questionnaire is included that may yield additional information about hidden dysphagia.

Experiences with the Montgomery Salivary Bypass Tube (MSBT)

Abstract: Patients with hypopharyngeal and cervical esophageal strictures and fistulas caused by advanced malignancy, ingestion of caustic material, or following surgery or radiation therapy often suffer from marked dysphagia. In such cases the implantation of a Montgomery Salivary Bypass Tube (MSBT) can be an effective therapeutic option to bridge the fistulous tract or bypass a stenosis. Being able to eat and drink without the need for intravenous supplementation or nasogastric or gastrostomy tube feeding in general greatly improves the patient's quality of life. Since 1981 we have successfully inserted the MSBT in 44 cases suffering from dysphagia of different etiology. Our experiences with the indications for implantation, insertion techniques, and postoperative results are presented. Three selected cases of progressive dysphagia in which the MSBT is demonstrated to be the treatment of choice are described in more detail. In one case, a tracheoesophageal fistula and in another a stricture of the upper esophageal sphincter (UES) were bypassed so that oral intake of soft food became possible again. The third patient suffered from a disturbance of the esophageal motility after resection of a Hippel-Lindau tumor in the spinal cord and syringe drainage; even swallowing saliva was impeded. After insertion of a MSBT, uncomplicated soft food intake became possible again.

Incomplete upper esophageal sphincter relaxation: association with achalasia but not other esophageal motility disorders.

Abstract: Incomplete upper esophageal sphincter (UES) relaxation is not well understood. We compared clinical and manometric characteristics of patients with normal and abnormal UES relaxation. Consecutive patients (n = 208) underwent manometric evaluation of the lower esophageal sphincter (LES), esophageal body, and UES/pharynx. The patients were divided into those with abnormal UES relaxation (residual pressure >6.7 mmHg) (n = 21) and normal relaxation (n = 187). Clinical and manometric profiles were compared. Sex, age, and presenting complaint did not correlate with UES relaxation. Normal esophageal peristaltic sequences were more frequently present in the normal UES group (73.6%) compared with the abnormal (55.8%) (p < 0.01). The UES relaxation was shorter in the group with abnormal relaxation (410.0 ms vs. 510.2 ms, p < 0.001). All other manometric parameters were not different between the two groups. When individual manometric diagnoses were analyzed, only achalasia was noted to be more common in the abnormal UES group (23.8% vs. 9.1%, p < 0.05), and a trend was noted toward diffuse esophageal spasm being more common (14.3% vs. 9.6%, not significant). We conclude that incomplete UES relaxation is a rare manometric finding, associated with achalasia and not specifically associated with any other motility disturbance. This finding may represent a secondary response to the poor esophageal emptying seen in achalasia.

Dysphagia in children with oculo-auriculo-vertebral spectrum.

Abstract: Feeding difficulty necessitating tube feeding after the infantile period was seen in 3 children with oculo-auriculo-vertebral spectrum. Videofluorographic imaging showed impaired pharyngeal function, which was thought to result from dysplasia of the pharyngeal muscles. Note should be made of feeding difficulty in patients with oculo-auriculo-vertebral spectrum.

Artificial Control of Glottic Adduction for Aspiration by Orderly Recruitment in the Canine

Abstract: Laryngeal adduction for swallowing chiefly involves contraction of the thyroarytenoid and lateral cricoarytenoid muscles to seal the glottic chink. Vocal cord elongation supplements closure through cricoarytenoid activation. Relaxation of the posterior cricoarytenoid muscle is also involved in the swallowing process. Recent interest has focused on stimulating the laryngeal nerves to protect the lower airway from conditions where normal muscular coordination may be disrupted (e.g., in aspiration following stroke). Unfortunately, electrical stimulation results in a generalized contraction of all the dependent intrinsic laryngeal muscles because the larger, more excitable axons fire before their smaller counterparts can be activated. In the physiological state, however, the smaller fibers are recruited first. The current study focuses on electronic manipulation of force in the glottic muscles involved in deglutition. We used a stimulator that could selectively activate the intrinsic laryngeal muscles based on their specific motor unit architectures. In 5 dogs, the circuit recruited the axons in the recurrent and superior laryngeal nerves from small to large. The muscles were identified according to the differential recruitment rates of their compound muscle action potentials as they appeared on the graph. The smaller axons in the thyroarytenoid recruited faster than the large ones found in the lateral cricoarytenoid muscles, with intermediate figures observed with the cricothyroid. The posterior cricoarytenoid presented with the slowest recruitment rates, as expected from this muscle's highest contingent of larger motor units. Latencies between the onsets of stimulations and muscle saturations also appeared stable. This approach to manipulating glottic force saves energy because it allows stimulating the adductory muscles with minimal interference from their abductor antagonist.

Isolated Lower Esophageal Sphincter Relaxation as ''Wave-Suppressed'' Secondary Peristalsis

Abstract: Esophageal venting following air insufflation may occur by secondary peristalsis or by isolated transient lower esophageal sphincter relaxation (TLESR). To identify factors determining venting by these two mechanisms, we analyzed the responses to esophageal air insufflation in 4 infants and in 2 adults. We used a nine-lumen dual-Dent-sleeve manometric catheter with an air insufflation esophageal side hole, identifying swallowing by pharyngeal manometry or submental electromyography. The time from the venting lower esophageal sphincter relaxation (whether part of a secondary peristalsis or an isolated TLESR) to the next swallow (whether spontaneous, in the infants, or on command, in the adults) was characterized as ≥15 sec or <15 sec. Of the 25 evaluable trials, the subsequent swallow was ≥15 sec after the venting response in 9 instances and <15 sec afterward in 16 instances. Eight of the 9 trials with delayed swallows (≥15 sec) were vented by secondary peristalsis, whereas 11 of the 16 with early swallows (<15 sec) were vented by TLESR (X2p < 0.01). TLESRs may be induced by esophageal stimuli, in which case they may represent ``wave-suppressed'' secondary peristaltic complexes.