Lateral pharyngeal wall motion during swallowing using real time ultrasound

Methodological Procedures to Acquire and Analyze Ultrasound Images of Swallowing: A Scoping Review

This scoping review aimed to identify methodological procedures for acquiring and analyzing ultrasound images related to swallowing in adults and older adults. The inclusion criteria were based on the PCC strategy (participants, concept, and context), as follows: population (adults and older adults), concept (ultrasound assessment), and context (swallowing assessment). The review included observational, experimental, descriptive, and analytical studies and excluded those that were not available in full, animal studies, in vitro studies, letters to the editor, errata, study protocols, and those that used ultrasound for purposes other than swallowing. There were no language and time restrictions. Two independent blinded professionals selected 81 articles that met the inclusion criteria from different databases. The most evaluated parameters included tongue morphology and movements, hyoid bone displacement, swallowing muscle area, and pharyngeal residue detection, such as pharyngeal wall mobility. They used convex and linear transducers (3 MHz to 8 MHz) positioned in the submental, laryngeal, and lateral regions of the neck. The subjects were seated and instructed to eat different food volumes and consistencies. The literature mapping showed that ultrasound is a promising diagnostic tool, helping clinicians understand swallowing disorders, as it provides static and dynamic images in different modes and positions. Also, patients receive real-time biofeedback of changes related to dysphagia.

Application of Real-time Submental Ultrasonography to Assess Swallowing

Background

Speech and swallowing dysfunction are common problems in head-and-neck cancer (HNC) survivors. Ultrasound (US) is a good method to assess suprahyoid muscles and hyoid bone movement, and it can provide valuable information on swallowing. The aims of this study were to measure the biometry of the supraglottic muscles and hyoid bone movement during swallowing and elucidate the application of real-time US for assessing swallowing dysfunction.

Methods

We collected data from HNC and thyroid cancer patients with dysphagia symptoms and healthy controls without a history of cancer or dysphagia symptoms for comparison. Real-time submental US was used to check the anterior belly of the digastric muscle, geniohyoid (GH) muscles, and hyoid bone movement during swallowing. Logistic regression analysis was used to explore significant US predictors of dysphagia. Based on the regression coefficients of independent variables, we established the nomogram prediction model for dysphagia.

Results

There were significant differences in GH size at contraction, GH size increase percentage, GH length at rest, GH length increase percentage, anterior displacement of the hyoid bone and superior displacement of the hyoid bone between the cancer survivors with dysphagia and volunteers without dysphagia. In multivariate logistic analysis, after adjusting for sex and age, the proportion of GH length contraction <22% (odds ratio [OR]: 6.8 95% confidence interval [CI]: 1.1-42.6) and hyoid bone superior displacement <3.3 mm (OR: 10.7, 1.8-64.1) were associated with a higher risk of dysphagia (P < 0.05).

Conclusion

We confirmed that GH muscle and hyoid bone movement are important for normal swallowing function. US is a good method to assess the suprahyoid muscles and hyoid bone movement, which could provide valuable information on swallowing.

Ultrasonography for Eating and Swallowing Assessment: A Narrative Review of Integrated Insights for Noninvasive Clinical Practice

Dysphagia is a syndrome of abnormal eating function resulting from a variety of causative diseases, and is associated with malnutrition. To date, the swallowing function has been difficult to examine without the use of invasive and expensive methods, such as the videofluorographic swallowing study or fiberoptic endoscopic evaluation of swallowing. In recent years, progress has been made in the clinical application of ultrasound equipment for the evaluation of body compositions near the body surface, including the assessment of nutritional status. Ultrasound examination is a noninvasive procedure and relatively inexpensive, and the equipment required is highly portable thanks to innovations such as wireless probes and tablet monitoring devices. The process of using ultrasound to visualize the geniohyoid muscle, digastric muscle, mylohyoid muscle, hyoid bone, tongue, masseter muscle, genioglossus muscle, orbicularis oris muscle, temporalis muscle, pharynx, esophagus, and larynx, and the methods used for evaluating these structures, are provided in this study in detail. This study also aims to propose a protocol for the assessment of swallowing-related muscles that can be applied in real-world clinical practice for the diagnosis of sarcopenic dysphagia, which can occur in elderly patients with sarcopenia, and has received much attention in recent years.

The prognostic role of ultrasound and magnetic resonance imaging in obstructive sleep apnoea based on lateral oropharyngeal wall obstruction

PURPOSE

This study examined the prognostic value of the lateral pharyngeal wall (LPW)-based obstruction and obstructive sleep apnoea (OSA) prediction using ultrasound (US) and MRI (magnetic resonance imaging).

METHODS

One hundred patients with and without OSA were enrolled, according to overnight polysomnography. The LPW thickness (LPWT) was measured using a Philips Ingenia 1.5 T MRI device, and US measurements were carried out at rest and during Müller's manoeuvre (MM) with a Samsung RS85 device. The obstruction was localised under drug-induced sleep endoscopy.

RESULTS

Significantly greater LPWT using MRI was observed in the OSA group compared to the control group, while US results showed a significant difference only in the case of LPWT during MM on the left side. Obese patients presented significantly higher LPWT values. A significant correlation between BMI and LPWT was observed. Men presented significantly higher LPWT MRI values and left-sided LPWT using US compared to women. LPWT and AHI parameters were significantly correlated. The severity of LPW obstruction correlated with LPWT, while the LPW collapse significantly correlated with AHI. The severity of LPW collapse differed depending on the AHI values. Using US LPWT values and anthropometric parameters, a 93% effectiveness in OSA prognostication and 89% in LPWT-based obstruction were detected. MRI detected OSA in 90% and LPW-based obstruction in 84%. US successfully detected LPW-based collapse severity in 67%.

CONCLUSION

US LPWT measurements were helpful in detecting OSA and LPWT-based obstruction. These examinations may be useful for surgical planning.

Emerging Role of Ultrasound in Dysphagia Assessment and Intervention: A Narrative Review

Ultrasonography has gained increasing attention as a non-invasive and radiation-free instrument for the assessment of swallowing function. In the past decades, an extensive repertoire of ultrasonographic techniques, such as, B-mode dynamic scanning, pixel analysis, M-mode, Doppler, 3D reconstruction, and sonoelastography, has been applied in the evaluation of oropharyngeal structures and movement. Yet, a universal consensus on the examination protocols and clinical implications remains to be established. This review aimed to provide a brief introduction of the application of ultrasound in dysphagia assessment and intervention, encompassing the ultrasonography of swallowing-related muscles, tongue movement, and hyolaryngeal excursion, as well as ultrasound-guided interventions in the management of dysphagia. In addition to non-invasiveness, ultrasonography, a portable, easy to use, and low-cost technique, could compliment videofluoroscopic swallowing study as a first-line screening and follow-up tool for the evaluation of swallowing function, although further study is warranted to provide quantitative diagnostic and prognostic values. Finally, ultrasonography aids in the precisely targeted injection of botulinum toxin in patients exhibiting oropharyngeal muscle spasticity.

Application of Ultrasound Biofeedback to the Learning of the Mendelsohn Maneuver in Non-dysphagic Adults: A Pilot Study

This study aimed to investigate the application of ultrasound to the learning of swallowing maneuver. Forty non-dysphagic adults of both genders who were naïve to the Mendelsohn maneuver participated in the study. They were randomly assigned to receive ultrasound or surface electromyography (sEMG) as biofeedback when acquiring the Mendelsohn maneuver. Thirty-eight subjects (n = 19) completed the Learning phase. Accuracy of executing the Mendelsohn maneuver was measured immediately (Post-training percentage accuracy) and one week post-training (Retention percentage accuracy). Whereas comparable numbers of training blocks were completed by the two groups (t(31.51) = 3.68, p = 0.330), the Ultrasound group attained significantly higher percentage accuracies than the sEMG group at both Post-training (t(28.88) = 4.04, p < 0.001, d = 1.309) and Retention (t(30.78) = 2.13, p = 0.042, d = 0.690). Ultrasound is a more effective biofeedback than sEMG in the acquisition of the Mendelsohn maneuver and may be adopted to the rehabilitative treatment for dysphagic individuals. Non-specificity of sEMG as biofeedback should be emphasized when it is employed in the training and learning of swallowing maneuvers. Findings from the present study suggest that ultrasound is preferable to sEMG as biofeedback in the learning of the Mendelsohn maneuver.

Reliability of Ultrasonography in Evaluating Hyoid Bone Movement

Background

Timely and adequate laryngeal elevation along with hyoid bone movement is an essential component of the swallowing movement under normal physiological conditions. The purpose of this study was to verify the reproducibility of using ultrasonography to evaluate hyoid bone displacement during swallowing through the assessment of inter- and intrarater reliability and examine its accuracy by comparing the results with videofluoroscopic swallowing study (VFSS).

Methods

A self-designed water balloon was fixed to the transducer, which provided good contact between the transducer and the submental skin. Ten participants with dysphagia were recruited. The measurements of hyoid bone displacement using ultrasonography were performed by two of the authors. All the participants underwent ultrasonographic examinations and VFSS within 24 hours.

Results

The intrarater intraclass correlation coefficient (ICC) of the two examiners was 0.996 and 0.959, respectively (p < 0.01); the interrater ICC between the two examiners was 0.892 (p < 0.05). ICCs between VFSS and ultrasonography for two researchers were 0.815 and 0.916 (p < 0.01).

Conclusion

Submental ultrasonography is a reliable and accurate method for assessing the hyoid bone movement.

Análise ultrassonográfica qualitativa e quantitativa da deglutição orofaríngea

RESUMO Objetivo: Analisar a influência do efeito da consistência do alimento e da idade sobre os parâmetros qualitativos e/ou quantitativas no exame ultrassonográfico (USG) da deglutição. Métodos: Foram realizadas avaliações ultrassonográficas da deglutição em 100 indivíduos sadios (divididos em quatro grupos com idades entre 20 e 60 anos) nas consistências líquida e purê. Para análise qualitativa, considerou-se a presença de cinco etapas durante a deglutição orofaríngea. Para a análise quantitativa, foram observados os parâmetros: duração da propulsão da língua durante a deglutição e a distância do deslocamento máximo do osso hióide durante a deglutição. Resultados: Na análise ultrassonográfica qualitativa, todos os indivíduos, independente da faixa etária, apresentaram o mesmo padrão de posição de língua para a recepção e apreensão do alimento e repouso (fases 1, 2 e 5) e houve grande variabilidade inter-sujeitos do movimento ondulatório da língua na fase 3. Na fase 4, o pico máximo do deslocamento do osso hióide aumentou em função da consistência de alimento. Na análise quantitativa, observou-se efeito da idade (p=0,03) e consistência (p=0,00), bem como para a interação entre idade*consistência (p=0,03) nos parâmetros USG analisados. De forma geral, o grupo de indivíduos entre 20 e 30 anos (G1) diferenciou-se dos demais grupos e a consistência purê aumentou os valores de duração e deslocamento. Conclusão: A ultrassonografia do movimento de língua mostrou-se um instrumento viável para avaliar alguns dos parâmetros da deglutição orofaríngea. Idade e consistência alimentar modificam as imagens USG do movimento de língua em indivíduos normais e devem ser consideradas conjuntamente na avaliação ultrassonográfica da deglutição.

Temporal measurements of deglutition in dynamic magnetic resonance imaging versus videofluoroscopy

OBJECTIVES

We undertook to provide data regarding temporal measurements of swallow function obtained by dynamic magnetic resonance imaging in a midsagittal plane and to compare these values to normative fluoroscopy data.

METHODS

Seventeen healthy female volunteers with no swallowing complaints underwent turbo-fast low-angle-shot magnetic resonance imaging with a 3-T scanner while swallowing liquid and pudding boluses delivered via syringe. Ninety sequential images were acquired with a temporal resolution of 113 ms per frame for each swallow. The imaging was performed in the midsagittal plane. The analyses focused on oral and pharyngeal transit times.

RESULTS

All subjects tolerated the protocol without complaints or adverse events. The mean (+/- SD) oral transit times for liquids and pudding were measured as 0.25 +/- 0.09 second and 0.25 +/- 0.13 second, respectively. This difference was not statistically significant (p = 0.74). The mean pharyngeal transit times for liquids and pudding were measured as 0.84 +/- 0.16 second and 1.11 +/- 0.21 seconds, respectively. This difference achieved statistical significance (p < 0.0001). The intrarater and inter-rater reliabilities for the measurements were excellent.

CONCLUSIONS

This sequence provided a high degree of temporal resolution of deglutition in the midsagittal plane. Furthermore, the temporal measurements acquired with dynamic magnetic resonance imaging were reliable and were relatively consistent with those of previous studies done with videofluoroscopy.

Dynamic magnetic resonance imaging of the pharynx during deglutition

OBJECTIVES

We utilized dynamic magnetic resonance imaging to visualize the pharynx and upper esophageal segment in normal, healthy subjects.

METHODS

A 3-T scanner with a 4-channel head coil and a dual-channel neck coil was used to obtain high-speed magnetic resonance images of subjects who were swallowing liquids and pudding. Ninety sequential images were acquired with a temporal resolution of 113 ms. Imaging was performed in axial planes at the levels of the oropharynx and the pharyngoesophageal segment. The images were then analyzed for variables related to alterations in the area of the pharynx and pharyngoesophageal segment during swallowing, as well as temporal measures related to these structures.

RESULTS

All subjects tolerated the study protocol without complaint. Changes in the area of the pharyngeal wall lumen and temporal measurements were consistent within and between subjects. The inter-rater and intra-rater reliabilities for the measurement tool were excellent.

CONCLUSIONS

Dynamic magnetic resonance imaging of the swallow sequence is both feasible and reliable and may eventually complement currently used diagnostic methods, as it adds substantive information.

Lateral pharyngeal wall motion analysis using ultrasonography in stroke patients with dysphagia

We aimed to analyze lateral pharyngeal wall (LPW) motion using ultrasonography. The subjects were stroke patients with dysphagia (n = 26) and normal controls (n = 15). The stroke patients were divided into two groups based on a videofluoroscopic swallowing study (VFSS). Group A (n = 12) had a penetration or aspiration in VFSS findings, while group B (n = 14) had no evidence of a penetration or aspiration. We assessed LPW motion using B/M-mode ultrasonography. We performed the comparative analysis among each group and the relationship between LPW motion parameters and the VFSS parameters of the pharyngeal phase. The mean LPW displacement of group A, B was significantly decreased than that of normal controls. The mean LPW duration of group A, B was increased than that of normal controls, but not statistically significant. The mean LPW displacement of group A was significantly correlated with the residue in valleculae, pharyngeal delay time and laryngeal elevation, but that of group B was not significantly correlated. The mean LPW duration of group A, B was not significantly correlated with the VFSS parameters of the pharyngeal phase. We suggest that LPW motion analysis could be a useful alternative method for the evaluation of the pharyngeal phase in stroke patients with a penetration or aspiration in VFSS findings.

Effects of Mendelsohn maneuver on measures of swallowing duration post stroke

PURPOSE

The purpose of this pilot study was to determine whether intensive use of the Mendelsohn maneuver in patients post stroke could alter swallow physiology when used as a rehabilitative exercise.

METHOD

Eighteen outpatients between 6 weeks and 22 months post stroke were enrolled in this prospective study using a crossover design to compare 2 weeks of treatment with 2 weeks of no treatment. Each participant received an initial videofluoroscopic swallow study (VFSS) and an additional VFSS at the end of each week for 1 month for a total of 5 studies. During treatment weeks, participants received 2 treatment sessions per day performing Mendelsohn maneuvers with surface electromyography for biofeedback. Measures of swallowing duration, penetration/aspiration, residue, and dysphagia severity were analyzed from VFSS to compare treatment and no-treatment weeks.

RESULTS

Significant changes occurred for measures of the duration of superior and anterior hyoid movement after 2 weeks of treatment. Improvements were observed for duration of opening of the upper esophageal sphincter (UES), but results were not statistically significant. Measures of penetration/aspiration, residue, and dysphagia severity improved throughout the study, but no differences were observed between treatment and no-treatment weeks.

CONCLUSIONS

Intensive use of the Mendselsohn maneuver in isolation altered duration of hyoid movement and UES opening in this exploratory study. Results can guide future research toward improved selection criteria and exploration of outcomes. Larger numbers of participants and variations in treatment duration and intensity will be necessary to determine the true clinical value of this treatment.

3 Tesla turbo-FLASH magnetic resonance imaging of deglutition

OBJECTIVES/HYPOTHESIS

In this article we describe a methodology for obtaining high-quality dynamic magnetic resonance imaging (MRI) sequences of the swallow sequence in healthy volunteers. The study includes comparison to previous work done in our lab using a 1.5 Tesla (T) magnet.

STUDY DESIGN

Case series.

METHODS

Three healthy volunteers underwent turbo-fast low angle shot MRI at 3T while swallowing liquid boluses delivered via intravenous tubing to the oral cavity. Imaging was performed in the sagittal and axial planes.

RESULTS

Imaging provided by this sequence provided high temporal resolution, with the ability to depict deglutition in the axial and sagittal planes. Comparison with imaging at 1.5 T demonstrated benefits in temporal resolution and signal-to-noise. Anatomic information provided differed from comparative videofluoroscopy.

CONCLUSIONS

MRI of swallowing using the described technique is reliable and provides a unique evaluation of the swallowing sequence.

Ultrasonographic evaluation of geniohyoid muscle movement during swallowing: a study on healthy adults of various ages

Our purpose in this study was to investigate the application of B+M-mode ultrasound (B/M-mode) imaging as a new approach to quantifying activity patterns of the geniohyoid muscles during swallowing and to assess how these patterns differ according to age and gender. Sixty healthy volunteers (30 men, 30 women) were divided into three age groups (20-39, 40-59, 60-79 years). The subjects were then given 10 ml of mineral water. Ultrasonographic imaging was repeated 5 times and measurements were averaged. Simultaneous B/M-mode images were captured at two regions along the lateral geniohyoid muscle wall. All geniohyoid muscle movement was recorded by real-time B/M-mode. In all cases, ultrasonographic images of the geniohyoid muscle movement during swallowing were easily visualized with the use of real-time B/M-mode. The average moving distance and the duration of movement of the geniohyoid muscle during contraction increased gradually with age. There was a significant difference in ultrasonic measurements of the moving distance and the duration of movement during swallowing between males and females in the three age groups (P < 0.05). B/M-mode imaging provides a simple, noninvasive technique for visual assessment of the lateral geniohyoid muscle wall and may provide a clinical method for evaluating swallowing.

Evaluation of effective dose from a RANDO phantom in videofluorography diagnostic procedures for diagnosing dysphagia

OBJECTIVES

Videofluorography (VF) is useful for diagnosing dysphagia; however, few reports have investigated appropriate effective doses for VF. The present study aimed to estimate the effective radiation dose in VF for diagnosis of dysphagia.

METHODS

Radiation doses to tissues and organs were measured using the anthropomorphic RANDO woman phantom as an equivalent to the human body. Effective doses were estimated according to the recommendations of the International Commission on Radiological Protection (ICRP) 60 in 1990 and IRCP 103 in 2007. The tissues measured were those recommended by ICRP 60 and ICRP 103 including gonads (ovaries and testes), red bone marrow and tissues in which excessive radiation commonly causes malignant tumours including lung, thyroid gland, stomach, large intestine, liver, oesophagus, bladder, breast, bone marrow, skin, brain and salivary gland. Skin dose was also measured using thermoluminescent dosimeters.

RESULTS

Using ICRP 103, the effective dose was estimated as 118.1 μSv at a tube voltage of 50 kV and 82.4 μSv at 45 kV. However, using ICRP 60 the effective dose for 1 min of VF was estimated at 62.4 μSv and 47.2 μSv under the same exposure conditions.

CONCLUSIONS

Using ICRP 103, the effective dose for VF per examination at a total estimation time of 1 min was estimated as approximately 2.5-8.3 times that observed for digital panoramic radiography and 1/12 to 3 times depending on the measurement device for cone beam CT (CBCT). This value can be decreased in the future using a smaller irradiation field and decreased time for examination in VF in the future.

Biomecânica ultra-sonográfica da deglutição: estudo preliminar

OBJETIVO: Verificar, por meio da ultra-sonografia, os parâmetros espaciais do complexo hiolaríngeo na dinâmica da deglutição e a associação entre idade e efeitos. MATERIAIS E MÉTODOS: Neste estudo quantitativo e prospectivo foram incluídos 39 indivíduos sadios, de ambos os gêneros, na faixa etária de 20 a 70 anos (média, 45,56; desvio-padrão, 14,53). Avaliou-se a biomecânica da deglutição correspondente à medida da distância entre a porção superior do osso hióide e a borda superior da cartilagem tireóide, no momento de máxima elevação laríngea. As medidas foram realizadas com a ingestão de alimentos de consistências líquida e pastosa. RESULTADOS: A variação da distância da laringe ao hióide apresentou associação positiva com a idade, somente na deglutição de alimento pastoso, consistência na qual é solicitada maior atividade de propulsão lingual do que nos líquidos. CONCLUSÃO: É possível que o aumento da distância entre o hióide e a laringe, que representa menor elevação laríngea, na deglutição de pastosos, ocorra por efeito do envelhecimento, processo no qual se verifica diminuição de reservas funcionais, mesmo em indivíduos sadios. A ultra-sonografia pode detectar comportamentos relacionados a consistências alimentares, o que mostra sua possível potencialidade diagnóstica na avaliação da deglutição.

Correlation of glottal closure using concurrent ultrasonography and nasolaryngoscopy in children: a novel approach to evaluate glottal status

OBJECTIVES

Endoscopic procedures to assess aerodigestive symptoms by evaluating glottal motion are not practical in neonates because of small nares, respiratory difficulties, or additional stress. Our objective was to determine the temporal correlation between concurrent nasolaryngoscopy (NLS) and ultrasonography (USG) evaluation of glottal motion.

METHODS

Simultaneous USG of the glottis was performed in 10 subjects (5 males, 5 females, age = 4.5 months to 7.1 years) that underwent diagnostic flexible outpatient NLS. The USG transducer was placed on the anterior neck at the level of the vocal cords. The video signals from NLS and USG were integrated and synchronized into real-time cine loops of 1-min duration.

RESULTS

Frame-by-frame evaluation of 10,800 frames identifying glottal opening and closure time was compared between the two modalities by three observers and the timing of glottal closure was marked. Two investigators, blinded to NLS images, identified ultrasonographically determined glottal closure with 99% and 100% accuracy, and the mean probability of missing a closure frame was 0.007 (95% CI = 0.0008-0.024).

CONCLUSIONS

Temporal characteristics of glottal motion can be quantified by USG with perfect reliability and safety. This method can be useful in measuring the presence and the duration of laryngeal adduction.

Dysphagia in stroke patients

Swallowing musculature is asymmetrically represented in both motor cortices. Stroke affecting the hemisphere with the dominant swallowing projection results in dysphagia and clinical recovery has been correlated with compensatory changes in the previously non-dominant, unaffected hemisphere. This asymmetric bilaterality may explain why up to half of stroke patients are dysphagic and why many will regain a safe swallow over a comparatively short period. Despite this propensity for recovery, dysphagia carries a sevenfold increased risk of aspiration pneumonia and is an independent predictor of mortality. The identification, clinical course, pathophysiology, and treatment of dysphagia after stroke are discussed in this review.

A guide to analysing tongue motion from ultrasound images

This paper is meant to be an introduction to and general reference for ultrasound imaging for new and moderately experienced users of the instrument. The paper consists of eight sections. The first explains how ultrasound works, including beam properties, scan types and machine features. The second section discusses image quality, including the interpretation of anatomical features and artefacts seen in the image. The third section discusses the validity of the data collection procedures, including the effects of stabilizing the transducer and head position, and discusses some methods for stabilization. Section four discusses validation of the ultrasound and stabilization systems. The fifth section presents a sample recording set-up, supplemental information, and normalization strategies for sessions and subjects. In section six are methods of extracting contours from ultrasound images, displaying them, and analysing them. The seventh section considers the tracking of pellets on the tongue surface and the differences between tracking tissue points and continuous surfaces. The last section presents methods, challenges and results of 3D, computerized reconstruction of tongue surfaces. An outline of the paper can be found in Appendix I.

Quantitative lingual, pharyngeal and laryngeal ultrasonography in swallowing research: a technical review

Because of its distinct advantage in radiation-free soft tissue imaging, ultrasonography has been widely used to study lingual, pharyngeal, hyoid, laryngeal, and even esophageal action during swallowing in individuals of all ages. Qualitative ultrasonographic observations have made considerable contributions to our understanding of deglutition. Quantitative ultrasonographic swallowing research has also grown by leaps and bounds over the years with advances in imaging technologies and analytical methodologies. As a technical primer for new investigators, this paper reviews the modem methods for quantitative analysis in ultrasonographic swallowing research. The intended outcome is a basic understanding of the application of ultrasonography with various analysis options to the quantitative study of the deglutitive action of selected upper aerodigestive structures. Though proven useful for swallowing research, ultrasonography has inherent limitations and methodological issues. Future technological advancement and sophisticated image processing and analysis algorithms will resolve some of these issues.

Surface electromyography of continuous drinking in healthy adults

OBJECTIVES

To give a description of normal surface electromyography (sEMG) aspects of uninterrupted (continuous) drinking and to establish normal sEMG values for swallowing 100 mL of water.

STUDY DESIGN

Prospective observational study of healthy volunteers.

SUBJECTS

Four hundred twenty apparently healthy male and female volunteers divided into three age groups (18-40, 41-65, 66+ years).

METHODS

The evaluated parameters included the total duration, number of swallows, amount of water per swallow, and voltage of the EMG activity of the orbicularis oris, masseter, and submental-submandibular muscles and the infrahyoid muscle groups covered by the m. platysma.

RESULTS

The overall normal mean values for duration, number of swallows, and amplitude of muscle activity during continuous drinking were compiled. The age-related increase in duration of swallows and of total drinking time was significant only in the older group (95% confidence interval, P < .05). There were no significant sex-related differences for any age group (P > or = .05). The mean electric activity (in muV) varied insignificantly among the age groups. The activity of the m. orbicularis oris was the least informative. An unexpectedly significant number of healthy subjects (14.25%, P < .05) performed a dry swallow after drinking.

CONCLUSION

The establishment of normal sEMG levels now makes this modality applicable for evaluating the swallowing mechanism among adults for potentially identifying and ruling out abnormalities. Its simplicity, noninvasiveness, and low level of discomfort also make it highly suitable for screening purposes.