Kinematic Features of Mandibular Movement during Mastication in Geriatric Individuals Who Are Provided with a Dysphagia Diet at Long-Term Care Facilities.

Providing a normal diet to a care recipient who is unable to form an adequate bolus may cause suffocation or aspiration pneumonia. We investigated whether differences in kinematic data of mandibular movements during mastication can be used as an indicator of the need for a dysphagia diet in the elderly in long-term care facilities. We included 63 participants who were provided with solid food in two long-term care facilities. The primary outcome variable was the kinematic data on mandibular movement during cracker chewing. The analysis results were compared between the normal and dysphagia diet groups. Logistic regression analysis and receiver operating characteristic curve analyses were performed. Significant differences were observed in the masticatory time, cycle frequency, total change amount, number of linear motions, and circular motion frequency between the normal and modified diet groups. The odds ratio for the circular motion frequency was -0.307, and the calculated cutoff value was 63%, with a sensitivity of 71.4%, a specificity of 73.5%, and an area under the curve of 0.714. Thus, these characteristics may be useful for detecting care recipients who need to be provided with a dysphagia diet. Moreover, the circular motion frequency could be used as a screening test to identify people who need a dysphagia diet.

Association of Oral Function and Dysphagia with Frailty and Sarcopenia in Community-Dwelling Older Adults: A Systematic Review and Meta-Analysis.

Studies investigating the associations of oral function and dysphagia with frailty and sarcopenia in community-dwelling older adults are increasing; however, they have not been systematically summarized. We conducted a systematic review to investigate these associations. We searched electronic databases and synthesized relevant data using conventional (frequentist-style) and Bayesian meta-analyses. Twenty-four studies were found to be eligible for our review, including 20 cross-sectional and four prospective cohort studies. Older adults with frailty or sarcopenia had lower tongue pressure, according to the results of conventional meta-analysis (mean difference [95% confidence interval or credible interval]: -6.80 kPa [-10.22 to -3.38] for frailty and -5.40 kPa [-6.62 to -4.17] for sarcopenia) and Bayesian meta-analysis (-6.90 kPa [-9.0 to -4.8] for frailty, -5.35 kPa [-6.78 to -3.89] for sarcopenia). People with frailty had a higher odds ratio (OR) for dysphagia according to the results of conventional meta-analysis (3.99 [2.17 to 7.32]) and Bayesian meta-analysis (1.38 [0.77 to 1.98]). However, the results were inconclusive for people with sarcopenia. A prospective association could not be determined because of the lack of information and the limited number of studies. Decreased oral function and dysphagia can be important characteristics of frailty and sarcopenia in community-dwelling older adults.

A Machine Learning-Based Screening Test for Sarcopenic Dysphagia Using Image Recognition.

BACKGROUND: Sarcopenic dysphagia, a swallowing disorder caused by sarcopenia, is prevalent in older patients and can cause malnutrition and aspiration pneumonia. This study aimed to develop a simple screening test using image recognition with a low risk of droplet transmission for sarcopenic dysphagia. METHODS: Older patients admitted to a post-acute care hospital were enrolled in this cross-sectional study. As a main variable for the development of a screening test, we photographed the anterior neck to analyze the image features of sarcopenic dysphagia. The studied image features included the pixel values and the number of feature points. We constructed screening models using the image features, age, sex, and body mass index. The prediction performance of each model was investigated. RESULTS: A total of 308 patients participated, including 175 (56.82%) patients without dysphagia and 133 (43.18%) with sarcopenic dysphagia. The area under the receiver operating characteristic curve (ROC-AUC), sensitivity, specificity, positive predictive value, negative predictive value, and area under the precision-recall curve (PR-AUC) values of the best model were 0.877, 87.50%, 76.67%, 66.67%, 92.00%, and 0.838, respectively. The model with image features alone showed an ROC-AUC of 0.814 and PR-AUC of 0.726. CONCLUSIONS: The screening test for sarcopenic dysphagia using image recognition of neck appearance had high prediction performance.

Effect of electromyography-triggered peripheral magnetic stimulation on voluntary swallow in healthy humans.

BACKGROUND: Electrical stimulation therapy is effective for patients with dysphagia. However, because of the pain, strong stimulation cannot be applied. Although magnetic stimulation induces less pain, there are no reports on magnetic stimulation being synchronised with a swallowing reflex. OBJECTIVE: This study aimed to determine whether it is possible to induce magnetic stimulation during a voluntary swallowing using electromyography (EMG)-triggered peripheral magnetic stimulation and to evaluate its effect on healthy individuals. METHODS: A total of 20 healthy adults in seated position were instructed to swallow saliva and 10 ml of barium under videofluoroscopy. For concomitant use of magnetic stimulation, a magnetic stimulus for suprahyoid muscles at 30 Hz frequency was applied for 2 s when the EMG level in the sternohyoid muscle exceeded the threshold. During the voluntary swallowing, the movement of the hyoid bone and opening width of the upper oesophageal sphincter (UES) were measured. Furthermore, pressure topography was evaluated in 6 subjects using high-resolution manometry. RESULTS: The magnetic stimulation significantly extended the movement time of the hyoid bone (p < 0.001). During liquid deglutition, significant increases were observed in the anterior maximum movement distance of the hyoid bone (p < 0.05), opening width of the UES (p < 0.001) and anterior movement distance of the hyoid bone at the maximum UES opening (p < 0.01). In the pressure topography, the maximum pressure immediately after UES closure significantly decreased with magnetic stimulation (p < 0.05). CONCLUSION: EMG-triggered peripheral magnetic stimulation made it possible to apply magnetic stimulation during a voluntary swallowing.

Prediction of oral intake recovery for inpatients with aspiration pneumonia by videoendoscopic evaluation using the Hyodo-Komagane score in Japan.

OBJECTIVE: To verify the validity of the prediction of oral intake recovery for inpatients with aspiration pneumonia using the Hyodo-Komagane score. BACKGROUND: Patients admitted for treatment of aspiration pneumonia sometimes have difficulty in resuming oral intake due to decreased swallowing function. Predicting whether the swallowing function will recover enough to achieve oral ingestion at discharge is an important factor in developing a treatment strategy. No studies have investigated the prediction of oral intake recovery using videoendoscopic examination. METHODS: Subjects were 65 patients who were admitted to an acute care hospital for the treatment of aspiration pneumonia. The patients were divided into two groups, the oral feeding group and the tube feeding group, according to their oral intake status at discharge or transfer. Logistic regression analysis was performed using the condition that tube feeding was not required as an objective variable and the items with significant differences between the two groups as explanatory variables. Additionally, the receiver operating characteristic curve was used to identify patients who could take food orally at discharge. RESULTS: The odds ratios for the Hyodo-Komagane score and the pharyngeal clearance score were 1.485 and 3.379, respectively. When the cut-off values of the Hyodo-Komagane score and the pharyngeal clearance score were 6 and 1, the sensitivity was 0.88 and 0.91, and the specificity was 0.64 and 0.70, respectively. CONCLUSION: The Hyodo-Komagane score and especially the pharyngeal clearance score are useful indices to predict oral intake recovery for inpatients with aspiration pneumonia.

Relationship between oral intake level and oral health assessment tool scores in the convalescent ward.

PURPOSE: To examine the relationship between oral intake function and oral health status in convalescent inpatients. METHODS: Subjects were 222 patients admitted to a convalescent hospital between 1 January and 30 June 2018. Investigation items were age, sex, causative disease, body mass index, functional oral intake scale (FOIS), functional independence measure, occlusal contact, assistance with oral cleaning, and oral health assessment tool (OHAT) scores. Multiple regression analysis was performed with FOIS as the dependent variable, and investigation items were related to FOIS as independent variables. RESULTS: Results of multiple regression analysis for all patients suggested that saliva and denture scores were significantly associated with FOIS. However, analysis excluding non-oral feeding patients did not show a significant association between FOIS and OHAT scores. CONCLUSION: The results of this study suggest that oral health status is associated with oral intake function. In addition, the oral health status of inpatients may be strongly related to whether or not they are eating orally. Therefore, it is necessary to take good care of oral health in non-oral feeding patients in the convalescent ward.

Submental Muscle Activity and Its Role in Diagnosing Sarcopenic Dysphagia.

PURPOSE: The objectives of this study were two-fold: 1) to investigate differences in activity duration and amplitude of the submental muscles during swallowing measured with surface electromyography (sEMG) in older patients with sarcopenic dysphagia compared to those without dysphagia and 2) to examine the diagnostic accuracy of submental sEMG signals for sarcopenic dysphagia. PATIENTS AND METHODS: Patients (n = 60) aged ≥65 years participated in this cross-sectional study. The submental muscle activity duration parameters were the duration from the onset of swallowing to the maximum amplitude (duration A), duration from the maximum amplitude to the end of the swallowing activity (duration B), and total duration. The amplitude parameters were mean and maximum amplitude. Maximum lingual pressures were also measured for comparison with sEMG parameters. RESULTS: Duration A was not significantly different between the groups (p = 0.15), but duration B (p < 0.001) and total duration (p < 0.001) were significantly different between the non-dysphagic and sarcopenic dysphagic groups. The mean (p = 0.014) and maximum (p < 0.001) amplitudes were significantly different between the groups. The area under the receiver operating characteristic curve (AUC) was 0.94 (95% confidence interval (CI) 0.87-0.98) for duration B, 0.95 (95% CI 0.89-0.99) for total duration, 0.76 (95% CI 0.63-0.87) for maximum amplitude, and 0.61 (95% CI 0.47-0.75) for mean amplitude. The AUC of the total duration was significantly greater than that of lingual pressure (p = 0.02). CONCLUSION: Patients with sarcopenic dysphagia had longer submental muscle activity duration and higher amplitude during swallowing as assessed using sEMG. The findings of this study can be useful in elucidating the underlying pathophysiology of sarcopenic dysphagia and in diagnosing sarcopenic dysphagia.

Effects of bolus consistency and reclining position on kinematic swallowing events in analysis using 320-row area detector computed tomography.

This study used 320-row area detector computed tomography (320-ADCT) to determine whether kinematic swallowing events and bolus movement through the oropharynx are affected by bolus consistency and angle of recline. Fourteen healthy adults (4 men, 10 women; age, 22-90 years) underwent 320-ADCT assessment during three 10-mL barium swallow tests, with honey-thick liquid at 60° recline (60°thick), thin liquid at 60° recline (60°thin), and thin liquid at 45° recline (45°thin). The times of swallowing events were measured and compared among the different tests. Bolus propulsion, onset time of true vocal cord (TVC) closure, and upper esophageal sphincter opening were significantly earlier for 60°thin than for 60°thick. Onset time did not significantly differ between 60°thin and 45°thin; however, greater variability was noted for onset of TVC closure with 45°thin, as the TVC started to close before onset of swallowing in 30% of participants. Modulation of TVC closure depends on bolus transport in different reclining positions. The 45° reclining position elicited pre-swallow TVC closure in some participants, which suggests that excessive recline can increase perceived risk of airway invasion during swallowing.

Time Course and Recovery of the Movements of Hyoid Bone and Thyroid Cartilage During Swallowing in a Patient With Sarcopenic Dysphagia.

Sarcopenia is known to adversely affect swallowing function. In this report, we describe the treatment progress of an older patient with dysphagia caused by sarcopenia and the analysis results from videofluorographic examination images. An 89-yr-old man who had been hospitalized for lumbar fracture experienced lower back pain and thus had his oral intake reduced. After transfer to a rehabilitation hospital, he developed aspiration pneumonia and then sarcopenia with low nutrition and low activity. At the beginning of intervention, he aspirated food paste, but he recovered sufficiently to be able to ingest a normal meal via a nutritional approach combined with rehabilitation at the time of discharge. During this process, the maximum amounts of displacements and maximum moving velocities of his hyoid bone and thyroid cartilage during swallowing of moderately thick water were improved. Adequate nutrition intake and training for hyoid muscles are considered effective for the patient with sarcopenic dysphagia. It was concluded that measuring the maximum displacements and moving velocities of the hyoid bone and thyroid cartilage during swallowing in patients with sarcopenic dysphagia was an effective way to monitor their improvement.

The Periodontopathic Bacterium Fusobacterium nucleatum Induced Proinflammatory Cytokine Production by Human Respiratory Epithelial Cell Lines and in the Lower Respiratory Organs in Mice.

BACKGROUND/AIMS: The most prevalent infectious disease, chronic periodontitis which leads to alveolar bone destruction and subsequent tooth loss, develops due to proinflammatory cytokine production induced by periodontopathic bacteria. Chronic obstructive pulmonary disease (COPD), a non-infectious disease, is the third leading cause of death globally. This condition exacerbates frequently, and which is attributable to proinflammatory cytokine production induced by infection by respiratory microorganisms such as Streptococcus pneumoniae. Although a positive association has recently been revealed between chronic periodontitis and COPD, how periodontitis contributes to the pathogenesis of COPD remains unclear. Therefore, we hypothesized that some periodontopathic bacteria are involved in the exacerbation of COPD through the induction of proinflammatory cytokine production by respiratory epithelial cells. In this connection, COPD develops in the airways; however, because most periodontopathic bacteria are anaerobic, they are unlikely to exhibit stable virulence in the lower respiratory organs in humans. Hence, we aimed to elucidate whether exposure to heat-inactivated periodontopathic bacteria induces proinflammatory cytokine production by several human respiratory epithelial cell lines and in the lower respiratory organs and serum in mice. METHODS: Real-time polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA) were used to investigate in vitro induction by heat-inactivated periodontopathic bacteria and S. pneumoniae for mRNA expression and protein production of interleukin (IL)-8 and IL-6 by human respiratory epithelial cell lines. ELISA was also used to determine in vivo induction of cytokine production in the lower respiratory organs and serum of intratracheally heat-inactivated Fusobacterium nucleatum-inoculated mice. RESULTS: Some, but not all, periodontopathic bacteria, especially F. nucleatum, strongly induced IL-8 and IL-6 production by BEAS-2B bronchial epithelial cells. In addition, F. nucleatum induced IL-8 production by A549 alveolar epithelial cells as well as IL-8 and IL-6 production by Detroit 562 pharyngeal epithelial cells. Furthermore, F. nucleatum induced considerably higher cytokine production than S. pneumoniae. This was also observed in the entire lower respiratory organs and serum in mice. CONCLUSION: Exposure to increased number of F. nucleatum potentially induces proinflammatory cytokine production by human bronchial and pharyngeal epithelial cells, which may trigger exacerbation of COPD.

Diagnostic accuracy of lip force and tongue strength for sarcopenic dysphagia in older inpatients: A cross-sectional observational study.

BACKGROUND & AIMS: Dysphagia can be caused by sarcopenia in older adults. Although sarcopenic dysphagia has been reported to be associated with low tongue strength, whether tongue strength can be useful as a diagnostic index for sarcopenic dysphagia remains unclear. In addition, the association between sarcopenic dysphagia and lip force is unknown. The aim of the present study was to clarify the association of lip force and tongue strength with sarcopenic dysphagia, and their diagnostic accuracy for sarcopenic dysphagia. METHODS: A cross-sectional study was conducted in consecutive 245 (166 women) inpatients aged ≥65 years in the post-acute phase of illness. The presence of sarcopenic dysphagia, lip force, and tongue strength were assessed. Additional factors were also assessed: cognitive function, nutritional status, comorbidity, oral intake level, occlusion status, physical function, and inflammatory status. Multivariable logistic regression analysis was conducted with the presence of sarcopenic dysphagia as a dependent variable. Lip force and tongue strength were assessed with the area under the receiver operating characteristic curve (AUC) to clarify diagnostic accuracy for sarcopenic dysphagia. In addition, the cut-off values of lip force and tongue strength for identifying sarcopenic dysphagia were determined according to sex. RESULTS: In total, 86 patients (35.1%) had sarcopenic dysphagia. Both men and women with sarcopenic dysphagia had lower lip force and tongue strength than men and women without dysphagia or sarcopenic dysphagia (p < 0.001 for all). In multivariable logistic regression analysis, sarcopenic dysphagia was significantly associated with lip force (OR = 0.63, 95% CI 0.53-0.74, p < 0.001) and tongue strength (OR = 0.92, 95% CI 0.87-0.98, p = 0.011). The AUCs for lip force in patients with sarcopenic dysphagia were 0.88 (CI 0.81-0.95, p < 0.001) for men and 0.84 (CI 0.77-0.90, p < 0.001) for women. The AUCs for tongue strength were 0.79 (CI 0.69-0.89, p < 0.001) for men and 0.74 (CI 0.65-0.82, p < 0.001) for women. The cut-off values for sarcopenic dysphagia in men were 10.4 N for lip force and 24.3 kPa for tongue strength; the cut-off values in women were 8.5 N for lip force and 23.9 kPa for tongue strength. CONCLUSION: In older inpatients who are suspected as having dysfunction due to sarcopenia, lip force and tongue strength can be independently useful indices for diagnosing sarcopenic dysphagia, and may be factors that prevent and improve sarcopenic dysphagia.

Low-intensity pulsed ultrasound induces cartilage matrix synthesis and reduced MMP13 expression in chondrocytes.

Low-intensity pulsed ultrasound (LIPUS) is used for bone healing in orthopedics. In previous in vivo and in vitro studies, LIPUS has been shown to have promising effects on cellular elements in articular cartilage, particularly chondrocytes in patients with osteoarthritis. However, the effects of LIPUS on the cellular mechanisms through which LIPUS alters extracellular matrix (ECM) synthesis in chondrocytes are unclear. In this study, we investigated the effects of the optimal intensity and cellular mechanisms of LIPUS on the regeneration of cartilage matrix in chondrocytes. LIPUS induced collagen synthesis and the remodeling of aggrecan via the activation of ERK1/2. In contrast, MMP13 expression was decreased in chondrocytes. Additionally, chondrocytes responded optimally to LIPUS at an intensity higher than the clinical setting for bone fracture healing. These results suggested that LIPUS induced ECM regeneration via increases in hypertrophic chondrocytes and delayed endochondral ossification in chondrocytes.

Relationship between tongue strength, lip strength, and nutrition-related sarcopenia in older rehabilitation inpatients: a cross-sectional study.

OBJECTIVE: The objective of this study was to clarify the relationship between tongue strength, lip strength, and nutrition-related sarcopenia (NRS). PATIENTS AND METHODS: A total of 201 older inpatients aged ≥65 years (70 men, median age: 84 years, interquartile range: 79-89 years) consecutively admitted for rehabilitation were included in this cross-sectional study. The main factors evaluated were the presence of NRS diagnosed by malnutrition using the Mini-Nutrition Assessment - Short Form, sarcopenia based on the criteria of the Asian Working Group for Sarcopenia, tongue strength, and lip strength. Other factors such as age, sex, comorbidity, physical function, cognitive function, and oral intake level were also assessed. RESULTS: In all, 78 (38.8%) patients were allocated to the NRS group, and 123 (61.2%) patients were allocated to the non-NRS group. The median tongue strength and lip strength (interquartile range) were significantly lower in the NRS group (tongue: 22.9 kPa [17.7-27.7 kPa] and lip: 7.2 N [5.6-9.8 N]) compared with the non-NRS group (tongue: 29.7 kPa [24.8-35.1 kPa] and lip: 9.9 N [8.4-12.3 N], P<0.001 for both). Multivariable logistic regression analysis showed that NRS was independently associated with tongue strength (odds ratio [OR] =0.93, 95% confidence interval [CI] 0.87-0.98, P=0.012) and lip strength (OR =0.76, 95% CI 0.66-0.88, P<0.001), even after adjusting for age, sex, comorbidity, physical function, cognitive function, and oral intake level. CONCLUSION: The likelihood of occurrence of NRS decreased when tongue strength or lip strength increased. Tongue strength and lip strength may be important factors for preventing and improving NRS, regardless of the presence of low oral intake level in older rehabilitation inpatients.

Tongue Strength is Associated with Grip Strength and Nutritional Status in Older Adult Inpatients of a Rehabilitation Hospital.

The aim of this cross-sectional study was to investigate whether tongue strength observed in older adult inpatients of a rehabilitation hospital is associated with muscle function, nutritional status, and dysphagia. A total of 174 older adult inpatients aged 65 years and older in rehabilitation (64 men, 110 women; median age, 84 years; interquartile range, 80-89 years) who were suspected of having reduced tongue strength due to sarcopenia were included in this study. Isometric tongue strength was measured using a device fitted with a disposable oral balloon probe. We evaluated age, muscle function as assessed by the Barthel index and grip strength, nutritional status as measured by the Mini Nutritional Assessment-short form (MNA-SF), body mass index, serum albumin, controlling nutritional status, and calf circumference and arm muscle area to assess muscle mass. In addition, the functional oral intake scale (FOIS) was used as an index of dysphagia. Multivariate linear regression analysis revealed that isometric tongue strength was independently associated with grip strength (coefficient = 0.33, 95 % confidence interval (CI) 0.12-0.54, p = 0.002), MNA-SF (coefficient = 0.74, 95 % CI 0.12-1.35, p = 0.019), and FOIS (coefficient = 0.02, 95 % CI 0.00-0.15, p = 0.047). To maintain and improve tongue strength in association with sarcopenic dysphagia, exercise therapy and nutritional therapy interventions, as well as direct interventions to address tongue strength, may be effective in dysphagia rehabilitation in older adult inpatients.

Video-endoscopic comparison of swallowing waxy rice mochi and waxy wheat mochi: improvement of a traditional Japanese food that presents a choking hazard.

Mochi is highly cohesive and adhesive, and easy to choke on. Many of the fatal suffocation accidents with mochi occur in the elderly aged 65 years or older. These circumstances prompted us to investigate a special property of waxy wheat which is similar in texture to waxy rice, but is less cohesive and adhesive. We compared the differences in chewing and swallowing movements associated with eating waxy rice mochi and waxy wheat mochi between healthy adults and healthy elderly. Healthy elderly chewed mochi more and longer than healthy adults. Although there was no difference in the number of chewing cycles or total duration of chewing between the two types of mochi, waxy wheat mochi was easier to chew and left less pharyngeal residue. These findings lead us to suggest that waxy wheat mochi is promising as a food that is easy to swallow and difficult to choke on.

Facial vibrotactile stimulation activates the parasympathetic nervous system: study of salivary secretion, heart rate, pupillary reflex, and functional near-infrared spectroscopy activity.

We previously found that the greatest salivation response in healthy human subjects is produced by facial vibrotactile stimulation of 89 Hz frequency with 1.9 µ m amplitude (89 Hz-S), as reported by Hiraba et al. (2012, 20011, and 2008). We assessed relationships between the blood flow to brain via functional near-infrared spectroscopy (fNIRS) in the frontal cortex and autonomic parameters. We used the heart rate (HRV: heart rate variability analysis in RR intervals), pupil reflex, and salivation as parameters, but the interrelation between each parameter and fNIRS measures remains unknown. We were to investigate the relationship in response to established paradigms using simultaneously each parameter-fNIRS recording in healthy human subjects. Analysis of fNIRS was examined by a comparison of various values between before and after various stimuli (89 Hz-S, 114 Hz-S, listen to classic music, and "Ahh" vocalization). We confirmed that vibrotactile stimulation (89 Hz) of the parotid glands led to the greatest salivation, greatest increase in heart rate variability, and the most constricted pupils. Furthermore, there were almost no detectable differences between fNIRS during 89 Hz-S and fNIRS during listening to classical music of fans. Thus, vibrotactile stimulation of 89 Hz seems to evoke parasympathetic activity.

[Dysphagia].

Swallowing function is deteriorated with age, and swallowing disorders can cause aspiration pneumonia that is the one of main causes of death for elderly. Accordingly, evaluation technique for swallowing function is important. Roughly, these are screening test and instrumental examination. Modified water swallowing test and cough test are valuable screening test for detecting dysphagia. Videofluorography and videoendoscopy as instrumental examination are definitive evaluation for swallowing function. These tests or examinations are useful to evaluate swallowing, but in other words, these evaluations are evaluative method only for swallowing. Therefore, other informations, such as age, phase of disease, nutrition status, dementia, teeth problem, or meal environment, should be taken into consideration when we decide feeding method of patients.

Changes in pyriform sinus morphology in the head rotated position as assessed by 320-row area detector CT.

In patients with unilateral pharyngeal paresis and dysphagia, the head is rotated to the paretic side to prevent food flow to the rotated side during swallowing. Only a few studies to date have reported on pyriform sinus morphology upon head rotation. The purpose of this study was to measure the volume, depth, and cross-sectional area of the pyriform sinus during head rotation using 320-row area detector computed tomography. We imaged the neck during head rotation at 0° and at 30°, 45°, and 60° to the left or right in nine healthy young adults and determined the volume, depth, and cross-sectional area of the pyriform sinus in each position. On the rotated side, volume and cross-sectional area were significantly decreased at 60°. In contrast, volume, cross-sectional area, and depth were all significantly increased on the opposite side at 60°. These results suggest that head rotation at 60° significantly increases the volume, cross-sectional area, and depth of the opposite side, and significantly decreases the volume and depth of the rotated side of the pyriform sinus.

Changes in localized arrangement into the hypoglossal nucleus after the neurectomy of unilateral hypoglossal nerve (medial branch) in cats.

We studied changes in orofacial behavior and the arrangement of bilateral hypoglossal nuclei after the neurectomy of the medial branch of the unilateral hypoglossal nerve in cats. After recovery from surgery in a head holder, the animals were acclimated to take and chew fish paste (1.8 g) from a spoon and lick milk from a wetted paintbrush. Next we performed a neurectomy in the unilateral hypoglossal nerve after training. We firstly recorded behavior during the taking of fish paste and licking of milk, and then performed a neurectomy in the unilateral hypoglossal nerve. After nerve cutting, the cats' tongue deviated toward the cut side when they licked food, and bilateral activities of EMGs in the genioglossus muscles became stable in about 1 month. After that, we injected two kinds of fluorescent dye (10% Evans blue, EB, and 3% Fast blue, FB) into the bilateral genioglossus muscles using syringes (0.15 ml in each), respectively. Although each injection of FB and EB into the bilateral genioglossus muscles in normal cats revealed cells positively stained with each dye in the hypoglossal nuclei of each injection site, in cats 1 month after nerve cutting, fluorescent dye was only observed in positive cells in the hypoglossal nucleus of the intact side and the dye injected into the neurectomy side showed a mixture into positive cells of the intact side. The findings suggest that muscles in the neurectomy side may be compensated by regeneration of the peripheral nerves on the intact side.