Understanding the motor innervation of the human cricopharyngeus muscle

Electromyography of the posterior cricoarytenoid muscles: a consensus guideline

PURPOSE

Since the introduction of transcutaneous-transcricoidal needle approaches, electromyography (EMG) of the posterior cricoarytenoid muscle (PCA) became easier to perform and teach. Among the Neurolaryngology working group of the European Laryngological Society, several centers have adopted PCA EMG as part of their routine EMG workup in vocal fold immobility collectively gathering long-term experience. The purpose is to give an update and an extension to already existing guidelines on laryngeal EMG with specific regard to PCA EMG.

METHODS

Consensus of all co-authors is based on continuous exchange of ideas and on joint laryngeal EMG workshop experiences over at least 7 years. A Delphi method of consensus development was used, i.e., the manuscript was circulated among the co-authors until full agreement was achieved.

RESULTS

Step-by-step instructions on how to perform and interpret PCA EMG are provided.

CONCLUSIONS

Further research should include the establishment of normal values for PCA and thyroarytenoid muscle (TA) EMG as well as studies on the nature of some unusual activation pattern commonly seen in chronically lesioned PCA.

Cricopharyngeal dysphagia and phenobarbitone-responsive sialoadenosis in a Miniature Poodle

CASE REPORT

An 11-year-old male neutered Miniature Poodle was investigated for ptyalism, weight loss and anorexia. Cricopharyngeal dysphagia was diagnosed using fluoroscopy, and non-inflammatory salivary disease was diagnosed using a combination of cytology and computed tomography. The dog was successfully managed with phenobarbitone.

CONCLUSION

To the authors' knowledge this is the first time acquired cricopharyngeal dysphagia and phenobarbitone-responsive sialoadenosis have been described together.

Topographic description of an alternative insertion technique for percutaneous approach of cricopharyngeus muscle electromyography: a cadaveric and clinical study

BACKGROUND

Cricopharyngeus is the only muscle for which electromyography is used in the differential diagnosis of swallowing disorders. Because of some practical difficulties, electrophysiologic tests for this muscle are not performed routinely. Thus we aimed to describe an alternative topographic way to reach the muscle easily.

METHODS

On 10 cadavers, a spinal needle (20 G) and on 37 patients a concentric needle electrode (26 G) were used. The needle was inserted percutaneous at the level of the superior border of the cricoid cartilage, anterior to the anterior border of the sternocleidomastoid muscle at 60 degrees angle to the frontal plane in the posteromedial direction.

RESULTS

We reached the muscle in all cadavers. In all of the patients, the needle entered the muscle on the first attempt; that was confirmed by electromyographic responses.

CONCLUSION

Our results show that this method can be useful for the practical application of cricopharyngeus muscle electromyography.

Pharyngeal dilation in cricopharyngeus muscle dysfunction and Zenker diverticulum

OBJECTIVES/HYPOTHESIS

Prolonged obstruction at the level of the lower esophageal sphincter is associated with a dilated, poorly contractile esophagus. The association between prolonged obstruction at the level of the upper esophageal sphincter (UES) and dilation and diminished contractility of the pharynx is uncertain. The purpose of this investigation was to evaluate the association between prolonged obstruction at the level of the UES and dilation and diminished contractility of the pharynx.

STUDY DESIGN

Case-control study.

METHODS

The fluoroscopic swallow studies of all persons with cricopharyngeus muscle dysfunction (CPD) diagnosed between January 1, 2006 and December 31, 2008 were retrospectively reviewed from a clinical database. Three categories of CPD were defined: nonobstructing cricopharyngeal bars (CPBs), obstructing CPBs, and Zenker diverticulum (ZD). The primary outcome measure was the pharyngeal constriction ratio (PCR), a surrogate measure of pharyngeal strength on fluoroscopy. Secondary outcome measures included pharyngeal area in the lateral fluoroscopic view and UES opening. The outcome measures were compared between groups and to a cohort of nondysphagic age- and gender-matched controls with the analysis of variance.

RESULTS

A total of 100 fluoroscopic swallow studies were evaluated. The mean age (+ or -standard deviation) of the cohort was 70 years (+ or -10 years). Thirty-six percent were female. The mean PCR progressively increased, indicating diminishing pharyngeal strength, from the normal (0.08), to the nonobstructing CPB (0.13), to the obstructing CPB (0.22), to the ZD group (0.28) (P < .001 with trend for linearity). There was a linear increase in pharyngeal area from the normal (8.75 cm(2)) to the nonobstructing CPB (10.00 cm(2)), to the obstructing CPB (10.46 cm(2)), to the ZD group (11.82 cm(2)) (P < .01 with trend for linearity).

CONCLUSIONS

The data suggest that there is an association between cricopharyngeus muscle dysfunction and progressive dilation and weakness of the pharynx. Laryngoscope, 2010.

Sihler's whole mount nerve staining technique: a review

Sihler's stain is a whole mount nerve staining technique that renders other soft tissue translucent or transparent while staining the nerves. It permits mapping of entire nerve supply patterns of organs, skeletal muscles, mucosa, skin, and other structures after the specimens are fixed in neutralized formalin, macerated in potassium hydroxide, decalcified in acetic acid, stained in Ehrlich's hematoxylin, destained in acetic acid, and cleared in glycerin. The unique advantage of Sihler's stain over other anatomical methods is that all the nerves within the stained specimen can be visualized in their three-dimensional positions. To date, Sihler's stain is the best tool for demonstrating the precise intramuscular branching and distribution patterns of skeletal muscles, which are important not only for anatomists, but also for physiologists and clinicians. Advanced knowledge of the neural structures within mammalian skeletal muscles is critical for understanding muscle functions, performing electrophysiological experiments and developing novel neurosurgical techniques. In this review, Sihler's stain is described in detail and its use in nerve mapping is surveyed. Special emphasis is placed on staining procedures and troubleshooting, strengths and limitations, applications, major contributions to neuroscience, physiological and clinical significance, and areas for further technical improvement that deserve future research.

Classification of pharyngeal muscles based on innervations from glossopharyngeal and vagus nerves in human

PURPOSE

The pharyngeal muscles are innervated by the glossopharyngeal and vagus nerves. However, their spatial interrelationships with the innervating branches have been unclear. This study examined the pharynx to elucidate their precise relationships for the anatomical evidence of the functional diagnosis.

METHOD

The muscles and nerves were dissected under a binocular microscope in 44 sides of 22 cadavers fixed with 8% formalin.

RESULTS

The pharyngeal muscles overlapped each other, and the pharyngeal constrictors sometimes linked to adjacent muscles. The uppermost part of the superior constrictor arose from the soft palate, and sometimes contained the fibers attaching to the petrous part of the temporal bone. Anomalous bundles were frequently found between the superior and middle constrictors and the stylopharyngeus. The stylopharyngeus and the glossopharyngeal part of the superior constrictor were innervated by the glossopharyngeal nerve, which occasionally penetrated the stylopharyngeus. The pharyngeal plexus not only spread onto dorsolateral surface of the pharynx but also sent branches between the constrictors. The plexus supplied the superior constrictor and salpingo- and palatopharyngei from their dorsal surface and the middle and inferior constrictors from their ventral and dorsal surfaces. The inferior constrictor received additional innervations from the laryngeal nerves.

CONCLUSIONS

The innervations pattern suggests that the pharyngeal muscles comprise four groups: the first innervated by the glossopharyngeal nerve, the second and third by the pharyngeal plexus, and the fourth by the plexus and the laryngeal nerves. The stylopharyngeus descends between the second and third groups, and its penetration may cause the anomalous bundles between them.

Prolonged cricopharyngeal muscle spasm after resection of the cervical vagus nerve in a 15-year-old

Cervical vagal schwannomas are rare pediatric head and neck neoplasms that present a surgical challenge if the nerve is intimately involved with the mass. In some instances, resection of the vagus nerve with the mass is required. This will usually result in vocal cord paralysis and uncommonly dysphagia due to unilateral cricopharyngeal spasm. We present a case in which these two complications resulted in significant dysphagia and aspiration, which improved with expectant management.

Optimal stimulus intensity and reliability of air stimulation technique for elicitation of laryngo-upper esophageal sphincter contractile reflex

To determine the optimal air stimulus intensity and duration for elicitation of the laryngo-upper esophageal sphincter (UES) contractile reflex, we studied 37 healthy volunteers 20 to 81 years of age. A sleeve device monitored the UES pressure. For laryngeal stimulation, we used an air stimulator unit (Pentax AP-4000) that incorporated a nasolaryngeal endoscope. The arytenoids and interarytenoid areas were stimulated at least three times by three different stimuli: 6-mm Hg air pulse with 50-ms duration, 10-mm Hg air pulse with 50-ms duration, and 6-mm Hg air pulse with 2-second duration. Of 1,165 air stimulations, 1,041 resulted in mucosal deflections. Of these, 451 resulted in an abrupt increase in UES pressure. The response/deflection ratio for 6-mm Hg stimulation with 2-second duration was significantly higher than those for air pulses with 50-ms duration (p < .001). We conclude that although the laryngo-UES contractile reflex can be elicited by an air pulse with 50-ms duration, this ultrashort stimulation is not reliable. Using longer-duration pulses (at least 2 seconds) improves the reliability of elicitation of the laryngo-UES contractile reflex.

Laryngo-upper esophageal sphincter contractile reflex in humans deteriorates with age

BACKGROUND & AIMS

Recent studies have shown the existence of several reflex connections between the aerodigestive and upper gastrointestinal tracts. Our aim was to study the effect of laryngeal stimulation on upper esophageal sphincter (UES) pressure and to determine the reproducibility of this effect.

METHODS

We studied 14 young and 10 elderly healthy nonsmoker volunteers and 7 patients with UES dysphagia using a concurrent manometric and video endoscopic technique. Three levels of laryngeal air stimulation were studied: 6 mm Hg/50 ms, 10 mm Hg/50 ms, and 6 mm Hg/2 s. Ten young subjects were studied twice.

RESULTS

For 6-mm Hg/2-s and 6-mm Hg/50-ms duration stimuli, the frequency of UES response to air stimulation as evidenced by mucosal deflection (response/deflection ratio) in the elderly volunteers was significantly lower compared with that of young subjects (P < 0.05). The response/deflection ratio of the 6-mm Hg/2-s stimulus was significantly higher than those induced by stimuli of shorter duration (P < 0.01). Poststimulation UES pressure was significantly higher than prestimulation pressure (P < 0.05) in both groups. The magnitude of the increase in poststimulation UES pressure in the elderly volunteers was similar to that of the young subjects. Findings were similar in repeated studies. Four of 7 dysphagic patients exhibited an abnormal response.

CONCLUSIONS

Afferent signals originating from the larynx reproducibly induce contraction of the UES: the laryngo-UES contractile reflex. This reflex is elicited most reliably by 6-mm Hg/2-s air stimulation. Frequency elicitation of this reflex decreases significantly with age while the magnitude of change in UES pressure remains unchanged, indicating a deleterious effect of aging on the afferent arm of this reflex. This reflex is altered in some dysphagic patients.