Flexible Endoscopic Evaluation of Swallowing with Sensory Testing

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Flexible Endoscopic Evaluation of Swallowing with Sensory Testing (FEESST), or laryngopharyngeal sensory testing, is a technique used to directly examine motor and sensory functions of swallowing so that proper treatment can be given to patients with swallowing difficulties to decrease their risk of aspiration (food and liquids going into the lungs instead of the stomach) and choking. FEESST was invented by Dr. Jonathan E. Aviv MD, FACS in 1993, [1] and has been used by otolaryngologists (ear, nose and throat doctors), [2] pulmonologists (lung doctors), [3] gastroenterologists (stomach and digestion doctors), [4] intensivists (intensive care specialists) [5] and speech-language pathologists [6] for the past 20 years.

Contents

Swallowing consists of two distinct but interrelated processes: 1. Moving food and liquids from the mouth into the stomach through a set of coordinated muscle movements of the mouth larynx, pharynx and the esophagus 2. Protecting the airway to prevent food and liquids from entering the lungs. [7] This natural process of swallowing can be disrupted in many ways. The problem can occur when the movements involved in swallowing are restricted due to a tumor, any type of blockage, or paralysis after a stroke. Besides the motor problems, swallowing can be impaired due to sensory dysfunction, meaning when sensation (the ability to feel) is lost or reduced anywhere in the throat area. The loss of sensation can be caused by a problem originating in the brain, such as what happens after certain types of stroke, or it can be a result of a nerve injury or swelling in the actual throat area.

FEESST is the only test currently available which can identify if there is any loss of sensation in the throat area. Before FEESST was invented, all tests of swallowing, be they X-ray based tests (Modified Barium Swallow (MBS) [8] or endoscopy-based tests (Fiberoptic Endoscopic Evaluation of Swallowing (FEES) [9] [10] solely looked at the motor component of swallowing without examining the sensory aspect of a swallow or the ability to feel.

Technique

FEESST is an outpatient procedure involving the passing of a thin flexible scope through the nose to the pharynx. The exam consisting of two parts. First part assesses sensation in the pharynx and airway protection. The airway protection is assessed by sending air-pulses to the throat area that is innervated by the vagus nerve, which is the region of the throat between the top of the vocal folds to the tip of the epiglottis in order to stimulate an airway protective reflex called the laryngeal adductor reflex (LAR). This reflex, which occurs when the tissues of the throat are stimulated, causes the vocal folds to close in order to protect the airway from food going into the lungs. Since the windpipe (trachea) is located so close to the food-pipe (esophagus) this is a critical reflex to be functioning well at all times. Stimulation of this reflex not only results in protection of the airway, it also initiates a swallow. When a swallow is initiated the larynx rises up to two inches, going further away from the esophagus, thereby acting as an additional cover for the airway.

During the air pulse administration part of the test it is determined if the reflex (LAR) that initiates the swallow is being responsive enough. The responsiveness depends on the ability of the vagus nerve to feel so that it can properly send the impulse to the brain to initiate the LAR. If there is any injury or swelling of the vagus nerve, the sensation will be diminished. As a result, the reflex responsible for protecting the airway will be affected. During sensory testing it has been shown that a much stronger stimulus is necessary to elicit the LAR if there is any desensitization to the vagus nerve. The second part of the FEESST test involves giving food to the patient and tracking where the food travels in the throat region. Green food coloring is typically given in the food to track the food as it travels along the natural pink-colored tissues of the throat.

If the food that is given is seen to stick to on one side of the throat, which is called food “residue”, that usually means that there is lack of sensation or possibly even a motor/movement problem on that particular side of the throat. The treatment for this discovered throat numbness is to then teach the patient to turn their head to the numb side of their throat when they swallow. This maneuver, called a "head turn" effectively closes off the numb side of the throat so when they swallow the food is only exposed to the normal side of the throat, thereby insuring a safer swallow (on the normal side there is no residue so there is no chance of the residue accidentally falling into the vocal folds and then into the lungs (aspiration).

Vagus Nerve Injury

When there is damage to the nerve that innervates the throat, the vagus nerve, both motor and sensory function can be affected since the vagus contains both motor and sensory nerve fibers. However, until sensory testing was developed there was no way to assess sensory loss from a vagus nerve injury. One of the most common symptoms of a vagus nerve injury is chronic cough. If a physician looked into the vocal cords of a patient with chronic cough it would appear they are opening and closing normally, however if sensory testing was performed it would give abnormal results thus indicating that the sensory nerve fibers of the vagus were somehow damaged. This would allow for a more precise diagnosis and treatment. [11] [12] [13]

Another clinical situation where assessment of laryngeal sensation is helpful is in patients complaining of throat pain. Again, when examining the throat of such patients, if everything seemed to be moving well, then clinicians are often befuddled as to what the source of the throat pain is. With sensory testing, one can demonstrate that the throat tissues are numb, signifying some damage to the sensory fibers of the vagus and thereby identify vagus nerve injury as the cause of the patient's pain. This is called vagus nerve neuralgia and treatment for neuralgia can then commence.

One always sensory tests both the right and left sides of throat and the sensory levels should be symmetric, that is, the right side of the throat should normally equal the left side. However, if during sensory testing it is determined that one side is normal and the other side has a sensory deficit, then likely something has injured the vagus nerve somewhere along it lengthy course from the brain into the neck. As a result, when there is asymmetric sensory nerve loss, imaging of the neck and brain must be done to see where along the course of the vagus nerve a blockage or injury might have taken place. [14] [15]

Indications For Sensory Testing of The Throat

Acid Reflux Disease

Over the past 20 years, primarily due to work with sensory testing performed by gastroenterologists (stomach doctors) and pulmonologists (lung doctors), sensory testing and FEESST have been shown to have additional applications beyond assessing swallowing function.

For example, people with acid reflux disease, especially those with Throatburn Reflux usually have swollen vocal cords due to years of acid damage. Untreated acid-injured vocal cords will not have as sharp reflexes as vocal cords that are not swollen. Therefore, aspiration is common in people with chronic acid reflux disease. Sensory testing can quantify and assess the swelling for better treatment. The strength of the air pulse given during sensory testing in acid-injured vocal cords due to acid reflux disease will necessarily be much greater in order to elicit an airway reflex than tissues that are not swollen. [16] [17] [18]

Related Research Articles

Vagus nerve Cranial nerve X, for visceral innervation

The vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that interfaces with the parasympathetic control of the heart, lungs, and digestive tract. It comprises two nerves—the left and right vagus nerves—but they are typically referred to collectively as a single subsystem. The vagus is the longest nerve of the autonomic nervous system in the human body and comprises both sensory and motor fibers. The sensory fibers originate from neurons of the nodose ganglion, whereas the motor fibers come from neurons of the dorsal motor nucleus of the vagus and the nucleus ambiguus. The vagus was also historically called the pneumogastric nerve.

Larynx Voice box, an organ in the neck of amphibians, reptiles, and mammals

The larynx, commonly called the voice box, is an organ in the top of the neck involved in breathing, producing sound and protecting the trachea against food aspiration. The opening of larynx into pharynx known as the laryngeal inlet is about 4–5 centimeters in diameter. The larynx houses the vocal cords, and manipulates pitch and volume, which is essential for phonation. It is situated just below where the tract of the pharynx splits into the trachea and the esophagus. The word ʻlarynxʼ comes from the Ancient Greek word lárunx ʻlarynx, gullet, throat.

Esophageal achalasia Rare, incurable, progressive motility disorder due to failure of esophogeal motor neurons

Esophageal achalasia, often referred to simply as achalasia, is a failure of smooth muscle fibers to relax, which can cause the lower esophageal sphincter to remain closed. Without a modifier, "achalasia" usually refers to achalasia of the esophagus. Achalasia can happen at various points along the gastrointestinal tract; achalasia of the rectum, for instance, may occur in Hirschsprung's disease. The lower esophageal sphincter is a muscle between the esophagus and stomach that opens when food comes in. It closes to avoid stomach acids from coming back up. A fully understood cause to the disease is unknown, as are factors that increase the risk of its appearance. Suggestions of a genetically transmittable form of Achalasia exist, but this is neither fully understood, nor agreed upon.

Swallowing, sometimes called deglutition in scientific contexts, is the process in the human or animal body that allows for a substance to pass from the mouth, to the pharynx, and into the esophagus, while shutting the epiglottis. Swallowing is an important part of eating and drinking. If the process fails and the material goes through the trachea, then choking or pulmonary aspiration can occur. In the human body the automatic temporary closing of the epiglottis is controlled by the swallowing reflex.

Gastroesophageal reflux disease Medical condition

Gastroesophageal reflux disease (GERD) or gastro-oesophageal reflux disease (GORD) is a chronic condition in which stomach contents and acid rise up into the esophagus, resulting in symptoms and/or complications. Symptoms include the taste of acid in the back of the mouth, heartburn, bad breath, chest pain, regurgitation, breathing problems, and wearing away of the teeth. Complications include esophagitis, esophageal stricture, and Barrett's esophagus.

Esophagitis Medical condition

Esophagitis, also spelled oesophagitis, is a disease characterized by inflammation of the esophagus. The esophagus is a tube composed of a mucosal lining, and longitudinal and circular smooth muscle fibers. It connects the pharynx to the stomach; swallowed food and liquids normally pass through it.

Laryngitis Medical condition

Laryngitis is inflammation of the larynx. Symptoms often include a hoarse voice and may include fever, cough, pain in the front of the neck, and trouble swallowing. Typically, these last under two weeks.

The pharyngeal reflex or gag reflex is a reflex muscular contraction of the back of the throat, evoked by touching the roof of the mouth, the back of the tongue, the area around the tonsils, the uvula, and the back of the throat. It, along with other aerodigestive reflexes such as reflexive pharyngeal swallowing, prevents objects in the oral cavity from entering the throat except as part of normal swallowing and helps prevent choking, and is a form of coughing. The pharyngeal reflex is different from the laryngeal spasm, which is a reflex muscular contraction of the vocal cords.

Nissen fundoplication Surgical procedure to treat gastric reflux and hiatal hernia

A Nissen fundoplication, or laparoscopic Nissen fundoplication when performed via laparoscopic surgery, is a surgical procedure to treat gastroesophageal reflux disease (GERD) and hiatal hernia. In GERD, it is usually performed when medical therapy has failed; but, with a Type II (paraesophageal) hiatus hernia, it is the first-line procedure. The Nissen fundoplication is total (360°), but partial fundoplications known as Thal, Belsey, Dor, Lind, and Toupet fundoplications are alternative procedures with somewhat different indications and outcomes.

Aspiration pneumonia Medical condition

Aspiration pneumonia is a type of lung infection that is due to a relatively large amount of material from the stomach or mouth entering the lungs. Signs and symptoms often include fever and cough of relatively rapid onset. Complications may include lung abscess. Some include chemical induced inflammation of the lungs as a subtype, which occurs from acidic but non-infectious stomach contents entering the lungs.

Oropharyngeal dysphagia arises from abnormalities of muscles, nerves or structures of the oral cavity, pharynx, and upper esophageal sphincter.

The cough reflex occurs when stimulation of cough receptors in the respiratory tract by dust or other foreign particles produces a cough, which causes rapidly moving air which usually remove the foreign material before it reaches the lungs. This typically clears particles from the bronchi and trachea, the tubes that feed air to lung tissue from the nose and mouth. The larynx and carina are especially sensitive. Cough receptors in the surface cells (epithelium) of the respiratory tract are also sensitive to chemicals. Terminal bronchioles and even the alveoli are sensitive to chemicals such as sulfur dioxide gas or chlorine gas.

Diffuse esophageal spasm Medical condition

Diffuse esophageal spasm (DES), also known as distal esophageal spasm, is a condition characterized by uncoordinated contractions of the esophagus, which may cause difficulty swallowing (dysphagia) or regurgitation. In some cases, it may cause symptoms such as chest pain, similar to heart disease. In many cases, the cause of DES remains unknown.

Laryngopharyngeal reflux Medical condition

Laryngopharyngeal reflux (LPR) is the retrograde flow of gastric contents into the larynx, oropharynx and/or the nasopharynx. LPR causes respiratory symptoms such as cough and wheezing and is often associated with head and neck complaints such as dysphonia, globus pharyngis, and dysphagia. LPR may play a role in other diseases, such as sinusitis, otitis media, and rhinitis, and can be a comorbidity of asthma. While LPR is commonly used interchangeably with gastroesophageal reflux disease (GERD), it presents with a different pathophysiology.

A hiccup is an involuntary contraction of the diaphragm that may repeat several times per minute. The hiccup is an involuntary action involving a reflex arc. Once triggered, the reflex causes a strong contraction of the diaphragm followed about a quarter of a second later by closure of the vocal cords, which results in the "hic" sound.

Cricopharyngeal spasms occur in the cricopharyngeus muscle of the pharynx. Cricopharyngeal spasm is an uncomfortable but harmless and temporary disorder.

Transnasal esophagoscopy (TNE) is a safe and inexpensive way to examine the esophagus in patients at risk for esophageal cancer and other disorders. TNE doesn't require sedation, unlike other techniques widely used to look into the esophagus. This is possible because TNE uses a camera that is passed through the nose, whereas other techniques, such as upper endoscopy, are performed through the mouth, requiring a patient to be sedated. TNE, as it is used today, was developed by Jonathan E. Aviv who published his findings on the first series of TNE that he performed. The origins of the idea to pass the camera through the nose date from 1993 as first described by C. A. Prescott, MD, a pediatrician otolaryngologist in Cape Town, South Africa and further embellished by Reza Shaker, MD, a gastroenterologist in Milwaukee, WI in 1994. However, it wasn't until the year 2000 when Jonathan E. Aviv, MD, published his findings on the first series of TNE he performed, that it began to have a widespread attention by ear, nose, and throat doctors. Since that time it has been used by both otolaryngologists and gastroenterologists as a diagnostic tool to detect globus, dysphagia, laryngopharyngeal reflux (LPR), gastroesophageal reflux disease (GERD). TNE may also be useful in detecting Barrett's, but there is incongruence between TNE findings and biopsy results. Experts in the field suggest that TNE may replace radiographic imaging of the esophagus in otolaryngology patients with reflux, globus, and dysphagia.

Jonathan E. Aviv is an American otolaryngologist–head and neck surgeon and a professor of Otolaryngology–Head and Neck Surgery at Icahn School of Medicine at Mount Sinai Hospital in New York City, New York. He is also Clinical Director of the Voice and Swallowing Center at ENT and Allergy Associates in New York City, New York. An inventor, author, educator, physician and surgeon, he is best known for his invention of Flexible Endoscopic Evaluation of Swallowing with Sensory Testing (FEESST), a medical device that allows office-based assessment of oropharyngeal dysphagia, or swallowing disorders, without the use of X-ray. He is also known for his development of Transnasal Esophagoscopy (TNE), a method of examining the esophagus without using conscious or intravenous sedation. From 1991 to 2009, he was a full-time academic surgeon and director of the division of head and neck surgery at Columbia University College of Physicians and Surgeons.

Endoscopic laser cordectomy, also known as Kashima operation, is an endoscopic laser surgical procedure performed for treating the respiratory difficulty caused as a result of bilateral abductor vocal fold paralysis. Bilateral vocal fold paralysis is basically a result of abnormal nerve input to the laryngeal muscles, resulting in weak or total loss of movement of the laryngeal muscles. Most commonly associated nerve is the vagus nerve or in some cases its distal branch, the recurrent laryngeal nerve. Paralysis of the vocal fold may also result from mechanical breakdown of the cricoarytenoid joint. It was first described in by Kashima in 1989.

Chronic cough is long-term coughing, sometimes defined as more than several weeks or months. The term can be used to describe the different causes related to coughing, the three main ones being upper airway cough syndrome, asthma and gastroesophageal reflux disease. It occurs in the upper airway of the respiratory system. Generally, a cough lasts around one to two weeks; however, chronic cough can persist for an extended period of time defined as six weeks or longer. People with chronic cough often experience more than one cause present. Due to the nature of the syndrome, the treatments used are similar; however, there are a subsequent number of treatments available, and the clinical management of the patients remains a challenge.

References

  1. ↑ Aviv JE, Martin JH, Keen MS, Debell M, Blitzer A. Air-pulse quantification of supraglottic and pharyngeal sensation: a new technique. Ann Otol Rhinol Laryngol 1993; 102: 777-780.
  2. ↑ Ulualp S Brown A, Sanghavi R, Rivera-Sanchez Y. Assessment of laryngopharyngeal sensation in children with dysphagia. Laryngoscope. 2013 Sep;123(9):2291-5.
  3. ↑ Phua SY, McGarvey LPA, Ngu MC, Ing AJ. Patients with gastro-oesophageal reflux disease and cough have impaired laryngopharyngeal mechanosensitivity Thorax 2005; 60:488-491.
  4. ↑ Aviv JE, Johnson LF. Flexible endoscopic evaluation of swallowing with sensory testing (FEESST) to diagnose and manage patients with pharyngeal dysphagia. Practical Gastro 2000; 24: 52-59.
  5. ↑ Clayton NA, Carnaby-Mann GD, Peters MJ, Ing AJ. The effect of chronic obstructive pulmonary disease on laryngopharyngeal sensitivity. Ear Nose Throat J. 2012 Sep;91(9):370-382.
  6. ↑ Setzen M, Cohen MA, Mattucci KF, Perlman PW, Ditkoff MK. Laryngopharyngeal sensory deficits as a predictor of aspiration. Oto Head Neck Surg 2001; 124: 622-624.
  7. ↑ Zamir Z, Ren J, Hogan W, Shaker R. Coordination of deglutitive vocal cord closure and oral-pharyngeal swallowing events in the elderly. European J Gastro Hepatol 1996; 8: 425-429.
  8. ↑ Brady S, Donzelli J. The modified barium swallow and the functional endoscopic evaluation of swallowing. Otolaryngol Clin North Am. 2013 Dec;46(6):1009-22
  9. ↑ Logemann, J. Role of the Modified Barium Swallow in Management of Patients with Dysphagia. Otolaryngol Head Neck Surg 1997;116: 335-338.
  10. ↑ Bastian RW. Videoendoscopic evaluation of patients with dysphagia: An adjunct to modified barium swallow. Otolaryngol Head Neck Surg 1991; 104: 339-350.
  11. ↑ Cukier-Blaj S, Bewley A, Aviv JE, Murry T. Paradoxical vocal fold motion: a sensory-motor laryngeal disorder. Laryngoscope 2008; 118:367-70.
  12. ↑ Aviv JE, Murry T. Sensory Testing Alone. In: Aviv JE, Murry T, eds. FEESST: Flexible Endoscopic Evaluation of Swallowing with Sensory Testing. San Diego, CA: Plural Publishing; 2005: 57-70.
  13. ↑ Aviv JE. Cough It Up! Cough and Throatburn Reflux. In Aviv JE. Killing Me Softly From Inside. The Mysteries and Dangers of Acid Reflux and Its Connection to America’s Fastest Growing Cancer with a Diet That May Save Your Life. North Charleston, SC: Create Space Independent Publishing Platform 2014: 23-33.
  14. ↑ Aviv JE, Murry T. Sensory Testing Alone. In: Aviv JE, Murry T, eds. FEESST: Flexible Endoscopic Evaluation of Swallowing with Sensory Testing. San Diego, CA: Plural Publishing; 2005: 57-70.
  15. ↑ Aviv JE, Collins S. Upper Aerodigestive Manifestations Of Gastroesophageal Reflux Disease in: Flint PW, Haughey BH, Lund VJ, Niparko JK, Richardson MA, Robbins KT, Thomas JR, Eds. Cummings Otolaryngology Head And Neck Surgery, 5th Edition, Philadelphia PA, Elsevier Mosby; 2009: 894-903.
  16. ↑ Phua SY, McGarvey LPA, Ngu MC, Ing AJ. Patients with gastro-oesophageal reflux disease and cough have impaired laryngopharyngeal mechanosensitivity Thorax 2005; 60:488-491.
  17. ↑ Clayton NA, Carnaby-Mann GD, Peters MJ, Ing AJ. The effect of chronic obstructive pulmonary disease on laryngopharyngeal sensitivity. Ear Nose Throat J. 2012 Sep;91(9):370-382.
  18. ↑ Botoman VA, Hanft KL, Breno SM, Vickers D, Astor FC, Caristo IB, Alemar GO, Sheth S, Bonner GF. Prospective controlled evaluation of pH testing, laryngoscopy and laryngopharyngeal sensory testing (LPST) shows a specific post inter-arytenoid neuropathy in proximal GERD (P-GERD). LPST improves laryngoscopy diagnostic yield in P-GERD. Am J Gastro 2002; 97: S11-12.
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