LaryngoSCOPE Vocal Fold Hypomobility Yolanda D. Heman-Ackah and Robert T Sataloff Yolanda D. Heman-Ackah, M.D. Robert T Sataloff, M.D.. D.M.A. ANATOMY AND FUNCTION with voice production except the cricothyroid muscles span the space OF THE LARYNX cricothyroid muscle. The joint space between the cricoid and thyroid car- between the arytenoid cartilage and tilages on the sides of the larynx. To- The movements of the vocal the cricoid cartilage is the cricoary- gether the thyroarytenoid muscle, its folds of the larynx are coordinated by tenoid joint. It is critical that the joint specialized mucosal membrane, and the activities of the muscles of the lar- space between the artenoid and its attachment onto the vocal process ynx, the cartilages of the larynx, and cricoid cartilage is mobile and allows of the arytenoid cartilage are referred the nerves that supply the muscles of a full range of motion of the ary- to as the vocal fold or true vocal fold. the larynx. 'The larynx sits above the tenoids. If this cartilaginous joint be- The vocal folds come together trachea and in front of the esophagus. comes immobile, the arytenoid carti- and meet in the midline when the thy- The larynx has two identical sides lage can not move well. Limited roarytenoid, interarytenoid, lateral that form a mirror image of each oth- mobility of the arytenoid cartilage im- cricoarytenoid, and cricothyroid mus- er and is composed of cartilage, mus- pairs the mobility of the vocal folds. cles contract. 1 These muscles help to cle, and mucous membranes. The muscles of the larynx at- bring the vocal folds together during The cartilage provides the struc- tach to the cartilages in different lo- swallowing and prevent the passage of tural support for the muscles and mu- cations. The main muscles of the lar- food particles and liquids into the tra- cous membranes similarly to the way ynx are the thyroarytenoids, the chea. Additionally, the laryngeal mus- in which the framework of a house posterior cricoarytenoids, the lateral cles contract to bring the vocal folds provides support for the walls and cricoarytenoids, the interarytenoids, together in voice production. When floors. The main cartilages of the lar- and the cricothyroids. Each side of air is pushed from the lungs past the ynx are the thyroid, cricoid, and ary- the larynx has a thyroarytenoid, a closed vocal folds, a sound is made. tenoid cartilages. The arytenoid carti- posterior cricoarytenoid, and a later- This sound is the voice. If the vocal lages sit on top of the cricoid cartilage al cricoarytenoid muscle. The inter- folds are able to make good contact, and serve as points of attachment for arytenoid muscles sit in the midline and if the movement of the mucosal all of the muscles that are involved of the back of the larynx, and the cover is normal, a clear sound is made. H4/AzL 2002 321 S. N. 4. tf. 21-21 2002 M*z,4 . T4 Yolanda D Heman-Ackah and Robert T. Sataloff When the cricothyroid and thy- After the superior laryngeal tient attempts to vocalize. The air roarytenoid muscles contract, they nerve branches, the vagus nerve from the lungs that is normally tense the vocal fold.' When there is a travels into the chest to supply neur- trapped below the vocal folds during lot of tension on the vocal fold, a high- al innervation to the heart, where it phonation is able to leak through this pitched sound is produced. When helps regulate heart rate and blood gap. The turbulent flow of air there is less tension on the vocal fold, pressure. While in the chest, the re- through the gap produces the sound lower-pitched sounds are produced. current laryngeal nerve separates that is perceived as breathiness. As When the posterior cricoarytenoid from the vagus nerve and courses air from the lungs continues to leak muscle contracts, it pulls the vocal back into the neck, where it enters through the vocal folds, prolonged folds open. The vocal folds open to the larynx. In the larynx, the recur- phonation becomes more effortful. allow the entrance of air into the air- rent laryngeal nerve supplies motor Many describe this sensation as vocal way when a breath is taken and to function to the thyroarytenoid, inter- fatigue. provide breaks between sounds dur- arytenoid, posterior cricoarytenoid, The vocal folds also help to pro- ing phonation. and lateral cricoarytenoid muscles. tect the lungs and the trachea from The larynx receives neural sup- The recurrent laryngeal nerve also aspiration of food and liquids during ply from two nerves, the superior la- supplies sensation to the vocal folds swallowing. If they are unable to ryngeal nerve and the recurrent la- and to the portions of the larynx and close completely during swallowing, ryngeal nerve. The superior laryngeal trachea below the vocal folds. aspiration may occur. If the sensa- nerve supplies motor function to the tion of the vocal folds and trachea is cricothyroid muscle and sensation to normal, choking or coughing may oc- the parts of the larynx above the vo- SYMPTOMS OF VOCAL cur each time food or liquid is aspi- FOLD HYPOMOBILITY cal folds. The recurrent laryngeal rated. If the sensation is not working correctly, aspiration may occur with- nerve supplies motor function to the A patient who has decreased vo- remaining muscles of the larynx and out signs of choking or coughing, a cal fold mobility will likely experi- phenomenon commonly referred to sensation to the vocal folds and the ence problems with hoarseness, a parts of the larynx below the vocal as "silent aspiration." Whether or breathy voice, and/or vocal fatigue.2 not the sensation in the nerve is af- folds. Hoarseness is sometimes perceived The recurrent laryngeal nerve fected depends on whether the mo- because of abnormal strain in the bility problems are due to nerve dys- and the superior laryngeal nerve are muscles around the larynx as the pa- branches of the vagus nerve. Each of function or other causes and on tient tries to bring the vocal folds to- whether the sensory portions of the these nerves is paired, with one of gether. This excess muscle tension the pair on each side of the neck and nerve are affected by the same prob- may sometimes result in false vocal lem that is limiting the motor func- larynx. The vagus nerve branches di- fold phonation, which has a more tion of the nerve. rectly off the brainstem, the portion raspy or hoarse quality than normal of the brain at the base of the skull. true vocal fold phonation. A breathy The vagus exits the base of the skull quality is produced as a result of air DIAGNOSIS OF VOCAL and enters the neck, where it branch- escape through the incompletely FOLD HYPOMOBILITY es twice. The superior laryngeal closed vocal folds. When there is nerve is the first branch. It courses paresis (weakness) or paralysis (im- Patients with movement disor- into the larynx above the thyroid car- mobility due to complete nerve dam- ders of the larynx may have com- tilage and divides into the internal age) of the vocal fold, the normal vo- plaints that range from hoarseness, and the external branches. The inter- cal fold must compensate for this breathiness with phonation, and vo- nal branch supplies sensation to the weakness by closing to the midline, cal fatigue to problems with swallow- portions of the larynx above the vo- and sometimes closing past the mid- ing, choking, shortness of breath, cal folds. The external branch sup- line, to meet the other vocal fold. If it and aphonia. The patient who has plies motor function to the cricothy- is unable to do this, there is a gap be- these complaints is generally evaluat- roid muscle. tween the vocal folds when the pa- ed by the otolaryngologist (an ear, 322 LaryngoSCOPE nose, and throat doctor) or laryngolo- pain, although it may cause a slight lage to a lesser degree, resulting in gist (an ear, nose, and throat doctor discomfort in the nose. The patient is tilting of the larynx towards the side who specializes in treating disorders seated and awake during the exami- of the weak superior laryngeal nerve of the larynx). The physician may nation. The flexible laryngoscope al- and cricothyroid muscle. ask the patient many questions about lows the physician to see the larynx If there are problems with both the symptoms to help exclude other in its natural position, without the superior laryngeal nerves, there will possible causes and to help narrow distortion that sometimes occurs be limitations in the ability to pro- the potential list of problems. with holding the tongue forward for duce a high pitch and in the ability to After the physician has complet- mirror and rigid telescopic examina- stretch the vocal folds on both sides.2 ed taking a history of the patient's tions. In viewing the larynx in its This diagnosis may be somewhat dif- problems, he/she will examine the natural position, the physician can ficult, especially if both nerves are in- patient. The physical examination assess changes in laryngeal muscle jured to the same degree. Both vocal will include a complete evaluation of tension while the patient is talking or folds will have limitations in their all of the structures of the head and singing. There are certain vocal ma- abilities to stretch, making the ability neck.3 This complete examination is neuvers that the otolaryngologist/ to see subtle abnormalities difficult performed because there are some laryngologist will ask the patient to for the examiner. disorders that affect many different perform during the flexible laryngo- Occasionally, with superior la- regions of the head and neck, and scopic examination.