By: Dr. Maria Cristina Iova
According to the Guinness World Records 2015, the largest tongue recorded in history belongs to Nick Stoeberl measuring 10.1 cm. Although this seems like an interesting trait, dentists confirm that having a large tongue is disadvantageous. The tongue is a specialized, muscular, and multifunctional organ that is part of the oral cavity, pharynx, and larynx.' It is essential in speaking, tasting, chewing, swallowing, and facial growth' and has tremendous importance in the airway path. It is particularly important to consider it when doing an orthodontic treatment or in obstructive sleep apnea (OSA). To understand the complications of a large tongue, the tongue will be first looked at the anatomical level so that the meaning of an oversized tongue and the different types of treatment solutions available to patients with specifically larger tongues can be discussed. In order to help the medical field, dentists need to pay more attention to the tongue by participating in and with clinical studies and publishing observations and information about the tongue, its size, and role in oral health.
The tongue is a muscular organ that lies partly in the mouth and partly in the oropharynx. It is covered by a thin specialized mucosa and is highly mobile, allowing it to take different positions when speaking, swallowing breathing, and at rest. It has four intrinsic muscles that form its body: superior longitudinal, inferior longitudinal, transversal, and vertical, and four extrinsic muscles that attach it to the bone: genioglossus, hyoglossus, palatoglossus, and styloglossus. Simply put, the intrinsic muscles allow the tongue to alter its shape while the extrinsic muscles change the position of the tongue. Moreover, from the frontal view, the tongue has two surfaces: the anterior surface that is highly specialized in taste and the posterior surface that forms the interior wall of the pharynx (Figure 1). From the sagittal view, there is the apex or the tip of the tongue (which is highly mobile), the body, and the root or base of the tongue which make up the other two-thirds of the tongue. The body is also highly mobile, surrounded by anterior and lateral teeth, and is rough due to the lingual papillae (taste buds). The root of the tongue attaches the tongue to the floor of the mouth and is located between the hyoid bone and the mandible (Figure 1).
Thereby, the five main functions of the tongue are: taste, speech, chewing, swallowing of the food, and cleaning of the mouth and teeth. The tongue has specialized mucosa and papillae that are receptors for taste. In speech, the tip of the tongue is very important, as it is mobile and uses the teeth and lips to make different sounds. Equally significant, the tongue helps the food to be broken down into smaller pieces, and it pushes it down the throat as the first part of the swallowing process. Lastly, the movements of the tongue dislodge food particles stuck between the teeth and gums so that they can be swallowed or spat out.
It is possible for the tongue to carry out these five functions due to its motor and sensory innervation. The motor innervation comes mainly from the hypoglossal nerve (cranial nerve 12, CN XII), and the palatoglossus muscle which is supplied by the pharyngeal plexus of cranial nerve X (CN X). The sensory innervation for taste includes the anterior two and the posterior one, the third chorda tympani, and the lingual branch of the glossopharyngeal nerve respectively. The sensory innervation for touch and temperature also includes the anterior two and the posterior one as well as the lingual nerve branch of CN V and the lingual branch of the glossopharyngeal nerve (CN IX)
The blood supply for the tongue comes from the lingual artery that comes from the external carotid. The deoxygenated blood is removed by the deep lingual vein that starts at the apex of the tongue, drains into the sublingual vein, and then into the inferior jugular vein. Hence, the lymphatic drainage happens in the following way: the root of the tongue drains into the superior deep cervical lymph nodes, the body (medial part) drains into the inferior deep cervical lymph nodes, the body (lateral parts) drains into submandibular lymph nodes, and the apex of the tongue drains into the submental lymph nodes.
Anatomy aside, the issue of the size of a tongue can be addressed. In dentistry normal size or large size tongues are talked about, especially in malocclusions, sleep apnea, and bad habits. The issue at hand is that there is no clear definition of what a "normal" tongue is which leads to further obscurity when deciding if the patient has macroglossia or microglossia. The definitions that are used are relative in functional or structural terms. As a result, clinical studies are limited by the lack of a clear definition of what normal is.
In light of this information, defining and understanding macroglossia will be focused on since this is the case that creates the most problems. There are two categories of macroglossia: pseudo-macroglossia and true macroglossia." Pseudo-macroglossia is any etiology that makes the tongue look large when actually it has a normal size. Such causes include maxillary and mandibular retrognathia, large adenoids or tonsils, a high palatal vault, and benign or malign tumors of the oral cavity and jaws. In the above cases, if the source is eliminated, for example treating and developing the jaws, surgically removing the tonsils and adenoids, or the excision of the tumors, the tongue can potentially assume a better position, and clinically a normal-sized tongue will be seen.
In true macroglossia where the tongue is actually large, it can be congenital or acquired. If it is congenital, it can come from: the trisomies (21 and 22), Beckwith-Wiedeman syndrome, hemangioma, lymphangioma, gargoylism, lingual thyroid, or muccopolysaccharidoses. Examples of true macroglossia from an acquired etiology are: hypothyroidism, diabetes, syphilis Ludwig's angina, pemphigus vulgaris, actynomycosis, tuberculosis, uremia, candidiasis, pellagra, carcinomas, sarcoidosis, and amyloidosis. There are two modalities of treatment for true macroglossia: indirect and direct." Indirect treatment means that more space is being created for a large tongue by acting on the surrounding structures in the mouth. This includes, hyoid advancement, tongue advancement (genioglossal advancement), genio-hyoid advancement, and mandibular advancement. Mandibular advancement can be done surgically or functionally with dental appliances. In contrast, the direct methods of treatment reduce the tongue directly through surgery, coblation, or radiofrequency waves.
If surgical treatment on the tongue is required, a partial glossectomy can be done. There are many ways of doing this, including many different types of incisions that can be made to different parts of the tongue. It can be acted on:
A. The tip of the tongue. Incisions can be made, from the anterior wedge resection, posterior keyhole, lateral borders resection, W-resection, or rhomboid resections. The indication here is to reduce the size of the tongue and improve the functionality. (Figure 2).
B. The base of the tongue. Being at a deeper level, this resection is more elaborate and customised to the patient's needs (See Figure 3 for identification of the base of the tongue).
Different resections provide reduction in different directions. Regardless of the approach chosen, the initial resection should be conservative as to prevent permanent problems that stem from overly aggressive resections like loss of taste, numbness, and fibrosis. Surgical corrections earlier in life minimize the patient's maxillofacial and speech problems and facilitates a healthy psychosomatic development and a better social integration.
Another technique for reducing the base of the tongue identified in Figure 3, is by making a 1 cm incision in the center of the tongue and inserting a coblation wand through this incision into the muscular bulk. When the wand is activated, an electrical current acts on a plasma layer that breaks the bond between the cells, then the muscles and the stroma of tissue surrounding the muscle start to liquefy, and the liquid is then suctioned out. A close analogy to this procedure is liposuction where fat is also aspirated.
On the base of the tongue, lymphoid glands called lingual tonsils can be found which, too, are of importance in many pathologies including sleep apnea. This area can sometimes be quite large, and it tends to collapse with the back wall of the pharynx during sleep, leading to obstruction of air, swallowing dysfunction, infections, and voice problems. This can happen to people of all body types and is not simply a condition of overweight people. Thin people can also have a large tongue base. It is important to note this because dentists cannot rule out the possibility of a patient having a large tongue base and possibly needing a tongue resection, based on his or her body type. This diagnostic can be made only with a fiberoptic laryngoscopy. Additionally, to be sure that the base of the tongue is obstructing the airway during sleep, a sedated endoscopy is obligatory. Also, in these cases, the same coblation technique can be used to eliminate the lingual tonsils (Figure 4). The difference is that it would be done without an incision, only by shaving the tissue slowly and carefully down to the tongue, much like sanding down a piece of wood (Figure 5).
The procedures can be done separately or in conjunction with general anesthesia where the patient is kept under observation for one day. Pain relief and normal talking and swallowing can be resumed in approximately 10 days to 4 weeks. Alternatively, radiofrequency treatment is another method for tongue reduction and is directed to specific sites in the tongue base without causing damage to the surrounding tissues. An electrical current of low frequency is introduced to the tissue that will determine its shrinkage. The patient is awake during the procedure, and a few sessions of treatment are necessary. Macroglossia is an issue that exists and is frequently overlooked. This is the result of a lack of a definition of what a "normal" sized tongue looks like. Dentists need to spend more time observing the tongues of their patients. Although it is not apparent, enough practice will lead to more abnormalities being detected. Photos of the tongue at rest or during swallowing need to be taken during the first visits for record collection. A video of the patient talking, smiling, swallowing, or even sticking out the tongue can also be helpful. Once pseudo macroglossia or true macroglossia are determined, the dentist can decide if a referral to an ENT or surgeon is necessary. Dentists already refer patients for tonsillectomies and adenoid removals as well as nose and sinus issues, then why not refer patients for tongue problems, too? Sleep apnea especially can be alleviated through partial glossectomies, coblation, and radiofrequency treatments. The results are positive: there is more space in the mouth, the breathing passage is not obstructed, therefore leading to better air flow, and the tongue is reduced to a more comfortable size. From speaking to numerous dentists and medical specialists, a normal-sized tongue has two attributes: the first is that it needs to be completely surrounded by the dental arches when the mouth is closed, and the dental arches must not leave any marks on it. The second characteristic can only be verified with a fiberoptic laryngoscopy to confirm that at the pharyngeal level, there is enough space between the tongue and the posterior wall of the pharynx, therefore letting air circulate freely, especially during sleep. Ergo, in combination with the first characteristic, the patient has a normal tongue. Looking for these two characteristics will help dentists reach faster and more precise conclusions about the patient's tongue size, and they will be able to get better results in treatments such as sleep apnea, orthodontics, and partial and fixed prosthetics.
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