|Year : 2022 | Volume
| Issue : 1 | Page : 27-31
Hearing loss in oral submucous fibrosis: A narrative review
Santosh Kumar Swain
Department of Otorhinolaryngology and Head and Neck Surgery, IMS and SUM Hospital, Siksha “O” Anusandhan University, Bhubaneswar, Odisha, India
|Date of Submission||11-Aug-2021|
|Date of Decision||02-Oct-2021|
|Date of Acceptance||05-Oct-2021|
|Date of Web Publication||13-Jan-2022|
Santosh Kumar Swain
Department of Otorhinolaryngology and Head and Neck Surgery, IMS and SUM Hospital, Siksha “O” Anusandhan University, K8, Kalinga Nagar, Bhubaneswar - 751 003, Odisha
Source of Support: None, Conflict of Interest: None
Oral submucous fibrosis (OSMF) is a chronic insidious disease of the oral cavity mucosa which often occurs due to areca nut chewing, consumption of spicy foods, autoimmunity and genetic predisposition. Burning sensation in the mouth, intolerance to spicy foods, and increasing restriction of mouth opening owing to oral mucosa fibrosis are all clinical signs of OSMF. Advanced cases of OSMF cause hearing loss by blocking of eustachian tube. The extension of the fibrosis towards nasopharynx results in blockage of the eustachian tube opening at the nasopharynx and cause hearing loss. OSMF reduce the eustachian tube patency and cause conductive hearing loss. Involvement of the palatal muscles in OSMF patient may reduce the patency of the eustachian tube, resulting in conductive hearing loss. OSMF patients need audiological early assessment and tympanogram to detect involvement of eustachian tube and middle ear. Pure tone audiometry is a common audiological test which determines the types, degree and configuration of the hearing impairment. As these audiological tests is non-invasive and less time consuming, so useful to help early detection of hearing loss and appropriate therapeutic intervention. There are very few literatures are available related to OSMF and hearing loss. This review article discusses about the etiopathology, epidemiology, clinical manifestations and management of the OSMF and hearing loss.
Keywords: Eustachian tube, hearing loss, oral cavity, oral submucous fibrosis
|How to cite this article:|
Swain SK. Hearing loss in oral submucous fibrosis: A narrative review. Apollo Med 2022;19:27-31
| Introduction|| |
Oral submucous fibrosis (OSMF) is a chronic oral cavity illness that can also affect the pharynx. It is usually recognized as a collagen disease with great similarity to morphea or localized scleroderma. Patients with OSMF usually present with blanching and stiffness of the oral mucosa, reduced mobility of the soft palate and tongue, difficulty in opening of the mouth, burning sensation in the mouth, absence of gustatory sensation, and mild deafness due to Eustachian tube dysfunction. OSMF is a potentially malignant disorder caused due to chewing the betel quid. OSMF is commonly seen in India; however, it has been reported in other countries as sporadic cases. The exact cause of OSMF is still obscure, but many etiological factors such as chewing betel nut, tobacco, pan masala, and smoking and consuming chilies have been contributing factors. OSMF is characterized by progressive fibrosis involving mucous membrane of the oral cavity, mainly buccal mucosa, soft palate, lip mucosa, and anterior pillars. Involvement of the soft palatal muscles often affects the function of the Eustachian tube. There is a paucity of information related to the involvement of OSMF in the adjacent areas of the oral cavity such as the ear (Eustachian tube), oropharynx, hypopharynx, and larynx, and very few studies are available to correlate to the Eustachian tube dysfunction with different clinical stages of OSMF. There is not much literature available for correlating hearing loss and OSMF. The epidemiology, etiopathology, clinical manifestations, investigations, and therapy of hearing loss in OSMF are discussed in this review paper.
| Methods of Literature Search|| |
Multiple systematic methods were used to find current research publications on oral submucous fibrosis causing hearing loss. We started by searching the Scopus, PubMed, Medline, and Google Scholar databases online. A search strategy using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was developed. This search strategy recognized the abstracts of published publications, while other papers were discovered manually from the citations. This search strategy recognized the abstracts of published publications, while other papers were discovered manually from the citations. There were total numbers of articles 78 (32 case reports, 34 cases series, and 12 original articles). This paper examines the epidemiology, etiopathogenesis, clinical manifestations, diagnosis, and treatment of OSMF causing hearing loss. This analysis provides a foundation for future prospective trials in OSMF and hearing loss. It will also serve as a catalyst for additional study into OSMF causing hearing loss and allowing early detection and treatment.
| Epidemiology|| |
OSMF is most commonly reported by Indians, both inside and outside India, to a lesser amount by other Asians, and infrequently by Europeans. OSMF is most typically found in Asian countries such as India, Bangladesh, Sri Lanka, Pakistan, Taiwan, and Southern China, where areca nut intake or its flavored formulations, or as an ingredient in betel quid, are more widespread. The overall prevalence of OSMF in India is about 0.2%–1.2% and prevalence by gender varying from 0.2% to 5% in males and 1.2%–4.5% in females. The malignant transformation of OSMF is found in 4%–13% of cases worldwide and 7.6% of cases of OSMF in the Indian population. In one study, in comparison to the control group, the OSMF group had a considerable degree of hearing loss, and advanced stages of OSMF were strongly related to mild conductive hearing loss (P < 0.001). Palatal muscle involvement in OSMF may reduce the patency of the Eustachian tube, resulting in conductive hearing loss. As a result, all OSMF patients should be tested for hearing loss and given treatment recommendations. In another study, 16% of cases of OSMF showed type B tympanogram, and 8.5% of cases showed type C tympanogram.
| Eustachian Tube Dysfunction in Oral Submucous Fibrosis|| |
The pharyngotympanic tube (Eustachian tube) connects the middle ear cavity to the nasopharynx. The physiological importance of the Eustachian tube's shutting and opening cannot be overstated. The opening of the Eustachian tube helps to equalize the atmospheric pressure in the middle ear, whereas the closing of the Eustachian tube protects the middle ear from pressure fluctuations and loud sounds. Impaired function of the Eustachian tube results in middle ear diseases which in turn can lead to hearing loss. In the case of OSMF, there is a chance of failure of the Eustachian tube to regulate the air pressure effectively. When the Eustachian tube's function deteriorates, the middle ear's air pressure drops, causing muffled ear noises and hearing loss.
| Etiopathology|| |
OSMF is mostly an oral and oropharyngeal clinical condition. The mucous membranes of the oral cavity, particularly the buccal mucosa, soft palate, lip mucosa, and anterior pillars, are affected by progressive fibrosis. In OSMF, there is characteristic fibrosis of lamina propria and submucosal with an increasing loss of tissue mobility. There are a variety of etiological agents such as capsaicin, betel nut alkaloids, autoimmunity, hypersensitivity, genetic predisposition, chronic iron deficiency, and chronic Vitamin B complex deficiency for causing OSFM, however, the most common agent is chewing areca nut. OSMF is often associated with vesicle formation and juxta-epithelial inflammatory reaction followed by changes in fibroblasts in the lamina propria with epithelial atrophy resulting in stiffness of the oral mucosa causing trismus and difficult to open mouth during eating. Different forms of tobacco that cause OSMF are pan masala, pan, gutkha, pan parag, and mawa. The mucosal linings of the pharyngeal box and vocal folds are rarely affected, however, the Eustachian tube can be affected. The palatal and paratubal muscles, such as the levator veli palatini, tensor veli palatini, tensor tympani, and salpingopharyngeus, are involved in the patency and function of the Eustachian tube's nasopharyngeal aperture. Further narrowing of the nasopharyngeal opening of the Eustachian tube results in defective regulation of the middle ear pressure which causes ear pain and loss of hearing. Hearing loss is linked to the degree of fibrosis of the palate muscles, which reduces the Eustachian tube's patency. In extensive fibrosis, it may spread to the oropharynx which alters the perception of the sound, which is evident in the advanced stage of the OSMF because of the changes in the patency of the Eustachian tube, which may happen due to progressive fibrosis of the palatal muscles, being directly proportional to the stage of the OSMF. In vitro studies using areca extracts or chemically pure arecoline on human fibroblasts support the notion of fibroblast proliferation and collagen synthesis, which is also demonstrated histologically in human tissue at OSMF. The role of areca alkaloids and copper in fibroblast proliferation and raised collagen synthesis, stabilization of collagen structure by tannins, fibrogenic cytokines, and genetic polymorphism leads to OSMF. The role of collagen-related genes such as COL1A2, COL3A1, COL6A1, COL6A3, and COL7A1 has been associated with OSMF.
| Grading of Oral Submucous Fibrosis|| |
Patients with Grade I (early OSMF) present with a burning sensation in the mouth to the hot and spicy diet. Examination of the oral cavity shows blanching, palpable fibrosis of the buccal mucosa, fibrosis of the tonsillar pillars, pterygopalatine raphe, and soft palate. Mouth opening in Grade I OSMF is 25–35 mm.
Patients with Grade II (moderate OSMF) present with a hot and spicy diet. Examination of the oral cavity shows fibrosis of the buccal mucosa, tonsillar pillars, pterygomandibular raphe, and soft palate which extends anteriorly to affect labial mucosa, the floor of the mouth, and tongue. Tongue movement is restricted to some extent. There is a loss of flexibility of the buccal mucosa. The mouth opening is 15–25 mm.
Patients with Grade III (severe OSMF) present with a burning sensation in the mouth even without the presence of any stimuli. Examination of the oral cavity shows severe fibrosis of the entire oral cavity. The tongue's movements are severely restricted, and the buccal mucosa's elasticity is severely reduced. Around the lips and mouth, there is a circular ring (fibrotic rim). The uvula is often shrunken due to fibrosis observed on the soft palate. The patient has trouble swallowing and deglutition. There is a problem with speech and a nasal voice. The patient has a restriction of mouth opening <15 mm.
| Clinical Presentations|| |
OSMF often affects the individuals in the second and third decades of life with male predominance. OSFM patients often present with the burning sensation of the oral cavity mucosa, ulceration, and pain. Patients of OSMF also present with reduced mobility and depapillation of the tongue, blanching and leathery texture of the oral cavity mucosa [Figure 1], loss of pigmentations of the mucosal lining of the oral cavity, and progressive reduction of the mouth opening. Lai's classification of OSMF is based on inter-incisional distance, and this classification includes Group A: >35 mm inter-incisional distance, Group B: 30–35 mm inter-incisional distance, Group C: 20–30 mm inter-incisional distance, and Group D: <20 mm inter-incisional distance. Advanced cases of OSMF may present with hearing loss because of obstruction of the Eustachian tube and difficulty in swallowing because of the fibrosis of the mucosal lining of the esophagus. In Grade 1 OSMF, most of the patients are in the age range from 15 to 30 years; in the case of Grade II OSMF, most of the patients are in the age range of 31–45 years; and in Grade III OSMF, the majority of the patients are in the age range of 31–45 years and 46–60 years. Palatal and paratubal muscles (levator veli palatini, tensor veli palatini, tensor tympani, and salpingopharyngeus) control the patency and function of the nasopharyngeal orifice of the Eustachian tube so may get affected in OSMF which result in impairment of the patency of the Eustachian tube. The impairment of the Eustachian tube leads to otalgia and mild-to-moderate conductive hearing loss. The Eustachian tube dysfunction results in otitis media with effusion and even otitis media with discharging ear and hearing loss.
|Figure 1: Oral submucous fibrosis patient showing blanching and leathery texture of the oral cavity mucosa|
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| Investigation|| |
The involvement of palatal muscles in OSMF may reduce the patency of the Eustachian tube, resulting in conductive hearing loss. Excess collagen fibers, narrowing of arteries, edema, excessive fibroblast deposition, and infiltration of inflammatory cells are histological abnormalities in OSMF. The pathological changes in OSMF not only involve the mucosa and submucosa but also affect underlying muscles and deeper tissues. One study with electron microscopy showed focal lysis and hypercontraction of myofibers and extensive fatty infiltration between the muscle bundles in biopsy specimens taken from the buccal mucosa of the oral cavity with OSMF. Gupta et al. had taken biopsy samples from the soft palate which showed degenerative changes in palatal and paratubal muscles in the form of atrophy, lack of cross striations, and edema of myoepithelium. Pure-tone audiometry often shows the conductive type of hearing loss in the affected side of the Eustachian tube by OSMF. The patients often show mild-to-moderate conductive hearing loss. Based on air conduction–bone conduction gap values, the hearing gloss is usually quantified as different categories such as 0–25 decibels – normal hearing, 26–40 decibels – mild deafness, 41–55 decibels – moderate deafness, 56–70 decibels – moderate-to-severe hearing loss, 71–90 decibels – severe hearing loss, and more than 90 decibels – profound hearing loss. Tympanometry test may reveal types B and C of tympanograms in case of Eustachian tube dysfunction by OSMF. All patients with OSMF and ulcerations should undergo a biopsy to confirm the diagnosis and also correlate the clinical and histopathological findings. Incisional biopsy should be taken from retromolar and buccal mucosal areas. Additional biopsies can be collected from places where the mucosa has changed clinically, indicating atypia or malignant transformation.
| Treatment|| |
The objective of the treatment of OSMF is to reduce the burning sensation in the mouth, improvement in mouth opening, and cessation of spread of oral OSMF to other areas such as the pharynx. There is no definitive treatment available for curing the OSMF rather than several treatment options [Table 1]. No single medication or drug has effectively reversed the initiation and development of the OSMF. This could be due to a variety of factors, including the disease's degenerative nature, a lack of thorough knowledge of the disease's pathophysiology, and the disease's limited administration routes. Habits of oral chewing of betel nut, gutkha, spicy foods, consumption of alcohol, and smoking should be stopped. Patients of OSMF with anemia should be treated and encouraged to eat a well-balanced diet. Intralesional injection of betamethasone, placentrex, and hyaluronidase may help relieve the restricted mouth opening and burn sensation in the mouth. These treatment options also help to stop the spreading of the diseases to other parts of the oral cavity and oropharynx. The treatment of OSMF is done based on the degree of involvement. Patients need treatment like trismus correction and reconstruction surgery. Intralesional steroids work by inhibiting the function of soluble factors released by sensitized lymphocytes after they have been activated by certain antigens or triggering stimuli, resulting in OSMF. By preventing inflammatory reactions, steroids prevent fibrosis by reducing fibroblastic proliferation and deposition of collagen. The symptomatic relief by intralesional steroids could be due to anti-inflammatory actions which help in decreasing the juxta-epithelial inflammation. Although uncommon, long-term intralesional injection of steroids has adverse effects such as osteoporosis, myopathies, peptic ulcer, or central serous chorioretinopathy. Hence, in the situation where adequate mouth opening is achievable by the use of intralesional injection of hyaluronidase alone, the use of steroids should be avoided to reduce the adverse effects. Placentrex is an aqueous extract of the human placenta which contains nucleotides, enzymes, vitamins, amino acids, and steroids. The action of placentrex is usually biogenic stimulation which stimulates the pituitary and adrenal cortex and regulates the metabolism of tissues. It also enhances the vascularity of the tissues. Hyaluronidase causes the breakage and dissolution of the fibrous band in the oral cavity and so relief from the OSMF. Hyaluronidase plays an important role in relieving the patients with restricted mouth opening and also blockage of the Eustachian tube. Aloe vera is an emollient and a protein that contains several amino acids known as wound healing hormones. Wound healing, anti-inflammatory, anti-cancer, immunomodulatory, and gastroprotective effects are all found in the polysaccharides found in A. vera gel. For the treatment of OSMF, local application of A. vera is beneficial as an adjuvant to pharmacological and surgical methods. OSMF is treated surgically by removing the fibrotic bands with a knife or a laser, with or without the use of inter-positional grafts to keep the mouth cavity open. Patients of OSMF with trismus should be advised to do mouth opening exercises for at least 20 min daily.
| Conclusion|| |
OSMF is a chronic, insidious, disabling disease affecting mucosa of the oral cavity, oropharynx, and rarely larynx. OSMF is often called a collagen metabolic disorder and is characterized by raised collagen deposition and decreased collagen degradation. OSMF affects the palatal muscles, which causes the Eustachian tube to become less patent, resulting in conductive hearing loss. All patients with OSMF require audiological assessment with pure-tone audiometry and tympanometry to rule out the involvement of Eustachian tube and hearing loss. Although no definitive treatment is available, several medical and surgical techniques have been tried in the treatment of OSMF and its complications. Because of the lack of curative treatment and precancerous nature of this disease, it is often essential to follow up with the patients on a regular basis along with available treatment for decreasing the fibrosis bands in the oral cavity and pharynx.
Declaration of patient consent
The patient consent was obtained.
The authors are thankful to hospital authority for their co-operation.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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