Mouth is the vital and most active part of the face adding expressions, beauty and words to the person’s identity. Mouth and oral cavity is extremely necessary for breathing, speech and eating as well.
Usually an individual can open mouth upto 35-45mm (which is approximately three fingers wide). Males have more mouth opening as compared to females. However, due to some reasons a person cannot open his mouth completely thereby, limiting his language and eating habits. Inability to open mouth (lockjaw in ancient literature) is known as trismus in medical terminology which is a frustrating and debilitating condition. Trismus, temporary or permanent, is a common problem prevalent worldwide with more than one million affected individuals every year.
If ignored for long, trismus may lead to several facial and general complications such as difficulty in breathing and malnourishment.
Common causes of trismus:
- Systemic conditions
- Fracture or trauma to the jaw
- Oral diseases
Post-surgical trismus is commonly seen in dental surgeries (wisdom tooth removal), TMJ surgery and radiation therapy. Common Systemic conditions associated with trismus include tetanus, sclerosis, Parkinson disease, rheumatoid arthritis, etc. and needs appropriate treatment. Severe stress may also be one cause for restricted mouth opening for brief period of time. Ankylosis or fusion of the lower and upper jaw at the temporomandibular joint (TMJ) level might occur in newly born babies due to forceps delivery or as a sequel to the unattended trauma to the joint in children and adults. Some fractures including lower jaw (mandible) fracture, facial and cheek bone fracture might be a cause for trismus.
Injury to the muscles of face specifically seen in assault injuries and road traffic accidents might cause pain and swelling and limited mouth opening temporarily, but in few cases may cause long term calcification in muscle fibres. Several lesions of the mouth (mostly suggestive of risk of cancer!!) can cause trismus. Immediate repair of the fracture is the treatment of choice in most of the facial fractures. Muscular injury can be treated with medicines (anti-inflammatory and steroids).
Ankylosis causes severe facial asymmetry and unaesthetic facial appearance (often referred as Andy Gump appearance) and dental problems. Removal of fused structure and mobilization of the joint is the ideal treatment followed by aggressive physiotherapy and further cosmetic surgeries, bone grafts, and dental treatment.
Succinyl choline, phenothiazines and tricyclic antidepressants may lead to trismus. This condition can be also seen as an extra-pyramidal side-effect of medicines such as metaclopromide, phenothiazines, etc.
Infections of facial region most commonly associated with tooth decay, Mumps or ear infections can cause trismus and antibiotic therapy with anti-inflammatory drugs are usual treatment of choice. Oral submucous fibrosis (OSMF) is a condition commonly seen in chronic tobacco chewers often complaining trismus and burning mouth sensation. World health organization (WHO) has considered such situations (OSMF, lichen planus, leukoplakia, etc.) into precancerous lesions and conditions which carries high risk of cancer of the mouth and other parts of the body as well! Biopsy and needful treatment is indicated in such patients. Cessation of the tobacco habit or smoking is of utmost importance for successful treatment. Injection therapy, laser, surgery and skin grafts, etc are treatment modalities available however, long term follows up and mouth opening exercises are needed for these patients.
Cases with oral cancer require multidisciplinary approach and aggressive treatment as in such cases rehabilitation can be done only after successful treatment of the tumor. Trismus has been commonly seen in patients after radiotherapy.
Trismus is a troublesome sign to the more serious underlying disease. The condition may often go unnoticed or ignored by the patients as it is slowly developing in many cases. Constant awareness among general population, physicians, ENT and dental surgeons is needed as they encounter the oral cavity frequently thereby motivating the patient for early diagnosis and prompt treatment.