In these cases it is usually the medial pterygoid or the buccinator muscles. Oral surgery procedures, as in the extraction of lower molar teeth, may cause trismus as a result either of inflammation to the muscles of mastication or direct trauma to the TMJ. Barbing of needles at the time of injection followed by tissue damage on withdrawal of the barbed needle causes post-injection persistent paresthesia, trismus and paresis. Treatment: in acute phase:
Heat therapy
Analgesics
A soft diet
Muscle relaxants (if necessary)
Note: When acute phase is over the patient should be advised to initiate physiotherapy for opening and closing mouth. Trauma
Fractures, particularly those of the mandible and fractures of zygomatic arch and zygomatic arch complex, accidental incorporation of foreign bodies due to external traumatic injury. Treatment: fracture reduction, removal of foreign bodies with antibiotic coverage

TMJ disorders
Extra-capsular disorders – Myofascial pain dysfunction syndrome
Intra-capsular problems – Disc displacement, arthritis, fibrosis,  etc. Acute closed locked conditions – displaced meniscus

Tumors and oral care
Rarely, trismus is a symptom of nasopharyngeal or infratemporal tumors/ fibrosis of temporalis tendon, when patient has limited mouth opening, always premalignant conditions like oral submucous fibrosis (OSMF) should also be considered in differential diagnosis. Drug therapy
Succinyl choline, phenothiazines and tricyclic antidepressants causes trismus as a secondary effect. Trismus can be seen as an extra-pyramidal side-effect of metoclopromide, phenothiazines and other medications. Radiotherapy and chemotherapy
Complications of radiotherapy:
Osteoradionecrosis may result in pain, trismus, suppuration and occasionally a foul smelling wound. When muscles of mastication are within the field of radiation, it leads to fibrosis and result in decreased mouth opening.
Prevention
Physical activity in extremely hot weather should be avoided. If a person starts to experience over heating, and symptoms of heat syncope, they should move or be moved to a shaded or cool area. It is also recommended to avoid alcoholic beverages in hot weather, because they cause dehydration which may worsen symptoms. Finally, drinking plenty of water with electrolytes is imperative when engaging in physical activity in hot weather. Treatment
The basic treatment for heat syncope is like that for other types of fainting: the patient is positioned in a seating or supine position with legs raised. Water containing salt, or another drink containing electrolytes, is administered slowly, and the patient is moved to a cooler area, such as the shade. The affected person should rest and recover, because heat syncope can lead to heat stroke or heat exhaustion. References


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