The effect of exercise therapy in head and neck cancer patients in the treatment of radiotherapy-induced trismus: A systematic review

Trismus is characterized by a reduced ability to open the mouth, directly affecting many aspects of daily life, such as chewing, swallowing, speaking and maintaining oral hygiene. Several studies have shown that trismus affects health related quality of life. Radiotherapy in the head and neck area is identified as one of the most frequent causes of trismus in head and neck cancer (HNC) patients. Currently, there is no standard treatment for trismus. Several stretching techniques and jaw mobilizing devices are available, but their effect in radiotherapy-induced trismus is still largely unknown. With this review we give an overview of the present relevant literature and compare the effect of exercise therapy versus no exercise therapy on jaw mobility, expressed in millimeters mouth opening, in HNC patients with radiotherapy-induced trismus. A systematic literature search in four electronic bibliographic databases was conducted in July 2014. Selected articles were critically appraised on relevance and validity. Best available evidence was analyzed and compared. Three of the four selected articles show a significant increase (p-value<0.05) in maximal interincisal opening (MIO) after exercise therapy using a jaw-mobilizing device. One article reports a significant decrease in MIO. However, this decrease is less in the intervention group, which implies a positive effect of exercise therapy. Based on this current best clinical evidence, it can be assumed that exercise therapy with a jaw-mobilizing device yields better results than no exercise, with regards to opening of the mouth in HNC patients with radiotherapy-induced trismus.