Trismus in head and neck oncology: a systematic review.

The aim of this review was to identify systematically, criteria for trismus in head and neck cancer, the evidence for risk factors for trismus and the interventions to treat trismus. Three databases were searched (time period 1966 to June 2003) for the text "trismus" or "restricted mouth opening". Included in the review were clinical studies (> or = 10 patients). Two observers independently assessed the papers identified. In 12 studies nine different criteria for trismus were found without justifying these criteria. Radiotherapy (follow-up: 6-12 months) involving the structures of the temporomandibular joint and or pterygoid muscles reduces mouth opening with 18% (sd: 17%). Exercises using a therabite device or tongue blades increase mouth opening significantly (no follow-up), effect sizes (ES) 2.6 and 1.5 respectively. Microcurrent electrotherapy (follow-up 3 months) and pentoxifylline (no follow-up) increases mouth opening significantly (ES for both: 0.3).