Background Trismus occurs frequently in patients with head and neck cancer. Determining the prevalence and associated factors of trismus would enable prediction of the risk of trismus for future patients. Methods Based on maximal mouth opening measurements, we determined the prevalence of trismus in 730 patients with head and neck cancer. Associated factors for trismus were analyzed using univariate analyses and multivariate logistic regression analyses. Based on the regression model, a calculation tool to predict trismus was made. Results Prevalence of trismus was 23.6%. Factors associated with trismus were: advanced age; partial or full dentition; tumors located at the maxilla; mandible; cheek; major salivary glands; oropharynx; an unknown primary; a free soft tissue transfer after surgery; reirradiation; and chemotherapy. Conclusion About one‐fourth of patients with head and neck cancer develop trismus. Based on prevalence and associated factors of trismus, a simple calculation tool predicts the risk of trismus in these patients.

Background: Trismus, a restricted mouth opening in head and neck cancer patients may be caused by tumor infiltration in masticatory muscles, radiation-induced fibrosis or scarring after surgery. It may impede oral functioning severely. The aims of our study were to determine: (1) the incidence of trismus at various time points; and (2) the patient, tumor, and treatment characteristics that predict the development of trismus after radiotherapy in head and neck cancer patients using a large database (n ¼ 641). Methods: Maximal mouth opening was measured prior to and 6, 12, 18, 24, 36, and 48 months after radiotherapy. Patient, tumor, and treatment characteristics were analyzed as potential predictors for trismus using a multivariable logistic regression analysis. Results: At six months after radiotherapy, 28.1% of the patients without trismus prior to radiotherapy developed trismus for the first time. At subsequent time points the incidence declined. Over a total period of 48 months after radiotherapy, the incidence of trismus was 3.6 per 10 person years at risk. Patients who had tumors located in the oral cavity, oropharynx or nasopharynx, and the salivary glands or ear, and who had a longer overall treatment time of radiotherapy, were more likely to develop trismus in the first six months after radiotherapy. Maximal mouth opening was a predictor for developing trismus at all time points. Conclusion: Incidence of trismus is 3.6 per 10 person years at risk. Tumor localization and overall treatment time of radiotherapy are predictors for developing trismus the first six months after radiotherapy. Maximal mouth opening is a significant predictor for developing trismus at all time points. Regular measurements of maximal mouth opening are needed to predict trismus.

PurposeTo compare the effects of two stretching devices, the TheraBite® Jaw Motion Rehabilitation System™ and the Dynasplint Trismus System®, on maximal mouth opening in head and neck cancer patients.MethodsPatients were randomly assigned to one of two exercise groups: the TheraBite® Jaw Motion Rehabilitation System™ group or the Dynasplint Trismus System® group. Patients performed stretching exercises for 3 months. During the three study visits, maximal mouth opening was measured and the patients completed questionnaires on mandibular function and quality of life.ResultsIn our study population (n = 27), five patients did not start the exercise protocol, eight patients discontinued exercises, and two patients were lost to follow-up. No significant differences regarding the change in mouth opening between the two devices were found. Patients had an increase in MMO of 3.0 mm (IQR − 2.0; 4.0) using the TheraBite® Jaw Motion Rehabilitation System™ and 1.5 mm (IQR 1.0; 3.0) using the Dynasplint Trismus System®. Exercising with either stretching device was challenging for the patients due to the intensive exercise protocol, pain during the exercises, fitting problems with the stretching device, and overall deterioration of their medical condition.ConclusionsThe effects of the two stretching devices did not differ significantly in our study population. The factors described, influencing the progression of stretching exercises, need to be taken into account when prescribing a similar stretching regimen for trismus in head and neck cancer patients.Trial registrationNTR - Dutch Trial Register number: 5589Electronic supplementary materialThe online version of this article (10.1007/s00520-019-05075-7) contains supplementary material, which is available to authorized users.