Overview of Radiation-Induced Trismus in Head and Neck Cancer

Overview of Radiation-Induced Trismus in Head and Neck Cancer

Trismus, commonly defined as restricted mouth opening, is a significant complication that affects patients diagnosed with head and neck cancer (HNC) following radiation therapy (RT). The prevalence of trismus post-radiation can range from 30% to 60%, severely impacting the quality of life by hindering essential functions such as eating, speaking, and maintaining oral hygiene (Aboelez et al., 2025). The pathophysiology of radiation-induced trismus is multifaceted, often resulting from fibrotic changes in the masticatory muscles and alterations in the temporomandibular joint (TMJ).

Radiotherapy targets malignant cells but also inadvertently damages surrounding healthy tissues, leading to inflammation, fibrosis, and subsequent muscle contraction (Smeets et al., 2022). This contraction can result in a maximal mouth opening (MMO) of less than 35 mm, which defines trismus (Elgohary et al., 2023). Consequently, effective management strategies are crucial for alleviating symptoms and improving the functional outcomes for patients undergoing treatment for HNC.

Common Symptoms and Diagnostic Challenges of Trismus

Patients suffering from radiation-induced trismus typically present with a constellation of symptoms, including:

• Restricted Mouth Opening: Difficulty in opening the mouth, which can lead to challenges with eating and oral hygiene.
• Facial Pain and Discomfort: Patients may experience pain in the jaw muscles or TMJ, further complicating their ability to function normally.
• Difficulty in Chewing and Speaking: As mouth opening decreases, patients may find it difficult to chew solid foods or articulate clearly.
• Psychological Impact: The inability to perform basic functions can lead to anxiety, depression, and social withdrawal (Cardoso et al., 2021).

Diagnosing trismus often involves clinical examination and self-reported symptoms. The Gothenburg Trismus Questionnaire (GTQ) has emerged as a reliable tool for evaluating the severity of trismus and its impact on patients’ quality of life (Johnson et al., 2012). Nonetheless, the subjective nature of symptoms can present diagnostic challenges, as many patients may underreport their difficulties due to embarrassment or normalization of their condition.

Treatment Modalities for Radiation-Induced Trismus

A variety of treatment modalities have been explored to alleviate radiation-induced trismus. These approaches can be categorized into conservative and surgical methods:

1. Conservative Treatments:

   • Physical Therapy: Exercises focused on the jaw muscles can help restore function and reduce stiffness. Techniques may include stretching exercises and the use of devices that aid in increasing mouth opening.
   • Low-Level Laser Therapy (LLLT): This modality utilizes low-intensity lasers to promote tissue healing, reduce pain, and improve mouth opening, with numerous studies showing its effectiveness in reducing trismus symptoms (Aboelez et al., 2025).
   • Threaded Tapered Screw Appliance (TTSA): This custom-made appliance is designed to gradually increase mouth opening by applying controlled pressure to the molars (Geethu et al., 2023). Patients are instructed to adjust the device themselves to promote progressive opening.

2. Surgical Treatments:

   • Surgical interventions may be considered in severe cases where conservative therapies fail. This can include procedures to release or lengthen the muscles and ligaments around the TMJ or even reconstructive surgeries to repair damaged tissues.

Table 1 summarizes the various treatment modalities and their effectiveness based on current literature.

Efficacy of Threaded Tapered Screw Appliance Therapy

TTSA has been shown to significantly improve MMO and reduce pain levels in patients with radiation-induced trismus. A randomized clinical trial involving patients who underwent RT for head and neck cancer indicated that those using TTSA displayed a marked increase in MMO after six months of treatment compared to baseline measurements (Aboelez et al., 2025). This gradual, patient-driven approach enables individuals to actively participate in their recovery, fostering a sense of control over their treatment.

The device’s design allows it to be easily adjusted, promoting consistent application of force, which is essential for muscle stretching and relaxation. Furthermore, patient compliance is typically high, as the device is non-invasive and easy to use, making it a favorable option in managing trismus.

Benefits of Low-Level Laser Therapy in Trismus Management

LLLT has gained recognition as an effective non-invasive intervention for managing trismus. The application of low-intensity lasers stimulates cellular metabolism and enhances tissue repair through photobiomodulation (Zecha et al., 2020). Studies have consistently demonstrated that patients receiving LLLT report reduced pain and increased MMO compared to those receiving no treatment or conventional therapies.

A systematic review indicated that LLLT not only alleviates pain but also enhances the healing process of damaged tissues, thereby addressing the underlying causes of trismus (Elgohary et al., 2023). Furthermore, LLLT is associated with minimal side effects, making it a preferred option for patients who may be apprehensive about more invasive treatments.

Comparative Analysis of Combined Treatment Approaches

The combination of TTSA and LLLT has emerged as a promising strategy for managing radiation-induced trismus. Clinical studies have shown that this combined approach yields superior outcomes compared to either modality used in isolation. For instance, Aboelez et al. (2025) found that patients receiving both therapies exhibited a greater reduction in pain scores and a more pronounced increase in MMO after six months of treatment.

The synergistic effects of combining LLLT with TTSA can be attributed to the complementary mechanisms of action. While LLLT promotes healing and reduces inflammation, TTSA mechanically facilitates mouth opening, thereby enhancing the overall efficacy of treatment. This approach not only addresses the symptoms of trismus but also improves patients’ quality of life by enabling better oral function and comfort.

Conclusion

In conclusion, effective management strategies for radiation-induced trismus in head and neck cancer patients are essential for improving their quality of life. The combination of threaded tapered screw appliance therapy and low-level laser therapy represents a promising approach, demonstrating significant improvements in maximum mouth opening and pain reduction. Continued research and clinical trials are warranted to further validate the efficacy of these modalities and explore additional treatment options.

FAQ

What is trismus? Trismus is a condition characterized by restricted mouth opening, often caused by muscle tension, fibrosis, or damage resulting from radiation therapy for head and neck cancer.

How prevalent is trismus in head and neck cancer patients? Trismus occurs in approximately 30% to 60% of patients following radiation therapy for head and neck cancer.

What are the common symptoms of trismus? Symptoms include difficulty opening the mouth, facial pain, discomfort when chewing or speaking, and potential psychological impacts from the inability to perform daily activities.

What treatment options are available for trismus? Treatment options include physical therapy, low-level laser therapy, threaded tapered screw appliances, and surgical interventions in severe cases.

How effective is the combination of TTSA and LLLT? Studies have shown that the combination of threaded tapered screw appliance therapy and low-level laser therapy significantly improves mouth opening and reduces pain compared to either treatment alone.

References

1. Aboelez, M. A., Ibrahim, A. M., ElSawy, M. A., & El-Khamisy, N. E. (2025). Efficiency of different treatment modalities on radiation induced trismus for maxillofacial cases: a parallel randomized clinical trial. BMC Oral Health. Retrieved from https://doi.org/10.1186/s12903-025-05600-7

2. Cardoso, R. C., Kamal, M. Z., Zaveri, J., et al. (2021). Self-reported trismus: prevalence, severity and impact on quality of life in oropharyngeal cancer survivorship: a cross-sectional survey report from a comprehensive cancer center. Support Care Cancer, 29(4), 1825–35. Retrieved from https://doi.org/10.1007/s00520-020-05630-7

3. Elgohary, H. M., Eladl, H. M., Soliman, A. H., & Soliman, E. S. (2023). Effects of Ultrasound, laser and exercises on Temporomandibular Joint Pain and Trismus following Head and Neck Cancer. Ann Rehabil Med, 42(6), 846–53. Retrieved from https://doi.org/10.5535/arm.2018.42.6.846

4. Johnson, J., Carlsson, S., Johansson, M., Pauli, N., Rydén, A., & Fagerberg-Mohlin, B. (2012). Development and validation of the Gothenburg Trismus Questionnaire (GTQ). Oral Oncol, 48(8), 730–6. Retrieved from https://doi.org/10.1016/j.oraloncology.2012.02.013

5. Zecha, J. A., Raber-Durlacher, J. E., Nair, R. G., Epstein, J. B., Elad, S., Hamblin, M. R., Barasch, A., Migliorati, C. A., Milstein, D. M., & Genot, M. T. (2020). Low-level laser therapy/photobiomodulation in the management of side effects of chemoradiation therapy in head and neck cancer: part 2: proposed applications and treatment protocols. Support Care Cancer, 24(6), 2793–805. Retrieved from https://doi.org/10.1007/s00520-016-3153-y