Bioelectrical activity changes of selected head and neck muscles in patients with centrally located oral cavity cancer before and after surgery – preliminary report

Introduction. One of the main factors affecting the quality of life is natural oral nutrition. Damage to oral cavity structures that is associated with the cancer treatment within the area of head and neck can impede or prevent oral nutrition. Return to natural nutrition requires muscle exercising that lead to the creation of a new swallowing pattern due to changes in the order and intensity of muscle contractions in the stomatognathic system resulting from their adaptation capability. Aim of the study. To evaluate the activity of selected head and neck muscles during swallowing after the removal of a centrally located oral cancer, and to undertake self-assessment of oral cavity functions performed by the patients after each electromyographic examination. Materials and methods. The study group comprised patients who underwent surgery due to centrally located cancer of the oral mucosa. In the early post-surgical period, the patients were practising to improve sealing of their mouths and saliva swallowing. Each patient was examined three times with the use of surface elctromyography (pre-operatively, at one month and at three months after the surgery). Bilateral masseters, sternocleidomastoids, suprahyoid and orbicularis oris muscles were the examined muscles. The examination was performed with the use of Zebris 8 EMG Bluetooth device (Zebris, Isny im Allgau, Germany) and surface electrodes. Compensatory mechanisms to facilitate swallowing and self-assessment by the patients to evaluate oral functions i.e. chewing, swallowing, speech according to Functional Intraoral Glasgow Scale were recorded. Results. During post-surgical examinations, a general increase in the activity of the majority of selected head and neck muscles was observed. There were no statistically significant differences between the average muscle tensions on the right or left side. Patients using compensatory mechanisms manifested a statistically higher tension of selected muscles. Chewing function was assessed by the patients as the worst before surgery, then it deteriorated after the procedure, and significantly improved three months post-surgically. Conclusion. The assumption that the extra-oral muscles are involved in the patient’s efforts aimed at maintaining nutrition naturally despite extensive removal of intra-oral structures responsible for swallowing was confirmed by the results of the research.