Occurrence, presence and severity of bruxism and its association with altered state of consciousness in individuals with severe acquired brain injury

Background Excessive jaw muscle activity is a frequent complication after acquired brain injury (ABI). Objective The study aimed to identify the occurrence and severity of jaw muscle activity and its association with altered state of consciousness in patients with ABI. Methods A total of 14 severe ABI patients with varied altered state of consciousness were recruited. A single‐channel electromyographic (EMG) device was used to assess the jaw muscle activity for three consecutive nights during Week 1 and Week 4 following admission. Differences in number of EMG episodes/h between Week 1 and 4 were analysed using non‐parametric tests and association between the EMG activity and altered state of consciousness were analysed using Spearman's correlation test. Results Nine of fourteen (64%) patients showed indications of bruxism (cutoff: >15 EMG episodes/h). The average EMG episodes/h at admission were 44.5 ± 13.6 with no significant changes after Week 4 of admission (43 ± 12.9; p = .917). The EMG episodes/h ranged from 2 to 184 during Week 1 and 4–154 during Week 4. There were no significant correlations between the number of EMG episodes/h during the three nights and the individuals altered state of consciousness during Week 1 and Week 4. Conclusion Patients with ABI had a conspicuously high but variable level of jaw muscle activity at admission and it tend to remain high after 4 week of hospitalisation which could potentially lead to adverse effects such as excessive tooth wear, headaches and pain in jaw muscles. The lack of associations between individuals altered level of consciousness and EMG activity could be due to low sample size and further studies are clearly warranted in this patient group with special needs. Single‐channel EMG devices can record jaw muscle activity early in the hospitalisation period and might be a helpful tools for early detection of bruxism in ABI patients. The main finding of the study was that the patients with severe acquired brain injury (ABI) showed a very high number and wide range of jaw muscle activity. The grinding activity during sleep in the ABI patients was almost on average five times higher when compared to the healthy participants and three times higher than definite bruxers but otherwise healthy measured using the same single channel ambulatory device.