Screen‐printed ambulatory electrode set enables accurate diagnostics of sleep bruxism
A definite SB diagnosis involves a combination of SB indicators confirmed by patient self‐report, clinical examination and PSG (Carra et al., 2014; Lobbezoo et al., 2013). In addition to high costs of sleep laboratory PSG, often it forms a poor representation of patients’ sleep due to disturbances caused by an unfamiliar sleep environment (Newell et al., 2012). Geographic availability of sleep laboratory PSG is also restricted only to cities and countries with high‐end healthcare facilities. Despite ambulatory PSG having better availability, the electrodes used for electroencephalography (EEG) are still difficult to apply, and this needs to be done by a technician to ensure a reliable recording.
Portable electromyography (EMG) devices have been developed for a more applicable approach compared with ambulatory PSG (Castroflorio et al., 2014; Jadidi et al., 2008; Mizumori et al., 2009; Shochat et al., 2007; Stuginski‐Barbosa et al., 2016; Yamaguchi et al., 2012). However, the use of these devices is mainly restricted to a supplementary role in SB diagnostics due to a possible overestimation of RMMA events. Overestimation happens because no audio‐video recording‐based distinction is made between EMG activity caused by RMMA and other orofacial or muscular activities (OFA/OMA), such as talking, swallowing or changing position (Carra et al., 2014). Even though most manufacturers include the possibility for audio recording in ambulatory PSG setups, video recordings are still rare. Furthermore, portable EMG devices include no EEG needed for sleep stage scoring. This leads to lack of assessment of whether or not a patient is asleep during the detected RMMA events. Thus portable EMG devices do not differentiate between SB and bruxism or OFA/OMA during wakefulness. Lack of sleep staging has been shown to cause significant overestimation of RMMA episodes in algorithm‐based RMMA detection from EMG signal (Dreyer et al., 2015). In addition, if total sleep time (TST) is not defined based on EEG recording, SB diagnosis may be even more inaccurate, as it is based on the number of RMMA events per hour of sleep (RMMA index; Carra et al., 2012, 2015; Rompre et al., 2007).
There is a need for a valid, reliable, widely available and cost‐efficient method for ambulatory SB diagnostics (Lobbezoo et al., 2013). Recently, the authors have introduced a silver ink screen‐printed and hydrogel‐coated electrode set (Lepola et al., 2014) for emergency assessment of EEG in patients with altered mental state (Muraja‐Murro et al., 2015). The electrode set is easy and quick to attach to the skin (Lepola et al., 2014), and it is also suitable for assessment of TST by sleep stage scoring (Myllymaa et al., 2016). The set includes electrodes placed near masseter muscles, generally used for RMMA recognition (Carra et al., 2012; Lavigne et al., 1996).