Dr Jean Benoit MartinotJean-Benoit Martinot, MD
A new study demonstrated that mandibular movements (MM) monitoring can be used to assess the efficacy of oral appliances used in treatment of sleep apnea.
The main objective was to document treatment response to oral appliance therapy in obstructive sleep apnea by evaluating the effectiveness of mandibular advancement splint therapy using respiratory effort index derived from MM characterization (MM-REI) compared with classical indices of obstructive sleep apnea severity like the apnea-hypopnea index (AHI) and oxygen desaturation index (ODI). The reduction of vertical respiratory MM estimated by MM-REI and sleep respiratory effort duration supplemented the decrease in obstructive hypopneas, AHI and ODI when snoring resolved in those treated with an optimally titrated mandibular advancement splint.

"Mandibular movement recordings provide accurate information that can supplement and even replace the routine indices (AHI and ODI) monitored during the titration of oral appliances. Of all the respiratory sleep disturbances, obstructive hypopnea seems to be the most responsive to mandibular advancement, and obstructive hypopneas can be identified by mandibular movements analysis,"  lead investigator Jean-Benoit Martinot, MD, Sleep Laboratory, CHU UCL Namur Site Sainte-Elisabeth told NeurologyLive. "The efficacy of oral appliances depends on the degree of mandibular advancement and is now titratable with precision using mandibular movement analysis. Detection of an absent response to oral appliances is facilitated and emergent central apneas/hypopneas is enabled."

In the study researchers fit 56 participants, with a mean age of 47, that had obstructive sleep apnea with a custom mandibular advancement splint and tracked midsagittal mandibular movement—participants were evaluated at the end of the titration process when no snoring was reported.2 During the procedure, various degrees of advancement were titrated to identify the single best amount to control apnea events for the specific participant. Researchers used a magnetometer to capture mandibular movements and assessed mandibular advancement splint efficacy as the percentage change from baseline, using Bayesian multilevel modeling.

The study concluded that MM monitoring represents a powerful tool to assess the efficacy of oral appliance therapy. Two-thirds of the participants demonstrated a reduction in AHI and ODI of at least 50%, however, only 20% reached values of AHI <5 when snoring disappeared.

Compared with baseline, all indications of obstructive sleep apnea decreased by the end of titration, AHI -61.5% (95% CI, -48.9% to -71.1%), ODI -66.1% (95% CI, -49.5% to -77.2%), with obstructive hypopnea index and MM-REI showing the greatest responses with a mean reduction of -78.99% (95% CI, -63.4% to -88.2%) for MM-REI and -88% (95% CI, 69.5% to -96.3%) for obstructive hypopnea index.

Participants demonstrated a reduction of vertical respiratory MM and sleep respiratory effort, as well as a significant decrease in obstructive hypopnea. A weaker effect of oral appliance therapy was observed on obstructive apneas compared with hypopneas. Researchers also reported that scores from the apnea-hypopnea index and oxygen desaturation index also dropped.

MM monitoring aided in the revelation of the presence of central apneas, allowing researchers to identify in a subgroup of participants a decrease in respiratory effort but no improvement or increase in sudden or sharp MM of high amplitude. This is indicative of emergent central apneas and could shed light on a predictor for poor response to oral appliance therapy.

"Using novel connected and artificial intelligence-supported technology for mandibular movement monitoring opens the way to precise domiciliary titration over multiple nights," Martinot added. "In addition to AHI and ODI, mandibular movement monitoring also provides total sleep time, duration of respiratory effort, and sleep fragmentation, providing comprehensive information about the restoration of sleep quality. Careful nightly titration prevents excessive and undesirable protrusion of the mandible (with potential harmful temporo-mandibular joint and dental adverse events) and facilitates success at lower degrees of mandibular advancement. Nasal CPAP efficacy can also be monitored by recording mandibular movements. Decreasing the respiratory peak to peak displacement of the mandible to keep the mouth closed as much as possible has been verified to increase treatment success."

Assessment of respiratory effort is crucial when titrating oral appliances and MM provide a comprehensive assessment and are superior to thoracic and abdominal movements. This study provides valuable information about the limitations of titration based only on AHI and ODI, and indices derived from MM allow for identification of subjects at risk for development of central events which can be utilized to better characterize the individual response to oral appliance therapy.
Martinot JB, Le-Dong N, Crespeigne E, et al. Mandibular Movement Analysis to Assess Efficacy of Oral Appliance Therapy in OSA. CHEST. 2018;154(6). doi:10.1016/j.chest.2018.08.1027.