Effect of the Enveloppe Linguale Nocturne on atypical swallowing: surface electromyography and computerised postural...

Swallowing is a neuromuscular mechanism regulated by many nervous reflex arcs. Persistence of child swallowing at the end of dental eruption is called atypical swallowing (AS). This condition is related to a dysfunction of vertical maxillary growth called open bite. The authors treated this malocclusion with the Enveloppe Linguale Nocturne (ELN), or tongue positioner, created by Dr. Bonnet. The aim of this work is to evaluate the effect of ELN on swallowing and the postural variation obtained by its use.

Seven patients affected by AS were evaluated. Surface Electromyography (sEMG) testing was performed on each patient with different tongue positions, and swallowing was evaluated with and without the ELN. A surface Electromyograph (Biopack) with 8 channels was used (4 channels for the right muscles and 4 for the left) on 4 groups of muscles: temporals, masseters (MM), submental (SUB) and sternocleidmastoids. On each patient a postural test using a computerised Postural test (Lizard) was also performed. Statistical analysis was done using the Graph pad Instat 3 both for sEMG activity and for computerised postural analysis.

All seven subjects had different results in the sEMG and footrest tests. The sEMG test results indicated that muscle activation and swallowing duration varied greatly with the use of ELN, with a reduction of time of swallow act (p = 0.002) and variation in contraction of muscles. Mean MM activation was higher without ELN than in tests performed with the appliance (p = 0.002). Mean SUB activation was higher with than without ELN (p = 0.0033). ELN has a therapeutic effect on posture too. Computerised postural test without device showed in all patients an alteration of barycentre as well as an elevated oscillatory record (A mmq; V mms). With ELN footrest kilogram difference (p = 0.0110), Oscillatory Area (P = 0.0102) and velocity of oscillation (P = 0.0102) presented a great reduction in respect to patients record without ELN.

With ELN the tongue reaches the physiologic position during the swallowing and it is possible to have a low dental contact without tongue interference. ELN has no dental retention or contact. For this reason sEMG swallowing test shows that ELN induces a Mm activation reduction compared to swallowing test without ELN (P = 0.002) and an increase of SUB activation (P = 0.0033). In the same way with ELN there is a significant reduction of time of swallowing (c.f. oral phase) (P = 0.002). Patients with ELN changed their posture with a complete modification of barycentre (Footrest unbalancing kg P = 0.0110), oscillatory movement area (Footrest Area difference P = 0.0102), and oscillatory Velocity (Footrest Velocity oscillation difference P = 0.0102). These data suggest that this appliance has a function in the rehabilitation of atypical swallowing. ELN produces a physiologic neuromuscular mechanism that induces the correction of tongue position.