Reliable Lip Force Measurement in Healthy Controls and in Patients with Stroke: A Methodologic Study

Abstract

A prefabricated oral screen has shown promising results as a muscle self-training device to improve the lip function of stroke patients affected by oropharyngeal dysphagia. However, a technique for the measurement of lip muscle force, whether in healthy individuals or in stroke patients, is lacking. The present study was designed to (1) test the intra- and interreliability of lip force measurements by means of a newly devised Lip Force Meter, LF100, (2) determine a normal lower limit for lip force in newtons (N), and (3) ascertain the instrument's sensitivity and specificity. LF100 is a modified strain gauge for recording the ability of lips to withstand pressure from a predentally placed oral screen. Forty-two healthy controls and 22 stroke patients agreed to participate in the trial. The controls and patients were examined three times with the LF100, with 2-min rest intervals, twice by investigator MH and once by investigator MO. Intrainvestigator reliability with the LF100 proved excellent in both controls and patients: ICC was 0.83 and 0.90, respectively. Interinvestigator reliability was good or excellent in both groups: ICC was 0.71 and 0.91. There was a significant difference in lip force between controls and stroke patients (mean = 24.7 +/- 6.3 N and 9.5 +/- 5.5 N, p < 0.001). The sensitivity of LF100 was 91% and the specificity 95%. The cutoff level for normal lip force was 15 N. The LF100 showed itself to be a suitable and reliable instrument for measuring lip force.

The effect of lip strengthening exercises in children and adolescents with myotonic dystrophy type 1

“…Their results indicated a decrease in orofacial muscle activity during oral functions but no significant change in tooth position. Hä gg et al [15] found in a retrospective study that self-training with an oral screen could improve lip force and swallowing capacity in stroke patients with oropharyngeal dysphagia. It was concluded that the treatment results were more likely attributable to sensory motor stimulation and the plasticity of the central nervous system, than the training of the lip muscles per se.…”

Longstanding Effect and Outcome Differences of Palatal Plate and Oral Screen Training on Stroke-Related Dysphagia

“…During training, the screen was inserted predentally behind closed lips and the patient had to sit in a chair or in the bed with the body in a strictly upright position, with support for the head. The patient had to hold the screen against the horizontal gradually increasing pulling pressure for 5-10 s while trying to resist the force by tightening the lips and pressing the head backward against a head rest [16,17,21]. The exercise was performed 3 times per session before eating, 3 times daily.…”

“…It improves the contact between tongue and palate, raises the tip of the tongue, helps the tongue to contract upward and backward, activates the levator anguli oris muscles (VII), the zygomaticus minor and major muscles, and the buccinator muscles, thus indirectly improving oropharyngeal swallowing [10,14,25]. PP was the first to be applied to sensorimotor training in dysphagia studies [14,15]; the OS device has more recently been introduced [16,17,21]. The OS training (Fig.…”

“…The OS training (Fig. 1) stimulates oropharyngeal tactile receptors and motor function in order to create lip closure and to raise activity of the buccinator mechanism [14,15,[21][22][23][24] supplied by facial nerves (VII), pharyngeal plexus including glossopharyngeal nerves (IX) and vagal nerves (X). When pulling the OS (Fig.…”

Facial palsy in individuals with thalidomide embryopathy: frequency and characteristics

“…8,9 Patients were seated in a stable position and instructed to keep the oral screen inside their lips while the examiner pulled the handle. The LF100 instrument recorded the maximum value measured during 10 seconds.…”