|Ph.D Student||Tov Naveh|
|Subject||Contractile Characteristics of the Tongue in Sleep Apnea|
|Department||Department of Medicine||Supervisor||Professor Arie Oliven|
The genioglossus (GG) muscle, the main tongue protrudor, is of prime importance in maintaining upper airway patency, and GG dysfunction has been often implicated in the pathogenesis of OSAS. Therefore, the study was undertaken to evaluate the neurophysiological properties of the tongue in patients with OSA, and compare these parameters to those of healthy subjects (HS).
We evaluated16 healthy males, age 27-73 yrs (mean±SE 39.8±3.2 yrs) and 32 OSAS males, 28-72 yrs old (50.3±2.0 yrs). All underwent a 3-6 hrs sleep study and were diagnosed as HS or OSAS patients. Tongue protrusion force (Ftp) was measured with a specially designed and constructed small water-filled, intra-oral plethysmograph. Electrical stimulation (ES) of the GG was performed with a specially designed sub-lingual U-shaped surface electrode. We measured volitional and ES parameters including maximal force, endurance, twitch variables and force:frequency curve for each subject.
OSAS patients produced lower maximal volitional & ES-induced (100 Hz) Ftp than healthy subjects (805±88 vs.1446±177 g, p<0.03 and 292 ±29.0 Vs. 387.6±53 g, p<0.05, respectively).
Based on the ES tests, no difference was found between HS and OSAS patients in parameters that characterize muscle fiber distributionl (Twitch contraction, half relaxation time and the shapes of the relative force:frequency curves) However, endurance was significantly reduced in OSAS patients, as compared to HS, (fatigue index 69 ±2.7 vs. 84.9±2.7% 100HZ frequency fatigue test, p<0.03). Reduced tongue endurance was significantly pronounced in severe OSAS patients, with higher RDI, lower minimal O2SAT and higher snore intensity.
We concluded that the tongue of patients with severe OSAS is weaker and fatigues faster than the tongue of healthy subjects.