Tongue Fat and its Relationship to Obstructive Sleep Apnea

STUDY OBJECTIVES: The objective of this study was to determine whether tongue fat is increased in obese sleep apneics compared to obese subjects without sleep apnea. We hypothesized that excess fat is deposited in the tongue in obese patients with sleep apnea. DESIGN: Case-control design. SETTING: Academic medical center. PATIENTS: We examined tongue fat in 31 obese controls (apnea-hypopnea index, 4.1 ± 2.7 events/h) and 90 obese apneics (apnea-hypopnea index, 43.2 ± 27.3 events/h). Analyses were repeated in a subsample of 18 gender-, race-, age-, and BMI-matched case-control pairs. INTERVENTIONS: All subjects underwent a MRI with three-point Dixon magnetic resonance imaging. We used sophisticated volumetric reconstruction algorithms to study the size and distribution of upper airway fat deposits in the tongue and masseter muscles within apneics and obese controls. MEASUREMENTS AND RESULTS: The data supported our a priori hypotheses that after adjustment for age, BMI, gender, and race, the tongue in apneics was significantly larger (P = 0.001) and had an increased amount of fat (P = 0.002) compared to controls. Similar results were seen in our matched sample. Our data also demonstrate that within the apneic and normal tongue, there are regional differences in fat distribution, with larger fat deposits at the base of the tongue. CONCLUSIONS: There is increased tongue volume and deposition of fat at the base of tongue in apneics compared to controls. Increased tongue fat may begin to explain the relationship between obesity and obstructive sleep apnea.