Does asymmetry in tongue anatomy affect asymmetry in tongue position? Glossectomy and control subjects

Glossectomy surgery removes part of the tongue due to cancer. The resulting anatomical asymmetries may affect motor symmetry. This study examines anatomical and positional tongue asymmetry in glossectomies and controls. The goals are to determine the extent of the anatomical asymmetries, and their effect on resting asymmetry. We expect that patients with unilateral resections will be more asymmetrical than controls, but that their midline tongue will be centered in the oral cavity (OC), because their dentition is unchanged and the tongue will rest in its familiar position. 3-D tongue volumes were extracted from high-resolution MRI data using Matlab. Tongue volumes were calculated for the whole tongue, both halves and the septum using ITK-SNAP. We bisected the OC in the sagittal plane from the mandibular symphysis to the center of the spinal cord. The tongue volume was calculated in each half of the OC. Results showed more anatomical asymmetry in the patients; seven patients and three controls had a volume difference of 3% or more between the left and right tongue. Positional measures showed that the septum was mostly in one half of the OC. When the septum volume was removed, the tongue volume distributed fairly equally in the OC.