Helical CT scanning of laryngeal deviation

To evaluate helical computed tomography (CT) scanning in patients with laryngeal deviation.

Five patients with laryngeal deviation and three control subjects underwent helical CT. The laryngeal deviation was idiopathic in one patient and acquired in four. Three-dimensional (3D) images of the laryngeal cartilages and bones, 3D airway surface models, and sequential coronal and axial images were reconstructed for assessment.

The thyroid cartilage was inclined and twisted to the right in three patients, inclined to the right and twisted to the left in one patient, and inclined to the left and twisted to the right in one patient. The infero-posterior part of the thyroid cartilage, and the cricoid and arytenoid cartilages were shifted to the left in four patients. The vocal cords were at the level of C4 approximately C4/C5 in two patients, C4/C5 in one, C4/C5 approximately C5 in one, and C5 approximately C5/C6 in one. In four patients, inclination of the laryngeal cavity to the right may have induced left false vocal cord protrusion. The levels of the two false vocal cords differed in all patients. When the inclination and twisting were corrected on the computer, 3D images of the laryngeal cartilages of the patients became almost the same as those of the control subjects, except for slight deformity of the thyroid cartilage. The width of the right and left thyroid alae was measured on the computer, and was almost equal in all patients. 3D airway surface models of the left hemilarynx resembled those of the right hemilarynx when the angle of view was changed on the computer.

Three-dimensional images of the laryngeal cartilages and bones, 3D airway surface models, and sequential coronal and axial CT scans were obtained using helical CT. This method allows the 3D observation of laryngeal deviation, and viewing of images from various directions on the computer was useful to understand the characteristics of laryngeal deviation.