VARIATIONS OF THE ETHMOID LABYRINTH AND SPHENOID SINUS AND CT IMAGING

Three hundred macerated and partly isolated postmortem mid-facial bone s were studied for the development, variations and dimensions of the s tructures of the nasal cavity. On 184 axial CT scans of bones (102 mal e, 82 female) from patients ranging in age from 1 to 90 years old, the dimensions of the ethmoid labyrinth and sphenoid sinus were studied i n detail in order to determine which anatomic situation might be unsaf e during clinical endoscopic interventions. Six anatomic variations we re identified. Most unsafe for surgery seemed to be the following type s: type III, in which the anterior diameter of the ethmoid labyrinth w as large and the posterior ethmoid and sphenoid diameters were relativ ely narrow; type V, in which both ethmoid dimensions were large and th e sphenoid diameter was narrow: type VI, in which the ethmoid labyrint h had an ''hour-glass'' shape. Present findings indicate that CT orien tation before any endoscopic intervention might help to avoid serious complications.