Original articles Significance of the auditory tube angle and mastoid size in chronic ear disease A. Sirikci 1 , Y.A. Bayazit 2 , M. Bayram 1 and M. Kanlikama 2 1 Department of Radiology, Faculty of Medicine, Gaziantep University 2 Department of Otolaryngology and Head and Neck Surgery, Faculty of Medicine, Gaziantep University, 27310 Gaziantep, Turkey Received September 12, 2000 / Accepted in final form January 07, 2001 Key words: Auditory tube - Mastoid bone - Chronic otitis media - Sigmoid sinus. Correspondence to: A. Siricki E-mail: sirikci@yahoo.com Abstract The aim of this study was to determine whether a relationship exists between mastoid size and auditory tube angle (ATA) and chronic ear disease. A radiological and clinical study was undertaken of the temporal bones of 36 subjects. There were 24 patients with unilateral chronic otitis media (COM) and 12 healthy controls (HC) the contralateral healthy ears of the COM patients were also used as control (CLHC). From each CT scan the distance between Henle spine and the sigmoid sinus (H- SS) and the ATA was assessed. The angle between a longitudinal line bisecting the transverse length of the external auditory canal and the longitudinal axis of the AT was calculated. A direct correlation between H-SS and ATA, both in COM and HC (p < 0.01), was observed, but not in CLHC (p > 0.05). There was no significant difference in the ATA results between COM and CLHC, or between COM and HC (p > 0.05), however there was a significant difference between CLHC and HC (p = 0.02). H-SS distances were not significantly different between COM and CLHC, or COM and HC, or CLHC and HC (p > 0.05). An association between ATA and mastoid size in both healthy and diseased ears was observed. The anatomical relationships of the AT, mastoid and middle ear, which form a functional unit, are not significantly important in chronic ear disease. Although chronic otitis media is a common problem worldwide, there is no single theory as to how or why an ear disease becomes chronic. The influence of genetic and/or environmental factors have been considered to be involved in the progression to the chronic state. In addition, craniofacial growth, as well as anatomical variations in craniofacial anatomy, have also been considered to be associated with middle ear disease, with several associations being described [10-12]. Amongst anatomical craniofacial structures, mastoid size and the auditory tube (AT) have been studied in detail [2, 7, 9, 12], with the majority of studies addressing the calibre and length of the AT. There is abundant literature concerning the functional status of the auditory tube, the assessment of the cartilaginous segment, isthmus and muscles of the AT, as well as their association with rhino -nasopharyngeal structures [4-6]. However, the possible significance of the angle that the bony segment of the AT forms at the tympanic opening on its way to the nasopharyngeal orifice has not been well studied. During a number of ear operations the authors have noticed that the AT appears more flat and has a wide and inferiorly displaced opening in a smaller mastoid process. This study was therefore conducted to determine whether there is a relationship between the size of the mastoid and AT angle (ATA) and chronic ear disease. Material and methods CT scans of the temporal bone and cranial base were obtained from 36 subjects, of whom 24 had unilateral chronic otitis media (12 with and 12 without cholesteatoma) and 12 were healthy controls (HC). Subjects (8 female, 16 male) with otitis media ranged in age between 30 and 88 years (mean 53.5 years), while the HC group (4 female, 8 male) ranged in age between 31 and 82 years (mean 44.8 years). CT scans of the temporal bones were obtained (1.5 mm section thickness, 1.5 table incrementation, 120 kV, 200 mA) parallel to the orbitomeatal line, from which the following assessments were made the shortest distance between the Henle spine and