The foreshortened malleus: Anatomic variant, not pathologic sign.

Abstract

To quantitatively study the appearance of the malleus as viewed through the external ear canal clinically to determine whether its shortened appearance in some ears is associated with otitis media. Postmortem material analysis. University temporal bone laboratory. A total of 41 adult crania without clinical otitis. The mastoid size indicator of previous childhood otitis media was quantified radiographically. On digitized photographs of the tympanic membranes (64 ears useable), two sets of measurements were performed: 1) the distance from the malleus' lateral process to the umbo and to the annulus; and 2) angles formed anteriorly and posteriorly at the umbo. The two metrics of malleus foreshortening did not correlate with one another, that is, the ratio manubrium-length/tympanic diameter did not correlate with the ratio posterior/anterior umbo angles (for right ears, r = -0.34; for left, r = 0.30). Mastoid size did not correlate with either metric of malleus foreshortening. As to right-left symmetry, the size of mastoid pneumatization had good correlation (r = 0.68, 95% confidence interval 0.47-0.82); but, r = 0.21 for lengths, r = 0.34 for angles, each confidence interval included zero. Because the data showed no correlation of the physical appearance of the malleus with the mastoid size indicator of otitis media, and right-left symmetry was only hinted, we contend that a foreshortened malleus lacks clinical relevance. Foreshortened malleus is an anatomic variant, not a sign of pathology.