6-year-old with Ear Pain

Recognition of tympanic membrane (TM, “eardrum”)  landmarks is an important clinical skill for clinicians performing otoscopy.  When the TM is normal, this is straightforward and digital otoscopy offers abundant time to practice identifying the malleus, evaluate for bulging, assess translucency, and visualize air-fluid levels. However, when the TM is abnormal, the picture becomes less clear. This case is a good test of that knowledge since bulging has obscured the most important landmark in our otoscopic evaluation—the malleus.

Like a compass needle guiding us north, recall that the malleus “points” toward the side of the TM being inspected—with the lateral process located in the upper right (right TM) or upper left (left TM). With mild bulging, the umbo and body of the malleus are less defined, but one can typically still identify the lateral process.  However, when bulging has progressed to the “angry donut” characteristic of moderate to severe bulging—it may disappear completely.  Despite this, the trained eye can often pick out a slight cleft or crease running from the center of the TM to the periphery. This cleft results from the bony attachment of the malleus to the medial surface of the TM.  Specifically, the umbo and the manubrium of the malleus limit the bulging along the axis of these attachments. The result is that the umbo attachment creates the donut center with the manubrium attachment, causing the subtle cleft—and therefore providing the compass pointing us toward the side of the TM in question.   In today’s case, the TM is moderately bulging, and the malleus is completely obscured--but the central umbo and manubrium cleft are visualized and point to the left.

WiscMed has created a guide to AOM diagnosis and treatment that can be found here.

In addition, a visual diagnosis guide to common ear pathology may be found here.