Plate 26: Acute Coalescent Mastoiditis (Sagging or drooping of spuerior canal wall) This is one of the earliest signs of coalescent mastoiditis. The edema of the external canal tissues lining the outer attic wall and antrum causes them to protrude down into the canal, thus obliterating from view the upper portion of the drum. This otoscopic picture is sometimes called "narrowing of the fundus."