To describe a novel radiographic sign (“halo
”) and a new classification method of an evolving perisigmoid
and present its correlation with intraoperative findings.
Retrospective and prospective cohort study in a tertiary academic children’s hospital.
The retrospective arm (15 children) was conducted between 1998 and 2007 and the prospective arm (11 children) between 2008 and 2013. The computerized tomographic appearance of the perisigmoid
region was classified into four groups: Class I, normal; Class II, smooth halo
; Class III, nodular halo
4 mm or less in diameter; and Class IV, gross nodular halo
more than 4 mm in diameter. Intraoperative findings of the perisigmoid
region were compared with the preoperative scan results.
The correlation between preoperative imaging and intraoperative findings of the retrospective arm was highly significant (p
= 0.007). The correlation between the preoperative imaging studies and intraoperative findings of the prospective arm was also highly significant (p
= 0.005). The interobserver agreement for the proposed classification method was high (Cohen kappa score, 0.76; weighted kappa score, 0.84).
A novel radiographic sign (“halo
”) and a new classification method for an evolving perisigmoid
in acute mastoiditis
are described. A thin and smooth halo
sign is not indicative of a true abscess
formation. Gross perisigmoid
granular changes, however, are highly suggestive of an epidural abscess
that warrants surgical intervention.