The Significance of Subperiosteal Abscess Volume in Acute Mastoiditis

ABSTRACT Objective To determine whether the subperiosteal abscess (SPA) volume in acute coalescent mastoiditis (ACM) as measured in imaging studies, should influence the decision‐making process between performing mastoidectomy versus needle aspiration or incision and drainage (I&D) as the initial treatment of SPA. Setting Single tertiary referral center. Patients and Methods The records of all pediatric patients admitted with ACM between 1/2012 and 12/2023 were retrospectively reviewed. Baseline abscess volumes were measured on dedicated segmentation software for analyzing imaging findings. SPA volumes of needle aspirations were compared with those following I&D. Outcomes were compared. Results In total, 99 patients (median [interquartile range] age 26 [11–35] months) were enrolled. The mean ± standard deviation white blood cell (WBC) counts and C‐reactive protein (CRP) levels were 14.5 ± 7.0 K/μL and 112 ± 42 mg/dL, respectively. Fifty‐seven patients were treated by needle aspiration and 42 by I&D. Age, WBC counts, and CRP levels were similar for both groups, as were SPA volumes as seen on imaging studies 2.0 ± 1.0 cm 3 for the former group and 2.0 ± 0.9 cm 3 for the latter group ( p = 0.955). Resolution rates were 75.4% and 76.2%, respectively ( p = 0.931). Resolved SPAs after needle aspiration and I&D had similar volumes 1.7 ± 0.9 and 1.7 ± 0.7 cm 3 , respectively, p = 0.931. Conclusion Both needle aspiration and I&D are safe methods to reduce the infective and inflammatory load and provide pus for culture. Higher volumes (~3 cm 3 and more) should be managed initially with cortical mastoidectomy since the risk of no improvement following needle aspiration or I&D is higher. Level of Evidence 3.