The Significance of Subperiosteal Abscess Volume in Acute Mastoiditis.

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 for the former group and 2.0 ± 0.9 cm 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, 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 and more) should be managed initially with cortical mastoidectomy since the risk of no improvement following needle aspiration or I&D is higher.