Acute sinusitis with subperiosteal abscess in an infant: A rare case requiring endoscopic sinus surgery

Acute bacterial rhinosinusitis (ABRS) is rare in infants, particularly those under three months. While orbital infections such as subperiosteal abscesses (SPA) are well documented in older children, they are uncommon in young infants and pose unique diagnostic and therapeutic challenges. We present the case of a 7-week-old previously healthy male who developed ABRS complicated by a SPA following a documented rhinovirus/enterovirus infection, who was successfully treated with endoscopic sinus surgery (ESS). A previously healthy 7-week-old full-term male with no medical comorbidities was transferred to our emergency department with a two-day history of left eye swelling and fever. Examination revealed left eye proptosis, periorbital edema, erythema, and elevated intraocular pressure (IOP) of 26 mmHg. CT Orbit revealed opacification of the maxillary and ethmoid sinuses with a left SPA lateral to the lamina papyracea, displacing the medial rectus muscle without intracranial extension. The patient underwent nasal endoscopy with anterior ethmoidectomy, allowing access to the subperiosteal space and orbital decompression. Intraoperative IOP decreased to 8 mmHg and remained ≤15 mmHg postoperatively. The patient improved clinically and was transitioned to oral clindamycin and discharged on postoperative day 2 with complete resolution of symptoms. This case highlights the potential for serious bacterial complications in low-risk infants and demonstrates the feasibility of surgical intervention in this age group. Our experience emphasizes the need for high clinical suspicion in infants with progressive ocular symptoms following a viral illness and supports ESS as a feasible, minimally invasive option in select infants.