When Recurrent Otitis Turns Dangerous: Skull Base Osteomyelitis in an Immunocompetent Child

To the Editors: Skull base osteomyelitis (SBO) is an uncommon but potentially life-threatening infection of the skull base and adjacent soft tissues. It typically affects elderly or diabetic adults but is rare in immunocompetent children, often delaying diagnosis.1,2 Infection may spread from the middle ear or mastoid through the petroclival synchondrosis or venous plexuses, leading to central skull base involvement.3–5 We report a 9-year-old previously healthy girl with SBO following recurrent otitis media. A 9-year-old healthy girl presented with left ear pain and otorrhea. She had a 2-year history of recurrent otitis media with limited response to amoxicillin-clavulanate and ceftriaxone. Temporal bone computed tomography (CT) revealed loss of mastoid and petrous air cell aeration with erosive changes. Despite adequate treatment, persistent opacification and bone erosion on CT suggested osteomyelitis, prompting contrast-enhanced magnetic resonance imaging (MRI) for evaluation of intracranial extension. She was afebrile on admission, showing left mastoid swelling, tenderness and mucopurulent otorrhea. Laboratory results revealed leukocytes 9.1 × 10³/µL, C-reactive protein 99 mg/L and erythrocyte sedimentation rate 94 mm/h. Otorrhea swab cultures, including bacteriological, mycological and mycobacterial analyses, yielded no growth. Mycobacterium tuberculosis polymerase chain reaction and interferon-gamma release assay were also negative. Empiric intravenous vancomycin (60 mg/kg/d) and cefepime (150 mg/kg/d) were initiated. MRI demonstrated effusion and abscesses involving the left mastoid, middle ear and petrous apex, with osteomyelitis of the basiocciput and clivus, posterior fossa pachymeningitis and inflammation extending through the carotid spaces (Fig. 1). The otolaryngology team advised against surgical intervention; therefore, conservative medical management was maintained. Due to inadequate improvement and concern for resistant pathogens, the antibiotic regimen was escalated to intravenous meropenem (120 mg/kg/d), linezolid (30 mg/kg/d) and ciprofloxacin (30 mg/kg/d). Immunologic evaluation, including immunoglobulins, lymphocyte subsets, oxidative burst and vaccine responses, was normal, excluding primary immunodeficiency.FIGURE 1.: Axial CT image (A) demonstrates opacification of the left mastoid air cells, middle ear cavity and petrous apex, with erosive changes along the petro-occipital fissure (arrow). Axial unenhanced T1-weighted MR image (B) shows abnormal marrow signal in the left basiocciput (arrow) and clivus (dashed arrow). Axial contrast-enhanced T1-weighted MR images (C, D) demonstrate enhancement of the clivus (blue arrow in C) and basiocciput (white arrow in C), with surrounding inflammation involving the petrous portion of the temporal bone (red arrows in C). The inflammatory process extends into the left masticator space (green arrows in C), retromandibular region (purple arrow in C), carotid space (yellow arrows in C) and temporal fossa (red arrow in D), encasing the left internal carotid artery (yellow arrow in D). A loculated hypodense area with peripheral enhancement consistent with focal necrosis and abscess formation is also observed (green arrow in D). (Parental written consent for image publication was obtained.)By week 8, C-reactive protein and erythrocyte sedimentation rate normalized with clinical and radiologic improvement. Follow-up MRI on day 56 demonstrated near-complete resolution of abscesses, osteomyelitis and meningeal enhancement. Given the favorable response, therapy was transitioned to oral ciprofloxacin and linezolid to complete a 12-week course. The patient subsequently achieved full clinical and radiological recovery without residual deficits. SBO in children may follow otitis media or externa, even without immunodeficiency.1,3,5Pseudomonas aeruginosa remains the predominant pathogen, although Staphylococcus aureus, Streptococcus species, and anaerobes are also reported.2,5 MRI is preferred for early diagnosis and follow-up, while prolonged antipseudomonal and antistaphylococcal therapy remains the mainstay of treatment.2,4 Extension to the carotid canal or cavernous sinus may lead to cranial neuropathies or vascular complications.2,4 This case demonstrates that SBO can occur even in immunocompetent children without underlying metabolic or otologic disorders, highlighting the importance of early imaging and multidisciplinary management to prevent intracranial complications.