Gas-Forming Intracerebral Abscess with Pediatric Parafalcine Subdural Empyema with Review of Literature

Despite the advent of modern neurosurgical techniques, new antibiotics, and new powerful imaging technologies, brain abscess remains a potentially fatal central nervous system infection.1 A brain abscess is a focal, intracerebral infection that begins as a localized area of cerebritis and develops into a collection of pus surrounded by a wellvascularized capsule.2 It results from direct extension of a cranial infection (e.g., subdural empyema, osteomyelitis, mastoiditis, and sinusitis), penetrating head wounds, or hematogenous spread (e.g., in bacterial endocarditis, bronchiectasis, congenital heart disease with right-to-left shunt, or intravenous (IV) drug abuse.3 Subdural empyema (before 1943, it was called subdural abscess) is a suppurative infection that forms in the subdural space, which has no anatomic barrier to spread. It should be distinguished from abscess which forms within brain substance, surrounded by tissue reaction with fibrin and collagen capsule formation.4 Overall, 20 to 25% of imaging studies showed that subdural empyema may be complicated by cerebral abscess.4 Subdural abscess is rare, occurring more commonly with sinusitis than with otitis media.5 Both acute and chronic otitis media are considered as serious diseases in children because of their possible extracranial and/or intracranial extension. The incidence of brain abscess varies from 1 to 2% of all intracranial space occupying lesions in the developed countries to 8% in the developing countries.6 Brain abscesses are associated with otitis media in around 30% of cases.7 It is estimated that only 1 in 2 10 episodes of otitis media results in a brain abscess.8 Early presumptive clinical diagnosis supported by radiological evidence (computerized axial tomography [CT] scan and magnetic resonance imaging [MRI]) is the mainstay of diagnosis.9 In this case, we witnessed a gas-forming brain abscess in the early stage related with chronic mastoiditis where gas formation disappeared in the later phase of the abscess formation.