Introduction
Otitis media is a disease of the middle ear marked by the inflammation of the mucosal lining. When it lasts more than two weeks, it develops into chronic otitis media (COM). Chronic otitis media is marked by the presence of a perforated tympanic membrane, and recurrent purulent discharge.1-3 Otitis media is one of the most common infections of childhood: by the age of 3 years more than 80% of children will have had at least 1 episode of otitis media.4 COM can lead to both extracranial, and intracranial complications. Sixty to seventy percent of these complications occur in children and young adults: during the first two decades of life.5-7 Intracranial complication is an infrequent complication with reported rates ranging from 0.3% in developed countries to 3% in developing countries.5,6Its pathogenesis, that is its spread from the ear canal, is through direct invasion of the bone, thrombophlebitis, haematogenous spread, and dissemination through congenital or traumatic bone defects.6,8,9
The most common intracranial complications are brain abscess, meningitis, and lateral sinus thrombosis.3,6,10Subdural empyema, the purulent collection between the dura and arachnoid matter, is a rare but serious intracranial complications of COM.8,11 It is exceedingly rare that a study by Dongol et al. found only one case of subdural empyema (3.7%) out of 27 patients of chronic otitis media with intracranial complications.7 Extension from otogenic infections is the most common cause of subdural empyema in older children.8,9,12 The most common pathogens areStreptococcus pneumoniae (most common), Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus and Gram-negative rods (Pseudomonas aeruginosa, Escherichia coli, Proteus, Klebsiella ) as well as anaerobic Bacteroides species.5,13,14 Patients with Subdural empyema present with fever, headache, vomiting, and altered mental status.11,14-16 MRI and CT scan are important in the diagnosis of subdural empyema; MRI being the most sensitive.6,8,12 Culture and sensitivity from the pus is necessary although the yield is low.14,5-8 The principles of treatment, common to all intracranial complications, include early definitive diagnosis, appropriate systemic antibiotic therapy, neurosurgical intervention, and treatment of the ear lesion after the patient stabilizes.