Infratentorial subdural empyema: clinical and computerized tomography findings. Report of three cases.

Infratentorial subdural empyemas are rare. The authors report three cases encountered between 1979 and 1988, representing a 3% incidence among all subdural empyemas. The common source was an ear infection. Clinical presentation encompassed a systemic febrile illness, headaches, and a stiff neck. Only one patient had an inconspicuous focal neurological deficit that suggested a cerebral location. Initial diagnosis was acute meningitis in each case. A lumbar puncture was ordered in all three cases but was actually performed in two without developing tonsillar herniation. Cerebrospinal fluid analysis confirmed the diagnosis of meningitis in one but was normal in the other. Computerized tomography allowed a precise diagnosis and localization of the pathology. All three patients received aggressive antibiotic therapy plus suboccipital craniectomy and aspiration of pus; catheter drainage was performed in two. Cultures were positive in one case and negative in the others. Two patients were cured without sequelae; the third patient was moribund at surgery and died. Although it is known that subdural empyemas may localize in the posterior fossa, only one previous report was found. Infratentorial subdural empyema may sometimes be an unrecognized companion of acute meningitis and is cured with antibiotic therapy alone.