Recurrent fever episodes after treatment of a subdural empyema: persisting infection or autoimmunological reaction?

Case Report: Subdural empyema is a serious complication of infections such as otitis or mastoiditis. Neurosurgical operation and antibiotic treatment are essential.

We report on a 2-year-old boy with recurrent fever episodes during the last 2 months. Due to extensive diagnostic testing, brain MRI demonstrated a massive subdural hygroma. The boy underwent neurosurgical treatment and antibiotic treatment was started. Microbiological analysis revealed Streptococcus pneumoniae via PCR; however, cultures remained negative. Although the boy was intensively treated, fever episodes reoccurred and infection parameters increased. Otolaryngologists diagnosed mastoiditis as putative infection source following surgical treatment. Nevertheless, the boy remained symptomatic. Intravenous antibiotic treatment was modified and continued for a total of 10 weeks. Follow-up MRIs demonstrated a continuous regression of the empyema; however, the remaining empyema wall was still visible. According to our neurosurgeons, a neurosurgical resection of the empyema wall was impossible. Generally, the boy still suffered from fever episodes and infection parameters remained elevated. To modify the immunological reaction, we added dexamethasone. This treatment improved the clinical condition dramatically. Later, the patient was discharged with oral antibiotic treatment and low-dose dexamethasone. An attempt to discontinue cortisone resulted again in fever and high infection parameters. Finally, antibiotic treatment was ended and the patient only received dexamethasone. Follow-up MRIs showed further regression of the empyema. Although antibiotic treatment was ended, no signs of recurrent infection became visible. A detailed immunological work-up identified no immunodeficiency.

In conclusion, the clinical course suggests that, apart from the primary bacterial infection, a secondary, potentially autoimmunological process might have been involved. In view of the long-term follow-up (currently 9 months), a persisting bacterial infection appears less likely.