A 21 year-old man on the rehabilitation service was evaluated for fever and headache. Approximately 1 year previously he was found to have a posterior fossa medulloblastoma that was resected and repaired with a bovine duragraft. Post-operative MRI showed no abnormal contrast enhancement and a lumbar puncture (LP) was unremarkable. Brain and spinal radiation therapy (XRT) were subsequently initiated. Seven weeks post-operatively he became febrile associated with worsening headaches. His neurological exam was remarkable for new neck stiffness. White blood cell (WBC) count was 4.4 x 103 /µl with 16.7% eosinophils. Repeat LP revealed marked CSF eosinophilia (138 WBC /mm3, 51% eos). Other CSF studies, including cytology, bacterial cultures, PCR for AFB and viral pathogens were all negative. Parasitic work up was negative. Repeat MRI showed slight enhancement along the duroplasty with adjacent fluid collections, interpreted by neuroradiology and neurosurgery as abnormal versus possibly normal post-surgical changes. Serum bovine dander IgE, sent to evaluate for allergy to the duragraft, was negative. Antibiotics and antivirals were given, and XRT was held for 1 week, though without clinical improvement. Suspected etiologies for eosinophilic meningitis included post-operative, radiation, and malignancy-induced inflammatory changes. High dose steroids were initiated followed by resolution of the fevers and neurologic symptoms. After the steroid course the CSF eosinophil count decreased to 57 WBC (57% eos).
Eosinophilic meningitis is a rare diagnosis defined as CSF leukocytes comprising of at least 10% eosinophils. Patients present with signs and symptoms of aseptic meningitis. Parasitic infections are the leading cause globally, usually Angiostrongylus cantonensis. Non-parasitic pathogens include Coccidioides immitis and Cryptococcus neoformans. Non-infectious etiologies include hematologic malignancies, idiopathic hypereosinophilic syndromes, ventriculoperitoneal shunts and allergic drug reactions. Bovine duragrafts are not a known cause, however both allergic and non-IgE mediated reactions are possible. Medulloblastoma is not associated with CSF eosinophilia however XRT is known to cause peripheral eosinophilia in patients with medulloblastoma or other malignancies. XRT is thought to cause tissue breakdown products that trigger eosinophilic reactions. Barring contraindications, steroids are the mainstay of treatment.
CSF eosinophilia in this patient was likely mediated by inflammatory responses to surgery, the bovine duragraft and radiation therapy. Steroid initiation resolved the severe neurologic sequelae and reduced the degree of CSF and peripheral eosinophilia. Given the frequency with which hospitalists co-manage surgical patients and perform consultations throughout the hospital, it is important to be aware of eosinophilic meningitis in the neurosurgical patient population and the appropriate workup and treatment.