[Aseptic meningitis as a complication caused by an allergic reaction after microvascular decompression: two case reports].

We report here two cases of patients complicated with aseptic meningitis after microvascular decompression (MVD). The first case, a 56-year-old female complained of headache with high fever 18 days after the MVD for right trigeminal neuralgia. The amount of cells in cerebrospinal fluid (CSF) had so much increased that bacterial meningitis was suspected. However, there was no improvement after antibiotics therapy, so immune globulin was injected and the meningitis gradually improved. Eosinophilia remained in peripheral blood and the symptoms improved rapidly after the steroid therapy. Because of this, we suspected that meningitis was caused by an abnormal allergic reaction. The second case, a 30-year-old male complained of headache with mild fever 15 days after MVD for left hemifacial spasm. The amount of cells in CSF increased, so bacterial meningitis was suspected. Eosinophilia remained in peripheral blood and the steroid therapy proved very effective for the meningitis. Because of this, we suspected that meningitis was caused by an abnormal allergic reaction. We suspected that the two patients suffered from aseptic meningitis caused by allergic reaction, and the antigen for this abnormal allergic reaction was the foreign materials used for MVD. The materials were Dacron for prostesis, Goatex or Lyodula for dural plasty, fibrin glue for preventing CSF leakage. We ascertained that the abnormal allergic reaction was caused by human fibrinogen in the second case. It is important to be aware of such allergic reaction to fibrin glue in the post-operative stage after MVD.