Acute disseminated encephalomyelitis following Tdap vaccination and bacterial meningoencephalitis

Introduction: Association of Acute Disseminated Encephalomyelitis (ADEM) with both recent vaccination and viral infections is well described in current literature. However, the coincidence of ADEM and bacterial infections has been rarely documented. In this report, we present a case of ADEM which occurred after bacterial meningoencephalitis and prior vaccination against tetanus, diphtheria, and pertussis (Tdap). Case presentation: A 62-year old woman was hospitalized with an upper respiratory tract infection three weeks after Tdap triple vaccination. A few days after admission, she became somnolent and developed meningism. Cerebrospinal fluid (CSF) analysis revealed pleocytosis and increased protein/lactate levels compatible with bacterial meningoencephalitis. The patient was treated with intravenous antibacterial triple therapy in combination with dexamethasone leading to a significant improvement of clinical symptoms and improvement of CSF parameters. Five days later, the patient's condition worsened again, and she developed aphasia and right-sided hemiparesis. A magnetic resonance imaging (MRI) scan revealed distinct fluid-attenuated inversion recovery sequence (FLAIR)-hyperintense lesions in both hemispheres. Following brain biopsy, the diagnosis of ADEM was made and methylprednisolone pulse therapy was initiated for five days leading to a nearly complete remission of symptoms. Conclusion: ADEM is a neurological syndrome which may be associated with bacterial infection of the central nervous system (CNS). We hypothesize that the preceding Tdap triple vaccination may have contributed to the development of ADEM.