Post Flu Shot Confusion – think ADEM!

Abstract

A 57-year-old Caucasian man with hypertension and diabetes presented with left arm weakness and headache for one day. He had an influenza vaccination 10 days prior to presentation. Computed tomography (CT) of the head showed a possible right MCA stroke. The next day he developed left hemiplegia. A repeat CT of the head exhibited a “mass like” effect in the right hemisphere. Magnetic resonance imaging (MRI) of the head showed a diffuse area of abnormal signals, involving both hemispheres, and diffuse white matter changes. His CSF showed WBC 4/mm3, RBC 1/mm3, glucose 97 mg/dl, and protein 96 mg/dl. He continued to deteriorate, developed encephalopathy, and had to be intubated. A repeat MRI of the head demonstrated extensive bilateral, poorly marginated white matter, and some grey matter involvement characteristic of acute disseminated encephalomyelitis (ADEM). He failed to respond to methylprednisolone 1 gram daily and was started on plasma exchange daily for 10 days. He started to improve after the second session. After five months he was essentially normal and had returned to work. This case demonstrates that routine vaccination can have important complications.