[Acute encephalitis complicating acute polyradiculoneuritis]

We report the case of a 43-year-old man who developed an acute encephalopathy after IVIg therapy for AIDP. Imaging studies showed predominantly posterior leukoencephalopathy. The signs and symptoms of the encephalopathy completely resolved by steroids. Two patients with acute encephalopathy, following IVIg therapy, were reported previously in the literature. However, our observation differed from them by the presence of a marked pleiocytosis of cephalospinal fluid before beginning of IgIV. Two hypothesis may be made: a post-infectious meningo-encephalo-AIDP or a complication of IgIV. This side effect, even rare, has not to be underestimated.