Generalised
epilepsy and cognitive deterioration were recently described in three children following human herpesvirus 6 (HHV6)-associated post-transplant acute
limbic encephalitis (PALE). Magnetic resonance imaging (MRI) showed bilateral signal change and/or
atrophy in the medial temporal structures and there was no evidence of an ongoing viral or immune-mediated process. We report another child who developed this condition after cord blood
transplantation for
congenital neutropenia at the age of three. He presented with epileptic
spasms four months after HHV6-associated PALE. Cognitive regression, prominent electroencephalographic abnormalities and different types of generalised
seizures ensued during the following months and proved refractory to
antiepileptic and immunomodulating treatment, which included
steroids,
immunoglobulin and
rituximab. MRI was normal at onset of
epilepsy but subsequently showed the development of right
hippocampal sclerosis. Results from serial blood and cerebrospinal fluid (CSF) analyses were inconclusive, including lack of patient's CSF and serum reactivity with cultures of dissociated rat hippocampal neurons. This report confirms the existence of a new
epilepsy syndrome featuring generalised
seizures and epileptic
encephalopathy after HHV6-associated PALE in children. Presentation with epileptic
spasms, lack of CSF and serum reactivity with cultured rat hippocampal neurons, and
rituximab inefficacy are novel features that contribute to delineate the syndrome and argue against an immune-mediated basis of this condition.