ABSTRACT
INTRODUCTION: Dengue is the most common of the arbovirosis that humans can suffer from. The frequency with which the central nervous system (CNS) is affected by this viral infection remains unknown, although isolated cases with neurological complications have been reported in Asia and South America. In Rio de Janeiro, Brazil, dengue virus infection has become an important public health concern. CASE REPORTS: The authors describe two cases of immune-mediated CNS involvement following classic infection by the dengue virus: one involving post-infectious disseminated acute encephalitis and the other consisting of Guillain-Barré syndrome. In both cases dengue was diagnosed using the ELISA technique, and other viral aetiologies in the cerebrospinal fluid (CSF) were excluded. A 10-year-old female, following a bout of classic dengue, presented symptoms of a diminished level of consciousness, spastic tetraparesis, cerebellar syndrome and frontal symptoms. A resonance brain scan showed areas of hypersignal in T2 sequences in the cerebral peduncle, lentiform nuclei and internal capsule on both sides of the brain, which suggested post-infectious encephalitis. The second patient, a 14-year-old male, presented an areflexive flaccid ascending tetraparesis that suggested acute polyradiculoneuritis, following a bout of classic dengue. CSF albuminocytologic dissociation was also observed. This patient's electroneuromyogram recording showed a polyradiculoneuropathy of a primarily demyelinating nature with an associated axonal component. CONCLUSIONS: The immunological mechanisms involved in the pathophysiology of this type of neurological complications after suffering from dengue may be part of the physiological response to the viral infection.