Coxsackie A9 focal encephalitis associated with acute infantile hemiplegia and porencephaly

Abstract

The factors underlying acute infantile hemiplegia are seldom identified. Coxsackie A9 focal encephalitis was documented for the 1st time in a 3 mo. old infant with fever, hemiconvulsions and hemiplegia followed by a static motor deficit and epilepsy. The acute infantile hemiplegia associated with encephalitis was thought to result from an arteritis or venous sinus thrombosis with subsequent cerebral infarction, but this was not observed in the patient. Rather, a series of brain scans, computerized tomograms, and a cerebral angiogram clearly documented the evolution of a focal necrotizing encephaloclastic process resulting in a porencephalic cyst. Serial CSF viral cultures were necessary to isolate the etiologic agent (Coxsackie A9). The infant did not have a neutralizing antibody response to the infecting viral agent despite an apparently intact immune system, which is possibly due to the development of immune tolerance or an insufficient amount of infecting viral antigen. This emphasizes that serologic studies alone may not be adequate to document an acute CNS viral infection. This patient also typifies the poor prognosis in infants presenting with acute hemiplegia, fever and convulsions in the absence of cerebrovascular occlusion.