Callosal Disconnection Syndrome in Transient Splenial Lesion of the Corpus Callosum

Introduction

The most frequent causes of solitary transient lesions in the splenium of the corpus callosum (SCC) are viral encephalitis, antiepileptic drug toxicity/withdrawal, and hypoglycemic encephalopathy.1, 2 Influenza, adenovirus, and mumps have been found in some patients but in most encephalitic cases the causative germ remained obscure. Other etiologies include rapid correction of hyponatremia resulting in osmotic myelinolysis, dural sinus thrombosis, multiple sclerosis,3 bacterial meningoencephalitis4 malnutrition,5 as well as systemic lupus erythematosus.6 In most of these latter conditions, however, the splenial lesion is not isolated. The clinical course is usually mild with good prognosis.1, 2, 7–9 Accompanying symptoms include disorientation, drowsiness, cognitive and memory impairments,4 hallucinations,7 headache,1 confusion,10 but detailed clinical description of callosal disconnection in patients with reversible lesions has only rarely been reported.11 Routine neuropsychological examination can miss these signs, which can often be detected only by targeted tests.

Abstract

A 64-year-old male patient presented with fever, agitation, and flu-like symptoms as well as difficulty in using his hands simultaneously. The brain magnetic resonance imaging (MRI) showed a solitary lesion in the splenium of the corpus callosum (SCC). The detailed neuropsychological examination revealed signs of disturbed interhemispheric transfer. The diagnosis of encephalitis was supported by the acute onset of brain dysfunction and the inflammatory changes of the cerebrospinal fluid (CSF). The clinical and MRI abnormalities completely recovered within one week without any treatment. In previously published reports of reversible focal lesions of the SCC, neuropsychological symptoms have rarely been reported. Our case underlines the importance of targeted neuropsychological examination in detecting callosal dysfunction and exemplifies the spontaneously benign prognosis of SCC.

Keywords

Encephalitis, corpus callosum, splenium