Mild encephalopathy with reversible splenial lesion (MERS) is a clinico-radiological syndrome characterized by a transient mild encephalopathy and magnetic resonance imaging findings of a reversible lesion in the splenium of corpus callosum. This syndrome is more frequently described in Asiatic population and has been associated with some viral and bacterial infections, including Influenza. In those cases, patients usually present with flu-like symptoms before the beginning of neurological symptoms.
We present a case report of an Influenza A-related MERS in a pediatric patient. He is an eleven year-old Caucasian male that presented with sudden abnormal behaviour and speech impairment, motor aphasia and dysarthria and episodic dystonic movements of his left upper limb. Brain CT and CT angiography were normal, but brain MRI demonstrated increased signals of restricted diffusion involving the corpus callosum and symmetrical extension to frontoparietal subcortical white matter. There was history of flu symptoms some days before and Influenza A was isolated on nasopharyngeal swab exam.
Neurological symptoms in MERS can be very variable, mainly in pediatric population. Clinicians should be aware of this disorder and include it in the differential diagnosis of encephalopathic patients, particularly during Influenza season. Prognosis is usually favourable with complete neurological and radiological resolution within days or weeks, as seen in our patient.
Key words: Influenza A, Encephalopathy, Mild Encephalopathy with Reversible Splenial lesion, Central Nervous System Infection, Corpus Callosum, Pediatrics
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