Reversible Splenial Lesion Syndrome (RESLES): What's in a Name?

The presence of transient lesions involving the splenium of the corpus callosum (SCC) has been described in patients with encephalitis or encephalopathy of varied etiology. We have termed it RESLES (reversible splenial lesion syndrome).To describe 3 additional patients (2 encephalitis, 1 hypoglycemia) and review the literature to define this syndrome, its etiology, presentation, prognosis, and possible pathophysiological mechanisms.Search of the MEDLINE database from 1966 through 2007. English language article titles and abstracts were screened and the appropriate articles reviewed. Additional articles cited by original references were also reviewed.RESLES is caused by antiepileptic drug withdrawal, infection, high-altitude cerebral edema (HACE), or metabolic disorders (hypoglycemia and hypernatremia). Complete resolution after a variable lapse is the rule. Clinical presentation is nonspecific, without evidence of callosal disconnection syndromes. Neuroimaging shows a nonenhancing, round-shaped lesion centered in the SCC that disappears after a variable lapse. Diffusion studies reveal DW hypersignal with low ADC values, suggestive of cytotoxic edema. Only HACE-related cases and 1 patient with pregabalin withdrawal showed high ADC values, consistent with vasogenic edema.RESLES is a distinct clinicoradiological syndrome of varied etiology and benign course except in those patients with an underlying severe disorder.