Encephalitis and Reversible Splenial Lesion Syndromes

Encephalitis encompasses a spectrum of inflammatory disorders of the brain parenchyma, most commonly triggered by viral or post-infectious immune responses. Clinically, it can present with fever, headache, altered consciousness, seizures or focal neurological signs. Within this context, reversible splenial lesion syndromes describe a distinct radiological pattern in which transient, focal abnormalities arise in the posterior segment of the corpus callosum, known as the splenium. These lesions demonstrate characteristic diffusion restriction on magnetic resonance imaging, reflecting cytotoxic oedema, yet resolve fully within days to weeks. Initially recognised in paediatric viral encephalitis, this syndrome has since been identified across a wide array of systemic infections, metabolic disturbances, drug exposures and autoimmune conditions. While most patients recover without sequelae, a subset may experience severe neurological impairment or herald the onset of chronic demyelinating disease, underscoring the clinical importance of prompt diagnosis and multidisciplinary management.

Research from Nature Portfolio

No recent Nature Portfolio content available.

Encephalitis and Reversible Splenial Lesion Syndromes publication trend

The graph below shows the total number of articles in encephalitis and reversible splenial lesion syndromes across all publications each year (not limited to Nature Index journals).

Technical terms

Encephalitis: Inflammation of the brain parenchyma, typically of infectious or immune-mediated origin.

Corpus callosum: The major white-matter tract connecting the two cerebral hemispheres; the splenium is its posterior region.

Reversible splenial lesion syndrome (RESLES): A clinico-radiological entity marked by a transient lesion in the splenium with diffusion restriction on MRI.

Cytotoxic oedema: Intracellular fluid accumulation due to energy failure, seen as restricted diffusion on MRI.

Diffusion-weighted imaging (DWI): MRI technique sensitive to the Brownian motion of water molecules, used to detect acute cellular injury.

Apparent diffusion coefficient (ADC): Quantitative map derived from DWI that reflects the magnitude of water diffusion within tissue.

References

1. Cytotoxic lesions of the corpus callosum: a systematic review. European Radiology (2023).
2. Reversible lesion in the splenium of the corpus callosum. Brain and Behavior (2019).
3. Mild encephalitis/encephalopathy with a reversible splenial lesion secondary to encephalitis complicated by hyponatremia. Medicine (2019).