Reversible splenial lesion syndrome associated with encephalitis/encephalopathy presenting with great clinical heterogeneity

Abstract

Background: Reversible splenial lesion syndrome (RESLES) is a disorder radiologically characterized by reversible lesion in the splenium of the corpus callosum (SCC). Most of patients with RESLES associated with encephalitis/encephalopathy were identified in Japanese population, but almost no Chinese patients were diagnosed as RESLES associated with encephalitis/encephalopathy.

Methods: Possible patients with reversible isolated SCC lesions were retrieved from January 2012 to July 2015 using keyword "restricted diffusion and isolated SCC lesion" in MRI report system from a large academic center. The clinical, laboratory and radiological data were summarized.

Results: A total of 15 encephalitis/encephalopathy patients (9 males and 6 females) were identified with a reversible isolated SCC lesion. Except for 13 patients with fever symptom, 8 patients also had cold symptoms before the onset of neurological symptoms. The neurological symptoms included headache, vertigo, seizure, disturbance of consciousness, and delirious behavior. Thirteen patients completely recovered within 1 month, but 2 patients who were subjected to mechanical ventilation had persistent neurological deficits. The initial MRI features showed isolated ovoid or extending SCC lesions with homogeneous hyperintense on diffusion weighted imaging (DWI) and decreased apparent diffusion coefficient (ADC) values. The follow-up MRI revealed that isolated SCC lesions with diffuse restriction disappeared at 10 to 32 days after the initial MRI study. Fractional anisotropy map revealed the decreased value of SCC lesion in a severe case with poor prognosis.

Conclusions: RESLES associated with encephalitis/encephalopathy is a reversible syndrome with an excellent prognosis in most patients, while a few patients required ventilator supporting at the early stage might have severe neurological sequelae. Reversible signal changes on DWI and ADC are identified in all patients, but fractional anisotropy values can be decreased in severe patient with neurological sequelae.

Keywords: Corpus callosum; Encephalitis; Encephalopathy; Poor outcome; Reversible splenial lesion syndrome.

Fig. 1

The cerebral MRI features of case 2. MRI revealed an isolated SCC lesion with obvious hyperintense on DWI (a, arrow), decreased ADC values (b), decreased fractional anisotropy value (c), and normally projecting direction of white matter fibers (f). At 16 days after initial MRI, second MRI showed the abnormalities of SCC nearly disappeared on DWI (d) and ADC (e)

Fig. 2

The cerebral MRI features of case 7. MRI showed an isolated SCC lesion with slight hyperintense on T2WI (a), slight hypointense on T1WI (b), hyperintense on DWI (c, arrow), and obvious decreased ADC values (d). At 32 days after first MRI, second MRI showed abnormal signals of the SCC completely disappearing on T2WI (e), T1WI (f), DWI (g) and ADC (h)