A case of recurrent RESLES type I: analysis of pathogenic factors and delayed imaging manifestations.

Reversible splenial lesion syndrome (RESLES) is a clinico-radiological syndrome characterized by a reversible lesion in the splenium of the corpus callosum. It is more common in children, and most patients recover completely with active treatment. However, recurrent RESLES is very rare and its etiology is unknown, posing significant challenges for clinicians in terms of prediction, diagnosis, and treatment. This article reports the first case of RESLES Type I in a young adult with five episodes and identifiable predisposing factors (intracranial infection and immunosuppressant dependence). By analyzing the patient's medical history, neuroimaging characteristics, body fluid test results, and response to immunomodulatory therapy, and reviewing recent literature on recurrent RESLES. The findings suggest that intracranial infection and immune dysfunction may be potential factors leading to the recurrence of RESLES Type I in this case, while serum sodium levels can remain within the normal range. Furthermore, we observed that infe cranial MRI lesions associated with RESLES in this patient often appeared 4-7 days after symptom onset, indicating a potential delay in imaging changes. Therefore, it is recommended that clinicians select appropriate timing for neuroimaging examinations and consider repeat scanning when necessary to reduce the risk of misdiagnosis or missed diagnosis.