Abstracts

Rationale: Transient lesions within the splenium have been described in epilepsy patients and, although the pathogenesis remains unclear, are believed related to alterations in antiepileptic medications. Further understanding of this “lesion” is important to avoid misdiagnosis as a similar-appearing lesion has been described in other clinical situations. The purpose of this retrospective review was to determine the incidence of the splenial lesion in patients referred to our hospital’s seizure-monitoring unit. Methods: Hospital scheduling records were used to identify all patients admitted to our hospital’s seizure monitoring unit over a 1 year period. Admission involved anti-epileptic drug withdrawal, continuous video-EEG telemetry and, in many cases, MR imaging. Patient charts and MR studies were reviewed with patient age, gender, relationship of patient admission to MR exam and antiepileptic drug withdrawal, and the presence or absence of a splenial lesion were recorded. Results: There were 245 patients (132 female, 113 male; average age 35 years) admitted to our seizure monitoring unit over the study period. Of these, 216 patients had MR imaging; 14 (6.5%) of which had a non-enhancing T2 hyperintense lesion demonstrating restricted diffusion centered within the splenium. Eleven of the 14 positive cases were imaged either during or within 2 weeks following hospital discharge. The remaining 3 cases had a splenial lesion detected on MR imaging that preceded hospital admission. Patients who had subsequent MR studies revealed the lesion to have resolved. Conclusions: Splenial T2 hyperintense lesions are a relatively common finding on MR studies of epilepsy patients with recent antiepileptic drug withdrawal, and may relate to reversible osmotic myelinolysis. Recognition and familiarity of this transient lesion is important to avoid mis-diagnosis as other pathologies can have a similar appearance.