Predictive factors of de novo epilepsy in reversible splenial lesion syndrome.

Objective: Reversible splenial lesion syndrome (RESLES) is a rare neurological disorder in East Asia with good prognosis. Herein, we investigated the predictive factors for de novo epilepsy in RESLES.

Methods: This single-centre cohort study was conducted at Sendai Medical Center in Japan, enrolling patients with RESLES without previous epilepsy treated between February 2008 and May 2023 with follow-up for at least 1 month. The outcome was de novo epilepsy during or after RESLES without other aetiologies of epilepsy. The variables during RESLES admission were compared between patients with (Group A) and without (Group B) de novo epilepsy. Statistical analyses were performed using the Mann-Whitney U or Fisher's exact tests.

Results: Twenty-two patients (males 11/22; 50 %) met the inclusion criteria. The mean age and median follow-up duration were 37 ± 20 years and 35.9 months (range: 2.4 to 199 months), respectively. The aetiologies included infection (10/22, 45.5 %), cerebrovascular disorders (3/22, 13.6 %), and others (8/22, 36.4 %). Acute symptoms included fever (14/22, 63.6 %), altered mental status (19/22, 86.4 %), seizures (8/22, 36.4 %), and status epilepticus (2/22, 9.1 %). MRI showed splenial lesions (mean vertical length 7.0 ± 1.7 mm and mean horizontal length 14.2 ± 7.6 mm) and extra splenium lesions of corpus callosum (1/22; 4.5 %). 9.1 % (2/22) developed de-novo epilepsy. Status epilepticus (2 vs 0; p = 0.001), long horizontal splenial lesions (24.7 mm vs 13.2 mm; p = 0.04), use of anti-seizure medication (3 vs 2; p = 0.04) were significantly more common in Group A than B.

Conclusions: Status epilepticus during the acute phase of RESLES may predict the development of epilepsy.