[Landau-Kleffner Syndrome and Continuous Spike-and-Wave During Sleep Syndrome: Comparison of Clinical, Neurophysiological, and Neuropsychological Characteristics].

Introduction: Landau-Kleffner Syndrome (LKS) is a subtype of epileptic encephalopathy with spike-wave activation during sleep (EESWAS), characterized by acquired aphasia associated with the emergence of epileptiform abnormalities.

Patients And Methods: A cross-sectional descriptive study was conducted in a tertiary hospital, involving one group of children with LKS and another with EESWAS. The aim was to compare the clinical, neurophysiological, and neuropsychological aspects of both groups.

Results: Seven patients with LKS and seven patients with EE-SWAS were analyzed; the samples were homogeneous in terms of sex, etiology, and type of electroencephalographic pattern. The mean ages of onset were 3.6 years in the LKS group, debuting with language and behavioral regression in 100% (five patients with expressive language impairment only), and 4 years in the EE-SWAS group, debuting with epilepsy in 100%, followed by behavioral regression. In 57% of the LKS group, evolving epilepsy was observed with predominantly posterior epileptic abnormalities during wakefulness. The mean duration of continuous spike-and-wave activity during sleep (SWAS) was longer in the LKS group (3.7 vs 1.8 years). Corticosteroids was the most effective treatment, with 86% of patients in both groups showing improvement. On a neuropsychological level, cognitive impairment was observed in 71% of the LKS group versus 43% in the EE-SWAS group; attention difficulties were present in all EE-SWAS patients and 85% of LKS patients.

Conclusions: EE-SWAS is characterized by cognitive-behavioral regression, with corticosteroids being the treatment of choice. LKS is a subtype of epilepsy within this group, with distinct features such as initial language impairment, posterior electroencephalogram (EEG) activity, and a longer duration of SWAS.