Marta García-Fernández

Objective: Inversion‐duplication syndrome of chromosome 15 (invdup15) is a chromosomal disorder characterized by an inverted duplication of 15q11.2‐q13.1. Epilepsy is highly prevalent (60%–80%), drug‐resistant, and may progress to developmental epileptic encephalopathies (DEEs) such as Lennox–Gastaut syndrome (LGS). Despite its impact, epilepsy and optimal treatments remain poorly described. Methods: A retrospective multicenter study across 37 Spanish hospitals analyzed 54 patients, divided into two genetic subgroups: invdup15q and intdup15q. Clinical and genetic data were reviewed, focusing on epilepsy onset, seizure types, syndrome progression, electroencephalographic (EEG) findings, and treatment response. Results: Epilepsy was present in 29 of 54 (54%) patients, with a mean age at onset of 7.4 years (range = 1 month–24 years, SD = 6.4). LGS (16/29, 55%) and focal epilepsy (15/29, 52%) were the most frequent epilepsy types, although infantile epileptic spasms predominated in younger patients (5/6, 83%). Late onset LGS (>8 years) occurred in 38%. Initial seizures were mostly focal motor (10/29, 34%) and generalized tonic–clonic seizures (8/29, 28%), later evolving to tonic, myoclonic, and atypical absence seizures. Twenty‐six of 29 (90%) reported drug‐resistant epilepsy. Epilepsy was more frequent (65% vs. 35%, p < .05) and had earlier onset (median = 5.7 vs. 12.3 years) in invdup15q than intdup15q. EEG demonstrated unusual activities including diffuse fast activity, along with repetitive trains of paroxysmal fast activity during sleep. The most effective antiseizure drugs were oxcarbazepine for focal (9/11, 81%) and for generalized (2/3, 67%) epilepsy and valproic acid (6/10, 60%) for generalized epilepsy, whereas vigabatrin, zonisamide, and brivaracetam showed limited efficacy. In LGS, oxcarbazepine (8/12, 66%), valproic acid (11/18, 61%), and cannabidiol (6/9, 66%) yielded the best responses. All patients had early developmental delay; autism spectrum disorder was diagnosed in 22 of 54 (41%) and behavioral disorders in 30 of 54 (56%). Significance: Epilepsy in invdup15 is highly drug‐resistant and exhibits features consistent with DEEs, particularly LGS. EEG findings may serve as disorder biomarkers. Oxcarbazepine and valproic acid were the treatments most often associated with seizure improvement in this sample.

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.