Relationships between continuous spike-waves during sleep (CSWS) and antiepileptic drug resistance

Abstract

Background and aims: The spectrum of neuropsychiatric disorders associated with continuous spike-waves during slow wave sleep (CSWS) syndromes is widely debated. Although seizures and CSWS disappear within puberty, heterogeneous neuropsychological and behavioural disorders can persist. This feature has increased the interest in etiopathogenesis and negative prognostic factors of these conditions. Delayed diagnosis and appropriate therapy, the high frequency, generalization, early onset, prolonged duration and drug resistance of EEG paroxysmal abnormalities are all unfavourable prognostic factors for neuropsychological and behavioural evolution. Pre-existing cerebral lesions, in some cases, may aggravate the prognosis. Case reports: We describe five patients with drug resistant CSWS presenting different clinical-EEG features. One of them had a typical picture of CSWS with paroxysmal abnormalities occupying more than 85% of N-REM sleep EEG recording (case 4); another had a classical Landau Kleffner Syndrome (LKS) (case 5). All cases presented CSWS resistant to several antiepileptic drugs; the localization of prevailing EEG paroxysmal abnormalities showed a good relation with neuropsychological findings, irrespective of IQ. All patients except case 1 presented IQ regression, with a significant gap between VIQ and PIQ to the detriment of the PIQ for cases 2, 3 and 4 and of VIQ for case 5 with LKS. IQ improved in cases 2 and 4 even if a gap remained to the detriment of PIQ in case 2. Cases 3 and 5 improved after CSWS disappearance even though both had a borderline FIQ at the last observation. Behavioural problems were present in all cases except the first, improving after CSWS fragmentation. Seizures occurred in all patients except case 3 representing the first symptom, but they generally disappeared before CSWS fragmentation. Cerebral lesions were present in cases 2 and 4 but did not seem to be responsible for CSWS evolution. Conclusion: It is necessary to be aware that CSWS can develop and that early diagnosis is very important to start an antiepileptic treatment. Further studies with a large sample and homogeneous EEG criteria are required to better characterize the enigma of CSWS.