Spatial and temporal dynamics of epileptic activity at sleep onset in the Encephalopathy with Status Epilepticus during slow sleep (ESES) after unilateral thalamic lesions

Continuous Spike-Waves during Slow Sleep Today: An Update

In the context of childhood epilepsy, the concept of continuous spike-waves during slow sleep (CSWS) includes several childhood-onset heterogeneous conditions that share electroencephalograms (EEGs) characterized by a high frequency of paroxysmal abnormalities during sleep, which have negative effects on the cognitive development and behavior of the child. These negative effects may have the characteristics of a clear regression or of a slowdown in development. Seizures are very often present, but not constantly. The above makes it clear why CSWS have been included in epileptic encephalopathies, in which, by definition, frequent EEG paroxysmal abnormalities have an unfavorable impact on cognitive functions, including socio-communicative skills, causing autistic features, even regardless of the presence of clinically overt seizures. Although several decades have passed since the original descriptions of the electroclinical condition of CSWS, there are still many areas that are little-known and deserve to be further studied, including the EEG diagnostic criteria, the most effective electrophysiological parameter for monitoring the role of the thalamus in CSWS pathogenesis, its long-term evolution, the nosographic location of Landau-Kleffner syndrome, standardized neuropsychological and behavioral assessments, and pharmacological and non-pharmacological therapies.

High incidence of early thalamic lesions in the Continuous Spike-Wave related with slow Sleep (CSWS)

OBJECTIVE

Continuous Spike-Wave during slow Sleep (CSWS) syndrome associates a clinically important neurocognitive regression with strong activation of non-REM sleep spikes. Its mechanisms remain unknown, but a contribution of rare perinatal thalamic injuries has been highlighted. We determine the incidence of such lesions in a cohort of CSWS patients.

METHODS

N = 65 patients with CSWS and a control group (N = 51) were studied. Spikes were quantified in long-term ambulatory EEGs, brain Magnetic Ressonance Imaging (MRI) structural lesions were assessed and thalamic volumetry was performed. A neurocognitive scale was used to assess dysfunction.

RESULTS

The most common etiologies in the control patients were not represented in the CSWS group. Structural lesions were detected in a minority of CSWS patients (25/53) but included a thalamic injury in the large majority (24/25). This ratio was 4/40 in controls. Lesions belonged to one of five types: 1. Circumscribed to the thalamus (N = 11); 2. Extending beyond the thalamus (N = 3); 3. Hypothalamic-Hamartomas (N = 4); 4. Periventricular-Leukomalacia (N = 4); 5. Hypoplasia-Polymicrogyria (N = 1). Most lesions were lateralized to one hemisphere, which in all cases corresponded to the lateralization of the CSWS.

SIGNIFICANCE

Thalamic lesions are present in most CSWS patients with abnormal MRIs, supporting an important role in its genesis.

Non-convulsive status epilepticus induced by acute thalamic lesions: A report of three cases

The thalamocortical network appears to play a pivotal role in ictogenesis. We herein present three cases of non-convulsive status epilepticus (SE), in adult patients without previous history of epilepsy or seizures, precipitated by acute thalamic vascular and metabolic-induced lesions. In all cases the EEG showed patterns consistent with generalized SE confirmed either by a fast and complete clinical and EEG response to anti-seizure medication or definitive subtle motor signs consistent with SE. We argue that the subcortical disruption of thalamocortical networks due to the thalamic lesion predisposed to the occurrence of non-convulsive SE. In patients with thalamic disorders and unexplained mental status changes EEG evaluation should always be considered.