Junctional instability in neuroepithelium and network hyperexcitability in a focal cortical dysplasia human model.

Focal cortical dysplasia is a highly epileptogenic cortical malformation with few treatment options. Here, we generated human cortical organoids from patients with focal cortical dysplasia type II. Using this human model, we mimicked some focal cortical dysplasia hallmarks, such as impaired cell proliferation, the presence of dysmorphic neurons and balloon cells, and neuronal network hyperexcitability. Furthermore, we observed alterations in the adherens junctions zonula occludens-1 and partitioning defective 3, reduced polarization of the actin cytoskeleton, and fewer synaptic puncta. Focal cortical dysplasia cortical organoids showed downregulation of the small GTPase RHOA, a finding that was confirmed in brain tissue resected from these patients. Functionally, both spontaneous and optogenetically-evoked electrical activity revealed hyperexcitability and enhanced network connectivity in focal cortical dysplasia organoids. Taken together, our findings suggest a ventricular zone instability in tissue cohesion of neuroepithelial cells, leading to a maturational arrest of progenitors or newborn neurons, which may predispose to cellular and functional immaturity and compromise the formation of neural networks in focal cortical dysplasia.

Associations between electroencephalographic and magnetic resonance imaging findings in tuberous sclerosis complex.

Nearly 90% of patients with tuberous sclerosis complex (TSC) develop epilepsy; however the mechanisms of epileptogenesis remain unclear. Some cortical tubers are thought to be epileptogenic while others are not. This study aimed to evaluate whether tuber burden, size or type seen on magnetic resonance imaging (MRI) co-registers with interictal epileptiform discharges on electroencephalogram (EEG). EEG and MRI data from 69 patients with TSC were reviewed by dividing the cerebrum into four quadrants. Quadrants containing greatest tuber burden, largest tuber, calcified tubers, cyst-like tubers, and no tubers were identified on MRI. For EEG analysis, spikes and sharp waves were counted and averaged to a value per minute, and each quadrant was assigned a score. MRI and EEG findings were compared in each patient. The presence of a cyst-like tuber in a quadrant correlated with a higher incidence of epileptiform activity in the same quadrant (p=0.002). This finding supports the notion that cyst-like cortical tubers may contribute to the more severe epilepsy profile seen in TSC patients with these lesions. Quadrants containing greatest tuber burden, largest tubers, and calcified tubers were not predictive of regional interictal epileptiform activity. Furthermore, quadrants without any apparent tuber co-registered with interictal epileptiform discharges in two patients, suggesting a multifactorial component of epileptogenicity in TSC.

Long-term outcome of symptomatic infantile spasms established by video-electroencephalography (EEG) monitoring.

In this study, we examine the long-term clinical outcome of children with symptomatic infantile spasm. The children between 2 and 18 years of age diagnosed with symptomatic infantile spasms were reviewed. Sixty-eight children (age range, 2-13 years; mean, 4.5 years) met the inclusion criteria. Children who underwent epilepsy surgery were excluded. Age of onset for infantile spasms ranged from 1 to 24 months (mean, 7.1 months). Developmental delay was noted in all; there was seizure freedom in 14 children (20.5%). Infantile spasms were reported as the only seizure type in 10 (14.5%) children older than age 2 years. During the follow-up; symptomatic generalized epilepsy was diagnosed in 23 children (34%) and focal epilepsy in 21 (31%). The long-term outcome of these children remains unchanged in the majority of the children with symptomatic infantile spasms. We could not establish any risk factor that might be related to favorable or adverse outcome.

Self-injurious behavior and tuberous sclerosis complex: frequency and possible associations in a population of 257 patients.

Self-injurious behavior (SIB) has been observed in people with tuberous sclerosis complex (TSC), although the frequency of SIB in TSC is largely unknown. SIB is associated with intellectual and developmental disabilities, but there is no single cause of SIB. We retrospectively examined the frequency of SIB in a population of 257 patients with TSC and determined possible associations with SIB. We found a 10% frequency of SIB in our TSC population. When compared with patients without psychiatric symptoms, we identified a significantly higher rate of electroencephalographic interictal spikes in the left frontal lobe and a significantly lower number of tubers in the left occipital, parietal, and posterior temporal lobes. We also found that frequency of TSC2 mutation, history of infantile spasms, history of seizures, mental retardation, and autism are significantly associated with SIB.