Relationship between cortical tuber subtypes and interictal epileptiform discharges in tuberous sclerosis complex:...

To investigate association between magnetic resonance imaging (MRI)-defined cortical tuber subtypes and interictal epileptiform discharges (IEDs) in Tuberous sclerosis complex (TSC).

Twenty-three patients with TSC underwent brain MRI and scalp electroencephalogram (EEG). We analyzed total of 184 cerebral lobes (bilateral frontal, temporal, parietal, occipital). Tubers were classified into Types A, B, and C based on their signal intensity on MRI with T1-weighted (T1W), T2-weighted (T2W), and fluid-attenuated inversion recovery (FLAIR) images. Type A was isointense on T1W and subtly hyperintense on T2W/FLAIR, while Type B was hypointense on T1W and homogeneously hyperintense on T2W/FLAIR. Meanwhile, Type C was hypointense on T1W, hyperintense on T2W, and heterogeneous on FLAIR, characterized by a hypointense central region surrounded by a hyperintense rim. IEDs were detected using automated software and confirmed by expert visual inspection. The association between tuber subtypes and IED presence was assessed using multivariable generalized estimating equations (GEE). A negative binomial generalized linear mixed model (GLMM) was used to assess the association between tuber counts and IED frequency.

Multivariable analyses revealed that Type C tubers were the only subtype independently associated with both the presence of IEDs (Adjusted odds ratio = 1.417, p = 0.011) and a higher frequency of IEDs (p < 0.001). The presence or number of Type A and B tubers were not significantly associated with either outcome.

Type C tubers demonstrate significantly higher cortical irritability than other subtypes, providing insights into varying irritability potential of different tuber types in TSC.