Lateralizing value of interictal epileptiform discharges and other parameters in hypothalamic hamartoma

Hypothalamic hamartomas (HHs) are associated with pharmacoresistant epilepsy. Stereotactic radiofrequency thermocoagulation (SRT) shows promise as a disconnecting intervention. Although magnetic resonance imaging (MRI) is typically used to determine the attachment and intervention side, it presents challenges in cases of bilaterally attached HH, where the epileptogenic side is unclear. The lateralizing potential of electroclinical parameters in such cases remains uncertain. This retrospective study evaluates the lateralization value of specific parameters, particularly in patients with unilateral HH, to improve future diagnostics and treatment approaches for bilateral HH.

Four lateralizing parameters-semiology, ictal electroencephalography (EEG), and interictal epileptiform discharges during awake (IEDs_w) and sleep states (IEDs_s)-were assessed for correlation with HH attachment side using Spearman's ρ. We calculated areas under the curves (AUCs) and cutoffs for left and right IED_s prognostic lateralizing value, plotting differences between IED_sright and IED_sleft in a receiver-operating characteristic(ROC) curve to establish the required preponderance of unilateral IEDs_s to differentiate between left and right HHs. Binomial logistic regression was employed to predict the HH attachment side.

We included 25 patients (2-55 years of age) with mainly unilateral (n = 22) HHs who underwent SRT and presurgical evaluation. All parameters correlated with HH attachment side (semiology R = -.62, p = .005; ictal EEG R = .51, p = .047; IED_s R = .55, p = .018; IED_w, R = .61, p = .018). AUC values for right and left IED_s were .76 (p = .047) and .85 (p = .019), respectively, with cutoffs of .34 and .15. The AUC for "IED_sright-IED_sleft" was .98 (p = .0018) with a cutoff of .16. IEDs_s and semiology were significant predictors, achieving 88% correct lateralization.

IEDs_s are promising biomarkers for HH lateralization in unilateral HH. The predominance of unilateral IEDs_s suggests ipsilateral HH. Even in cases with predominantly bilateral IEDs_s, a slight preponderance of unilateral IEDs_s can indicate the attachment side. In addition, combining IEDs_s and semiology provides a predictive model for HH lateralization.