Small sharp spikes precede the development of epileptiform discharges in temporal lobe epilepsy

Small sharp spikes (SSS), traditionally regarded as benign EEG variants, have increasingly been linked to temporal lobe epileptogenicity. However, their potential role as early EEG biomarkers of temporal lobe epilepsy (TLE) remains unclear. We analyzed 11 patients with or without a prior epilepsy diagnosis whose initial EEGs demonstrated isolated SSS in the absence of interictal epileptiform discharges (IEDs). The cohort included 8 females and 3 males with a median age of 35 years (IQR 26-43). Four patients had a diagnosis of epilepsy at presentation, whereas seven did not. Over a median follow-up of 5 months (IQR 4-18), all patients subsequently developed IEDs and/or ictal patterns on follow-up EEGs. Initial SSS consistently localized to the temporal lobe and lateralized to the same hemisphere in which later epileptiform discharges or seizures emerged, both in patients with and without epilepsy at presentation. Notably, all seven patients without an initial epilepsy diagnosis were ultimately diagnosed with epilepsy. In two patients who underwent intracranial monitoring, scalp-recorded SSS were time-locked to mesial temporal epileptiform discharges. These findings suggest that isolated SSS may precede conventional epileptiform abnormalities. SSS may therefore represent early electrophysiologic biomarkers of TLE.