Age-dependent semiology of frontal lobe seizures

Frontal lobe epilepsy is the second most frequent origin of focal epilepsy. Various studies have discussed localizing aspects of ictal signs in frontal lobe epilepsy; the effect of age on semiological manifestations has, however, not been analyzed so far.

We retrospectively analyzed video-documented semiological signs in a cohort of 122 consecutive patients aged 0-70 years (mean age: 24.9 years) with EEG/MR evidence for frontal lobe epilepsy undergoing video-EEG telemetry assessment between 1999 und 2016.

In this patient cohort, most common etiologies were focal cortical dysplasia (48%) and tumors (16%). Most frequent ictal manifestations overall were impaired language comprehension (60.3%), unilateral tonic posturing (58.9%), unilateral cloni (46.6%), versive movements (44.5%), vocalization (42.5%) and impaired reactivity to non-verbal stimuli (40.4%). With increasing age, sign of four (p = 0.019), dystonic posturing (p = 0.026), changes in heart rate (p = 0.014) and impaired reactivity to non-verbal stimuli (p = 0.009) occurred significantly more frequently. In contrast, myoclonic components were significantly less frequent observed in the higher age group (p = 0.037).

Frontal lobe seizures can be categorized into different behavioral manifestations related to involved symptomatic brain regions, including clonic, bilateral asymmetric tonic seizures and complex motor phenomena. In this cross-sectional study, we found age-related changes in the frequency of both, motor and non-motor semiological elements. Especially simple lateralized motor signs like dystonic posturing, sign of four and version were more common with increasing age. Age-dependent alterations in phenomenology may reflect maturation in connectivity and seizure propagation within and beyond the frontal lobe, and affect the localizing and lateralizing value of ictal phenomena.