Discussion:
Although ictal pain is often associated with other seizure symptoms, it can be the only manifestation of focal epilepsy and differentiating them from others can be challenging. Among patients with ictal pain, those who report it to their limbs are more likely to have an epileptic cause1.
Under some pathophysiological conditions, operculo-insular lesions may produce location-specific painful epileptic seizures. Functional imaging studies have identified several cortical areas activated by painful stimuli, referred as “pain matrix”, including, among others, the primary somatosensory area, the supplementary motor area, the insula, the anterior frontal or the posterior parietal cortices4. Some cases of ictal pain with foci originating in the frontal, parietal and temporal regions have been described with surface EEG3,5. However, data from functional cortical mapping by using direct cortical stimulation suggests that the origin of painful somatosensory seizures arises solely from the medial part of parietal operculum or the posterior and upper part of the insular cortex6,7.
Taking into account the cortical mapping studies and the localization of our patient’s glioblastoma, we suggest that the painful seizure has a left operculo-insular origin and that the rhythmic activity captured on the surface EEG represents propagation to the primary parietal cortex.
Paroxysmal contralateral pain can be the only manifestation of epileptic seizures with operculo-insular cortex involvement. This knowledge is useful to avoid misdiagnosis and to prompt appropriate management with antiepileptic drugs.