Seizure localization in patients with multiple tubers: presurgical evaluation in tuberous sclerosis

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder. Epileptic seizure is the most common neurological symptom. Medically intractable epilepsy in these patients is candidates of epilepsy surgery. We report two cases of TSC with ictal electroencephalography (EEG) arising from right temporal lobe who underwent video-EEG monitoring. Two of these patients were first diagnosed with TSC at age 30 and 23 years old, partly because of their mild accompanying symptoms other than epileptic seizures. Case 1 had a long history of epilepsy since three years old. Although she had multiple cortical tubers on her magnetic resonance imaging (MRI) scan, all the recorded ictal and interictal EEG indicated epileptic focus on right temporal region, suggesting that cortical tuber located at the anterior temporal region as epileptogenic tuber. Case 2 also had long history of epilepsy since three years old. His brain MRI revealed numerous tubers in his brain including one at the right hippocampus. His ictal EEG originated from right temporal area, suggesting hippocampus as epileptic focus. Epileptic focus in TSC are commonly localized to one of the multiple cortical tubers, which is epileptogenic. The localization of epileptogenic zone can be aided with interictal and ictal EEG, brain MRI, subtracted ictal-interictal SPECT co-registered with MRI (SISOM) and positron emission tomography (PET).