Figure 3.

Clinical vignette. A 24-year-old left-handed female, like her father, began with epilepsy at age 15. Semiology began as a non-specific abdominal sensation, loss of awareness, speaking “gibberish”, or changing subjects of conversations. The seizures were often associated with lacrimation, salivation, and chewing automatisms with a frequency of 2 seizures per month. There was no tendency to progress to bilateral tonic-clonic. She has tried more than 7 antiseizure medications. Interictal Scalp encephalography (EEG) findings in Epilepsy Monitoring Unit admissions were unremarkable with no interictal discharges with the exception of rare left posterior temporal polyspikes during sleep (T5 spreading to O1-T3). Ictal Scalp EEG showed onset over the same area, but the scalp EEG changes did not precede clinical manifestations by more than 30 s. MRI Brain, was unremarkable, positron emission tomography (PET) CT showed no definite quantitative or qualitative hypometabolic focus. SPECT showed no clear focal area of hyperperfusion but showed a non-specific increase in perfusion in the left temporoparietal region. The neuropsychological evaluation showed left-hemispheric language dominance and mild memory impairment. The case was presented to a multidisciplinary team and stereo-encephalography (SEEG) implantation was decided. Limbic coverage with an emphasis on the temporo-parietal occipital junction (due to the EEG, SPECT, neuropsychological findings) and the opercular-insular region (because of clinical findings) was decided. After presurgical investigations were completed, resective surgery was not decided due to the risk of global aphasia. (A) Trajectory planning of SEEG electrode insertion with Renishaw Neuroinspire™ software, co-registered with MRI. (Image courtesy of Dr. David Steven and Dr. Greydon Gilmore, London Health Sciences Centre, London, Ontario, Canada). (B) Insertion of Depth electrodes by Renishaw Neuro-Mate. Neurosurgeon and robot assisting device when installing depth electrodes in the operating room. (Image courtesy of Dr. David Steven and Dr. Greydon Gilmore, London Health Sciences Centre, London, Ontario, Canada). (C) Interictal SEEG: Longitudinal bipolar montage of intracranial SEEG recording with a sampling rate of 1,280, showing synchronized spikes seen as runs lasting up to 4 s at a time involving the neocortical temporal, temporo-occipital, and parietal-occipital region. Synchronic interictal findings are a frequent finding of temporal lobe epilepsy and its connections. (D) Ictal SEEG: (D1) Longitudinal bipolar montage of intracranial SEEG recording with a sampling rate of 1,280, showing an attenuation of the background activity, with low voltage fast activity in the same regions of synchronization seen in A for 5-6 s. (D2) Previously seen attenuation is followed by a high-voltage spike that runs over the mesial temporal regions. (D3) As the seizure propagates, the activity spreads to the neocortical temporal regions. (D4) Periods of attenuation occur until the final offset is seen as attenuation. (E) Cortical stimulation showed a wide hyperexcitable epileptogenic network involving the parieto-temporo-occipital region, both mesial and neocortical. When stimulating the left mesial temporal region, anomia occurred (pink color in co-registered MRI) and when stimulating the neocortical temporo-occipital region, speech arrest occurred.