Summary: Purpose:We report on the efficacy and safety of extended one-stage callosal section performed in a large and homogeneous series of patients.Methods: Seventy-six patients with Lennox-Gastaut (n = 28) and Lennox-like (n = 48) syndrome were studied (42 male patients; mean age, 11.2 years). All patients had multiple seizure types per day, including atonic, tonic-clonic, atypical absence, myoclonic, and tonic seizures. All of them were developmentally impaired. The EEG showed intense secondary bilateral synchrony in all of them. All patients were submitted to an extended, one-stage, callosal section, leaving only the splenium intact. Mean follow-up time was 4.7 years.Results: Worthwhile improvement (>50%) was noted in 69 of 76 patients; 52 patients had a ≥90% reduction in seizure frequency. Seven patients were seizure free after surgery. The seizure patterns most responsive to surgery were atonic (92%), atypical absence (82%), and tonic-clonic (57%) seizures. All patients had some degree of a transient acute postoperative disconnection syndrome. A consistent increase in attention level was observed postoperatively.Conclusions: We report one of the larger homogeneous series of patients submitted to callosotomy and are the first to report on the effectiveness and safety of performing extended callosal section in a single stage in this patient group. Extended callosal section should be considered a good palliative surgical option for suitable candidates. The increase in attention level was as useful as seizure control in improving quality of life of these patients.

Callosotomy might be preferred as the primary treatment in children with Lennox-Gastaut syndrome, and no specific findings on MRI if atonic seizures prevail in the patient's clinical picture; when myoclonic seizures prevail, the same might hold true in favour of VNS. When atypical absence or generalised tonic-clonic seizures are the main concern, although both procedures carry similar effectiveness, VNS might be considered a good option as an initial approach, taking into account the adverse event profile. Patients should be advised that both procedures are not very effective in the treatment of tonic seizures.

All patients benefit from the procedure. The CM seems to play a role in modulating the epileptic discharges and attention in these patients. On the other hand, it is not the generator of the epileptic abnormality and appeared not to be involved in non-REM sleep-related interictal spiking modulation.

Summary:Purpose: To study the efficacy of extensive coverage of the brain surface with subdural grids in defining extratemporal cortical areas amenable for resection in patients with refractory extratemporal epilepy (R-ExTE) and normal or nonlocalizing magnetic resonance imaging (MRI) scans.Methods: Sixteen patients with R-ExTE were studied. Eleven patients had simple partial, eight had complex partial, and three had supplementary motor area seizures. Seizure frequency ranged from three per month to daily episodes. Interictal EEG showed large focal spiking areas in 11 patients, secondary bilateral synchrony in four, and was normal in one patient. Surface ictal recordings were nonlocalizing in six patients, and in 10, they disclosed large ictal focal spiking areas. MRI was normal in 10 patients, and in six patients, focal nonlocalizing potentially epileptogenic lesions were found. All patients were given an extensive coverage of the cortical convexity with subdural electrodes through large unilateral (n ‫ס‬ 13) or bilateral (n ‫ס‬ 3) craniotomies. Bipolar cortical stimulation was carried out through the implanted electrodes.Results: Interictal invasive recording findings showed widespread spiking areas in 13 patients and secondary bilateral synchrony in three. Ictal invasive recordings showed focal seizure onset in all patients. There were six frontal, two parietal, one temporooccipital, four rolandic, and three posterior quadrant resections. Thirteen patients had been rendered seizure free after surgery, and three had ജ90% of seizure-frequency reduction. Pathologic findings included gliosis (n ‫ס‬ 10), cortical dysplasia (n ‫ס‬ 5), or no abnormalities (n ‫ס‬ 1). Six patients had transient postoperative neurologic morbidity.Conclusions: Extensive subdural electrodes coverage seems to be an effective way to investigate patients with R-ExTE and normal or nonlocalizing MRI findings.

Macrostimulation might be used to confirm that the hardware was working properly. There was no typical RR derived from each studied thalamic nuclei after LF stimulation. On the other hand, absence of such RRs was highly suggestive of hardware malfunction or inadequate targeting. Thalamic-DBS (Th-DBS) RR was always bilateral after unilateral stimulation, although they somehow prevailed over the stimulated hemisphere. Contrary to Th-DBS, Hip-DBS gave rise to localized RR over the ipsolateral temporal neocortex, and absence of this response might very likely be related to inadequate targeting or hardware failure. Increased spiking was seen over temporal neocortex during hippocampal electrode insertion; this might point to the more epileptogenic hippocampal region in each individual patient. We did not notice any intraoperative response difference among patients with temporal lobe epilepsy with or without MTS. The relationship between these intraoperative findings and seizure outcome is not yet clear and should be further evaluated.