L’hémisphérotomie péri-insulaire : technique chirurgicale, monitoring EEG intraopératoire et résultats sur le contrôle de l’épilepsie

Second surgery after vertical paramedian hemispherotomy for epilepsy recurrence

Background

Vertical Paramedian Hemispherotomy (VPH) is considered an effective surgical treatment for drug-resistant epilepsy with 80% of patients experiencing seizure freedom or worthwhile improvement. Identifying persistent connective tracts is challenging in failed VPH.

Methods

We reviewed our series of consecutive patients undergoing VPH for hemispheric drug-resistant epilepsy and included cases with recurrent epileptic seizures undergoing second surgery with at least 6 months of postoperative follow-up. The cases were extensively assessed to propose a targeted complementary resection.

Results

Two children suffering from seizure recurrence following hemispherotomy leading to second surgery were included. After complete assessment, persisting amygdala residue was suspected responsible for the epilepsy recurrence in both patients. Complementary resection of the amygdala residue led to seizure freedom for both patients (Engel IA/ILAE Class 1) without complication. Different diagnostic tools are used to assess patients after failed hemispherotomy including routine EEG, prolonged video EEG, MRI (particularly DTI sequences), SPECT or PET scans and clinical evaluation. These tools allow to rule out epileptic foci in the contralateral hemisphere and to localize a potentially persisting epileptogenic zone. Assessment of these patients should be as systematic and integrated as the initial workup. Although our two patients suffered from Rasmussen's encephalitis, seizure recurrence after VPH has been described in other pathologies.

Conclusion

Lying deep and medially in the surgical corridor of VPH, the amygdala can be incompletely resected and cause recurrent epilepsy. Complementary selective resection of the amygdala residue may safely lead to success in epilepsy control.

Periinsular hemispherotomy in children with stroke-induced refractory epilepsy

OBJECT

Ischemic cerebral vascular accidents (CVAs) in children result in epilepsy in 25% of patients, which is refractory in 7% of cases. Repeated seizures worsen the global and cognitive prognosis of these patients. To evaluate the prognosis of epilepsy and cognitive development in children with refractory seizures following a CVA, the authors retrospectively studied the effectiveness of periinsular hemispherotomy in the treatment of these patients.

METHODS

Between March 1995 and November 2007, 8 children who suffered from stroke-induced refractory epilepsy underwent a periinsular hemispherotomy. All patients' charts were reviewed in a retrospective manner. Age at the time of the CVA, imaging studies, cause of the ischemic event, onset of the first seizure, patient's handedness, the extent of the parenchymal damage, electroencephalography findings, type of epileptic seizures, number of seizures per day, number of antiepileptic medications, preoperative neuropsychological evaluation, and surgical outcome with regard to the patient's seizure activity were analyzed.

RESULTS

There were 7 boys and 1 girl in this study. The mean age at stroke was 23 months (range birth-5 years). The mean age at onset of epilepsy was 22 months (range 0-60 months). The mean age at the time of the hemispherotomy was 7 years (range 54-130 months). The average delay prior to the hemispherotomy was 5 years and 3 months (range 23-115 months). Prior to surgery, the average number of seizures per day was 35 (range 5-100). The average number of antiepileptic medications introduced before the hemispherotomy was 8 (range 6-12). Six patients required only 1 surgical intervention and 2 necessitated 2 separate operations:1 underwent a 2-staged hemispherotomy and the other underwent a prior callosotomy. There were no reported surgical complications in this series. Seven children are seizure free. However, the remaining child, after a 3.5-year disease-free interval, has recently started having seizures. No child demonstrated an improvement in neuropsychological evaluation.

CONCLUSIONS

The periinsular hemispherotomy must be considered an alternative in the therapeutic approach to stroke-induced pediatric refractory epilepsy. It is effective in controlling seizure activity. The authors believe the delay before hemispherotomy must be shortened in children with post-CVA refractory epilepsy.