Introduction: Patients with medically intractable focal epilepsy have a variety of underlying pathologies, many of which are surgically amenable. When patients undergo surgical treatment and continue to have seizures, this poses a significant dilemma to the epilepsy management team. There are currently no studies examining the safety and efficacy of subdural grid placement in patients with a history of prior craniotomy.
Methods: We conducted a retrospective review of the medical records of all patients with a prior history of craniotomy for any underlying cause (i.e. trauma, prior epilepsy surgery, vascular pathology, tumor, etc) followed by subdural grid and depth electrode insertion for the evaluation of medically intractable focal epilepsy between 2000 and 2012 at the Cleveland Clinic. In total, 107 patients were included in this study. Information was collected from the medical records regarding patient demographics, medical and surgical history, seizure history, surgical pathology from the index surgery and secondary resection, Engel classification at last follow-up, and complications related to each surgery performed.
Results: The mean age of seizure onset was 15.9 years and mean age for index surgery was 24.2. Three patients began having seizures after the index surgery (two had tumor resections and one had a vascular malformation resected). 100 patients (93%) had no complication associated with the subdural grid placement, and 92 (86%) had no complication after subsequent resection which was equivalent to the index procedure. A total of 48 patients (44%) were Engel Class I (seizure free) at last follow-up.
Conclusions: In patients who have had a prior craniotomy with continuing medically intractable focal epilepsy, further surgical intervention with SDG monitoring does not appear to be associated with increased risk of complications. The seizure free rate in this group appears to be satisfactory and so this may be a viable option in this difficult to treat group.
Patient Care: This research study will aid patients and surgeons in the decision making process regarding whether or not they should undergo repeat craniotomy for insertion of subdural grids and depths. No studies have ever examined this and it is important because reoperation allowed for a 44% rate of seizure freedom in this difficult to treat group.
Learning Objectives: By the conclusion of this session, participants should be able to 1) Describe the difficulties related to Subdural Grid placement in patients with prior craniotomies, 2) Identify patients who are at a higher risk of postoperative complication and 3) Identify patients who are more likely to become seizure free after subdural grid removal.
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