Purpose: Intracranial monitoring (IM) is a key diagnostic procedure for select patients with treatment-resistant epilepsy (TRE). Seizure focus resection may improve seizure control in both lesional and nonlesional TRE. IM itself is not considered to have therapeutic potential. We describe a cohort of patients with improved seizure control following IM without resective surgery.
Methods: Over 12.5 years, 161 children underwent 496 surgeries including intracranial monitoring. We retrospectively reviewed the patients’ charts, operative reports, and radiologic scans, under an institutional review board–approved protocol.
Key Findings: Seventeen patients underwent only IM, without additional resective surgery, and seven had a dramatic improvement in their epilepsy; six of the seven patients are seizure-free (Engel class I), and one rarely has seizures (Engel class II). All seven patients had frequent seizures that led to IM: either daily (five patients) or 1–2 per week (two patients). The mean age (± standard deviation, SD) at seizure onset was 1.6 ± 1.3 years (range 0.5–4 years). Etiologies were tuberous sclerosis (3 patients), trauma (1 patient), and unknown (3 patients). Mean age at surgery (± SD) was 4.1 ± 2 years (range 1–7 years), and duration of epilepsy 2.5 ± 1.1 years (range 0.5–4 years). Duration of IM was 11.7 ± 5.6 days (5–19 days). Six patients had bilateral and one unilateral invasive electrodes. At last follow-up, four patients required fewer antiepileptic drugs (AEDs), one had the same medication but a higher dose, and two patients were taking additional AEDs. Follow-up was 30.6 ± 9.5 months (range 19–41 months).
Significance: Although uncommon, patients with TRE may improve after IM alone. The explanation for this observation remains unclear; however, perioperative medications including steroids, direct cortical manipulation, or other factors may influence the epileptogenic network.