Prolonged Blood-Brain Barrier Disruption Following Laser Interstitial Ablation in Epilepsy: A Case Series with a Case Report of Postablation Optic Neuritis.

OBJECTIVE: Laser interstitial thermal therapy has become increasingly popular for targeting epileptic foci in a minimally invasive fashion. Despite its use in >1000 patients, the long-term effects of photothermal injury on brain physiology remain poorly understood.

METHODS: We prospectively followed clinical and radiographic courses of 13 patients undergoing laser ablation for focal epilepsy by the senior author (N.T.). Only patients with nonenhancing lesions and patients who had a delayed postoperative magnetic resonance imaging (MRI) scan with gadolinium administration approximately 6 months after ablation were considered. Volumetric estimates of the amount of enhancement immediately after ablation and on the delayed MRI scan were made.

RESULTS: Median interval between surgery and delayed postoperative MRI scan was 6 months (range, 5-8 months). In 12 of 13 cases, persistent enhancement was seen, consistent with prolonged blood-brain barrier dysfunction. Enhancement, when present, was 9%-67% (mean 30%). There was no correlation between the time from surgery and the relative percentage of postoperative enhancement on MRI. The blood-brain barrier remained compromised to gadolinium contrast for up to 8 months after thermal therapy. There were no adverse events from surgical intervention; however, 1 patient developed delayed optic neuritis.

CONCLUSIONS: Prolonged incompetence of the blood-brain barrier produced by thermal ablation may provide a path for delivery of macromolecules into perilesional tissue, which could be exploited for therapeutic benefit, but rarely it may result in autoimmune central nervous system inflammatory conditions.