Serious Adverse Effects of Gamma Knife Radiosurgery for Mesial Temporal Lobe Epilepsy

Abstract

Gamma knife radiosurgery (GKRS) for mesial temporal lobe epilepsy (MTLE) has been proposed as an alternative to surgical resection. We report serious adverse effects of the treatment after follow-up periods over 9 years in 11 patients treated with GKRS between 1997 and 2000. The target volume of the entorhinoamygdalohippocampectomy area was 4.8-17.1 ml. Marginal dose of 20-25 Gy to the 50% isodose was delivered. One patient was drowned after suffering seizure 7 months after GKRS. Two patients did not show any reduction in seizure frequency over 9 and 18 months. Both patients requested open surgery and became seizure-free postoperatively. Four of the other eight patients were classified as Engel's class I within 4 years after GKRS. One of the four patients experienced symptomatic radiation-induced cerebral edema transiently, one developed radiation necrosis and required surgery 5 years after GKRS, and one developed cognitive impairment with hemiparesis 10 years after GKRS. Magnetic resonance (MR) imaging showed a large cyst in the irradiated temporal lobe. This patient recovered fully after the cyst excision. Only one patient became seizure-free and antiepileptic drug-free without symptomatic radiation-induced complications. However, MR imaging revealed abnormal enhancement, cyst formation, and diffuse white matter change in the irradiated temporal lobe 9 years after GKRS. GKRS for MTLE causes adverse effects of delayed seizure remission and symptomatic radiationinduced complications. Therefore, GKRS cannot be considered as an ideal alternative to surgery for MTLE. Long-term follow-up studies including MR imaging with contrast medium are required for the patients even after successful control of seizures.

Stereotactic radiosurgery for the treatment of mesial temporal lobe epilepsy

“…A total of 13 studies were included in the meta‐analysis . The characteristics of these studies, the results of which were published between 1999 and 2012, are summarized in Table .…”

“…The percentage of male participants in the included studies ranged from 9.1% to 63.2%, with one study not reporting data on the participants' gender . The study designs also varied: three studies used a retrospective design , six used a prospective design , and the design of four studies was not reported . Most of the studies were single‐arm, except for that of Barbaro and colleagues , which had high‐ and low‐dose arms.…”

“…Seven of the 13 studies reported the time interval to seizure cessation and were included in the meta‐analysis . The individual and overall means for the included studies are presented in a Forest plot in Fig.…”

Radiosurgery for Functional Neurosurgery

“…Other possible complaints have been found such as headache, vomiting, nausea and depression, which may need steroids prescription. Also, complications such as cerebral edema, radiation necrosis, motor deficits, cognitive impairment and cyst formation have been reported 25 .…”

Surgical strategies for pediatric epilepsy

“…With regard to radiosurgery, the possibility for significant post-treatment edema and radiation necrosis exists (108). The benefits of radiosurgery may also be delayed, and the interval between treatment and response can lead to continued seizurerelated functional decline (109). Laser ablation can also lead to damage to surrounding structures and subsequent neurologic sequelae (110).…”