Gamma Knife radiosurgery for recurrent or residual seizures after anterior temporal lobectomy in mesial temporal lobe epilepsy patients with hippocampal sclerosis: long-term follow-up results of more than 4 years

A Potential Risk of Radiation-Induced Cavernous Malformations Following Adjuvant Gamma Knife Radiosurgery for Mesial Temporal Lobe Epilepsy

OBJECTIVE

Several clinical studies have explored the feasibility and efficacy of radiosurgical treatment for mesial temporal lobe epilepsy, but the long-term safety of this treatment has not been fully characterized. This study aims to report and describe radiation-induced cavernous malformation as a delayed complication of radiosurgery in epilepsy patients.

METHODS

The series includes 20 patients with mesial temporal lobe epilepsy who underwent Gamma Knife radiosurgery (GKRS). The majority received a prescribed isodose of 24 Gy as an adjuvant treatment after anterior temporal lobectomy.

RESULTS

In this series, we identified radiation-induced cavernous malformation in three patients, resulting in a cumulative incidence of 18.4% (95% confidence interval, 6.3% to 47.0%) at an 8-year follow-up. These late sequelae of vascular malformation occurred between 6.9 and 7.6 years after GKRS, manifesting later than other delayed radiation-induced changes, such as radiation necrosis. Neurological symptoms attributed to intracranial hypertension were present in those three cases involving cavernous malformation. Of these, two cases, which initially exhibited an insufficient response to radiosurgery, ultimately demonstrated seizure remission following the successful microsurgical resection of the cavernous malformation.

CONCLUSION

All things considered, the development of radiation-induced cavernous malformation is not uncommon in this population and should be acknowledged as a potential long-term complication. Microsurgical resection of cavernous malformation can be preferentially considered in cases where the initial seizure outcome after GKRS is unsatisfactory.

The Use of Stereotactic Radiosurgery to Treat Functional Disorders: A Topic Discussion

Stereotactic radiosurgery (SRS) is a well-known modality for the treatment of malignant brain tumors. SRS, however, can also be used to treat non-malignant functional disorders such as epilepsy, tremor, trigeminal neuralgia (TN), obsessive compulsive disorder (OCD), and intractable pain among others. Given the limited prospective data guiding treatment of these benign disorders, this article serves as a consolidated discussion of the application of SRS for functional ailments, hopefully serving as a reference for those considering application of this technique in clinical practice.

Epilepsy

GKNS has been introduced as an alternative to microsurgery for the treatment of certain types of focal epilepsy. It was first noted that epilepsy associated with AVMs often improved before the obliteration of the vascular lesion. It was subsequently shown that the treatment could be effective in mesial temporal lobe epilepsy (MTLE) producing remission in around 60% of patients, provided the treatment was carried out as originally designed. GKNS has also been useful in the treatment of gelastic epilepsy associated with hypothalamic hamartomas.

Salvage gamma knife radiosurgery in the management of dysembryoplastic neuroepithelial tumors: Long-term outcome in a single-institution case series

BACKGROUND

Dysembryoplastic neuroepithelial tumors (DNT/DNET) are rare epileptogenic tumors. Microsurgery remains the best treatment option, although case reports exist on the use of gamma knife radiosurgery (GKRS) in selected cases. We investigated the long-term outcome of GKRS-treated DNTs at our institution in the context of current diagnostic and treatment options.

CASE DESCRIPTIONS

We conducted a retrospective review of three consecutive adult patients (≥18 years) treated with salvage GKRS between 2002 and 2010 at Karolinska University Hospital, Stockholm, Sweden. The case series was supplemented by a review of current literature. A 20-year-old male underwent subtotal resection (STR) in 1997 and 2002 of DNT resulting in temporary control of intractable epilepsy despite antiepileptic drug treatment (AED). Long-term seizure control was obtained after GKRS of two separate residual DNT components along the surgical margin (2005 and 2010). A 27-year-old male undergoing gross total resection of the contrast-enhancing portion of a DNT (1999) resulted in temporary control of intractable epilepsy despite AEDs; lasting clinical control of seizures was achieved in 2002 after GKRS of a small, recurrent DNT component. A 28-year-old male underwent STR of DNT (1994 and 2004) resulting in temporary control of intractable epilepsy. Lasting seizure control was gained after GKRS of a residual tumor (2005).

CONCLUSION

GKRS as performed in our series was effective in terms of tumor and seizure control. No adverse radiation effects were recorded. Prospective studies are warranted to establish the role of GKRS in the treatment of DNTs.