Abstract

In pharmacoresistant focal epilepsies involving primary motor cortex, risk of motor deficit generally contraindicates cortical resection. Gamma knife radiosurgery (GK) is an established treatment for certain focal epilepsies, notably mesial temporal epilepsy and epilepsy associated with hypothalamic hamartoma. However the safety profile and efficacy of GK in motor cortex epilepsies has not previously been demonstrated. We report 4 patients (18–31 years) with focal motor epilepsy seizures arising from primary motor cortex (paracentral lobule), demonstrated by stereoelectroencephalography (SEEG). Two patients had undergone prior cortical resection involving paramedian premotor regions. A marginal dose of 24 Gy was delivered to a focal zone involving paracentral lobule. Volume of treatment in the 4 patients ranged from 1.6 cm³ to 3.18 cm³ (mean 2.33, median 2.34). No motor deficit or other adverse affect occurred. Follow up was available for at least 3 years (range 36–78 months; median 49). On patient was unchanged; another had temporary improved seizure control but subsequent relapse; and 2 patients achieved Engel's Class 1B outcome. Both improved patients had gradual disappearance of objective motor ictal semiology (6–12 months post-GK), preceding reduced seizure frequency (12–18 months onwards). Cerebral MRI showed no significant change during the follow-up period. Conclusion: GK is a potentially useful treatment for focal extra-temporal epilepsies, including when the epileptogenic zone includes highly functional cortex.