Deep brain stimulation of two unconventional targets in refractory non-resectable epilepsy

Abstract

Introduction: Several deep brain targets have been assessed for the treatment of unresectable refractory epileptic conditions. Adrian Upton in 1985 proposed deep brain stimulation (DBS) of the anterior nucleus of the thalamus for the treatment of seizures and psychosis [Cooper I.S., Upton A.R.: Biol Psychiatry 1985;20:811-813]. Francisco Velasco, in 1987, introduced DBS of the thalamic centromedian nucleus, proposing its employment for Lennox-Gastaut syndrome and for multifocal epilepsy. Other proposed targets are the subthalamic nucleus, caudate nucleus, Forel fields and mammillothalamic tract. We employed DBS for stimulating 2 'unconventional targets', the posterior hypothalamus (pHyp) and caudal zona incerta (CZi), for the treatment of 2 patients with multifocal epilepsy and behavioural comorbidity, and 2 patients with sensorimotor focal seizures, respectively. Such patients did not meet criteria for resective surgery.

Material and methods: In our institution, between January 2003 and May 2004, we started DBS in 2 epileptic patients The former patient was affected by multifocal epilepsy, and the second one by refractory partial motor and secondary generalized seizures. The chosen targets were the pHyp in the former case and the CZi in the latter. The encouraging results obtained led us to replicate such a favourable experience in 2 more patients, 1 with focal motor epilepsy once again (resulting in status epilepticus) and the other with behavioural comorbidity and multifocal epilepsy.

Results: A significant reduction in seizure frequency was observed, and the 2 patients with behavioural comorbidity also showed a dramatic improvement in their disruptive behaviour. The patient with motor focal seizures showed a 70% reduction in seizure frequency, and in the last patient remission from status epilepticus was obtained.

Conclusion: Our data confirm DBSof deep brain structures modulates the functional activity of the cerebral cortex as suggested by Adrian Upton in 1985. In the reported series, deep-brain stimulation of 2 unconventional targets belonging to the reticulo-cortical system (the brainstem-diencephalon functional system including structures that act as remote controls in modulating cortical excitability) was found to be effective in controlling otherwise refractory multifocal (pHyp) and focal sensorimotor (CZi) epilepsy when resective surgery was not feasible.