We present here a review of the work on neuromodulation - defined as application of
an inhibitory or excitatory current - on intracranial structures for the treatment
of drug-resistant epilepsy. Near 250 patients were treated using a neuromodulation
technique of the cerebellum (paravermian cortex), the CM-pf nucleus of the thalamus,
the hippocampus, epileptogenic foci, and anterior ventral nucleus of the thalamus,
with a one- to 15-year follow-up. Four contact strips were used for cerebellar and
functional region neuromodulation, and DBS-type depth electrodes were stereotactically
implanted for CM-pf and anterior nuclei of the thalamus and hippocampal neuromodulation.
Electric stimulation was cyclic in almost all trials, using low frequency (10-40 Hz)
for excitation and high frequency (60-185 Hz) for inhibition. Seizure frequency reduction
was variable, depending on the neuromodulation site and patient selection, although
seizure duration decreased in most patients. Cerebellar neuromodulation was followed
by a 78% reduction in tonic and tonic-clonic seizures, CM-pf neuromodulation by an
83% reduction in tonic-clonic seizures and atypical absence of Lennox-Gastaut syndrome,
with a 17.2% seizure-free and drug-free patient rate. Hippocampal neuromodulation
was followed by a 73% reduction in partial complex seizures, with a 33% seizure-free
patient rate. Anterior ventral nucleus of the thalamus was followed by a 63% reduction
in tonic-clonic, tonic and atonic seizures. Several prognostic factors were identified
in order to improve future results. There was no mortality and morbidity was limited
to skin erosion at the neurostimulator site. Seizure reduction was associated with
improved neuropsychological performance and better quality of life. Neuromodulation
is safe and effective for the treatment of epileptic seizures of various origins.
Several targets may be associated in a single patient, especially when bilateral hippocampal
seizure foci are present.