Rationale:
High frequency stimulation is the most common stimulation paradigm used in DBS therapies. The purpose of this study was to assess the clinical impact on seizure frequency of low vs high frequency stimulation.
Methods:
We studied twelve patients with generalized and multi-focal drug-resistant epilepsy (DRE) who underwent CM-DBS, associated or not with VNS therapy. All patients were implanted bilaterally with rechargeable IPGs. All patients were initially submitted to bipolar continuous stimulation, 300usec, 4 to 5.5V, 130-180Hz (high frequency stimulation; HF-CMDBS) and then moved to 6-10 Hz (low frequency stimulation; LF-CMDBS). Baseline was defined as seizure frequency before DBS frequency reduction. Patients were reevaluated regarding seizure frequency after one month, three months, six months, and one year. ASM remained stable.
Results: Ten patients were re-evaluated after one month, eight after 3 months, eight after
six months, and six after 1 year. After one month under LF-CMDBS, four
(33,3%) patients noted a reduction in bilateral tonic-clonic seizure (BTC)
frequency, one patient (8,33%) had reduction of tonic seizures (TO), three
patients (25%) had reduction in absence seizures (AB), one patient (8,33%) had
reduction in myoclonic seizures (MY), and one (8,33%) had reduction in focal
seizures (FO). Atonic seizures (AT) were not affected after one month. One
patient (8,33%) noticed that BTC became more prolonged and one had
behavioral deterioration and was moved back to HFS with resolution of the
symptoms. All the patients had an improvement in attention, as reported by the
parents or caregivers. After three months, compared to the 1 month visit, the
patient that initially had more prolonged BTC noticed improvement in both
seizure frequency and duration, one patient (8,33%) had the same frequency of
AT, three patients (25%) had the same frequency of TO, five patients (41,6%)
had the same frequency of AB and one patient (8,33%) had an improvement in
AB frequency. FO, BTC, and MY remained stable in all the patients. At six
months, AT remained stable in two patients (16.6%), three patients (25%)
remained stable regarding TO, two patients (25%) remained stable regarding
FO, six patients remained stable regarding AB, six patients (50%) had no
modification in BTC and two (16,6%) had no modification regarding AB. After
one year, two patients (16,6%) remained stable regarding AT, three (25%) had
no modification in TO, five (41,66%) remained stable regarding BTC and four
(33,3%) remained stable regarding AB. No patient presented with worsening of
any seizure type frequency. The improvement in attention noted after one
month persisted over the studied period.
Conclusions:
LF-CMDBS requires less IPG energy and patients require much less frequent recharges.Some studies suggested a better outcome using low frequency compared to high frequency stimulation in patients with focal epilepsy submitted to ANT-DBS (7). We report for the first time that LF-CMDBS might offer a better outcome compared to HF-CMDBS in patients with generalized or multifocal DRE. If confirmed, this might represent a major paradigm shift in the neuromodulation of these patients.
Funding: None