Prospective long-term study of vagus nerve stimulation for the treatment of refractory seizures.
OBJECTIVE
To determine the long-term efficacy of vagus nerve stimulation (VNS) for refractory seizures. VNS is a new treatment for refractory epilepsy. Two short-term double-blind trials have demonstrated its safety and efficacy, and one long-term study in 114 patients has demonstrated a cumulative improvement in efficacy at 1 year. We report the largest prospective long-term study of VNS to date.


METHODS
Patients with six or more complex partial or generalized tonic-clonic seizures enrolled in the pivotal EO5 study were prospectively evaluated for 12 months. The primary outcome variable was the percentage reduction in total seizure frequency at 3 and 12 months after completion of the acute EO5 trial, compared with the preimplantation baseline. Subjects originally randomized to low stimulation (active-control group) were crossed over to therapeutic stimulation settings for the first time. Subjects initially randomized to high settings were maintained on high settings throughout the 12-month study.


RESULTS
The median reduction at 12 months after completion of the initial double-blind study was 45%. At 12 months, 35% of 195 subjects had a >50% reduction in seizures, and 20% of 195 had a >75% reduction in seizures.


CONCLUSIONS
The efficacy of VNS improves during 12 months, and many subjects sustain >75% reductions in seizures.
DeGiorgio
C M
CM
Olive View/UCLA Medical Center and UCLA Department of Neurology, Los Angeles, California 91342, USA. cmd@ucla.edu
Schachter
S C
SC
Handforth
A
A
Salinsky
M
M
Thompson
J
J
Uthman
B
B
Reed
R
R
Collins
S
S
Tecoma
E
E
Morris
G L
GL
Vaughn
B
B
Naritoku
D K
DK
Henry
T
T
Labar
D
D
Gilmartin
R
R
Labiner
D
D
Osorio
I
I
Ristanovic
R
R
Jones
J
J
Murphy
J
J
Ney
G
G
Wheless
J
J
Lewis
P
P
Heck
C
C
D004599:Electric Stimulation Therapy; D004827:Epilepsy / Q000628:therapy*; D006801:Humans; D008137:Longitudinal Studies; D011446:Prospective Studies; D016896:Treatment Outcome; D014630:Vagus Nerve / Q000502:physiology*