Vagal Nerve Stimulator

Background

• Mechanism of action

o Desynchronizing cortical activity

• First invented 1987 (by Zabara and Reese)

• FDA approved 1997

Efficacy

• 4 blinded, RCTs – in patients with focal seizures

• Overall patients with >50% in seizures 26-57%

• 3 out of 4 trials reported substantially better results with high stimulation (vs low stim)

• There is a trend to ongoing improvements over 48 months

• Seizure freedom rates ~5.1% at 4 months and 8.2% AT 48 months

• Limited data suggests improves in QOL measures

• May be a reduction in SUDEP incidence

• Predictors of response:

o Non-lesional

o Epilepsy <10 years

o Children

o LGS

• Autostim

o Extra stimulation in response to ictal tachycardia

o Triggered by an increase from a moving baseline (therefore does not trigger during exercise where there is gradual increase in heart rate)

o Evidence shows a good responder rate (but it is not clear this has been compared to baseline in rigorous study?)