Abstracts

VNS is being used increasingly as treatment for intractable epilepsy. There is to date no long term study investigating the satisfaction of patients with this emerging therapy, and few data on outcome at more than five years We performed a retrospective study of 62 patients with intractable epilepsy, who were treated at King[apos]s College Hospital between 1995 and 2000, by RPS and CEP.
The patients[apos] mean age at time of implantation of VNS was 28.7 years (range 6 to 59 years); the average duration of epilepsy at implantation was 20.4 years (4 to 56); the mean age at seizure onset was 8.8 years (0 to 50); mean follow-up was 76 months (51 to 114). 3 patients died of sudden unexpected death in epilepsy.
We questioned patients on overall benefit of their VNS treatment, and differences in memory, achievements, mood, verbal skills, alertness, cluster seizures and post-ictal confusion. The median pre- and post-implantation monthly seizure frequency in the 35 patients who continue to use the device are 24 (3 to 1800) and 4.5 (0 to 1000) respectively (mean improvement 59.1%, median follow-up 71 months). Retention rate is 59%. Corresponding median monthly seizure frequency in all patients was 22 (1 to 1800), and 9.5 (0 to 1000).
26 patients (44.1%) had no improvement, 5 (8.5%) had less than 50% improvement, 26 (44.1%) had greater than 50% improvement in seizure frequency (including 4 seizure-free), and 2 patients (3%) were worse.
24 patients who no longer use the device have undergone explantation (median 71 months follow-up; one infection, 23 non-efficacy).
27 patients (45.8%) were dissatisfied with VNS, 26 (44.1%) were satisfied, and 6 (10.1%) were undecided.
Of 28 patients who had no improvement or a deterioration in their seizure frequency, 1 was satisfied with the VNS experience, 3 were undecided, and 24 were dissatisfied. Of the 31 patients who experienced an overall improvement in seizure frequency, 3 were dissatisfied, 3 were undecided, and 25 were satisfied.
Mean quality of life measures showed an improvement in all domains. VNS shows a long term retention rate and efficacy which is highly favourable when compared to medical treatments for intractable epilepsy. 44.1% of our patient group was satisfied with VNS, and 45.8% of patients was dissatisfied.