Abstracts

RATIONALE: A small number of studies and anecdotal reports suggest that Vagal Nerve Stimulation (VNS) for the treatment of epilepsy is associated with improvements in alertness and attention as reported by patients or parents. The only study to date using objective measurements of attention did not find VNS-associated improvements in adults (Dodrill & Morris, Epilepsy Behav 2001; 2; 46-53). The goal of this study was to test the assumption that VNS is associated with improvements in alertness and attention in children and to determine whether any post-operative improvements in attention are related to quality of life.
METHODS: Nineteen children and adolescents aged 8 to 18 were assessed pre- and post-VNS (Mean age = 13.3, SD = 3.3). Participants had severe, medically refractory epilepsy and had been through multiple medication trials and/or epilepsy surgery (N =2) without substantial improvement in seizure control. Participants were administered a measure of auditory attention (digit recall task), a parent-rated measure of attention and impulsivity (ADHD-RS-IV), a measure of general mental status consisting of a modified Mini-Mental State Exam for children (3MS) and measures of general and temporal orientation from the Children[ssquote]s Orientation and Amnesia Test (COAT). Parent ratings of global and epilepsy-specific quality of life were also obtained (Impact of Neurologic Handicap Scale). Post-VNS scores were obtained approximately 5 months after implantation. Eight of the 19 children (42%) had improvements in seizure control based on Engel seizure outcome classification. Non-parametric tests for paired samples were used to assess for significance of pre- and post-VNS differences in variable means (i.e., Wilcoxon Signed Ranks Test).
RESULTS: No pre-post differences in either an objective test of auditory attention (digit recall task) or in subjective ratings of attention by parents (ADHD-RS-IV) were found. General mental status was also unchanged post-implantation. However, temporal orientation as measured by the COAT was significantly improved (p [lt] .03), as was the overall COAT score (p [lt] .03). Both global quality of life and epilepsy-specific quality of life were improved post-VNS (p [lt]. 05). However, post-VNS attentional functioning, mental status, and general orientation scores were not associated with changes in quality of life or with improvements in seizure control as measured by Engel outcome classification.
CONCLUSIONS: There was minimal evidence for improvements in attention and mental status post-VNS in this sample of children with intractable seizures. Improvements in both global and epilepsy-specific quality of life were found, but these improvements did not relate to attention, mental status or general orientation levels. Some improvements were suggested in terms of temporal orientation as a result of VNS. However, given the small sample size and possibility of confounding from maturation and practice effects, these findings need replication using both a larger sample and control children with intractable seizures tested over time.
[Supported by: British Columbia Medical Services Foundation/Vancouver Foundation]