Abstracts

RATIONALE: Vagus nerve stimulation (VNS) has been well accepted as an alternative measure to treat refractory epilepsy. Previous studies have showed [gt] 50% seizure reduction rate. However, the relationship between the etiologies and the efficacy of VNS is uncertain. The objective of this study is to discuss the relationship of etiologies of epilepsy and the outcome of seizure control with VNS.
METHODS: Seizure frequency data from 22 patients (10 male & 12 female; 17 - 71 years) with refractory complex partial seizures (+ secondary convulsion, atonic, tonic seizures) were obtained prospectively at our university center (VNS implants were placed between 4/1998 and 4/2001). Seven patients had also undergone previous epileptic surgeries. All patients had had long term video EEG monitoring. All patients (except one) have more than 10 year seizure history at the time of VNS placement. They continue with two (or more as necessary) anti-epileptic drugs during the follow-up period. The preVNS minimum number of seizure per month was 10 except one (average 3).
RESULTS: Twelve patients had[gt] 75% seizure reduction and one more had[gt] 50 % reduction. Of these responders, there were 2/5 patients with encephalitis, 2/4 with congenital cerebral anomalies (CCA), 4/4 with traumatic brain injuries and 6/9 with idiopathic epilepsy. All patients in the traumatic brain injury group responded well while approximately 40 to 50% of the other three groups responded. Twelve of fourteen responders showed significant seizure reduction within the first month after VNS use. One patients has remained seizure-free for more than 8 months.
CONCLUSIONS: VNS implant appears to be a useful therapeutic adjunctive measure in patients with intractable epilepsy regardless of etiology. Most responders in our small series demonstrated improvement within the first month of VNS use.[table1]