Vagus nerve stimulation in children with refractory epilepsy: unusual complications and relationship to sleep-disordered breathing.

BACKGROUND: Vagus nerve stimulation (VNS) is approved for use in patients with refractory epilepsy over the age of 12 years. While this procedure is widely used, there is little data on adverse events in young children. MATERIALS AND METHODS: A retrospective chart review was conducted on 26 children who had VNS implantation for refractory epilepsy from 1998 to 2004. RESULTS: Ages ranged from 3 to 17 years (16 boys and 10 girls). Seventy-seven percent had moderate to severe mental retardation. Sixty-five percent had more than 30 seizures per month. Symptomatic-generalized epilepsy was the predominant epilepsy syndrome seen in 77% of children. The duration of VNS treatment ranged from 1 month to 8 years (mean = 3.5 years). Twenty of 26 patients (77%) were on rapid-cycling mode. More than 50% reduction in seizure frequency was noted in 54% with two patients achieving seizure freedom. Twenty-three percent had less than 50% seizure reduction. Four patients were able to terminate seizures with use of the magnet. VNS was removed from one patient because of intractable cough persisting in spite of stimulation being turned off for 1 month. Another patient had it removed twice for infection. Obstructive sleep apnea (OSA) was observed in four patients (15%) after placement of VNS. CONCLUSION: VNS appears to be an effective treatment for children with refractory epilepsy. Development of intractable cough in one patient in spite of device being turned off and recurrent infection-related removal in another are unusual complications. Polysomnography before implantation of VNS should be considered to identify patients with pre-existing OSA.

Efectos vasculares del tiopental / Vascular efects of thiopental

Se evaluaron los efectos del tiopental en anillos de aorta de rata. El anestésico produjo contracción que aumentó al quitar el endotelio y no se inhibió con indometacina (10-5M). Prazosina (10-6M) o idazoxan (10-6M) o diltiazem (10-6M) pero disminuyó en un medio sin calcio. Por otra parte, el tiopental relajó anillos aórticos precontraídos con fenilefrina (10-6M), angiotensina II (10-7), serotonina (3.1 x 10-5 M) o KCI (40 mM), en forma independiente del endotelio. Finalmente, la exposición al tiobarbitúrico (3.1 mg/ml) inhibió reversiblemente la relajación ocasionada por histamina, pero no por el nitroprusiato de sodio o por el A23187. Los resultados permiten concluir que, en la aorta de rata, el tiopental produce: a) contracción modulada inhibitoriamente por el endotelio y dependiente del calcio extracelular que ingresa a través de canales insensibles a diltiazem, y que no es mediada por prostaglandinas o receptores adrenérgicos; b) relajación independiente tanto del endotelio como del agente contráctil empleado; c) inhibición de la relajación dependiente de endotelio ocasionada por histamina. Efecto que no parece deberse a alteración de la guanilato ciclasa o de la sintasa de óxido nítrico, puesto que el anestésico no inhibió el efecto del nitropusiato de sodio o del A23187. Por lo anteriormente expuesto, consideramos posible que los diversos efectos vasculares del tiopental se asocien con su capacidad para disolverse en las membranas del músculo liso y del endotelio de la aorta, alterando componentes funcionales de las mismas