AIRWAY EFFECTS OF DIRECT LEFT-SIDED CERVICAL VAGAL-STIMULATION IN PATIENTS WITH COMPLEX PARTIAL SEIZURES

Airway nerves have been implied in obstructive lung diseases for many years. In experimental animals, vagal stimulation produces several fea tures of asthma, including airflow obstruction and airway plasma exuda tion. Vagal stimulation is a novel and effective therapy in patients w ith refractory epilepsy. We evaluated the airway response to left-side d cervical electrical stimulation using 1 Hz (low stimulation: 30 s, o nce every 90 min) and 30 Hz (high stimulation: 30 s, every 5 min) in a randomized double-blinded fashion for 3 months in epileptic patients participating in a phase two efficacy study. In eight patients with hi gh stimulation and six with low stimulation, no effect on FEV1 (forced expiratory volume in 1 s) was seen over 3 months chronic stimulation. In a follow-up, up to 9 months, no further deterioration of lung func tion was observed. Of five patients without concomitant lung disease w ho consented to more extended experiments, one patient produced a redu ction of FEV1 with variable frequency and current stimulation (10-87 H z and 0.5-2.5 mA respectively). In one patient with obstructive lung d isease, however, increased frequency and current stimulation led to a stimulation-dependent decrease in FEV1. After the addition of inhaled ipratropium bromide (160 mu g, dry powder) to this patient, there was a clear improvement of baseline FEV1, but only a slight improvement of the stimulation-induced deterioration of FEV1. We conclude that long- term vagal stimulation in patients without concomitant lung disease do es not induce any significant changes in FEV1. However, in patients wi th obstructive lung disease, intense vagal stimulation can cause a det erioration of lung function. To our knowledge, this may be the first o bservation of the involvement of bronchoconstrictive vagal nerves in m an.