Depression, Depressionen

What Is Vagus Nerve Stimulation?

How Effective and Safe is VNS in Patients with Epilepsy?

Two double-blind studies (labeled E03 [Ben-Menachem et al 1994 and E05 [Handforth et al 1998) were conducted in patients with epilepsy, with a total of 313 treatment-resistant completers. In this difficult-to-treat group, the mean decline of overall seizure frequency was about 25‐-30% compared with baseline. Data from uncontrolled observations suggest that, contrary to a tolerance effect, improvement in seizure control is maintained or may improve over time (Morris et al 1999; Salinsky et al 1996). In the second controlled study (E05) of VNS in patients with epilepsy, no serious adverse events (AEs) that were judged by investigators to be probably or definitely related to VNS occurred during treatment (Handforth et al 1998; Schachter and Saper 1998). In three out of 199 patients (1.5%), infection following surgery led to device removal. Other surgery-related AEs, all of which dissipated over time, included left vocal cord paralysis (2/199 [1%] lower facial muscle paresis (2/199 [1%] and pain and accumulation of fluid over the pulse generator requiring aspiration (1/199 [0.5%]). The perioperative AEs reported by at least 10% of patients were pain (29%), coughing (14%), voice alteration (13%), chest pain (12%), and nausea (10%).

The AEs reported in patients in the treatment group at some time during treatment that were significantly in creased from baseline were voice alteration/hoarseness, cough, throat pain, nonspecific pain, dyspnea, paresthesia,dyspepsia, vomiting and infection. The only AEs that occurred significantly more often in the treatment group than in the control group were dyspnea and voice alteration. Adverse events were judged to be mild or moderate 99% of the time. No cognitive. sedative, visual, affective or coordination side effects were reported. No significant changes occurred in Holter monitoring, in the results of pulmonary function tests, or in subjects‘ hematology values or common chemistry values (Schachter and Saper 1998). No subjects died during the E03 or E05 controlled studies (N = 313). In sum, short-term AEs that are surgery related are rare and usually resolve. Stimulation-related AEs (i.e., those that occur only when the vagus nerve is stimulated) can be reduced by lowering the current level. Stimulation-related AEs can also be aborted by the patient placing a handheld magnet over the generator that turns the device off until a physician decreases the stimulation intensity. These AEs rarely lead to VNS therapy discontinuation (Morris et al 1999; Schachter and Saper 1998). Although the neurology community was initially skeptical about VNS, a recent reassessment by the American Academy of Neurology concluded that VNS for epilepsy is both “effective and safe“ (Fisher and Handforth 1999).