Abstracts

Rationale: VNS is a therapy that has been available for the treatment of refractory epilepsy since 1994 in Europe and 1997 in USA. It was also approved for treating depression in 2001 in Europe and 2005 in the USA. Our department was one of the very first to begin implantation of VNS in 1990 when the first trials were initiated and has continued to perform implantations ever since, with a relatively stable number of operations every year. In spite of over 20 years of availability, discussion of safety and efficacy are still ongoing. Safety concerns must be seen in long-time perspectives. Many patients receive their VNS when they are young and are expected to use it for the many years. At our center, all the VNS patients have been recorded in a local registry since the start up of VNS implantation. Our aim was to analyze surgical and hardware complications in a longitudinal retrospective study since the beginning of VNS implantation in 1990.Methods: We analyzed surgical and hardware complications in 247 patients that underwent implantation of a VNS-device between 1990 and 2014. The mean follow up time was 12 years.Results: In total 488 procedures were performed. 14.7% of the patients suffered from complications related to surgery. 3.3% had hardware complications. Surgical complications were: post operative hematoma in 1.9%, infection in 2.6%, vocal cord paralysis in 1.4%, facial palsy in 0.2%, pain and sensory related 1.4%, aseptic reaction 0.2%, cable discomfort 0.2%, surgical cable break 0.2%, oversized stimulator pocket 0.2% and battery displacement in 0.2%. Hardware related complications were: lead fracture/malfunction in 2.9%, spontaneous VNS turn on in 0.2%, and lead disconnection in 0.2%. No patient experienced an episode of asystole or bradycardia or permanent vocal cord paralysis.Conclusions: VNS implantation is a relatively safe procedure but it still involves certain risks. The most common complications are post-operative hematoma, infection, and vocal cord paralysis. Although their occurrence rates are rather low at about 2%, they may cause major suffering and even be life threatening. In order to reduce complications it is important to have a long-term perspective. The 25 years follow up time of this study is of great strength considering that VNS can be a life long treatment for many patients. Thus it is important to include repeated surgeries such as battery and lead replacements, given that complications also may occur with these surgeries.