Health Technology Assessment Report on Vagus Nerve Stimulation in Drug-Resistant Epilepsy

Surgical complications of vagus nerve stimulation surgery: A 14-years single-center experience

Introduction

Vagus nerve stimulation (VNS) is the most frequently used neuromodulation treatment for Drug-Resistant Epilepsy (DRE) patients. Complications of VNS surgery include surgical site infection and unilateral vocal cord paresis. Complication rates vary across studies.

Research question

What is the safety profile of VNS related surgeries?

Materials and methods

Retrospective cohort study using patient files of DRE-patients who had undergone primary implantation of a VNS-system, replacement of the VNS pulse generator, replacement of the lead, replacement of both pulse generator and lead, or VNS removal surgery in the Maastricht UMC+. Multiple Imputation was used for missing data. Univariable and multivariable logistic regression analysis were performed to analyze possible risk factors, in case of a small sample size, an independent-samples t-test and Fisher's exact test or Pearson's X2-test were used. The complication rate was calculated as percentage.

Results

This study included a total of 606 VNS surgical procedures, leading to 67 complications of which 3 permanent complications. Complication rate after primary implantation was 13.4%; 2,5% for pulse generator replacement; 21.4% for lead revision and 27.3% for complete VNS removal. No statistically significant results were found when analyzing the results of adults and children <18 years separately.

Discussion and conclusion

Complication rates of VNS-related surgeries in our own institutional series are low and comparable to previously reported series. VNS surgery is a relatively safe procedure. The complication rate differs per type of surgery and mean surgery duration was longer for patients with complications after lead revision surgery compared to patients without complications.

Development of localized interictal epileptiform discharges following vagus nerve stimulation for lennox-gastaut syndrome: a case report

Background

Lennox-gastaut syndrome (LGS) is an epileptic encephalopathy often associated with behavioral and psychiatric disorders. Vagus nerve stimulation (VNS) has been approved effective for LGS treatment. Surgical resection is also an option for LGS patients with focal pathology, offering a high probability of seizure control. However, it is challenging to accurately localize the seizure focus.

Case presentation

The case presented here is a 19-year-old male with a 16-year history of epilepsy with comorbid severe cognitive and psychiatric disorders. He was diagnosed with LGS due to generalized slow spike-wave discharges and multiple seizure types. He was treated with VNS in 2017 at the age of 15. After that, the frequency of the short tonic seizures decreased from 4–5 times per day to 2–5 times per year, and the generalized tonic–clonic seizure pattern did not recur, which had a frequency of 2–4 times per month before the surgery. In 2019, the generalized abnormal interictal epileptiform discharges changed to be localized in the right frontal–temporal lobe at the age of 17 years (2019).

Conclusions

This case report suggested that the generalized epileptiform discharges evolve into localized discharges after VNS treatment, which may help reveal the primary seizure focus for resection surgery in patients with LGS.

Socio-economic impact of epilepsy in Italy

The World Health Assembly recognizes the growing economic and societal burden of neurological disorders, a leading cause of disability and the second cause of mortality in the world. In this context we analysed the socio-economic impact of epilepsy in Italy with a specific focus on hospitalizations and costs related to disability pensions (DPs) and ordinary disability allowances. In the case of epilepsy, between 2009 and 2015 we observed an alarming increasing trend for DPs (+26%), indicating that substantial expenses must be supported throughout the patients' lifetimes by both the social security system and the National Health Service (NHS) on top of the impact on caregivers. We also analysed the hospital expenditure on epilepsy through the information available in the Hospital Discharge Cards between 2015 and 2018. Almost all admissions (76% ordinary hospitalizations, 24% day hospitals) were acute (95%), followed by rehabilitation (4%) and long-term care (1%). The cost of acute and ordinary hospitalizations was by far the highest in 2018, the last year of analysis. This large expense due to hospitalizations could be reduced through the implementation of different organizational and management approaches. Our recommendation is that the policy maker should consider the best approach to ensure an early diagnosis for patients and provide early access to drugs and/or surgery. Finally, the adoption of new innovative treatments should improve effectiveness and, at the same time, reduce the expense of the NHS, of the social system as a whole, with a tangible improvement in patients' quality of life.

Role of Neuromodulation for Treatment of Drug-Resistant Epilepsy

The choice of neuromodulation techniques has greatly increased over the past two decades. While vagal nerve stimulation (VNS) has become established, newer variations of VNS have been introduced. Following the SANTE's trial, deep brain stimulation (DBS) is now approved for clinical use. In addition, responsive neurostimulation (RNS) has provided exciting new opportunities for treatment of drug-resistant epilepsy. While neuromodulation mostly offers only a 'palliative' measure, it still provides a significant reduction of frequency and intensity of epilepsy. We provide an overview of all the techniques of neuromodulation which are available, along with long-term outcomes. Further research is required to delineate the exact mechanism of action, the indications and the stimulation parameters to extract the maximum clinical benefit from these techniques.