Insights in Neurosurgery

Epilepsy 2019: Vagus Nerve Stimulation (VNS) is an adjunctive treatment in Iraqi patients with drug resistant epilepsy a Anmar Oday Hatem - Baghdad Teaching Hospital

Despite the introduction of new antiepileptic drugs (AEDs) and advances in the surgical treatment of epilepsy, an important group of patients still remains uncontrolled by any of these methods. Vagus nerve stimulation (VNS) is an adjunctive treatment for those with drug resistant epilepsy. In addition to the reduction in seizure frequency, there is other variables need to be assessed for better determination of VNS efficacy like quality of life (QOL) improvement.

Aims of the study: Evaluate the effectiveness of VNS, for Iraqi patients with drug resistant epilepsy, in reducing seizure frequency and improving QOL of these patients.

Method and Patients: Forty-six patients of drug resistant epilepsy were retrospectively examined. They underwent implantation of a stimulator in Baghdad medical city during 2015, and with a follow-up of one year. They were 25 male and 21 females, and their ages at VNS implantation was ≥18 year old for 28 patients and between11-17 year old for 18 patients. Analysis of seizure reduction (using McHugh classification) with the effect of demographic and clinical variables on it, and assessment of QOL (using QOLIE-35 and QOLIE-AD 48 scales) were done in this study. SSPS v.22 was used for the statistical analysis.

Results: The total well response rate (including class I and II and equal to reduction in seizure frequency ≥ 50%) was 58.7 % (27/46 patients), 6 cases became seizure free, and 6 cases reported no improvement, we also found that the factors of gender, age and predominant seizure type had clinical outcome effects. The mean seizure frequency and number of AEDs that used by the patients reduced. The mean of all domains and overall score of QOL scales improved and some domains had statistically significant improvement.

Conclusion: VNS is a safe, well-tolerated and effective treatment in reducing seizure frequency and improving QOL for patients with drug resistant epilepsy.

Patients and Methods: This study is designed as a retrospective study to analyze the efficacy and tolerability of VNS Therapy in patients with drug resistant epilepsy. The study conducted at medical city in Baghdad/ Iraq. The surgical procedure performed during 2015 and all data are collected retrospectively during the follow up visits at 2016 in the epilepsy clinic of Baghdad Teaching Hospital, these data are

collected from the patients, their families and their available medical records from baseline to 12 months after VNS implantation. Forty-six patients diagnosed as drug resistant epilepsy, according to ILAE criteria (6), and on VNS Therapy were interviewed and enrolled in this study. Detailed demographic and clinical data can be seen in table (1).The QOL  assessed through a standard scale for each age groups. The QOLIE-31scale used as a survey of health related QOL for adult patients(≥18 year-old), while the QOLIE-AD-48 designed for adolescent patients (11-17 year-old) (7,8,9).

The Results:

The seizure frequency outcomes after one year of follow up according to the McHugh classification is shown in table (2). 

For all patients, the mean frequency of seizure prior to VNS implantation was 7.69± 3.81 per week, while after 1 year of VNS was 3.97± 4.56 per week, the p-value was significant for this reduction (0.002).

Regarding the age at VNS implantation, there was significant response to VNS therapy in both age groups, with more response rate among those with 11-17year-old, and  according to the seizure type, the response was well in both groups but it was significant in patient with predominant focal seizure type.

The mean number of AEDs taken by our patients was 3.13±0.45 for the pre-VNS period while this number decreased to 2.739±0.53 in the post-VNS period. So, there was significant reduction in AEDs number after VNS therapy.

The side effects and complications that are considered to be related to VNS were analyzed in our study as shown in table (3).

Table (3): Side effects and complications following VNS implantation in 46 patients with treatment-resistant epilepsy. 

According to the QOLIE-31 data for ≥18-year-oldpatients, all domains showed improvement, but not all were statistically significant. Domains with higher impact (statistically significant)from VNS therapy were social functioning, scoring 44.1 ± 8.8 before VNS therapy and 62.7 ± 10.5 after therapy; emotional well-being, scoring 60.2 ± 12.1 before treatment and 68.4 ± 9.9 after treatment; and overall quality of life, scoring 45.3 ±10.3 before treatment and 59.3 ± 12.1 after treatment(Figure 1).

Conclusion:
In patients with drug resistant epilepsy, VNS is a safe, well-tolerated and effective treatment, but it is not considered as a first line therapy and instead is considered only after medical therapy has failed and a patient has been unsuitable for resection or is unwilling to accept the risks of surgery. the VNS is effective in reducing seizure frequency and improving  of QOL in patients with drug resistant epilepsy after VNS Therapy.

Author(s):

Anmar Oday Hatem

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