Long term outcomes of occipital nerve stimulation

Four Decades of Occipital Nerve Stimulation for Headache Disorders: A Systematic Review

PURPOSE OF REVIEW

Chronic headaches are a significant source of disability worldwide. Despite the development of conventional strategies, a subset of patients remain refractory and/or experience side effects following these treatments. Hence, occipital nerve stimulation (ONS) should be considered as an alternative strategy for intractable chronic headaches. This review aims to provide a comprehensive overview of the effectiveness, safety, mechanisms and practical application of ONS for the treatment of headache disorders.

RECENT FINDINGS

Overall response rate of ONS is 35.7-100%, 17-100%, and 63-100% in patients with cluster headache, chronic migraine and occipital neuralgia respectively. Regarding the long-term effectivity in all groups, 41.6-88.0% of patients remain responders after ≥ 18.3 months. The most frequently reported adverse events include lead migration/fracture (13%) and local pain (7.3%). Based on our results, ONS can be considered a safe and effective treatment for chronic intractable headache disorders. To support more widespread application of ONS, additional research with larger sample sizes should be conducted.

Breaking the cycle: unraveling the diagnostic, pathophysiological and treatment challenges of refractory migraine

Background

Refractory migraine is a poorly described complication of migraine in which migraine has chronified and become resistant to standard treatments. The true prevalence is unknown, but medication resistance is common in headache clinic patient populations. Given the lack of response to treatment, this patient population is extremely difficult to treat with limited guidance in the literature.

Objective

To review the diagnostic, pathophysiological, and management challenges in the refractory migraine population.

Discussion

There are no accepted, or even ICHD-3 appendix, diagnostic criteria for refractory migraine though several proposed criteria exist. Current proposed criteria often have low bars for refractoriness while also not meeting the needs of pediatrics, lower socioeconomic status, and developing nations. Pathophysiology is unknown but can be hypothesized as a persistent "on" state as a progression from chronic migraine with increasing central sensitization, but there may be heterogeneity in the underlying pathophysiology. No guidelines exist for treatment of refractory migraine; once all guideline-based treatments are tried, treatment consists of n-of-1 treatment trials paired with non-pharmacologic management.

Conclusion

Refractory migraine is poorly described diagnostically, its pathophysiology can only be guessed at by extension of chronic migraine, and treatment is more the art than science of medicine. Navigating care of this refractory population will require multidisciplinary care models and an emphasis on future research to answer these unknowns.

Histopathological changes in tissues surrounding vagal nerve stimulation generators: A retrospective analysis of revision surgeries

PURPOSE

Vagal nerve stimulation (VNS) is an effective treatment for patients with epilepsy, depression, and other neuropsychiatric conditions. Understanding the tissue changes associated with VNS devices is crucial for optimizing patient outcomes and device development. This study aimed to investigate the histopathological changes in the tissues surrounding the VNS generator and explore potential correlations with clinical factors and battery performance.

METHODS

A total of 23 patients who underwent VNS generator revision surgery owing to battery depletion were included. Tissue samples from the areas surrounding the VNS generator were obtained and analyzed for histopathological changes. Demographic and device-related variables were also recorded.

RESULTS

Capsule formation was observed in all patients. Acute inflammation were not detected in any case. Perivascular lymphocytic infiltration, foreign-body giant cell reaction (FBGCR), and calcification were observed in 8.7%, 26.1%, and 43.5% of patients, respectively. Crystalloid foreign body appearance was noted in 4 patients. The median output current of the generator was higher in patients with lymphocytic infiltration than in those without lymphocytic infiltration. The median off time was higher in patients with skin retraction than in those without skin retraction. Moreover, discomfort was associated with the presence of FBGCR.

CONCLUSION

Our study provides insights into the tissue changes associated with the VNS generator, with capsule formation being a common response. Crystalloid foreign body appearance was not reported previously. Further research is needed to understand the relationship between these tissue changes and VNS device performance, including the potential impact on battery life. These findings may contribute to VNS therapy optimization and device development.