Intraneural ganglion cyst of the peroneal nerve and coronavirus disease-19 vaccination: Relationship and possible mechanism

Dear Editor, we found that the article on “Intraneural ganglion cyst of the peroneal nerve occurring after coronavirus disease-19 vaccination: A case report”¹ is interesting. The case presented describes a 58-year-old woman who developed acute right-foot drop and subsequent dorsiflexor weakness in her right foot after receiving the Pfizer-BioNTech COVID-19 vaccine. Imaging and diagnostic tests revealed the presence of intraneural cysts within the right common peroneal nerve. Surgical removal of the cyst resulted in gradual improvement of symptoms. The case suggests that intraneural ganglion cysts (INGCs) can be a potential complication following COVID-19 vaccination. This case highlights the importance of considering INGC-induced peroneal palsy as a possible complication after COVID-19 vaccination. While ganglion cysts are relatively common, INGCs within peripheral nerves are rare and not well understood. The temporal relationship between the onset of symptoms and the vaccination date, along with the improvement of symptoms following surgical removal of the cyst, suggests a potential association.

Asymptomatic COVID-19 can manifest at any time,² including before, during, or after infection, as well as after receiving the COVID-19 vaccine or at any other time. It is possible for COVID-19 to co-occur even in the absence of noticeable symptoms. Undiagnosed asymptomatic COVID-19 may have an impact on immunological responses. Without proper laboratory testing, it is not possible to completely rule out asymptomatic infection. In the current scenario, genetic factors are increasingly being considered. The response of the immune system to the vaccine may vary depending on individual genetic characteristics. To gain a better understanding, it is important to conduct multicenter trials with larger sample sizes. This will enable extensive epidemiological studies to explore the relationships between illness and vaccination.

If there is a potential association between the onset of symptoms and the COVID-19 vaccination in the case of INGCs, it raises questions about the possible mechanisms behind this occurrence. While the exact mechanisms are not well understood, there are a few hypotheses to consider. First, it is possible that the immune response triggered by the COVID-19 vaccination could lead to an inflammatory reaction within the peripheral nerves, potentially contributing to the development or exacerbation of ganglion cysts. Second, vaccination can induce changes in the vascular system, including increased blood flow or alterations in the microcirculation. These vascular changes may affect the nutrition and oxygen supply to the peripheral nerves, potentially leading to the development or aggravation of ganglion cysts. Third, certain genetic factors may make individuals more susceptible to the development of ganglion cysts or the exacerbation of existing cysts following vaccination. Genetic variations could influence the structural integrity or function of peripheral nerves, making them more vulnerable to the effects of vaccination. Fourth, it is important to note that the temporal relationship between vaccination and the onset of symptoms does not guarantee a causal relationship. It could be a coincidental occurrence, and further research is needed to establish a definitive link between COVID-19 vaccination and the development or exacerbation of ganglion cysts. To gain a better understanding of the mechanisms involved, additional research, including laboratory studies and clinical trials, would be necessary. This would help elucidate the specific pathways and factors that contribute to the potential association between COVID-19 vaccination and INGCs.

Authors’ contribution

SW 50% ideas, writing, analyzing, approval.

VW 50% ideas, supervision, approval.

Disclosure statement

No potential conflict of interest was reported by the author(s).