Aseptic Meningitis after Meningioma Resection

We were interested to read the article by Gu et al. on a retrospective study on the risk factors for postoperative meningitis after resection of a meningioma [1] .Of 937 patients who underwent meningioma resection by craniotomy between 2021 and 2024, 5% suffered postoperative meningitis [1] .Risk factors for postoperative meningitis in the multivariate analysis were the location of the tumor at the base of the skull, the duration of surgery >3h, the bleeding volume during surgery >400ml and the length of stay [1] .It was concluded that the location of the tumor at the base of the skull, a longer duration of surgery, a higher bleeding volume during surgery and a longer hospital stay are independent risk factors for postoperative meningitis [1] .The study is noteworthy, but several points should be discussed.The first point is the retrospective design of the study [1] .Retrospective designs have several disadvantages [2] .A retrospective design allows only limited control over the sampling of the population and only limited control over the type and quality of the predictor variables.In addition, the relevant predictors may not have been recorded in the medical record and confounding variables and causality may be difficult or impossible to establish.In addition, some information may inevitably be missing as the data is based on the review of medical records that were not originally designed for the collection of data for research purposes.Selection and recall errors also affect the results, and the reasons for differences in the number of lost follow-ups often cannot be determined, which can lead to bias [2] .The second point is that the CSF culture for bacteria and fungi was negative in all 47 patients included [1] .What type of meningitis was diagnosed?Was it viral meningitis in all 47 patients or did some patients have aseptic meningitis?What were the results of the viral panel?Was meningitis diagnosed based only on clinical presentation or was there thickening and enhancement of the meninges on imaging?The third point is that the study was conducted during the pandemic and started when vaccines against SARS-CoV-2 were just becoming available.Since SARS-CoV-2 infection can be complicated by meningitis [3] , we should know whether all included patients were routinely tested for SARS-CoV-2, how many tested positive and in how many the meningitis was due to SARS-CoV-2.It is also known that SARS-CoV-2 infection reduces immunocompetence and is therefore susceptible to infections with other viruses, bacteria or fungi.Meningitis has also been reported after SARS-CoV-2 vaccination [4] .We should know how many of the patients were vaccinated shortly before surgery.The fourth point is that compliance with hygiene rules by neurosurgeons, anesthesiologists, nurses and surgical assistants was not considered as a predictor of meningitis complications.Since the postoperative infection rate may strongly depend on the hygienic conditions during surgery and in the first days after surgery, we should know in how many cases the hygiene rules were disregarded or negligently violated.The fifth point is that immune status was not assessed before surgery and was not considered a predisposing factor for meningitis.How many of the included patients were regularly taking immunosuppressants?How many of the included patients had an immunologic disease, especially an autoimmune disease, or a hereditary immunodeficiency?Was the immune system routinely checked for integrity prior to surgery?To summarize, this interesting study has limitations that affect the results and their interpretation.Addressing these limitations could strengthen the conclusions and support the message of the study.One would expect meningitis after meningioma resection to be bacterial, but not viral or aseptic.