Pneumacephalus after Influenza virus infection and its implication to modern anterior skull base surgery Commentary on Widespread subarachnoidal pneumocephalus development as a complication of influenza: a case report

case report about pneumacephalus after influenza virus infection, a topic that may be underestimated in its incidence. Delayed pneumocephalus represents a rare but well-reported complication of cerebrospinal fluid (CSF) diversion diseases that may be also the origin of the disease in the presented case. The exact pathophysiology of the development of pneumocephalus after influenza virus infection is not yet known, but may be related to the disruption of the olfactory mucosa [2]. Mucosal destructions of the olfactory fila can therefore permit to transport the air into brain [2]. There is an ongoing discussion about the best treatment modality of anterior skull base fistulas. It is generally believed that such persistence of pneumacephalus is – at least partly – due to depression of intra-cranial pressure [3]. As a further consequence of this, the risk of intracranial infection is increased in association with a hypoliquorrhea [3]. In the special case of underlying viral encephalitis, we know that PCR virus identification in CSF for secondary neurological syndromes, as e.g. pneumocephalus, is difficult [2] and that lumbar punction remains often false negative sterile [2]. The main problem of PCR interpretation may be related to the bloodbrain-barrier (BBB) that represents cellular interface between the circulating blood and neural environment, and is created by apposed endothelial cells and their intercellular tight junctions. Many aspects of how the BBB functions at the molecular level remain unresolved that hinders exact interpretation of PCR in cerebrospinal fluid [4]. However, this uncertainty of diagnosis may be one reason that explains the lack of general accepted treatment recommendations. Generally, every fistula of the paranasal sinuses is to be closed watertight and secure surgically because of its potential risk of ascending bacterial meningitis, even years or decades after the initial event [5]. Rather, Kotan suggests that as “CSF paranasal fistulas may be healed spontaneously, endoscopic paranasal exploratory surgery does not require”. 1Departments of Neurological Surgery, University of Paris, France 2Co-Editor of Archives of Medical Science