Object: Cases of infected dermal sinus are scarce and detailed surgical anatomical descriptions are hardly found in literature. The clinical, radiological, and surgical findings in four cases of an infected dermal sinus located at the lower spine are presented to elucidate the pathological anatomical configuration.
Clinical material: The first case showed two dermal sinuses with a parallel course extra- and intradurally, ending in a confluence of cavities connected to the conus. In this case, as well as in the fourth case, the signs and symptoms were those of meningitis. The second case presented with meningitis and a subdural empyema, while the third case presented with an intradermoid-intramedullary abscess at the junction between the DS and the conus. This child probably showed signs and symptoms of conus involvement as early as during pregnancy.
Conclusion: The anatomy of the nervous elements in this congenital anomaly is heavily disturbed, more particularly in case of infection, due to extensive arachnoidal scarring. The latter renders dissection laborious and recognition of anatomical details difficult, resulting in complete excision of a dermal sinus in less than half of the cases. Despite their variability in presentation, most cases of an infected dermal sinus show similar characteristic features.