Response to: Radiological demonstration of spontaneous resolution of Type 1 Chiari malformation in a 17-year-old patient

We congratulate with this description of a resolution of Chiari I without evident cause. We agree with the authors that it is important to recognise that CMI could be a dynamic condition not only for tumours or other CMI acquired-type cases, but also in ‘ true ’ severe malformations under C1 level. Probably in the future, with the extensive use of MRI studies and more important, prolonged surveys, this observation will become more frequent (Fig. 1). We consider these observations very important, not only for academic reasons, but also for ethical and informed consent implications. It is known that posterior fossa decompression is a secure procedure in expert hands with low rate complications. However, low rates are not zero and severe complications and life-threatening signs have been described. 2 Moreover, the better results published for surgically-treated CMI reach only to 70 – 80%, with reoperation relatively frequent. 3 In this situation, if CMI becomes a ‘ reversible ’ condition in some cases, the surgeons will have to balance carefully with patients and relatives, surgery options versus conservative treatments. 4,5