Sagging and swelling of the midbrain suggest spontaneous intracranial hypotension rather than a malformation

Sir, In a recent Brain review article, Barkovich et al. (2009) proposed a new classification for midbrain–hindbrain malformations that takes into account a vast amount of neuroimaging data, as well as results of research in developmental biology and molecular genetics. Based on these findings, the authors also envisage the existence of some malformation that is still not completely understood and for which the pathogenetic mechanism is inferred from biological and genetic studies in animal models. This is the case in a malformation secondary to early anteroposterior transformation at the diencephalic–mesencephalic junction, resulting in shortening and thickening of the midbrain with midline mesencephalic cleft (labelled in the article: Group 1, A.1.c. Gain of diencephalon and loss of midbrain). This malformation is shown in Fig. 4.The magnetic resonance images presented in the figure, however, are identical to those observed in a subgroup of the most severe cases of spontaneous intracranial hypotension, reported in the literature and examined with diffusion studies by our group (Savoiardo et al. , 2007).Spontaneous intracranial hypotension, usually due to …