Although genetic defects are the leading cause of central nervous system malformations including in the posterior fossa, specific malformative patterns should alert the clinician to consider rather a teratogenic etiology. We discuss the imaging features of 2 mid-hindbrain malformations consecutive to the intake of isotretinoin (Roaccuatane®; case 1) and misoprostol (Cytotec®; case 2) during pregnancy and review the pertinent literature. We correlate the morphological appearance of the mid-hindbrain malformation, as seen on high-resolution magnetic resonance imaging to possible drug-induced pathogenetical mechanisms. The recognition of characteristic imaging patterns enables diagnosis of and/or confirmation of suspected drug-induced hindbrain malformations. This has important medicolegal implications and also clinical significance to avoid unsuccessful and misleading genetic testing.
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