Question: An 8 year-old girl presents with cognitive delay and incoordination. What is the diagnosis? See below for the answer.
It goes without saying that neurologists must learn to interpret radiographic images; residents look at so many CTs and MRIs that it’s almost impossible not to develop some competence in this area. It’s important to develop, like our neuroradiology colleagues, a systematic approach to image interpretation–one can’t just scan the DWI or FLAIR images for areas of bright signal. Moreover, and as the senior residents are well aware, the RITE has a bunch of unusual imaging questions like the one above; indeed the exam includes a whole booklet of questions based on radiographic and pathological images.
Residents might find a recent Continuum issue on neuroimaging to be a helpful resource. It has an introductory chapter on MRI physics, and goes on to cover advances in stroke imaging, imaging patients with epilepsy, brain tumors, spinal cord disorders, etc.
There’s a particularly good chapter on imaging congenital malformations. This high-yield chapter covers a lot of topics pertinent to both pediatric neurologists and adult neurologists taking the RITE and boards (i.e. just about everybody). In addition to being a very good issue in general, that chapter would serve very well for test preparation.
Finally, here’s a link to an interesting podcast episode from The Guardian’s Science Weekly (episode 28). It covers the history of MRI and includes a digestible explanation of MR physics.
Answer: Dandy-Walker malformation. The cerebellum is hypoplastic. The fourth ventricle and posterior fossa are enlarged, and the cerebellar remnant is displaced superiorly.