Usefulness of phase contrast cine mode magnetic resonance imaging for surgical decision making in patients with hydrocephalus combined with achondroplasia. Case report.

A 1-year 9-month-old girl presented with achondroplasia. Serial magnetic resonance (MR) imaging demonstrated mild compression of the medulla oblongata by the occipital bone, macrocrania, and progressive hydrocephalus. Cerebrospinal fluid (CSF) flow study using MR imaging clearly demonstrated CSF flow disturbance at the cervicospinal junction. Foramen magnum decompression was performed for her hydrocephalus and compressed medulla. Postoperative CSF flow study demonstrated improvement of CSF flow at the craniocervical junction. The patient has remained in a stable condition for 7 months postoperatively. Achondroplasia represents hydrocephalus or medullary compression caused by narrowed foramen magnum, which can result in sudden death in some infants. Surgical indications and methods for hydrocephalus combined with achondroplasia remain controversial because the natural history of the hydrocephalus has remained unclear. CSF flow study using MR imaging can provide useful information regarding the surgical indication and methods for the treatment of hydrocephalus combined with achondroplasia.