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.

Dynamic cervicomedullary cord compression and alterations in cerebrospinal fluid dynamics in children with achondroplasia. Report of four cases.

Achondroplasia is the most common of the heritable skeletal dysplasias. Compression at the cervicomedullary junction can result in myelopathy, hypotonia, sleep apnea, and even sudden death. However, most children with achondroplasia do not suffer from severe neurological symptoms and achieve normal motor and intellectual development without surgical intervention. At the authors' institution, magnetic resonance (MR) imaging and cerebrospinal fluid (CSF) flow studies have been incorporated in the assessment of children with achondroplasia for cervicomedullary junction compression. The authors recently identified four children with achondroplasia who had normal findings on MR imaging and flow studies obtained in the neutral position. On flexion studies, however, three had complete blockage of CSF flow, and more dramatic posterior cervicomedullary compression was demonstrated on extension studies. Some of these patients had severe neurological abnormalities and sleep apnea, while others just developed headaches and/or had apnea episodes when sleeping or in a car seat. Three children underwent decompressive surgery with dramatic improvement or resolution of signs and symptoms. The fourth patient had increased CSF pressure on MR images obtained in the flexed position, possibly due to venous outflow obstruction. Her condition improved dramatically after placement of a ventriculoperitoneal shunt. The increased risk of dynamic cord compression and alterations in CSF dynamics in patients with achondroplasia constitute indications for surgical intervention.

Hydrocephalus in achondroplasia: a possible mechanism.

The relationship of achondroplasia and hydrocephalus has long been the subject of debate. The authors present two patients with these conditions who responded dramatically to shunting procedures. Diagnostic studies implicated venous outflow obstruction in the pathogenesis of their disease.