Half of patients with the Dandy-Walker malformation (DWM) have normal intellectual development. We aimed to identify feature on MRI associated with good intellectual prognosis. We reviewed 20 patients with DWM diagnosed on MRI, mean age 14.6+/-9.9 years. We assessed their intellectual development and related it to the MRI features. We found two groups with a statistically different intellectual outcome. All 14 patients with normal intellectual development had a normal lobulation of the vermis, without supratentorial anomalies. Of the six patients with mental retardation, three had an abnormal vermis, together with dysgenesis of the corpus callosum. In the other three, there were normal vermian anatomy with associated anomalies. Normal lobulation of the vermis, in the absence of any supratentorial anomaly, appears to be a good prognostic factor in DWM. Preservation of cerebrocerebellar pathways and neonatal plasticity could explain the normal intellectual development. These findings might be useful in prenatal diagnosis.

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It has been difficult to define and evaluate accurate principles for a medical imaging strategy in this group of patients. Analysis of plain radiographs is essential before and after reduction of the joint, and it is important to perform postreduction CT in every patient whose joint space remains widened. A radionuclide bone scan should be performed between the second and third weeks after injury to assess epiphyseal vascularity. With the use of specific sequences, MRI may be an alternative modality to assess epiphyseal vitality.

Infection of the pediatric skeletal system is a dramatic diagnostic and therapeutic challenge. The consequences of a missed diagnosis could lead to long-lasting functional sequelae. This disease has multiple aspects according to the clinical presentation and evolution, the causative microorganism, the site of infection, and, finally, the patient's age and immunological status. The choice of the most appropriate imaging modality according to the clinical presentation is very important to assess the diagnosis, the extent of the disease, and to obtain the causative germ when needed; thus, plain films, ultrasound, nuclear medicine, computed tomography, and MR imaging are discussed, each of them having pros and cons. This multimodality approach of the musculoskeletal infections is mandatory to guide surgery, to deliver an appropriate antibiotic therapy, and to reduce the rate of long-term functional sequelae.