Cranial MRI in the Nijmegen breakage syndrome.

We present the results paragraph signof MRI examinations in ten patients with documented Nijmegen paragraph signbreakage syndrome (NBS), aged 1.75-19 years. T1-, Proton-Density- and T2-weighted spin-echo sequences were performed in three planes. All patients showed microcephaly with decreased size of the frontal lobes and narrow frontal horns. In four patients agenesis of the posterior part of the corpus callosum was found, with colpocephaly and temporal horns dilatation. In one patient callosal hypoplasia was accompanied by abnormal cerebrospinal fluid spaces and wide cerebral cortex, suspicious of pachygyria. Sinusitis was present in all ten patients, as a result of primary immunodeficiency. As in ataxia teleangiectasia and other breakage syndromes, patients with NBS show an inherited susceptibility to malignancy and hypersensitivity to X- and gamma-radiation. CT is therefore contraindicated in these patients and MRI should be the method of choice for diagnostic imaging.