[Pelizaeus-Merzbacher disease: the diagnostic contribution of MRI]. / La maladie de Pelizaeus-Merzbacher: contribution diagnostique de l'IRM.

Pelizaeus-Merzbacher disease is a rare sex-linked leukodystrophy. Its metabolic basis has not been identified yet and diagnosis in mainly based on clinical findings and pathological investigation. Cerebral biopsy is not always performed because of lack of available therapy. Genetic counseling can be provided if the diagnosis is secured. Four cases are reported, in children with characteristic signs, who underwent magnetic resonance (MR) Imaging. MR Imaging appears to be more sensitive than computed tomography to visualize white matter disease: T1 weighted images suggest hypomyelination, in conformity with abnormal myelination. T2 weighted images show a non specific high signal in the white matter.

Radioclinical problems raised by megalodolichobasilar artery. 17 cases and a review of the literature.

Megalodolichobasilar artery (MDBA) is a vascular abnormality characterized by a regular increase in caliber and lengthening of the vertebrobasilar system (VBS), with varying degrees of displacement. Several physiopathological theories have been put forward. Clinically, MDBA may compress the cranial nerves and may be responsible for ischaemic accidents of the brain stem, hydrocephalus or mass syndrome. The radiological images may be misleading. The diagnosis of MDBA should be considered on the basis of CT findings, and its should be confirmed by vertebral arteriography at the slightest doubt.