[Subacute leukoencephalopathy of the rhombencephalon after pituitary radiotherapy].

Two patients had early delayed leucoencephalopathy mainly confined to the brainstem after radiotherapy for pituitary tumours. To our knowledge, we report the first MRI description. The patients had somatotroph cell adenomas (associated with prolactin secretion, patient 2). Surgical removal of the adenomas were complete (patient 1) and partial (patient 2). Both underwent pituitary irradiation: patient 1, 55.8 Gy (31 x 1.8 Gy); patient 2, 54 Gy (27 x 2 Gy). Six weeks after completion of radiation, the patients had low vigilance, sleepiness, cerebellar symptoms, optic neuropathy (patient 1), CSF inflammatory reaction. T2-weighted MRI scans showed hypersignal in brainstem, cerebellar peduncles (both patients), temporal lobe white matter (patient 2). T1-weighted images showed hyposignals, pseudonecrotic and contrast-enhanced images in brainstem (patient 1). Both patients responded to intravenous then oral steroid treatment with a progressive and complete clinical recovery. Radiological abnormalities improved with clinical statement. Present characteristics support a demyelinating mechanism of early delayed cerebral radiation injuries.