EARLY DELAYED RHOMBENCEPHALIC LEUKOENCEPH ALOPATHY SECONDARY TO PITUITARY IRRADIATION

Two patients had early delayed leucoencephalopathy mainly confined to the brainstem after radiotherapy for pituitary tumours. To our knowled ge, we report the first MRI description. The patients had somatotroph cell adenomas (associated with prolactin secretion, patient 2). Surgic al removal of the adenomas were complete (patient I) and partial (pati ent 2). Both underwent pituitary irradiation : patient 1, 55.8 Gy (31 x 1.8 Gy); patient 2, 54 Gy (27 x 2 Gy). Sir weeks after completion of radiation, the patients had low vigilance, sleepiness, cerebellar sym ptoms, optic neuropathy (patient 1), CSF inflammatory reaction. T2-wei ghed MRI scans showed hypersignal in brainstem, cerebellar peduncles ( both patients), temporal lobe white matter (patient 2). T1-weighted im ages showed hyposignals, pseudonecrotic and contrast-enhanced images i n brainstem (patient 1). Both patients responded to intravenous then o ral steroid treatment with a progressive and complete clinical recover y. Radiological abnormalities improved with clinical statement. Presen t characteristics support a demyelinating mechanism of early delayed c erebral radiation injuries.