[Diagnosis of extrapontine myelinolysis preceding central pontine myelinolysis].

An MR study performed on a patient who presented a tetraplegia after liver transplantation, revealed bilateral hypersignal of internal globus pallidus on T2 weighted images. Diagnosis of extrapontine myelinolysis was proposed based on clinical presentation and lesions topography, although absence of natremic disorders. Confirmation of diagnosis was obtained on an MR study performed a month later, which demonstrated a pontine extension. Extrapontine myelinolysis can precede pontine involvement. Diagnosis of myelinolysis should be evoked although MR normal appearance of the pons.