Introduction: Extrapontine myelinolysis is an acute unusual process, included in demyelinating syndromes of metabolic etiology, which differentiate from central pontine myelinolysis, by affecting other brain areas with clinical manifestation such as dystonia, catatonia, postural tremor, myoclonic spasm, parkinsonism or pyramidal sings.
Objective: Present clinical, electrolytic, hormonal and neuroradiologic findings with emphasis in the unusual location of this disease.
Conclusion: Unlike central pontine myelinolysis, extrapontine has a lower incidence. Trismus, manifested in this patient is an unusual sign. The treatment is only supportive, with a high probability of mortality.
