Trismus in adults has a wide range of known causes, though few cases have ever been reported secondary to central pontine myelinolysis (CPM). This report describes a case of severe trismus without clear etiology successfully treated with onabotulinum toxin-A following development of CPM. Patient was a female aged in her early thirties who presented to the hospital with ascending weakness five days following hyponatremia correction at rates within guideline recommendations. MRI revealed increased...