Consideration for Hemiballismus in the Differential Diagnosis: A Rare Case of Hyperosmolar Hyperglycemic State

We present a case of a 58-year-old male with a past medical history of hypertension and diabetes mellitus presenting to the emergency department with a complaint of abnormal and uncontrollable right arm jerking motions occurring since the afternoon on the day prior to presentation. Arm movements such as these may be consistent with either focal seizures or hemiballismus, a movement disorder classified as a choreiform subtype consisting of involuntary violent movements of an extremity with wide amplitudes. Although oftentimes focal seizures and hemiballismus are associated with neurologic etiologies such as strokes, the second most common cause of hemiballismus appears to be non-ketotic hyperosmolar hyperglycemia. While symptomatic treatment in managing focal seizures and hemiballismus may consist of benzodiazepines and dopamine receptor antagonists, respectively, it is important to treat the underlying cause, which in this case was the non-ketotic hyperosmolar hyperglycemic state associated with this patient's long-standing history of poorly controlled diabetes mellitus.