Rapidly Progressive Dementia and Temporal Lobe Atrophy in a Case of Nonketotic Hyperglycemic Hemichorea.

Hemichorea has been well-reported in association with nonketotic hyperosmolar hyperglycemia (NKHH), but reports of concurrent temporal lobe involvement are rare. We present the case of a man with NKHH who developed hemichorea in the setting of rapidly progressive memory and cognitive impairments. He demonstrated the unilateral striatal T1 hyperintensities expected for NKHH-induced hemichorea but was also found to have fluid-attenuated inversion recovery hyperintensity, contrast enhancement, and eventual atrophy of his ipsilateral temporal lobe. A review of similar case reports and radiologic findings was performed. His temporal lobe injury shows a progression mimicking that seen in cortical laminar necrosis, suggesting transient ischemia to this lobe as a consequence of either blood hyperviscosity or vasoconstriction; atypical infections or parainfectious processes cannot fully be excluded, however. In addition to hemichorea or focal neurologic deficits, NKHH may also be associated with a rapidly progressive dementia and temporal lobe injury, with deficits that may not fully reverse after glycemic control.