Understanding the pathophysiology of hyperglycemia-associated chorea-ballism: a systematic review of positron emission tomography findings.

Hyperglycemia-associated chorea-ballism (HCB) is an infrequent neurological syndrome whose pathophysiology remains poorly understood. Positron emission tomography (PET) studies have offered valuable information regarding regional glucose metabolism. The studies included were published between 1980-2017 and reported demographic, clinical, laboratory and imaging data from patients with HCB in whom a PET scan had been performed. Eleven patients were evaluated (women 82%, Asian origin 91%, mean age 71 years). The main findings were an increase in glucose metabolism at the contralateral motor cortex related to recent episodes of hemiballism-hemichorea in 2 patients, and an altered metabolism in the affected basal ganglia in all of them: decreased in 10 patients (91%) and increased in 1 (9%). However during the acute period the patients showed only an increased metabolism, or even no changes. Contrary to what has previously been suggested in a metabolic failure hypothesis, changes in glucose metabolism in the basal ganglia may not be a key factor in the pathogenesis of HCB, and may potentially be a direct result of histological changes such as cellular ischemia and gliosis related to HCB development.