Relationship Between Diabetic Chorea and Timing of MRI Findings: A Systematic Review with Case Reports.

Background: Diabetic chorea is a rare complication of diabetes mellitus for which head MRI is the most common diagnostic imaging modality. Cases have been reported where CT and/or MRI findings are inconsistent or clinical symptoms and imaging findings do not appear simultaneously. We aimed to compile the cases in which imaging findings appeared on MRI retests and to examine in a systematic review whether temporal differences in the appearance of imaging findings correlate with clinical characteristics. Case Presentation: An 80-year-old man with type 2 diabetes mellitus came to a hospital with abnormal movements of the left upper and lower extremities. Two days after the first visit, his symptoms flared up, and his head MRI showed an old cerebral infarction and no new lesion. On day 14, he retested T1-weighted imaging and showed a high signal in the right putamen, which was considered diabetic chorea. Blood glucose was controlled with insulin, and the involuntary movements disappeared. Methods: PubMed and ICHUSHI were searched to identify patients with diabetic chorea who had undergone MRI retests. Patients grouped by the temporal change in the presence/absence of imaging findings were compared on age, sex, duration of diabetes mellitus, blood glucose level, HbA1c level, side of involuntary movement, time to first MRI, and follow-up MRI. Results: Of the 64 cases analyzed, 43 (67.2%) were female. The mean age was 69.0 years. 16 (25.0%) had worsening findings upon MRI retesting, 37 (57.8%) had improvement, and 10 (15.6%) had unchanged findings. There were no significant differences in age, sex, mean blood glucose level or HbA1c at onset among the groups. Conclusion: There was no association between the pattern of appearance of imaging findings over time and clinical characteristics, including glucose levels. If initial MRI findings are negative, MRI retesting after a certain time may help diagnose diabetic chorea.