Objective:To investigate the clinical and imaging characteristics of central pontine myelinolysis (CPM) without hyponatremia and explore its pathogenesis.Methods:A retrospective analysis was performed. Six CPM patients without hyponatremia, admitted to Department of Neurology, He'nan Provincial People's Hospital from March 2021 to March 2023 were chosen. Demographic information, causes, medical history, clinical presentations, and MRI features at onset, and 1 and 3 months after onset were analyzed. The prognoses were evaluated by modified Rankin Scale (mRS) scores 3 months after onset: mRS scores≤2 was classified as good prognosis, and mRS scores>2 as poor prognosis.Results:In these 6 CPM patients without hyponatremia, 4 were males and 2 females; 4 patients had dizziness, 3 headache, 4 limb weakness, 2 cognitive decline, and 2 slow reaction. Four CPM patients had a history of hypertension, 5 had a history of diabetes, and 1 had a history of alcoholic cirrhosis. Hormone therapy, nutritional support and symptomatic treatment were given; 5 patients had obvious improvement, and 1 had poor prognosis 3 months after onset. MRI showed asymmetrical abnormal signal in the basal pons and bilateral brachium pontis, with T1WI hypointensity, T2WI hyperintensity, T2-FLAIR hyperintensity, DWI hyperintensity and clear boundary, and without obvious mass effect or enhancement. DWI sequence enjoyed good diagnostic sensitivity in early stage of CPM: high signal changes could occur within 24 h of clinical symptoms, and isointensity 3 months after onset.Conclusion:Causes of CPM without hyponatremia are mostly hypokalemia, diabetes, malnutrition, and chronic alcoholism; its characteristic MRI manifestations are "pig nose sign", "bat wing sign" and "trident sign".

Objective To analyze the clinical and imaging features of hemichorea associated with non-ketotic hyperglycemia(HC-NH)and to explore the perfusion of cerebral blood flow in the patients.Methods A retrospective study was conducted on 23 HC-NH patients diagnosed in Henan Provincial People's Hospital from January 2018 to December 2023.The clinical manifesta-tions,imaging features and prognosis were collected and analyzed,and the correlation with cere-bral blood flow hypoperfusion was investigated.Results The symptoms were all lateral involun-tary movements,of which 4 cases presented only single upper limb(1 case was left upper limb,the other 3 cases were right upper limb),and 19 cases had both upper and lower limbs involved(10 cases were left limb,and 9 cases were right limb).After the onset of the symptoms,the blood glucose level was 19.72±4.72 mmol/L,glycated hemoglobin level was(13.60±3.68)％,but all of patients were negative to urine ketone bodies.Hyperdense lesions in the contralateral basal ganglia region on CT images were observed in 6 cases.Strip or patchy hyperintensity was seen on T1-weighted MR images.All patients had ipsilateral stenosis of the vessels and regional hypoperfu-sion of cerebral blood flow as shown by MR perfusion-weighted imaging.All symptoms were re-lieved after actively controlling blood glucose,improving blood circulation,and symptomatic man-agement.Conclusion HC-NH is quite rare in clinical practice,and its occurrence may be related to cerebral blood flow hypoperfusion triggered by basal nucleus degeneration.