The Extrapyramidal Syndromes of Chronic Kidney Disease and Dialysis (EPS-CKDD): diagnostic criteria, risk factors and prognosis.

BACKGROUND Acute extrapyramidal movement disorders in dialysis patients are rare, inconsistently defined and have uncertain aetiology and prognosis. AIM Define diagnostic criteria, prognosis and risk factors. DESIGN & METHODS Retrospective case series review of 20 patients (14 female, mean age 62 years) receiving dialysis for a median of 15 (IQR 4-35) months who presented with acute parkinsonism (AP = 11) or chorea/athetosis (CA = 9). RESULTS All patients had type 2 diabetes (HbA1c 6.8 ± 1.0) and had received metformin. Lactic acidosis was present in 2 patients at presentation and serum lactate was elevated in 7/15 patients tested. No patient had abnormal copper or thyroid metabolism and 5/8 patients tested returned marginal abnormalities in heavy metal screening. MRI revealed characteristic bilateral symmetric T2 hyperintensity of the basal ganglia, predominantly putamen and globus pallidus (the lentiform nucleus) and more extensive involvement of the external and internal capsules in patients with AP presentation. Post mortem demonstrated cytotoxic necrosis of the basal ganglia. Therapy included thiamine, intensive dialysis and cessation of metformin. 2 patients died acutely, 9 recovered and 9 had residual symptoms. Median survival did not differ by presentation: AP 24 (95%CI 21-27) and CA 33 (95%CI 32-35) months, p = 0.21. CONCLUSIONS There are 2 distinct clinical extrapyramidal movement disorders associated with specific diagnostic MRI imaging that support the diagnosis of the Extrapyramidal Syndromes of Chronic Kidney Disease and Dialysis (EPS-CKDD). The associations with diabetes, metformin and metabolic acidosis suggest a common pathogenic mechanism but require additional study. Early recognition and treatment may improve outcomes.