PURPOSE: Extrapontine myelinolysis (EPM) is a highly uncommon, life-threatening disease, particularly in individuals who initially appear with severe clinical symptoms. Here, we describe a case of EPM caused by the rapid correction of hyponatremia that had severe clinical signs at first but parkinsonism symptoms were fully improved after treatment. CASE REPORT: A 46-year-old female patient was admitted to the hospital due to impaired consciousness. Her medical history reveals that she has PAI, or primary adrenal insufficiency. Initial laboratory measurements showed that the serum's sodium (Na) concentration was 104 mEq/L, chloride (Cl) content was 70 mmol/L, potassium (K) content was 4.95 mEq/L, glucose was 42 mg/dL, hydrogen potential (Ph) was 7.12, and bicarbonate (HCO3) concentration was 10 mmol/l. The adrenocorticotropic hormone (ACTH) level was 21 mg/ml, while the cortisol level was 1.2ug/dl. Her mental state was unclear, she had sluggish hypophonic speech, generalized akinesia/rigidity in both upper and lower extremities, trouble swallowing solid and liquid meals, and sialorrhea were all discovered after the Na level was corrected. Hyperintense lesions were visible in the bilateral putamen and caudate nuclei of the Magnetic Resonance Imaging (MRI) T2 and flair-weighted scans, which indicate EPM. EPM was treated with corticosteroids and dopamine agonists, and she was eventually released after complete recovery. CONCLUSION: Even if there are severe clinical symptoms at first, prompt diagnosis and treatment, such as dopaminergic, corticosteroid, and palliative therapy, can save a patient's life.