A 52-year-old woman developed severe hyponatremia following treatment for hypertension with chlorthalidone. Rapid correction of hyponatremia resulted in coma, quadriplegia and hypopnea compatible with central pontine myelinolysis. She recovered with residual facial hypomimia, bradykinesia, cogwheel rigidity and coarse resting tremor, responding to dopaminergic treatment. Her symptoms and signs, which are quite similar to idiopathic Parkinson's disease, are still responsive to treatment 7 years after onset.