Celine Dion told NBC's Hoda Kotb that trying to sing while having stiff-person syndrome is "like somebody is strangling you."

Celine Dion is opening up about how stiff person syndrome affects her singing voice. The 56-year-old singer discussed her battle with the rare neurological disorder in a preview released Friday on Today of a new interview with Hoda Kotb.

Stiff-person syndrome, which affects about one in a million people and has no cure, is characterized by muscle rigidity and spasms, heightened sensitivity to sound and lights, and emotional distress that can cause spasms, according to the National Institute of Neurological Disorders and Stroke.