Celine Dion diagnosed with stiff-person syndrome: What is it?

(NEXSTAR) – Celine Dion revealed to her fans Thursday she has been diagnosed with stiff-person syndrome, a rare neurological disorder that affects about 1 or 2 people per million, according to Johns Hopkins Medicine.The disease "is characterized by fluctuating muscle rigidity in the trunk and limbs and a heightened sensitivity to stimuli such as noise, touch, and emotional distress, which can set off muscle spasms," according to the National Institute of Neurological Disorders and Stroke (