For some people, walking may become difficult, and they become more prone to falls and injury. Sometimes overall mobility becomes more difficult and a variety of assistive devices including a walker or wheelchair may be necessary. Other less common symptoms with SPS include shortness of breath or a sense of requiring more work to breathe, the foundation explains. Some patients report spasms of the face or a change in their appetite. SPS is an extremely rare disorder, the National Organization for Rare Disorders said. The exact incidence and prevalence of SPS are unknown, although one estimate places the incidence at approximately 1 in 1,000,000 individuals in the general population.
