A condition characterized by focal
dystonia that progresses to involuntary spasmodic contractions of the
muscles of the legs, trunk, arms, and
face. The hands are often spared, however, sustained axial and limb contractions may
lead to a state where the body is grossly contorted. Onset is usually in the first or second decade. Familial patterns of inheritance, primarily autosomal dominant with incomplete
penetrance, have been identified. (Adams et al., Principles of
neurology, 6th ed, p1078)