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A state of abnormal (either hypo- or hyper-) tonicity in any of the tissues resulting in impairment of voluntary movement. [dys- + G. tonos, tension]

- d. lenticularis d. resulting from a lesion of the lenticulate nucleus.

- d. musculorum deformans a genetic, environmental, or idiopathic disorder, usually beginning in childhood or adolescence, marked by muscular contractions that distort the spine, limbs, hips, and sometimes the cranial-innervated muscles. The abnormal movements are increased by excitement and, at least initially, abolished by sleep. The musculature is hypertonic when in action, hypotonic when at rest. Hereditary forms usually begin with involuntary posturing of the foot or hand (autosomal recessive form [MIM*224500]) or of the neck or trunk (autosomal dominant form [MIM*128100]); both forms may progress to produce contortions of the entire body. SYN: torsion disease of childhood, torsion d., Ziehen-Oppenheim disease.

- torsion d. SYN: d. musculorum deformans.

dys·to·nia dis-'tō-nē-ə n a state of disordered tonicity of tissues (as of muscle)

dys·ton·ic -'tän-ik adj

muscle dysfunction characterized by spasms or abnormal muscle contraction. One form is a postural disorder often associated with disease of the basal ganglia in the brain. There may be spasm in the muscles of the face, shoulders, neck, trunk, and limbs; the arm is often held in a rotated position and the head may be drawn back and to one side. Other forms of dystonia include torticollis, blepharospasm, and writer's cramp. Dystonic conditions, including blepharospasm, may be helped by the injection of botulinum toxin.

• dystonic adj.