dystonia musculorum deformans

noun

dystonia mus·​cu·​lo·​rum de·​for·​mans -ˌməs-kyə-ˈlȯr-əm-di-ˈfȯr-ˌmanz 

: a rare inherited neurological disorder characterized by progressive muscular spasticity causing severe involuntary contortions especially of the trunk and limbs

called also torsion dystonia