- Clinically diagnosed CBS, consisting of progressive asymmetric rigidity and apraxia and additional findings suggesting cortical (e.g., one or more of the following: alien limb phenomenon, apraxia of speech, cortical sensory loss, constructional dyspraxia, hemisensory neglect, myoclonus, mirror movements) and basal ganglionic (e.g., one or more of the following: bradykinesia, dystonia, tremor, postural instability) dysfunction.