A tale of two tauopathies.

A77-year-old man developed progressive language and balance difficulties. He had difficulty rising from a chair, with falls occurring within the first year of symptoms. After 1 year, rapid, spontaneous jerks appeared in the left hand, which he described as “useless.” Neurologic examination 3 years after his initial symptoms demonstrated 23/30 on the Mini-Mental State Examination and an applause sign. He had apathy, without a pseudobulbar affect. Aside from mild word-finding difficulties, his language examination was normal. Cranial nerve examination showed vertical gaze limitation with loss of vertical fast phases on testing of optokinetic nystagmus (OKN). Vertical gaze limitations could be overcome with oculocephalic maneuvers. Motor examination revealed markedly increased tone in his left arm, with moderate left greater than right bradykinesia, without tremor. Left ideomotor apraxia was present. Action and postural myoclonus was present in the left arm. There was neck extension and axial rigidity. Gait was slow and slightly wide-based with impaired postural reflexes. Stereognosis and graphesthesia were intact. A trial of levodopa/carbidopa 900 mg per day showed no symptomatic benefit. Brain MRI without gadolinium revealed asymmetric, focal atrophy of the right frontoparietal area and the midbrain tegmentum (figure).