Differentiation of PA from early PSP with different patterns of symptoms and CBF reduction

To clarify the features of pure akinesia (PA) and progressive supranuclear palsy (PSP) in the early stage of disease.

We investigated 15 PA and 41 PSP patients' clinical and radiologic features including head MRI, ethyl cysteinate dimmer-single photon emission-computed tomography (ECD-SPECT) and iodine-123 meta-iodobenzyl guanidine (123I-MIBG) myocardial scintigraphy. In ECD-SPECT study, cerebral blood flow (CBF) reduction was quantitatively expressed as Z-score, and that in the frontal lobe was evaluated.

Many PSP patients claimed falls as the initial symptom but no PA patients did. Eye movement, as well as optokinetic nystagmus elicitation, was more frequently disturbed in PSP. Dementia, dysarthria and rigidity were also more frequent in PSP than in PA. Midbrain tegmentum atrophy in head MRI was more frequently observed in PSP. CBF in the frontal lobe, especially in the frontal eye field, was significantly lower in PSP than in PA. MIBG myocardial scintigraphy showed no difference between two groups.

PA and PSP show distinct symptoms from the early stage, indicating that they are distinct disorders. The occurrence of falls and eye movement disturbance, as well as CBF reduction at the frontal eye field, is very important for distinguishing these disorders.