The clinical manifestations of progressive supranuclear palsy (PSP) are known to be highly heterogeneous, and this variability is particularly important for movement disorders. 1,2In particular, although a subtype of PSP with predominant cerebellar ataxia (PSPcerebellar type) has been reported, 3 it might be challenging for clinicians to include PSP in the differential diagnosis when cerebellar ataxia is the predominant clinical feature, which often leads to delays in making a definitive diagnosis.We encountered a patient with cerebellar ataxia in whom brain MRI revealed no lesion to account for the symptoms, whereas the findings of dopaminergic imaging using N-(3- 18 Ffluoropropyl)-2-carboethoxy-3-(4-iodophenyl) nortropane positron-emission tomography (FP-CIT PET) raised an early suspicion of PSP.A 62-year-old male patient visited the hospital with complaints of slurred speech and gait unsteadiness that had first appeared approximately 1 year ago.He reported having experienced a fall about 1 month earlier.He has neither a past medical history nor a family history of neurological disorders.He was a former smoker but did not consume alcohol.A neurological examination revealed mild dysarthria without fatigability.The patient exhibited not only saccadic overshoot but also mild saccadic slowing.There were no bradykinesia, rigidity, upper motor neuron signs, or pathological reflexes.Instead, the patient exhibited mild cerebellar ataxia in finger-to-nose testing as well as mild gait disturbance, including impaired tandem walking.The patient's initially mild cerebellar ataxia was followed longitudinally for 1 year in the outpatient clinic, during which it gradually worsened (Supplementary Video 1 in the online-only Data Supplement).At 2 years after symptom onset the patient's saccadic slowing had become more pronounced along with the appearance of the "round-the-houses" sign, and both limb and axial ataxia had progressed further.A laboratory workup for ataxia was unremarkable, including for vitamin deficiencies and paraneoplastic antibodies.Autonomic dysfunction was absent, including for orthostatic hypotension and urinary symptoms.Visual inspection of the brain MRI scans detected midbrain atrophy, and while mild cerebellar vermis atrophy was attributed to age-related changes, no distinct pontine and cerebellar atrophy or lesions were evident (Fig. 1A).Brain CT performed 3 years later revealed midbrain atrophy but no other significant findings (Supplementary Fig. 1 in the online-only Data Supplement).Dopaminergic imaging using FP-CIT PET revealed mild-to-moderate dopaminergic loss especially in the posterior left caudate nucleus and putamen, which had progressed at the 1-year follow-up (Fig. 1B).In addition, contrast-enhanced CT of the chest and abdomen produced unremarkable findings.Although the patient presented with predominant cerebellar ataxia, he was not diagnosed
You et al. (Thu,) studied this question.