Objective: To present a patient with cerebellar ataxia and a pathologically confirmed diagnosis of PSP.

Background: Progressive supranuclear palsy (PSP) is an atypical form of parkinsonism. Typical symptoms include postural instability, symmetric hypokinetic-rigid motor symptoms, axial rigidity, gait freezing, vertical supranuclear gaze palsy, dysarthria, dysphagia and fronto-subcortical cognitive impairment. Several PSP subtypes have been described: PSP-RS (PSP-Richardson’s syndrome), PSP-P (PSP-parkinsonism), PSP-PAGF (PSP-pure akinesia with gait freezing), PSP-PNFA (PSP-progressive non-fluent aphasia) and PSP-bvFTD (PSP-behavioural variant of frontotemporal dementia). Cerebellar signs have been reported in a small proportion of PSP patients in previous studies (PSP-C or PSP with predominant cerebellar ataxia).

Methods: For the post-mortem examination, the brain was embedded in paraffin after fixation in 10% buffered formalin. Sections from the frontal lobe, temporal lobe, hippocampal region, striatum, subthalamic nucleus, brainstem, area striata and cerebellum were prepared. Immunohistochemical analysis for hyperphosphorylated tau-protein, beta-amyloid, ubiquitin, TDP-43 and p62 proteins was performed.

Results: The patient developed cerebellar ataxia and gait impairment at age 60. In the following years, disease progression with a symmetric hypokinetic-rigid syndrome, prominent postural instability and supranuclear oculomotor abnormalities was observed. Magnetic resonance imaging of the brain showed midbrain atrophy. Dopamine transporter imaging was abnormal with reduced striatal tracer uptake. Post-mortem microscopic examination of the brain revealed extensive tau-positive pathology, predominant in the brainstem, substantia nigra, dentate nucleus and subthalamic nucleus. The pallidum and the iso- and allocortical regions were less severely affected. The dentate nucleus in particular was severely affected with numerous globose neurofibrillary tangles and grumose degeneration.

Conclusions: In the differential diagnosis of atypical parkinsonism, it remains important to remember that a minority of PSP patients can present with predominant cerebellar symptoms. Postmortem brain pathological examination in a PSP patient with prominent cerebellar signs revealed severe neuronal loss and globose neurofibrillary tangles in the dentate nucleus. Further studies are needed to clarify the potential relation between the severity of cerebellar pathology and the PSP-C phenotype.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/cerebellar-signs-in-progressive-supranuclear-palsy/