Clinical heterogeneity in progressive supranuclear palsy: challenges to diagnosis, pathogenesis and future therapies

Protracted Course-Progressive Supranuclear Palsy (PC-PSP)

BACKGROUND

Progressive Supranuclear Palsy (PSP) encompasses a broader range of disease courses than previously appreciated. The most frequent clinical presentations of PSP are Richardson's Syndrome (RS) and PSP with a predominant Parkinsonism phenotype (PSP-P). Time to reach gait dependence and cognitive impairment have been proposed as prognostic disease milestones. Genetic polymorphisms in TRIM11 and SLC2A13 genes have been associated with longer disease duration (DD).

METHODS

Retrospective chart review, genetic single nucleotide polymorphism (SNP) analyses (in 3 cases), and neuropathology.

RESULTS

We identified four cases with long (>10-15 years) or very long (>15 years) DD. Stage 1 PSP tau pathology was present in 2 cases (one PSP-P and one undifferentiated phenotype), whereas pallido-nigro-Luysian atrophy (PSP-RS) and stage 4/6 (PSP-P) PSP pathology was found in the other 2 cases. Three cases were homozygous for the rs564309-C allele in the TRIM11 gene and the H1 MAPT haplotype. Two were heterozygous for rs2242367 (G/A) in SLC2A13, while the third was homozygous for the G-allele.

CONCLUSIONS

We propose a protracted course subtype of PSP (PC-PSP) based on clinical or neuropathological criteria in 2 cases with anatomically restricted PSP pathology, and very long DD and slower clinical progression in 2 cases. The presence of the rs564309-C allele may influence the protracted disease course. Crystallizing the concept of PC-PSP is important to further understand the pathobiology of tauopathies in line with current hypotheses of protein misfolding, seeding activity and propagation.

Association of Progressive Supranuclear Palsy Rating Scale with Progressive Supranuclear Palsy Quality of Life Scale

INTRODUCTION

There is growing interest in using patient-reported outcomes as end points in clinical trials, such as the progressive supranuclear palsy quality of life (PSP-QoL) scale. However, this tool has not been widely validated and its correlation with validated motor scales has not been explored. To evaluate the potential utility of using PSP-QoL as an outcome, it is important to examine its relationship with a standard scale used to evaluate neurologic parameters, such as the PSP Rating Scale.

METHODS

PSP-QoL and PSP Rating Scale scores were gathered from 60 clinically diagnosed PSP patients, including patients with Richardson syndrome PSP (PSP-RS, n = 43) and those with non-RS PSP variants (n = 17). Linear regression analysis adjusted for age, sex, and disease duration was used to evaluate the cross-sectional relationship between the total and subscale scores of the 2 instruments.

RESULTS

Among 60 PSP patients, there was a significant correlation between total PSP-QoL and PSP Rating Scale scores. The physical and mentation subscales of each instrument also demonstrated significant correlations. Comparisons among PSP subtypes indicated that worsening PSP-QoL Total and Physical subscale scores correlated with worsening PSP Rating Scale gait subscale scores more strongly for the non-RS PSP variants than for PSP-RS.

DISCUSSION

There is a significant association between the total scores and many of the subscale scores of the PSP-QoL and the PSP Rating Scale. Additionally, the relationship between these measures may differ for PSP-RS and non-RS variants. These findings suggest that the PSP-QoL may be useful in clinical trials as a patient-reported outcome measure. Large prospective multicenter studies utilizing the PSP-QoL are necessary to examine its relationship to disease evolution and changes in the PSP Rating Scale.

Progressive supranuclear palsy as differential diagnosis of Parkinson's disease in the elderly

INTRODUCTION

Progressive supranuclear palsy (PSP) is a syndrome characterized by progressive parkinsonism with early falls due to postural instability, typically vertical gaze supranuclear ophthalmoplegia, pseudobulbar dysfunction, neck dystonia and upper trunk rigidity as well as mild cognitive dysfunction. Progressive supranuclear palsy must be differentiated from Parkinson's disease taking into account several so-called red flags.

MATERIALS AND METHODS

We report a case series hallmarked by gait abnormalities, falls and bradykinesia in which Parkinson's disease was the initial diagnosis.

RESULTS

Due to a torpid clinical course, magnetic resonance imaging (MRI) was performed demonstrating midbrain atrophy, highly suggestive of progressive supranuclear palsy.

CONCLUSION

The neuroradiological exams (magnetic resonance imaging, single photon emission computer tomography, and positron emission tomography) can be useful for diagnosis of PSP. Treatment with levodopa should be considered, especially in patients with a more parkinsonian phenotype.

Diagnostic potential of dentatorubrothalamic tract analysis in progressive supranuclear palsy

BACKGROUND

The differentiation of progressive supranuclear palsy-parkinsonism (PSP-P) from Parkinson's disease (PD) remains a major clinical challenge.

OBJECTIVES

To evaluate the diagnostic potential of observer-independent assessments of microstructural integrity within infratentorial brain regions to differentiate PSP-Richardson's syndrome (PSP-RS), PSP-P and PD.

METHODS

3T MRI parameters of mean diffusivity, fractional anisotropy, grey and white matter volumes from patients with PSP-RS (n = 12), PSP-P (n = 12) and mean disease duration of 2.4 ± 1.7 years were compared with PD patients (n = 20) and healthy controls (n = 23) by using statistical parametric mapping and the spatially unbiased infratentorial template. Subsequently MRI measurements of the dentatorubrothalamic tract were determined observer-independently by a validated probabilistic infratentorial atlas. The impairment of gait and postural stability was evaluated by a sum-score derived from the Unified Parkinson Disease Rating Scale.

RESULTS

Significant mean diffusivity increases, fractional anisotropy decreases and corresponding volume loss were localized in mesencephalic tegmentum, superior cerebellar peduncle, decussation of superior cerebellar peduncle and dentate nucleus in PSP-RS and PSP-P compared to PD and healthy controls. Altered microstructural integrity of the dentatorubrothalamic tract in PSP-RS was significantly more pronounced compared to PSP-P and correlated significantly with the gait and postural stability sum-score. Linear discriminant analysis identified diffusion tensor imaging measures of the dentatorubrothalamic tract and the gait and postural stability sum-score to classify correctly 95.5% of PRP-RS, PSP-P and PD patients.

CONCLUSIONS

Observer-independent analysis of microstructural integrity within the dentatorubrothalamic tract in combination with assessments of gait and postural stability differentiate PSP-P from PSP-RS and PD in early to moderately advanced stages.

Unusual phenotype of pathologically confirmed progressive supranuclear palsy with autonomic dysfunction and cerebellar ataxia: Case report

BACKGROUND

Based on the results of recent multicenter clinical-pathological studies, it seems that the clinical heterogeneity of progressive supranuclear palsy (PSP) is much broader than previously thought. We will report 2 cases of patients with unusual manifestation of pathologically confirmed PSP.

METHODS

Two female patients were diagnosed with the parkinsonian phenotype of multiple system atrophy (MSAP) according to current clinical diagnostic criteria at the ages of 55 and 60 years, respectively. The patients were followed up for the next 5 and 7 years. In both cases, a detailed neuropathological examination of the brain was conducted postmortem.

RESULTS

In the first case, the overall pathological picture corresponded with the diagnosis of 4R tauopathy. In the second case, the brain pathology corresponded with a combination of 4R tauopathy and neocortical amyloidopathy.

CONCLUSION

Some of the main symptoms of MSA, such as cerebellar ataxia and orthostatic hypotension, are not rare parts of the clinical picture of PSP. PSP can thus be mistakenly diagnosed as MSA. In order to determine the most accurate clinical diagnosis of PSP, a revision of its current clinical diagnostic criteria seems appropriate.

Progressive supranuclear palsy (PSP): Richardson syndrome and other PSP variants

Phenotypic heterogeneity of progressive supranuclear palsy (PSP) has been increasingly reported in the literature and can be the source of incorrect clinical diagnosis particularly in the early stages of the disease when the classically associated symptoms of early falls and supranuclear gaze palsy may not be apparent. In addition to Richardson syndrome (RS), several atypical clinical phenotypes have been described. Advances in genetic, neuroimaging, and biochemical/molecular technologies contribute to the identification of these clinical subtypes in the context of typical PSP pathological findings. Our goal is to review the phenomenology reported in the literature that is associated with confirmed histopathological changes consistent with a PSP diagnosis and to highlight the clinical spectrum of PSP. A systematic review of the literature in PubMed through July 2015 using MeSH terms and key words related to PSP was conducted. Articles describing PSP classifications, diagnostic criteria, and case reports were reviewed and summarized. Additional PSP phenotypes not seen in recent clinicopathological studies are included. These include primary lateral sclerosis, pallido-nigro-luysian degeneration, axonal dystrophy, and multiple system atrophy in the spectrum of atypical PSP variants beyond the traditionally classified PSP subtypes. This review is intended to help with the diagnostic challenges of atypical PSP variants. We believe that large multicenter clinicopathological studies will help expand our understanding of etiology and specific mechanisms of neurodegeneration and will aid in the appropriate interpretation of outcomes when conducting clinical and basic science research.

MR parkinsonism index predicts vertical supranuclear gaze palsy in patients with PSP-parkinsonism

Objective:

To identify a biomarker for predicting the appearance of vertical supranuclear gaze palsy (VSGP) in patients affected by progressive supranuclear palsy–parkinsonism (PSP-P).

Methods:

Twenty-four patients with PSP-P were enrolled in the current study. Patients were clinically followed up every 6 months until the appearance of VSGP or the end of the follow-up (4 years). Participants underwent MRI at baseline and at the end of follow-up. Magnetic resonance parkinsonism index (MRPI), an imaging measure useful for diagnosing PSP, was calculated.

Results:

Twenty-one patients with PSP-P completed follow-up, and 3 patients dropped out. Eleven of 21 patients with PSP-P developed VSGP after a mean follow-up period of 28.5 months (range 6–48 months), while the remaining 10 patients with PSP-P did not develop VSGP during the 4-year follow-up period. At baseline, patients with PSP-P who later developed VSGP had MRPI values significantly higher than those of patients not developing VSGP without overlapping values between the 2 groups. MRPI showed a higher accuracy (100%) in predicting VSGP than vertical ocular slowness (accuracy 33.3%) or postural instability with or without vertical ocular slowness (accuracy 71.4% and 42.9%, respectively).

Conclusions:

Our study demonstrates that MRPI accurately predicted, on an individual basis, the appearance of VSGP in patients with PSP-P, thus confirming clinical diagnosis in vivo.

Cerebellar ataxia in progressive supranuclear palsy: An autopsy study of PSP-C

BACKGROUND

Cerebellar ataxia is an exclusion criterion for the clinical diagnosis of progressive supranuclear palsy, but a variant with predominant cerebellar ataxia has been reported. The aims of this study were to estimate the frequency of progressive supranuclear palsy with predominant cerebellar ataxia in an autopsy series from the United States and to compare clinical, pathologic, and genetic differences between progressive supranuclear palsy with and without predominant cerebellar ataxia.

METHOD

We selected 100 consecutive patients with pathologically confirmed progressive supranuclear palsy who had been evaluated at the Mayo Clinic (referred to as the Mayo Clinic patient series) from our brain bank database (N = 1085). We next enriched in cases likely to have cerebellar ataxia by searching the remaining 985 cases for (1) an antemortem diagnosis of multiple system atrophy or (2) neuropathologic evidence of prominent degeneration of the cerebellum or cerebellar afferent nuclei. Subsequently, clinical, pathologic, and genetic features were compared between the two groups.

RESULTS

One patient in the Mayo Clinic patient series (1%) met criteria for progressive supranuclear palsy with predominant cerebellar ataxia and had both cerebellar and mild midbrain atrophy on MRI. Four patients were identified with the targeted search. Four of the five patients were clinically misdiagnosed as multiple system atrophy. The severity of tau-related pathology and cerebellar degeneration were not different between the two groups. No differences were detected in tau genotypes.

CONCLUSION

Although our data cannot provide definitive information about how to make an accurate clinical diagnosis, they should serve to raise awareness of progressive supranuclear palsy with predominant cerebellar ataxia in the differential diagnosis of multiple system atrophy. © 2016 Movement Disorder Society.

Clinical Approach to Progressive Supranuclear Palsy

Sixty years ago, Steele, Richardson and Olszewski designated progressive supranuclear palsy (PSP) as a new clinicopathological entity in their seminal paper. Since then, in addition to the classic Richardson’s syndrome (RS), different clinical phenotypic presentations have been linked with this four-repeat tauopathy. The clinical heterogeneity is associated with variability of regional distribution and severity of abnormal tau accumulation and neuronal loss. In PSP subtypes, the presence of certain clinical pointers may be useful for antemortem prediction of the underlying PSP-tau pathology. Midbrain atrophy on conventional MRI correlates with the clinical phenotype of RS but is not predictive of PSP pathology. Cerebrospinal fluid biomarkers and tau ligand positron emission tomography are promising biomarkers of PSP. A multidisciplinary approach to meet the patients’ complex needs is the current core treatment strategy for this devastating disorder.