Neuroanatomical correlates of the progressive supranuclear palsy corticobasal syndrome hybrid

Comparing classic-onset corticobasal syndrome to speech/language-onset corticobasal syndrome

INTRODUCTION

Patients with classic-onset corticobasal syndrome (CBS) present with asymmetric limb apraxia and parkinsonism. We have, however, observed patients who initially present with speech and/or language (SL) problems and several years later develop CBS (i.e., SL-onset CBS). We aimed to compare clinical, neuroimaging and pathological characteristics of classic-onset CBS with SL-onset CBS.

METHODS

We conducted a retrospective cohort study of 62 patients who met criteria for CBS (17 presented with classic-onset CBS and 45 had SL-onset CBS). We compared demographics, clinical characteristics, and grey and white matter volume loss with SPM12 between groups and assessed pathology and corticobasal degeneration (CBD) pathological lesion counts in patients who had died and undergone autopsy.

RESULTS

Median age at CBS diagnosis was 66.4 years in classic-onset CBS and 73.6 years in SL-onset CBS. Classic-onset CBS had higher frequencies of dystonia, myoclonus, and alien limb phenomenon, while SL-onset CBS had a higher frequency of vertical supranuclear gaze palsy. Both groups showed smaller frontoparietal volumes than controls, with SL-onset CBS having greater volume loss in the left supplementary motor area than classic-onset CBS. All three classic-onset CBS cases with autopsy (100 %) had CBD pathology while 8/21 of SL-onset CBS cases (38 %) had CBD. Pathological lesion burden (including astrocytic plaques) did not differ between classic-onset and SL-onset CBS.

CONCLUSION

Classic-onset and SL-onset CBS appear to be different syndromes, with the former being a more profuse motor syndrome. The more widespread volume loss in SL-onset CBS likely reflects longer disease course.

Frontal hypometabolism in the diagnosis of progressive supranuclear palsy clinical variants

OBJECTIVE

Frontal hypometabolism on FDG-PET is observed in progressive supranuclear palsy (PSP), although it is unclear whether it is a feature of all PSP clinical variants and hence whether it is a useful diagnostic feature. We aimed to compare the frequency, severity, and pattern of frontal hypometabolism across PSP variants and determine whether frontal hypometabolism is related to clinical dysfunction.

METHODS

Frontal hypometabolism in prefrontal, premotor, and sensorimotor cortices was visually graded on a 0-3 scale using CortexID Z-score images in 137 PSP patients. Frontal asymmetry was recorded. Severity scores were used to categorize patients as premotor-predominant, prefrontal-predominant, sensorimotor-predominant, mixed-predominance, or no regional predominance. Frontal ratings were compared across PSP clinical variants, and Spearman correlations were used to assess relationships with the Frontal Assessment Battery (FAB).

RESULTS

97% showed evidence of frontal hypometabolism which was most common (100%) in the speech-language (PSP-SL), corticobasal (PSP-CBS), and frontal (PSP-F) variants and least common in the progressive gait freezing (PSP-PGF) variant (73%). PSP-SL and PSP-CBS showed more severe hypometabolism than Richardson's syndrome (PSP-RS), Parkinsonism (PSP-P), and PSP-PGF. A premotor-predominant pattern was most common in PSP-SL and PSP-CBS, with more mixed patterns in the other variants. Hypometabolism was most commonly asymmetric in PSP-SL, PSP-P, PSP-F and PSP-CBS. Worse hypometabolism in nearly all frontal regions correlated with worse scores on the FAB.

CONCLUSIONS

Frontal hypometabolism is a common finding in PSP, although it varies in severity and pattern across PSP variants and will likely be the most diagnostically useful in PSP-SL and PSP-CBS.

Progression to corticobasal syndrome: a longitudinal study of patients with nonfluent primary progressive aphasia and primary progressive apraxia of speech

BACKGROUND AND OBJECTIVES

Nonfluent variant primary progressive aphasia (nfvPPA) and primary progressive apraxia of speech (PPAOS) can be precursors to corticobasal syndrome (CBS). Details on their progression remain unclear. We aimed to examine the clinical and neuroimaging evolution of nfvPPA and PPAOS into CBS.

METHODS

We conducted a retrospective longitudinal study in 140 nfvPPA or PPAOS patients and applied the consensus criteria for possible and probable CBS for every visit, evaluating limb rigidity, akinesia, limb dystonia, myoclonus, ideomotor apraxia, alien limb phenomenon, and nonverbal oral apraxia (NVOA). Given the association of NVOA with AOS, we also modified the CBS criteria by excluding NVOA and assigned every patient to either a progressors or non-progressors group. We evaluated the frequency of every CBS feature by year from disease onset, and assessed gray and white matter volume loss using SPM12.

RESULTS

Asymmetric akinesia, NVOA, and limb apraxia were the most common CBS features that developed; while limb dystonia, myoclonus, and alien limb were rare. Eighty-two patients progressed to possible CBS; only four to probable CBS. nfvPPA and PPAOS had a similar proportion of progressors, although nfvPPA progressed to CBS earlier (p-value = 0.046), driven by an early appearance of limb apraxia (p-value = 0.0041). The non-progressors and progressors both showed premotor/motor cortex involvement at baseline, with spread into prefrontal cortex over time.

DISCUSSION

An important proportion of patients with nfvPPA and PPAOS progress to possible CBS, while they rarely develop features of probable CBS even after long follow-up.

Longitudinal clinical decline and baseline predictors in progressive supranuclear palsy

INTRODUCTION

Progressive supranuclear palsy (PSP) is associated with several clinical variants defined based on ocular motor dysfunction, postural instability, akinesia, and cognitive dysfunction, although little is known about how these features progress over time. We aimed to assess the evolution of these core clinical features across variants and assess baseline clinical and neuroimaging predictors of progression.

METHODS

Ninety-three PSP patients were recruited by the Neurodegenerative Research Group, Mayo Clinic, and underwent two visits 1-year apart, with baseline MRI and [18F]flortaucipir PET. We compared baseline and annualized rates of clinical change on the PSP Rating Scale (total, ocular motor, gait/midline scores) and Montreal Cognitive Assessment, across PSP-Richardson's, PSP-Cortical and PSP-Subcortical variants and assessed relationships between rates of change and baseline regional imaging.

RESULTS

Ocular motor scores differed across groups at baseline and follow-up, with lowest scores observed in PSP-subcortical, but no differences were observed in rate of change across groups. PSP Rating Scale total and gait/midline scores differed across groups at follow-up and in rates of change, with PSP-subcortical showing the least impairment and slowest progression. Greatest cognitive impairment was observed in PSP-Cortical. Sample size estimates for treatment trials differed across PSP variants. Greater baseline flortaucipir uptake, but not volume, of midbrain and motor cortex correlated with faster rates of clinical decline.

CONCLUSION

The PSP Rating Scale and its subscores might be useful markers for the prognostic stratification of PSP variants. Flortaucipir imaging at baseline may help predict rate of decline.

Autopsy Validation of Progressive Supranuclear Palsy-Predominant Speech/Language Disorder Criteria

BACKGROUND

Progressive supranuclear palsy (PSP) may present as a speech/language disorder (PSP-SL).

OBJECTIVE

We assessed pathological correlates of patients with PSP-SL who retained the suggestive of PSP-SL (s.o. PSP-SL) diagnosis versus those who progressed to possible/probable (poss./prob.) PSP.

METHODS

Thirty-four prospectively recruited patient with s.o. PSP-SL completed comprehensive speech/language and neurological assessments longitudinally, died, and underwent autopsy.

RESULTS

Twelve patients (35%) evolved to poss./prob PSP, while 22 (65%) remained as s.o. PSP-SL. Pathological diagnoses differed across the groups (P = 0.025). Patients with s.o. PSP-SL had four different neuropathologies (corticobasal degeneration [59%], PSP [13%], Pick's disease [14%], and frontotemporal lobar degeneration with TDP-43 [14%]), while all patients with poss./prob. PSP had a 4R-tauopathy (PSP [67%] and corticobasal degeneration [33%]). Development of poss./prob. PSP increased the chance of having PSP pathology by 2.38 times.

CONCLUSIONS

PSP-SL is associated with heterogenous pathologies. Evolution of PSP-SL into poss./prob. PSP is more predictive of underlying PSP pathology than s.o. PSP-SL. © 2021 International Parkinson and Movement Disorder Society.

Brainstem Biomarkers of Clinical Variant and Pathology in Progressive Supranuclear Palsy

BACKGROUND

Magnetic resonance brainstem measurements are useful structural biomarkers in the Richardson's syndrome variant of progressive supranuclear palsy (PSP). However, it is unclear how these biomarkers differ across the phenotypic spectrum of PSP and how they relate to underlying pathology.

OBJECTIVE

The aim of this study was to compare brainstem imaging measures across clinical variants of PSP and determine sensitivity and specificity based on pathologically diagnosed cases.

METHODS

A total of 153 patients with PSP who represented eight clinical variants were recruited at Mayo Clinic (Rochester, MN, USA) and underwent structural magnetic resonance imaging (MRI). Midbrain and pons area and superior and middle cerebellar peduncle width measurements were performed, and midbrain/pons ratio and Magnetic Resonance Parkinsonism Index (MRPI) were calculated. Among the 43 patients who later died, PSP pathology was confirmed in 29, whereas 14 had other pathology.

RESULTS

Brainstem measurements varied across PSP clinical variants and were most abnormal in PSP-Richardson's syndrome and frontal variants, followed by PSP-corticobasal, PSP-speech/language, and PSP-parkinsonism variants. All these variants showed abnormalities compared with controls. The PSP-gait freezing variant and patients with prominent corticospinal tract signs showed normal brainstem measures. Among cases with confirmed PSP pathology, the midbrain area, midbrain/pons ratio, and MRPI were all more abnormal compared to those with other pathologies, with best differentiation obtained with the MRPI (sensitivity = 83%; specificity = 85%).

CONCLUSIONS

MRI brainstem measures show utility as diagnostic biomarkers across PSP clinical variants and have the potential to be useful in predicting underlying pathology. © 2021 International Parkinson and Movement Disorder Society.

The evolution of parkinsonism in primary progressive apraxia of speech: A 6-year longitudinal study

INTRODUCTION

Primary progressive apraxia of speech (PPAOS) is a neurodegenerative syndrome in which patients present with an isolated motor speech disorder. Some PPAOS patients develop parkinsonism and other features of progressive supranuclear palsy (PSP) and/or corticobasal syndrome (CBS) over time. We aimed to assess the evolution of parkinsonian characteristics in PPAOS patients who had been followed yearly for at least six years.

METHODS

From a large cohort of 46 PPAOS patients, eight were followed yearly for > 6-years in multiple NIH-funded grants. Parkinsonian and other features, including bradykinesia, tremor, rigidity, postural instability, apraxia, ocular motor function and cognition were assessed at each visit, and research criteria applied for PSP and CBS diagnosis. Neurological, speech-language test scores, and [¹⁸F]fluorodeoxyglucose PET (FDG-PET) and MRI midbrain volumes were assessed.

RESULTS

A Parkinson's plus syndrome developed in all eight patients (100%). Bradykinesia was the earliest feature, followed by rigidity and postural instability. Tremor was not a significant feature. Parkinsonism, limb apraxia and ocular motor impairment tended to develop four-to-five years after onset with some patients having slight asymmetric parkinsonism. Six patients (75%) met research criteria for probable PSP, although only one for PSP-Richardson's syndrome; three patients met criteria for possible CBS. Slightly asymmetric, left-sided, hypometabolism was observed on FDG-PET, not matching asymmetry of Parkinsonism. Midbrain hypometabolism was absent-minimal. Three patients had progressive midbrain volumes in the PSP-Richardson's syndrome range.

CONCLUSIONS

A Parkinson's plus syndrome may inevitably develop in PPAOS supporting PPAOS as an early presentation of a Parkinson's plus disorder.

Brain volume and flortaucipir analysis of progressive supranuclear palsy clinical variants

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All PSP variants showed atrophy or flortaucipir uptake in subcortical structures.

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Speech/language, frontal and corticobasal variants showed cortical involvement.

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Dentatorubrothalamic tract involvement was only seen in some variants.

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PSP variants show different patterns of damage to subcortical-cortical circuitry.

Background and purpose

Progressive supranuclear palsy (PSP) is a neurodegenerative tauopathy that is associated with different clinical variants, including PSP-Richardson's syndrome (PSP-RS), PSP-parkinsonism (PSP-P), PSP-corticobasal syndrome (PSP-CBS), PSP-frontal (PSP-F), PSP-progressive gait freezing (PSP-PGF) and PSP-speech/language (PSP-SL). While PSP-RS has been well-characterized on neuroimaging, the characteristics of the other atypical variants are less well defined and it is unknown how they compare to each other or relate to neuropathology. We aimed to assess and compare regional atrophy on MRI and [¹⁸F]flortaucipir uptake on PET across PSP variants.

Materials and methods

105 PSP patients (53 PSP-RS, 23 PSP-SL, 12 PSP-P, 8 PSP-CBS, 5 PSP-F and 4 PSP-PGF) underwent volumetric MRI, with 59 of these also undergoing flortaucipir PET. Voxel-level and region-level analyses were performed comparing PSP variants to 30 controls and to each other. Semi-quantitative tau burden measurements were also performed in 21 patients with autopsy-confirmed PSP.

Results

All variants showed evidence for atrophy or increased flortaucipir uptake in striatum, globus pallidus and thalamus. Superior cerebellar peduncle volume loss was only observed in PSP-RS, PSP-CBS and PSP-F. Volume loss in the frontal lobes was observed in PSP-SL, PSP-CBS and PSP-F, with these variants also showing highest cortical tau burden at autopsy. The PSP-P and PSP-PGF variants showed more restricted patterns of neurodegeneration predominantly involving striatum, globus pallidus, subthalamic nucleus and thalamus. The PSP-SL variant showed greater volume loss and flortaucipir uptake in supplementary motor area and motor cortex compared to all other variants, but showed less involvement of subthalamic nucleus and midbrain. Compared to PSP-RS, PSP-P had larger midbrain volume and greater flortaucipir uptake in putamen.

Conclusion

The PSP variants have different patterns of involvement of subcortical circuitry, perhaps suggesting different patterns of disease spread through the brain. These findings will be important in the development of appropriate neuroimaging biomarkers for the different PSP variants.

Sensitivity and Specificity of Diagnostic Criteria for Progressive Supranuclear Palsy

BACKGROUND

In 2017, the International Parkinson and Movement Disorder Society put forward new clinical criteria for the diagnosis of PSP, recognizing diverse PSP phenotypes. In this study, we compared the sensitivity and specificity of the new criteria with the National Institutes of Neurological Disease and Society for Progressive Supranuclear Palsy criteria at different times.

METHODS

Patients with clinical parkinsonism, clinical and/or neuropathological diagnosis of PSP, were identified from the Society for Progressive Supranuclear Palsy brain bank. All patients had neuropathologic diagnoses and detailed clinical examination performed by a neurologist at 1 of the 3 Mayo Clinic sites, in Florida, Arizona, and Minnesota. Clinical symptoms and signs were abstracted retrospectively in a blinded fashion and used to determine whether patients met either diagnostic criterion. Patients were divided into early and late disease stage groups using a 3-year cutoff.

RESULTS

A total of 129 patients were included, of whom 66 had PSP pathology (51%). The remainder had other neurodegenerative diseases. The overall sensitivity of the International Parkinson and Movement Disorder Society criteria was 87.9%, compared with 45.5% for the National Institutes of Neurological Disease and Society for Progressive Supranuclear Palsy criteria, whereas the specificity of the International Parkinson and Movement Disorder Society probable PSP criteria was 85.7%, compared with 90.5% for the National Institutes of Neurological Disease and Society for Progressive Supranuclear Palsy. Individual patients were noted to have features of multiple PSP phenotypes.

CONCLUSION

The International Parkinson and Movement Disorder Society criteria recognize several phenotypes of progressive supranuclear palsy and hence have higher sensitivity than the previous criteria. © 2019 International Parkinson and Movement Disorder Society.

Corticobasal degeneration with TDP-43 pathology presenting with progressive supranuclear palsy syndrome: a distinct clinicopathologic subtype

Corticobasal degeneration (CBD) is a clinically heterogeneous tauopathy, which has overlapping clinicopathologic and genetic characteristics with progressive supranuclear palsy (PSP). This study aimed to elucidate whether transactive response DNA-binding protein of 43 kDa (TDP-43) pathology contributes to clinicopathologic heterogeneity of CBD. Paraffin-embedded sections of the midbrain, pons, subthalamic nucleus, and basal forebrain from 187 autopsy-confirmed CBD cases were screened with immunohistochemistry for phospho-TDP-43. In cases with TDP-43 pathology, additional brain regions (i.e., precentral, cingulate, and superior frontal gyri, hippocampus, medulla, and cerebellum) were immunostained. Hierarchical clustering analysis was performed based on the topographical distribution and severity of TDP-43 pathology, and clinicopathologic and genetic features were compared between the clusters. TDP-43 pathology was observed in 45% of CBD cases, most frequently in midbrain tegmentum (80% of TDP-43-positive cases), followed by subthalamic nucleus (69%). TDP-43-positive CBD was divided into TDP-limited (52%) and TDP-severe (48%) by hierarchical clustering analysis. TDP-severe patients were more likely to have been diagnosed clinically as PSP compared to TDP-limited and TDP-negative patients (80 vs 32 vs 30%, P < 0.001). The presence of downward gaze palsy was the strongest factor for the antemortem diagnosis of PSP, and severe TDP-43 pathology in the midbrain tectum was strongly associated with downward gaze palsy. In addition, tau burden in the olivopontocerebellar system was significantly greater in TDP-positive than TDP-negative CBD. Genetic analyses revealed that MAPT H1/H1 genotype frequency was significantly lower in TDP-severe than in TDP-negative and TDP-limited CBD (65 vs 89 vs 91%, P < 0.001). The homozygous minor allele frequencies in GRN rs5848 and TMEM106B rs3173615 were not significantly different between the three groups. In conclusion, the present study indicates that CBD with severe TDP-43 pathology is a distinct clinicopathologic subtype of CBD, characterized by PSP-like clinical presentations, severe tau pathology in the olivopontocerebellar system, and low frequency of MAPT H1 haplotype.

Mild Cognitive Impairment and Progression to Dementia in Progressive Supranuclear Palsy

BACKGROUND

Cognitive deficits are common in progressive supranuclear palsy (PSP), but their relevance and the progression to dementia are still poorly described. The recently revised criteria for PSP consider cognitive dysfunction in the diagnostic work-up.

METHODS

The study retrospectively evaluated a series of 99 PSP patients with Richardson syndrome (PSP-RS), subgrouped according to cognitive and behavioural performances into PSP with normal cognition (PSP-NC), PSP with mild cognitive impairment (PSP-MCI), and PSP with dementia (PSP-D). The progression to dementia at the 3-year follow-up was assessed.

RESULTS

At baseline, 15.2% of patients were classified as PSP-NC, 43.4% as PSP-MCI, and 41.4% as PSP-D. During the 3-year follow-up, 21 out of 29 patients, previously classified as PSP-NC or PSP-MCI, converted to dementia, with an incidence rate of 241 per 1,000 patients/year. Nineteen out of 21 PSP patients (90%) developed the behavioural variant frontotemporal dementia phenotype. The only factor associated with conversion to dementia was MCI diagnosis at baseline (p = 0.023).

CONCLUSION

Cognitive decline occurs in a great proportion of PSP-RS patients early during the disease course. In the absence of a specific phenotype, the diagnosis of MCI might identify PSP patients at greatest risk of developing dementia and should be considered further in the diagnostic assessment.

Radiological biomarkers for diagnosis in PSP: Where are we and where do we need to be?

PSP is a pathologically defined neurodegenerative tauopathy with a variety of clinical presentations including typical Richardson's syndrome and other variant PSP syndromes. A large body of neuroimaging research has been conducted over the past two decades, with many studies proposing different structural MRI and molecular PET/SPECT biomarkers for PSP. These include measures of brainstem, cortical and striatal atrophy, diffusion weighted and diffusion tensor imaging abnormalities, [18F] fluorodeoxyglucose PET hypometabolism, reductions in striatal dopamine imaging and, most recently, PET imaging with ligands that bind to tau. Our aim was to critically evaluate the degree to which structural and molecular neuroimaging metrics fulfill criteria for diagnostic biomarkers of PSP. We queried the PubMed, Cochrane, Medline, and PSYCInfo databases for original research articles published in English over the past 20 years using postmortem diagnosis or the NINDS-SPSP criteria as the diagnostic standard from 1996 to 2016. We define a five-level theoretical construct for the utility of neuroimaging biomarkers in PSP, with level 1 representing group-level findings, level 2 representing biomarkers with demonstrable individual-level diagnostic utility, level 3 representing biomarkers for early disease, level 4 representing surrogate biomarkers of PSP pathology, and level 5 representing definitive PSP biomarkers of PSP pathology. We discuss the degree to which each of the currently available biomarkers fit into this theoretical construct, consider the role of biomarkers in the diagnosis of Richardson's syndrome, variant PSP syndromes and autopsy confirmed PSP, and emphasize current shortfalls in the field. © 2017 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Genetics of Progressive Supranuclear Palsy

Progressive supranuclear palsy (PSP) is a neurodegenerative syndrome that is clinically characterized by progressive postural instability, supranuclear gaze palsy, parkinsonism and cognitive decline. Pathologically, diagnosis of PSP is based on characteristic features, such as neurofibrillary tangles, neutrophil threads, tau-positive astrocytes and their processes in basal ganglia and brainstem, and the accumulation of 4 repeat tau protein. PSP is generally recognized as a sporadic disorder; however, understanding of genetic background of PSP has been expanding rapidly. Here we review relevant publications to outline the genetics of PSP. Although only small number of familial PSP cases have been reported, the recognition of familial PSP has been increasing. In some familial cases of clinically probable PSP, PSP pathologies were confirmed based on NINDS neuropathological diagnostic criteria. Several mutations in MAPT, the gene that causes a form of familial frontotemporal lobar degeneration with tauopathy, have been identified in both sporadic and familial PSP cases. The H1 haplotype of MAPT is a risk haplotype for PSP, and within H1, a sub-haplotype (H1c) is associated with PSP. A recent genome-wide association study on autopsyproven PSP revealed additional PSP risk alleles in STX6 and EIF2AK3. Several heredodegenerative parkinsonian disorders are referred to as PSP-look-alikes because their clinical phenotype, but not their pathology, mimics PSP. Due to the fast development of genomics and bioinformatics, more genetic factors related to PSP are expected to be discovered. Undoubtedly, these studies will provide a better understanding of the pathogenesis of PSP and clues for developing therapeutic strategies.

Midbrain atrophy is not a biomarker of progressive supranuclear palsy pathology

BACKGROUND AND PURPOSE

Midbrain atrophy is a characteristic feature of progressive supranuclear palsy (PSP), although it is unclear whether it is associated with the PSP syndrome (PSPS) or PSP pathology. The aim of the present study was to determine whether midbrain atrophy is a useful biomarker of PSP pathology, or whether it is only associated with typical PSPS.

METHODS

All autopsy-confirmed subjects were identified with the PSP clinical phenotype (i.e. PSPS) or PSP pathology and a volumetric MRI. Of 24 subjects with PSP pathology, 11 had a clinical diagnosis of PSPS (PSP-PSPS), and 13 had a non-PSPS clinical diagnosis (PSP-other). Three subjects had PSPS and corticobasal degeneration pathology (CBD-PSPS). Healthy control and disease control groups (i.e. a group without PSPS or PSP pathology) and a group with CBD pathology and corticobasal syndrome (CBD-CBS) were selected. The midbrain area was measured in all subjects. [Correction added on 21 June 2013, after first online publication: the abbreviation of corticobasal degeneration pathology was changed from CBD-PSP to CBD-PSPS.]

RESULTS

The midbrain area was reduced in each group with clinical PSPS (with and without PSP pathology). The group with PSP pathology and non-PSPS clinical syndromes did not show reduced midbrain area. Midbrain area was smaller in the subjects with PSPS than in those without PSPS (P < 0.0001), with an area under the receiver operator curve of 0.99 (0.88, 0.99). A midbrain area cut-point of 92 mm(2) provided optimum sensitivity (93%) and specificity (89%) for differentiation.

CONCLUSION

Midbrain atrophy is associated with the clinical presentation of PSPS, but not with the pathological diagnosis of PSP in the absence of clinical PSPS. This finding has important implications for the utility of midbrain measurements as diagnostic biomarkers for PSP pathology.

Neuropsychiatry of corticobasal degeneration and progressive supranuclear palsy

Corticobasal syndrome (CBS) and progressive supranuclear palsy syndrome (PSPS) are two of the atypical Parkinsonism syndromes, in that patients exhibit rigidity, occasional tremor and postural instability, but do not symptomatically respond to dopamine replacement. CBS and PSPS can often present with complex cognitive difficulties and neuropsychiatric disturbances. Symptoms of depression, apathy, or agitation can be subtle and are often overlooked as reactions to learning a new diagnosis of Parkinsonism. These symptoms may be the earliest presenting evidence of CBS or PSPS, and these syndromes can be misdiagnosed with a primary psychiatric disorder rather than a neurodegenerative condition. Patients may be inappropriately treated with antipsychotic medications that exacerbate the extra-pyramidal motor features of the syndromes. When symptoms are considered to comprise a neurodegenerative syndrome, it may be an inaccurate diagnosis as many features of CBS and PSPS not only overlap with each other, but also with other dementia syndromes. This review discusses similarities and differences between the syndromes of CBS and PSPS in terms of neuropsychiatric features. Improved characterization of the clinical syndromes is necessary to better predict underlying pathology. Improved education about these diseases would help patients, caregivers and clinicians to anticipate symptom progression and avoid premature nursing home placement.

Imaging brain atrophy in progressive supranuclear palsy and corticobasal syndromes: potential for diagnosis and monitoring of disease progression

SUMMARY The progressive supranuclear palsy syndrome (PSPS) and corticobasal syndrome (CBS) are atypical parkinsonian disorders that are both associated with characteristic patterns of atrophy that can be detected on MRI and can be diagnostically useful for the clinician. Much recent work has focused on developing imaging biomarkers, particularly utilizing measurements of the brainstem, which can differentiate PSPS from CBS and other parkinsonian disorders. The utility of longitudinal measures of atrophy as biomarkers of disease progression has also been assessed with a view to how these measures could be utilized in clinical treatment trials. Here, these studies are reviewed and the potential value of imaging biomarkers to aid diagnosis and monitor disease progression in PSPS and CBS will be discussed.