Dementia as the most common presentation of cortical-basal ganglionic degeneration

Pathological heterogeneity of clinically diagnosed corticobasal degeneration

Two patients fulfilling suggested clinical diagnostic criteria for corticobasal degeneration (CBD) are presented, who were found at postmortem to have alternative pathological diagnoses not suspected during life, namely, Alzheimer's disease and Pick's disease, respectively. The nosological position of these cases is considered in light of a literature review of previous reports of clinically diagnosed corticobasal degeneration with atypical (not corticobasal degeneration) pathology. Since such phenocopies may be common, we suggest that all clinically diagnosed cases of corticobasal degeneration should initially be labelled as "corticobasal degeneration syndrome" (CBDS) to emphasize that this is a diagnosis based on clinical phenotype, with the term corticobasal degeneration being reserved for the specific neuropathological phenotype, which itself may have a variety of clinical presentations.

Corticobasal degeneration as a cognitive disorder

The presence of cognitive impairment in corticobasal degeneration (CBD) is now widely recognised. Our review of the literature reveals that, although the pattern and severity of neuropsychological impairments can be highly variable across patients, several general trends can be identified. The most characteristic impairments are limb apraxia (usually ideomotor), constructional and visuospatial difficulties, acalculia, frontal dysfunction, and nonfluent aphasia. The limb apraxia is associated with deficits in drawing, copying, and handwriting, but there is emerging evidence that the problems with handwriting are not due exclusively to the apraxia. The findings with respect to episodic memory are more variable, but when there is impairment in this area, it tends to be milder than that seen in Alzheimer's disease. Semantic memory functioning appears relatively preserved but has been poorly studied. Problems with speech are common, and may be due to dysarthria or buccofacial apraxia. Aphasia, although initially considered rare, is in fact a common accompaniment of CBD, may be the presenting feature, and is typically nonfluent in type. More systematic investigation of the clinical and neuropathological overlap between progressive nonfluent aphasia (generally considered to be a form of frontotemporal dementia) and CBD is needed.

Unclassifiable parkinsonism in two European tertiary referral centres for movement disorders

In view of reports on high frequencies of atypical parkinsonism from different parts of the world and in non-white communities in the United Kingdom, we have prospectively surveyed 1,000 consecutive patients with parkinsonism presenting to two European tertiary referral centres for movement disorders (London, UK, and Barcelona, Spain). The aims of our study were to assess in a cross-sectional, prospective manner the proportion of patients who could not be classified diagnostically, to identify the factors precluding classification, and to determine which diagnostic measures would increase the rate of classifiable cases. Diagnoses were established using published clinical diagnostic criteria for Parkinson's disease (PD) and for other conditions associated with parkinsonism. Twenty-nine patients in London and 25 in Barcelona were initially considered unclassifiable; nine could be classified after further investigations. Levodopa (L-dopa) responsiveness was found to have a pivotal role in establishing a clinical diagnosis in previously unclassifiable patients: In those 45 patients who remained unclassifiable, failure to respond to L-dopa without other exclusion criteria for PD was the most common finding in each centre. Our results show that 4.0 to 5.0% of parkinsonian patients presenting to specialist clinics in Western Europe cannot be categorised using currently available clinical diagnostic criteria for parkinsonian syndromes. Prolonged follow-up and neuropathological diagnosis will be needed to determine whether all these cases represent atypical presentations of established clinico-pathological entities or whether some represent unrecognised new disorders.

Essentials of the proper diagnoses of mild cognitive impairment, dementia, and major subtypes of dementia

Loss of cognitive function in the elderly population is a common condition encountered in general medical practice. Diagnostic criteria and approaches have become more refined and explicit in the past several years. Precise diagnosis is feasible clinically. In this article, the precursor state and major subtypes of dementia are considered. Mild cognitive impairment is the term given to patients with cognitive impairment that is detectable by clinical criteria but does not produce impairment in daily functioning. When daily functioning is impaired as a result of cognitive decline, dementia is the appropriate syndromic label. Specific causes of dementia tend to have distinctive clinical presentations: the anterograde amnesic syndrome of Alzheimer disease; the syndrome of dementia with cerebrovascular disease; the syndrome of Lewy body dementia with its distinctive constellation of extrapyramidal features, disordered arousal, and dementia; the behavioral-cognitive syndrome of frontotemporal dementia; the primary progressive aphasias; and the rapidly progressive dementias. Because dementia syndromes have distinctive natural histories, precise diagnosis leads to a better understanding of prognosis. As new treatments become available for Alzheimer disease, the most common of the dementias, accurate diagnosis allows the appropriate patients to receive treatment.

The youngest reported case of corticobasal degeneration

Corticobasal degeneration (CBD) is a movement disorder characterized by early apraxia and asymmetric parkinsonism that responds poorly to anti-Parkinson medications. There are clinical manifestations reflecting dysfunction in both the cerebral cortex and the basal ganglia. Patients typically present between the sixth and seventh decades. Previously, the youngest clinically diagnosed individual was 40 years old. Here we describe a 34-year-old woman who meets the clinical diagnostic criteria for CBD with onset of symptoms at age 28. In this patient, the first symptom was an 'uncooperative' right hand. This was soon followed by right hand dystonia. Symptoms progressed rapidly, and she developed generalized bradykinesia, rigidity, and corticospinal tract signs with preservation of the initial asymmetry. Her symptoms did not respond to a daily dose of 1200 mg of immediate release levodopa. Extensive laboratory workup and brain imaging were normal. Neuropsychological evaluation revealed mild deficits consistent with frontal-subcortical dysfunction. The chronic, progressive course, asymmetric limb rigidity, apraxia, focal dystonia, and lack of response to levodopa suggest CBD. To our knowledge, this is the youngest reported case of clinically probable CBD.

Corticobasal degeneration: Selected developments

Corticobasal degeneration (CBD) is now classified as a four-repeat tauopathy. The presence of neuronal and glial tau-immunoreactive lesions is critical to the pathological diagnosis. It is increasingly recognised that a variety of clinical phenotypes can occur as a consequence of this pathological state and that several other pathological conditions may be associated with the perceptuo-motor syndrome first associated with the pathological features of CBD (now referred to as the corticobasal syndrome). The high rate of diagnostic inaccuracy must be considered when interpreting previous literature dealing with cases presumed to be CBD. There is considerable clinical, pathological, and genetic overlap between CBD and progressive supranuclear palsy (PSP); however, the etiological and pathogenetic relationships between the two remain uncertain. There are reasons to believe that these diseases could be different phenotypes of a single process. Even if they are eventually found to be distinct disorders, treatments that alter the progression of one may have similar ameliorative effects on the other. Each of these issues are discussed in this selective review of CBD.

Pick's complex and FTDP-17

This essay advances the thesis with a review of the evidence that Pick's disease, frontotemporal dementia, primary progressive aphasia, corticobasal degeneration, and progressive supranuclear palsy should be regarded as a clinically and biologically cohesive spectrum. The historically correct eponymic term Pick's complex, for both the clinical and pathological varieties is preferred. The discovery of tau mutations in frontotemporal dementia and parkinsonism linked to specific mutations in chromosome 17 and their resemblance to the sporadic cases validates the concept of Pick's complex. There are recently discovered overlaps between the three-repeat and four-repeat tauopathies, and the tau-negative varieties with or without motor neuron disease-type inclusions may be deficient in normal tau, therefore may be tauopathies also. Although clinical, pathological, and biochemical distinctions continue to be important, integration promises to be productive in this family of not so rare diseases.

Frontotemporal and motor neurone degeneration with neurofilament inclusion bodies: additional evidence for overlap between FTD and ALS

We present the case of a patient who had clinical frontal lobe dementia without apparent motor neurone disease (MND), with pathologic findings not typical of any single currently classified frontotemporal degeneration (FTD). At autopsy, the brain had frontal and temporal atrophy with neuronal loss, gliosis, and superficial spongiosis, typical of all FTDs. There were at least three different morphologic types of intracytoplasmic neuronal inclusions in a variety of brain and brainstem regions, including the hippocampal dentate gyrus and pyramidal neurones, the neocortex (in particular, the motor cortex), basal ganglia, thalamus, subthalamic nucleus, basis pontis, and inferior olivary nuclei. Inclusions had the morphologies of Pick-like bodies, pleomorphic inclusions, and hyaline conglomerate (HC)-like inclusions. None of these were positive with tau immunostains. Pick-like bodies in the dentate gyrus were labelled with ubiquitin. The pleomorphic inclusions in the neocortex and dentate gyrus and the HC-like inclusions in the motor and parietal cortex were strongly positive with immunostains for neurofilament. We discuss the differential diagnosis and compare this case with those disorders to which it is most similar. In particular, we compare the unique neurofilament-positive inclusions to the inclusions of FTD-MND, to Pick bodies, and to the basophilic and HC inclusions that are occasionally seen in amytrophic lateral sclerosis (ALS). Although FTD-MND may be found in ALS, the findings in this case may have additional implications for a link between FTD and ALS.

Movement Disorders Society Scientific Issues Committee report: SIC Task Force appraisal of clinical diagnostic criteria for Parkinsonian disorders

As there are no biological markers for the antemortem diagnosis of degenerative parkinsonian disorders, diagnosis currently relies upon the presence and progression of clinical features and confirmation depends on neuropathology. Clinicopathologic studies have shown significant false-positive and false-negative rates for diagnosing these disorders, and misdiagnosis is especially common during the early stages of these diseases. It is important to establish a set of widely accepted diagnostic criteria for these disorders that may be applied and reproduced in a blinded fashion. This review summarizes the findings of the SIC Task Force for the study of diagnostic criteria for parkinsonian disorders in the areas of Parkinson's disease, dementia with Lewy bodies, progressive supranuclear palsy, multiple system atrophy, and corticobasal degeneration. In each of these areas, diagnosis continues to rest on clinical findings and the judicious use of ancillary studies.

Calculation impairment in neurodegenerative diseases

We examined oral calculation in patients with corticobasal degeneration (CBD; N=17), frontotemporal dementia (FTD; N=17), and Alzheimer's disease (AD; N=20), as well as 17 healthy seniors matched for age and education. Our calculation model involves at least three components: numerosity, combinatorial processes, and executive resources such as working memory. We assessed addition, subtraction, multiplication, and division involving small numbers (small, single-digit answers) and large numbers (larger, single- and double-digit answers). We also assessed dot counting for small numbers (2-5) and large numbers (6-9), as well as a measure of working memory. All patient groups differed from healthy seniors in oral calculation. CBD (36% correct) and FTD (65% correct) demonstrated a significant overall impairment in oral calculation relative to AD (76% correct). CBD (66% correct) had more difficulty counting dots overall relative to AD (94% correct) and FTD (86% correct), consistent with our hypothesis that the calculation deficit in CBD is due in large part to a numerosity deficit. FTD had more difficulty relative to AD in their performance of reverse digit span, consistent with our hypothesis that FTD patients' executive resource limitation contributes to their pattern of calculation impairment.

Clinical manifestations of Parkinson's disease and parkinsonism

The most common disorder in a patient presenting to a movement disorder clinic will be parkinsonism. The challenge is to provide the patient with the most accurate diagnosis and prognosis possible. The assumption at the time of initial presentation of the clinical diagnosis of Parkinson's disease is often wrong (20-25%). Waiting to see the pattern of progression, and response to medication provides invaluable additional information. This manuscript summarizes the clinical manifestations of Parkinson's disease and the main akinetic-rigid syndromes (progressive supranuclear palsy, multiple system atrophy, cortical-basal ganglionic degeneration, and dementia with Lewy bodies) that make up the differential diagnosis.

Office of Rare Diseases neuropathologic criteria for corticobasal degeneration

A working group supported by the Office of Rare Diseases of the National Institutes of Health formulated neuropathologic criteria for corticobasal degeneration (CBD) that were subsequently validated by an independent group of neuropathologists. The criteria do not require a specific clinical phenotype, since CBD can have diverse clinical presentations, such as progressive asymmetrical rigidity and apraxia, progressive aphasia, or frontal lobe dementia. Cortical atrophy, ballooned neurons, and degeneration of the substantia nigra have been emphasized in previous descriptions and are present in CBD, but the present criteria emphasize tau-immunoreactive lesions in neurons, glia, and cell processes in the neuropathologic diagnosis of CBD. The minimal pathologic features for CBD are cortical and striatal tau-positive neuronal and glial lesions, especially astrocytic plaques and thread-like lesions in both white matter and gray matter, along with neuronal loss in focal cortical regions and in the substantia nigra. The methods required to make this diagnosis include histologic stains to assess neuronal loss, spongiosis and ballooned neurons, and a method to detect tau-positive neuronal and glial lesions. Use of either the Gallyas silver staining method or immunostains with sensitive tau antibodies is acceptable. In cases where ballooned neurons are sparse or difficult to detect, immunostaining for phospho-neurofilament or alpha-B-crystallin may prove helpful. Methods to assess Alzheimer-type pathology and Lewy body pathology are necessary to rule out other causes of dementia and Parkinsonism. Using these criteria provides good differentiation of CBD from other tauopathies, except frontotemporal dementia and Parkinsonism linked to chromosome 17, where additional clinical or molecular genetic information is required to make an accurate diagnosis.

Signature tau neuropathology in gray and white matter of corticobasal degeneration

Corticobasal degeneration (CBD) is an adult-onset progressive neurodegenerative disorder characterized by L-dopa-resistant rigidity, focal cortical deficits, and variable dementia. The neuropathological hallmark of CBD is the deposition of filamentous inclusions in neurons and glia composed of hyperphosphorylated tau with only four microtubule-binding repeats (4R-tau). To characterize the regional burden of tau pathology in CBD, we studied 12 brains with the neuropathological diagnosis of CBD using biochemical and histochemical techniques. Eleven brain regions were evaluated including gray and white matter from frontal, parietal, temporal, and occipital lobes and cerebellum as well as basal ganglia. Although the distribution of tau pathology was variable, neuropathological and biochemical data showed a similar burden of tau abnormalities in frontal, temporal, and parietal lobes and basal ganglia of both hemispheres. This included abundant, sarkosyl-insoluble 4R-tau in both gray and white matter of two or more of these cortical regions and basal ganglia, and to a lesser extent, cerebellar white matter. The insoluble tau pathology in gray and white matter showed overlapping but distinct phosphorylated epitopes suggesting cell-type and subcellular localization (ie, cell bodies versus cell processes)-specific differences in tau phosphorylation. In contrast, soluble tau was composed of normal 4R/3R-tau ratios indicating no gross abnormality in tau splicing. Thus, although clinically heterogeneous, CBD is a distinct lobar and basal ganglionic tauopathy with selective aggregation of 4R-tau.

Presenile dementia syndromes: an update on taxonomy and diagnosis

The four major degenerative dementias that often begin in presenescence: are reviewed. These are Alzheimer's disease, frontotemporal dementia, dementia with Lewy bodies, and Creutzfeldt-Jakob disease. Their epidemiological, genetic, and clinical features are reviewed, and controversies in taxonomy arising from recent discoveries described. Particular attention is given to the pathological role of protein aggregation, which appears to be a factor in each disease.

Lumping and splitting the Parkinson Plus syndromes: dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, and cortical-basal ganglionic degeneration

The atypical parkinsonian or Parkinson Plus syndromes are often difficult to differentiate from Parkinson's disease and each other. In this article, the clinicopathological characteristics of dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, and cortical-basal ganglionic degeneration are discussed. These disorders, although clinically distinct, may have more similarities than previously thought, based on modern immunocytochemical techniques and new genetic findings. These intriguing interconnections at a basic molecular level have provided the scientific rationale for lumping these diseases into two groups, the synucleinopathies and the tauopathies.

Truncal and limb apraxia in corticobasal degeneration

We report a patient with probable corticobasal degeneration with prominent truncal apraxia, and review the literature.

Corticobasal syndrome with tau pathology

Six cases with a clinical corticobasal syndrome (progressive asymmetric apraxia and parkinsonism unresponsive to levodopa) and tau pathology were selected from 97 brain donors with parkinsonism. Postmortem volumetric measures of regional brain atrophy (compared with age/sex-matched controls) were correlated with clinical features and the degree of underlying cortical and subcortical histopathology. At death, no significant asymmetry of pathology was detected. All cases had prominent bilateral atrophy of the precentral gyrus (reduced by 22-54%) with other cortical regions variably affected. Subcortical atrophy was less severe and variable. Two cases demonstrated widespread atrophy of basal ganglia structures (44-60% atrophy of the internal globus pallidus) and substantial subcortical pathology consistent with a diagnosis of progressive supranuclear palsy (PSP). The remaining four cases had typical pathology of corticobasal degeneration. In all cases, neuronal loss and gliosis corresponded with subcortical atrophy, while the density of cortical swollen neurons correlated with cortical volume loss. Atrophy of the internal globus pallidus was associated with postural instability, while widespread basal ganglia histopathology was found in cases with gaze palsy. This study confirms the involvement of the precentral gyrus in the corticobasal syndrome and highlights the variable underlying pathology in these patients.

An overview of common non-alzheimer dementias

Approximately 20% to 40% of dementia is caused by diseases other than Alzheimer's disease. This article reviews the major categories of non-Alzheimer dementia, including dementia associated with cerebrovascular disease, dementia associated with extrapyramidal features, and the frontotemporal dementias. Dementia associated with cerebrovascular disease is a heterogeneous condition the importance of which is often misunderstood. Dementia with Lewy bodies, the most common of the dementias associated with extrapyramidal disease, is becoming better recognized for its unique management issues. At least some of the frontotemporal dementias, which in this article encompass the progressive aphasias, have mutations in the tau gene that account for some of the phenotypic variations.

Dystonia in corticobasal degeneration

OBJECTIVE

To characterize the clinical features, particularly dystonia, in patients with clinically diagnosed or pathologically proven corticobasal degeneration (CBD).

BACKGROUND

Although dystonia has been reported in many neurodegenerative disorders, it has not been studied in CBD. Dystonia, often accompanied by painful rigidity and fixed contractures, is one of the most disabling features of CBD.

METHODS

The medical records, imaging studies, and videotapes of 66 patients who satisfied the clinical criteria of CBD, evaluated between 1988 and 1998, were reviewed. The occurrence, nature, and distribution of dystonic features were analyzed and correlated with other features of CBD.

RESULTS

Of the 66 patients with CBD, 39 (59.0%) had dystonia. The mean age at onset of initial symptoms was 63.9 years (range 44--75). In 20 (51.0%) patients, dystonic symptoms began in one arm, while 13 (33.0%) patients had initial leg involvement. At least one arm was affected in 36 (92.0%) dystonic patients. Although 11 (28.0%) patients had leg dystonia, the leg was the predominant site of involvement in only 1 patient. Only 12 (31.0%) patients had dystonia involving the head, neck, or trunk in the course of the disease. The diagnosis of CBD was confirmed in all 4 patients who had autopsies.

CONCLUSION

In this large series of CBD patients we found that asymmetric limb dystonia, particularly affecting one arm, is a common manifestation of CBD; dystonia may be the initial manifestation of this neurodegenerative disorder. Axial or leg dystonia, without significant involvement of an arm, is rare. There is no effective treatment for this relentless disorder, except for temporary relief of dystonia and pain, with local botulinum toxin injections.

Assessment of suspected dementia

At the Second Canadian Consensus Conference on Dementia (CCCD) (February, 1998), a group of neurologists, geriatricians, and psychiatrists met to consider guidelines for evaluation of dementia in Canada. This review paper formed a background paper for their discussion of dementia diagnosis. These experts from across the country concluded that diagnosis of suspected dementia cases continued to rest on skilled clinical assessment. Mental status exam, preferably in some quantifiable form, has become an essential part of the assessment. Selected laboratory tests are advisable in all cases (CBC, TSH, electrolytes, calcium, and glucose), but the CCCD continued to advise that CT scanning was mandatory only in selected cases where clinical findings pointed to another possibility besides Alzheimer's disease. The growing list of other diagnostic measures with potential usefulness in diagnosis of Alzheimer's disease or dementia in general was reviewed, but the evidence was judged as insufficient to support routine use of these tests by physicians. As new treatments for Alzheimer's disease become available, neurologists face new diagnostic challenges--differentiating Mild Cognitive Impairment, Frontotemporal dementias and Mixed dementias, and Lewy Body Dementia. Guidelines to aid in differential diagnosis are presented.

Cortical-basal ganglionic degeneration: a clinical, functional and cognitive evaluation (1-year follow-up)

We decided to evaluate a patient who was diagnosed with cortical-basal ganglionic degeneration from a clinical, instrumental and neuropsychological perspective. Our aim was to employ a new instrumental tool, functional magnetic resonance, in order to evaluate his cortical damage. We then followed the pathological course for 1 year and tested the patient again: we discuss the results of our evaluation, having an overview of the literature on the topic. In particular, we focused our attention on his apraxia, trying to suggest a dynamic and anatomical model to guarantee a possible explanation of his behavior.

New insights into genetic and molecular mechanisms of brain degeneration in tauopathies

Abundant neurofibrillary lesions consisting of the microtubule associated protein tau and amyloid beta peptide deposits are the defining lesions of Alzheimer's disease. Prominent filamentous tau pathology and brain degeneration in the absence of extracellular amyloid deposition characterize a number of other neurodegenerative disorders (i.e. progressive supranuclear palsy, corticobasal degeneration, Pick's disease) collectively referred to as tauopathies. The discovery of multiple tau gene mutations that are pathogenic for hereditary frontotemporal dementia and parkinsonism linked to chromosome 17 in many kindreds, as well as the demonstration that tau polymorphisms are genetic risk factors for sporadic tauopathies, directly implicate tau abnormalities in the onset/progression of neurodegenerative disease. Different tau gene mutations may be pathogenic by impairing the functions of tau or by perturbing the splicing of the tau gene, thereby resulting in biochemically and structurally distinct tau aggregates. However, since specific polymorphisms and mutations in the tau gene lead to diverse phenotypes, it is plausible that additional genetic or epigenetic factors influence the clinical and pathological manifestations of both familial and sporadic tauopathies. Thus, efforts to develop animal models of tau-mediated neurodegeneration should provide further insights into the onset and progression of tauopathies as well as Alzheimer's disease, and they could accelerate research to discover more effective therapies for these disorders.

Frontotemporal dementia

Frontotemporal dementia (FTD) is a unique neurodegenerative disease that can be differentiated from Alzheimer's disease and other diseases that result in cognitive complaints. The primary anatomic focus of degeneration determines the clinical presentation, which can vary from aphasia to behavioral symptoms. Expanding knowledge about the genetics and biochemistry of FTD may lead to specific treatments.