Pathologic heterogeneity in clinically diagnosed corticobasal degeneration.

BACKGROUND: Early reports suggested that corticobasal degeneration (CBD) is a distinct clinicopathologic entity. Because patients have had a fairly consistent constellation of clinical and laboratory findings, many have proposed that the pathologic diagnosis can be surmised with confidence during life. OBJECTIVE: To analyze the pathologic findings in a large series of cases with clinically diagnosed CBD. METHODS: Using the medical research linkage system of the Mayo Clinic for the period January 1990 to December 1997, we identified cases diagnosed during life with CBD who subsequently underwent autopsy. All patients had progressive asymmetric rigidity and apraxia (except one with rigidity but no apraxia) with other findings, suggesting additional cortical and basal ganglionic dysfunction. All cases underwent standardized neuropathologic examination with the distribution and severity of the pathologic changes determined for each case and the pathologic diagnoses based on currently accepted criteria. RESULTS: Thirteen cases were identified. The pathologic diagnoses were CBD in seven, AD in two, and one each for progressive supranuclear palsy, Pick's disease, nonspecific degenerative changes, and Creutzfeldt-Jakob disease. Two cases had negligible basal ganglia and nigral degeneration despite previously having obvious extrapyramidal signs. However, all patients had focal or asymmetric cortical atrophy with coexisting neuronal loss and gliosis with or without status spongiosis, which was maximal in the parietal and frontal cortical regions. CONCLUSIONS: The constellation of clinical features considered characteristic of CBD is associated with heterogeneous pathologies. Furthermore, this syndrome can occur in the absence of basal ganglia and nigral degeneration. The one invariable pathologic abnormality in patients with this syndrome, however, is asymmetric parietofrontal cortical degeneration. At present, accurate diagnosis of CBD requires tissue examination.     

Cortico-basal degeneration

Cortico-basal degeneration (CBD) or cortico-basal ganglionic degeneration is a condition characterised by selective cortical atrophy of parietal and in a lesser extent, frontal lobe associated with dysfunction of the basal ganglia. The clinical symptoms of CBD, predominantly extrapyramidal signs (bradykinesia and rigidity) and apraxia, affect often only one body side in the onset phase, with the left one being more frequent. Neuropathological studies reveal neuronal loss, gliosis, and achromasia chiefly in frontal and parietal cortex, as well as in basal ganglia and substantia nigra. Functional investigations, such as SPECT, disclose similar distribution of abnormalities (hypometabolism). The aetiology and causative treatment of CBD are unknown. The authors highlight the diagnostic difficulties in CBD including a necessity of a prolonged patient's observation in order to ascertain the differential diagnosis of other neurodegenerative disorders, in particular progressive supranuclear palsy, Alzheimer's disease and Parkinson's disease.     

The multiple phenotypes of corticobasal syndrome and corticobasal degeneration: implications for further study

Corticobasal degeneration (CBD) is a complex neurodegenerative disorder which nomenclature of which its nomenclature and characterization continues to evolve. The core clinical features that have been considered characteristic of the disorder include progressive asymmetric rigidity and apraxia, with other findings suggesting additional cortical (e.g., alien limb phenomena, cortical sensory loss, myoclonus, and mirror movements) and basal ganglionic (e.g., bradykinesia, dystonia, and tremor) dysfunctions. The characteristic findings at autopsy are asymmetric cortical atrophy that is typically maximal in the frontoparietal regions, as well as basal ganglia and nigral degeneration. Microscopically, abnormal accumulations of the microtubule-associated tau protein are found in both neurons and glia, and this disorder is now considered one of the “tauopathies.” CBD was initially thought to represent a distinct clinicopathologic entity. Recent studies have shown considerable clinicopathologic heterogeneity, leading some to use the term “corticobasal syndrome” (CBS) for the constellation of findings initially considered characteristic of the disorder, and the term “corticobasal degeneration” for the histopathologic disorder. In this review, the multiple phenotypes/syndromes associated with CBD pathology, and multiple diseases associated with the CBS, are presented. The clinicopathologic heterogeneity in CBS/CBD and the implications of this heterogeneity on clinical practice, on understanding the focal/asymmetric cerebral degeneration syndromes, and on future research are all reviewed.     

Corticobasal degeneration: a pathologically distinct 4R tauopathy

Corticobasal degeneration (CBD) is a rare, progressive neurodegenerative disorder with onset in the 5(th) to 7(th) decade of life. It is associated with heterogeneous motor, sensory, behavioral and cognitive symptoms, which make its diagnosis difficult in a living patient. The etiology of CBD is unknown; however, neuropathological and genetic evidence supports a pathogenetic role for microtubule-associated protein tau. CBD pathology is characterized by circumscribed cortical atrophy with spongiosis and ballooned neurons; the distribution of these changes dictates the patient's clinical presentation. Neuronal and glial tau pathology is extensive in gray and white matter of the cortex, basal ganglia, diencephalon and rostral brainstem. Abnormal tau accumulation within astrocytes forms pathognomonic astrocytic plaques. The classic clinical presentation, termed corticobasal syndrome (CBS), comprises asymmetric progressive rigidity and apraxia with limb dystonia and myoclonus. CBS also occurs in conjunction with other diseases, including Alzheimer disease and progressive supranuclear palsy. Moreover, the pathology of CBD is associated with clinical presentations other than CBS, including Richardson syndrome, behavioral variant frontotemporal dementia, primary progressive aphasia and posterior cortical syndrome. Progress in biomarker development to differentiate CBD from other disorders has been slow, but is essential in improving diagnosis and in development of disease-modifying therapies.     

Corticobasal degeneration with olivopontocerebellar atrophy and TDP-43 pathology: an unusual clinicopathologic variant of CBD

Corticobasal degeneration (CBD) is a disorder affecting cognition and movement due to a progressive neurodegeneration associated with distinctive neuropathologic features, including abnormal phosphorylated tau protein in neurons and glia in cortex, basal ganglia, diencephalon, and brainstem, as well as ballooned neurons and astrocytic plaques. We identified three cases of CBD with olivopontocerebellar atrophy (CBD-OPCA) that did not have α-synuclein-positive glial cytoplasmic inclusions of multiple system atrophy (MSA). Two patients had clinical features suggestive of progressive supranuclear palsy (PSP), and the third case had cerebellar ataxia thought to be due to idiopathic OPCA. Neuropathologic features of CBD-OPCA are compared to typical CBD, as well as MSA and PSP. CBD-OPCA and MSA had marked neuronal loss in pontine nuclei, inferior olivary nucleus, and Purkinje cell layer. Neuronal loss and grumose degeneration in the cerebellar dentate nucleus were comparable in CBD-OPCA and PSP. Image analysis of tau pathology showed greater infratentorial tau burden, especially in pontine base, in CBD-OPCA compared with typical CBD. In addition, CBD-OPCA had TDP-43 immunoreactive neuronal and glial cytoplasmic inclusions and threads throughout the basal ganglia and in olivopontocerebellar system. CBD-OPCA met neuropathologic research diagnostic criteria for CBD and shared tau biochemical characteristics with typical CBD. These results suggest that CBD-OPCA is a distinct clinicopathologic variant of CBD with olivopontocerebellar TDP-43 pathology.     

Basal ganglia lesions in corticobasal degeneration differ from those in Pick's disease and progressive supranuclear palsy: A topographic neuropathological study of six autopsy cases

The distribution of the lesions of the basal ganglia including the striatum, pallidum and subthalamic nucleus were investigated neuropathologically in six Japanese autopsy cases of corticobasal degeneration (CBD) using routine staining including the hematoxylin-eosin (HE) and Holzer methods. We compared the distribution of these lesions with those reported in Pick's disease and progressive supranuclear palsy (PSP). The lesions were classified as mild, moderate or severe. The extent and distribution of basal ganglia lesions in all six cases was uniform: the pallidum showed severe lesions, the striatum moderate lesions, and the subthalamic nucleus mild lesions. In CBD, the degree and distribution of the lesions within the basal ganglia differed from those reported for Pick's disease and PSP; in Pick's disease the lesions of the striatum are more prominent than that of the pallidum, and in PSP the involvement of the subthalamic nucleus is more pronounced than that of the striatum. These neuropathological findings have implications for the morphological differential diagnosis among Pick's disease, CBD, and PSP.     

From Progressive Nonfluent Aphasia to Corticobasal Syndrome: A Case Report of Corticobasal Degeneration

In a previous report, we presented longitudinal clinical, cognitive and anatomical data of a right-handed woman, whose clinical picture evolved from progressive nonfluent aphasia with apraxia of speech to corticobasal syndrome (CBS) in the last stage of the disease. The patient died at age 57 and pathological examination revealed severe atrophy in the left frontal operculum and left premotor area. On histological examination, there was diffuse tau-positive pathology in gray and white cortical hemispheric gray and white matter, basal ganglia and substantia nigra, compatible with corticobasal degeneration (CBD). This case demonstrates the clinical overlap between frontotemporal lobar degeneration and CBD. In this case, early motor speech impairment predicted earlier and more accurately than CBS the presence of underlying tau-pathology and CBD.     

From progressive nonfluent aphasia to corticobasal syndrome: a case report of corticobasal degeneration

In a previous report, we presented longitudinal clinical, cognitive and anatomical data of a right-handed woman, whose clinical picture evolved from progressive nonfluent aphasia with apraxia of speech to corticobasal syndrome (CBS) in the last stage of the disease. The patient died at age 57 and pathological examination revealed severe atrophy in the left frontal operculum and left premotor area. On histological examination, there was diffuse tau-positive pathology in gray and white cortical hemispheric gray and white matter, basal ganglia and substantia nigra, compatible with corticobasal degeneration (CBD). This case demonstrates the clinical overlap between frontotemporal lobar degeneration and CBD. In this case, early motor speech impairment predicted earlier and more accurately than CBS the presence of underlying tau-pathology and CBD.     

In vivo imaging of microglial activation with [11C](R)-PK11195 PET in corticobasal degeneration.

Corticobasal degeneration (CBD) is a neurodegenerative parkinsonian disorder of unknown cause that shows considerable clinical heterogeneity. In CBD, activated microglia have been shown to be associated closely with the extensive tau pathology found in the affected basal ganglia, brainstem nuclei, and cortical regions. We report on the use of [(11)C](R)-(1-[2-chlorophenyl]-N-methyl-N-[1-methylpropyl]-3-isoquinoline carboxamide) (PK11195) positron emission tomography (PET), a marker of peripheral benzodiazepine binding sites (PBBS) that are expressed by activated microglia, to demonstrate in vivo the degree and distribution of glial response to the degenerative process in 4 patients with CBD. Compared with normal age-matched controls, the CBD patient group showed significantly increased mean [(11)C](R)-PK11195 binding in the caudate nucleus, putamen, substantia nigra, pons, pre- and postcentral gyrus, and the frontal lobe. [11C](R)-PK11195 PET reveals a pattern of increased microglial activation in CBD patients involving cortical regions and the basal ganglia that corresponds well with the known distribution of neuropathological changes, which may therefore help to characterize in vivo the underlying disease activity in CBD.     

Apraxia of eyelid opening in a case of atypical corticobasal degeneration

Summary. Apraxia of eyelid opening (AEO) occurs in several clinical conditions, even in the absence of any other neurological sign; nonetheless, in most of the cases AEO has been reported in association with basal ganglia diseases, such as corticobasal degeneration (CBD). We describe a patient with a clinical diagnosis of frontotemporal dementia who, later, developed parkinsonian signs and AEO. We suggest that the finding of AEO in patients with a frontotemporal syndrome could be a helpful expedient for the early diagnosis of atypical clinical findings of CBD, characterised by behavioural and cognitive aspects at first.Received March 8, 2003; accepted June 11, 2003 Published online August 13, 2003     

Neuroimaging features in progressive supranuclear palsy and corticobasal degeneration]

Progressive supranuclear palsy (PSP) and cortocobasal degeneration (CBD) are often clinically confused with each other. In this paper, based our previous and on-going morphological and functional neuroimaging studies, the features characteristic of the two diseases are discussed. In PSP patients, the atrophic and metabolic changes are dominant in the frontal lobes, basal ganglia, and midbrain, while in CBD patients, the changes are dominant in the parietal lobe. There is little overlap of topographical distribution of atrophy and functional changes between PSP and CBD, despite the considerable similarity of symptoms of the two disorders. The clear distinction between the two diseases may be in part caused by the criteria-based subject selection process; based on stringent clinical diagnostic criteria for each disorder, which have a high specificity and a low sensitivity, only patients that are typical of each disease are compared. Nevertheless, these neuroimaging features appear to reflect different clinical and pathologic phenotypes between the two diseases. These findings suggest that neuroimagings facilitate the differential diagnosis between patients with PSP and those with CBD.     

Magnetic Resonance Imaging of Corticobasal Degeneration

Corticobasal degeneration (CBD) is an adult–onset, progressive parkinsonian syndrome with strikingly asymmetrical features, and signs and symptoms referable to both cerebral cortex and basal ganglia. Although once considered rare, it is now recognized with increasing frequency during life. Eight patients with clinically diagnosed CBD and 8 age– and sex–matched patients with Parkinson's disease underwent high–field–strength magnetic resonance imaging (MRI) of the brain. MRIs were graded by a blinded neuroradiologist using a semiquantitative (0–3) scale. MRI of patients with CBD revealed significantly greater T2–weighted signal hypointensity in the putamena and globi pallidi, and ventricular enlargement. When specifically sought, asymmetrical cortical atrophy was identified in 5 of 8 CBD patients. Increased T2–weighted lenticular signal hypointensity, ventricular enlargement, and asymmetrical cortical atrophy are supportive MRI findings of CBD.     

Distribution of basal ganglia lesions in Pick's disease with Pick bodies: A topographic neuropathological study of eight autopsy cases

The distribution of the basal ganglia lesions, including the amygdala, striatum, and pallidum, were investigated neuropathologically in eight Japanese autopsy cases of Pick's disease with Pick bodies. The lesions were classified as mild, moderate or severe. The degree and distribution of basal ganglia lesions in all eight cases were uniform: the amygdala showed severe to moderate lesions, the caudate nucleus and putamen showed moderate to mild lesions, and the pallidum showed mild lesions. Furthermore, the lesions in the amygdala were more prominent in the basolateral group than in the corticomedial group. In Pick's disease with Pick bodies, the degree and distribution of the lesions within the basal ganglia differs from those reported in both ‘Pick's disease without Pick bodies’ and corticobasal degeneration (CBD), in which severe lesions were present in the pallidum. These neuropathological findings may contribute to the morphological differential diagnosis among Pick's disease with Pick bodies, ‘Pick's disease without Pick bodies’, and CBD.     

Exome sequencing in familial corticobasal degeneration

BackgroundCorticobasal degeneration (CBD) is a neurodegenerative, sporadic disorder of unknown cause. Few familial cases have been described.ObjectiveWe aim to characterize the clinical, imaging, pathological and genetic features of two familial cases of CBD.MethodsWe describe two first cousins with CBD associated with atypical MRI findings. We performed exome sequencing in both subjects and in an unaffected first cousin of similar age.ResultsThe cases include a 79-year-old woman and a 72-year-old man of Native American and British origin. The onset of the neurological manifestations was 74 and 68 years respectively. Both patients presented with a combination of asymmetric parkinsonism, apraxia, myoclonic tremor, cortical sensory syndrome, and gait disturbance. The female subject developed left side fixed dystonia. The manifestations were unresponsive to high doses of levodopa in both cases. Extensive bilateral T1-W hyperintensities and T2-W hypointensities in basal ganglia and thalamus were observed in the female patient; whereas these findings were more subtle in the male subject. Postmortem examination of both patients was consistent with corticobasal degeneration; the female patient had additional findings consistent with mild Alzheimer's disease. No Lewy bodies were found in either case. Exome sequencing showed mutations leading to possible structural changes in MRS2 and ZHX2 genes, which appear to have the same upstream regulator miR-4277.ConclusionsCorticobasal degeneration can have a familial presentation; the role of MRS2 and ZHX2 gene products in CBD should be further investigated.     

The overlap of corticobasal degeneration and Alzheimer changes: An autopsy case

The aspects of various neurodegenerative diseases can be observed overlapping with each other during autopsy. Corticobasal degeneration (CBD) is a rare neurodegenerative disease, whereas Alzheimer disease (AD) is the most common cause of dementia. In this article, we present the combination of CBD and AD in an autopsy case. The patient, an 82‐year‐old right‐handed woman developed asymmetrical parkinsonism, visuospatial dysfunction and memory loss, as well as subsequent non‐influent aphasia over the past 10 years. The autopsy revealed characteristic CBD‐related pathology, ballooned neurons, globose tangles and astrocytic plaques, mainly in the frontal cortex and basal ganglia. The Alzheimer‐related pathology was also present concomitantly. Senile plagues deposited diffusively throughout the hippocampus and neocortices. Neurofibrillary tangles (NFTs) were more confined to the hippocampus. The autopsy demonstrated pathological overlap of CBD and AD, which therefore explained the clinical early development of dementia and parkinsonism. We should suspect the concurrence of various neurodegenerative disorders in any case with atypical or complex clinical manifestations. Tau pathology is a prominent feature in both CBD and AD. Such a combination would be a clue for the pathogenesis of various tauopathies.     

Imaging of activated microglia with PET and [11C]PK 11195 in corticobasal degeneration.

Positron emission tomography (PET) using [(11)C]PK 11195, a ligand for peripheral benzodiazepine receptor binding sites, offers the opportunity to image activated microglia in vivo. This tool may therefore be used to display the occurrence of microglial activation in the course of neurodegeneration. A patient with the clinical diagnosis of corticobasal degeneration (CBD) and left-sided symptoms was studied using fluorodeoxyglucose (FDG) and [(11)C]PK 11195 PET. We found a marked right hemispheric hypometabolism and asymmetric microglial activation in corresponding areas of the basal ganglia and right temporal and parietal cortex. [(11)C]PK 11195 PET suggests involvement of microglial activation in the pathogenesis of CBD.     

Basal ganglia lesions in ‘Pick complex’: A topographic neuropathological study of 19 autopsy cases

The distribution of basal ganglia lesions, including the amygdala, striatum (caudate nucleus, putamen), pallidum, and substantia nigra, were reinvestigated in 19 Japanese autopsy cases of ‘Pick complex’, consisting of five patients with corticobasal degeneration (CBD), 10 patients with Pick's disease with Pick bodies (PDPB), and four patients with generalized variant of Pick's disease (gvPD). The lesions in the amygdala, striatum, and pallidum were classified into three categories (severe, moderate, and slight). The lesions in the substantia nigra were qualitatively judged, compared with normal controls. In CBD, basal ganglia lesions in all five cases were uniform: the pallidum showed severe lesions, the striatum moderate lesions, the amygdala slight lesions, and obvious neuronal loss of the substantia nigra was verified in all five cases. Basal ganglia lesions in 10 cases of PDPB were also uniform: the amygdala disclosed severe to moderate lesions, the striatum moderate to slight lesions, the pallidum slight lesions, while obvious neuronal loss of the substantia nigra was found in only two of nine cases in which this structure was examined. Furthermore, basal ganglia lesions in all four cases of gvPD were uniform: the caudate nucleus showed severe lesions, the putamen and amygdala severe to moderate lesions, the pallidum moderate to slight lesions, and obvious neuronal loss of the substantia nigra was confirmed in all four cases. This study, using conventional staining such as hematoxylin‐eosin and Holzer, clarified that there were prominent lesions in the pallidum in CBD, in the amygdala in PDPB, and in the caudate nucleus in gvPD, respectively. In addition, nigral involvement was usually found in CBD and gvPD, but was rarely seen in PDPB. These neuropathological findings may help to elucidate the pathological heterogeneity of basal ganglia lesions in ‘Pick complex’.     

Pathologically confirmed corticobasal degeneration presenting with visuospatial dysfunction

Corticobasal degeneration (CBD) typically manifests as progressive asymmetric rigidity and apraxia, although other non-motor presentations have been reported. We report two patients with pathologically diagnosed CBD who presented with prominent visuospatial dysfunction. The pathological changes were maximal in the visual association cortices, but absent in 31 cases of pathologically proven CBD with more typical antemortem features. Underlying CBD should be considered in the differential diagnosis of patients with findings reflecting posterior cerebral dysfunction.     

Corticobasal degeneration: etiopathological significance of the cytoskeletal alterations

We have studied brain tissues from three patients with corticobasal degeneration (CBD) histologically, ultrastructurally and immunohistochemically. Ballooned neurons in the cerebral cortex and severe degeneration of the substantia nigra were observed in them all and weakly basophilic neurofibrillary tangles (NFTs) were distributed widely in the basal ganglia and brain stem. Ultrastructural examination demonstrated that the NFTs comprised characteristic 15-nm-wide straight tubules, which showed positive immunohistochemical staining with an antibody against tau, but not ubiquitin. Tau-immunoreactive neuronal cell bodies without NFTs also were found in the cerebral cortex and subcortical nuclei, predominantly in the brain stem, and the greatest number of tau-positive glial inclusions occurred in the cerebral gray and white matter of the pre- and post-central gyri. These inclusions comprised tubular structures with diameters of about 15 nm and were localized in the oligodendroglial cellular cytoplasm and processes. These findings indicate that there is a close cytoskeletal pathological relationship between CBD and progressive supranuclear palsy.     

Bilateral upper limb rehabilitation with videogame-based feedback in corticobasal degeneration: a case reports study

Corticobasal degeneration (CBD) is a neurodegenerative disorder characterized by a combination of cortical and basal ganglia signs. We reported two cases treated with a bilateral upper limb rehabilitation tool with videogame based feedback for 3 time per week for 8 weeks. Both patients showed an improvement of pinch and grasp forces and motor function. However, both of them reported an increased upper limb pain. Bilateral upper limb mechanical device with exergame feedback was effective also in the two patients suffering of CBD for limiting the effects of apraxia by performing intensive purposeful task training.