Electron microscopic study of neurofibrillary tangles in Steele-Richardson-Olszewski syndrome

Problems in the Diagnosis of Progressive Supranuclear Palsy (Steele — Richardson — Olszewski Syndrome)

Five patients with progressive supranuclear palsy are described, in whom the ophthalmoplegia developed late in the course of the disease. In two, an internuclear component was identified in the ophthalmoplegia, and one patient had an alternating nystagmus of a type not previously described in this condition.

The late appearance of the ophthalmoplegia, with a corresponding delay in establishing the diagnosis, is compared to the similar experience of Pfaffenbach et al (1972) in six patients.

Other clinical features, previously seldom described, have been encountered. Dysphasia was seen in two cases, both of whom had evidence of cortical atrophy on neuro-radiological investigation. The evidence that cortical changes, in particular the presence of neurofibrillary tangles, may be a specific morphological characteristic of the disease rather than a chance association is discussed. Disorders of respiratory rhythm in four patients were similar to those described by Mastaglia et al. (1973), and indistinguishable from those occurring after encephalitis lethargica.

A review of cases resembling progressive supranuclear palsy in the early part of the century fails to show any with post-encephalitic features, nor does a search of reviews of eye movement disorders in encephalitis lethargica and post-encephalitic Parkinsonism provide comparable cases. None of the forty patients with post encephalitic Parkinsonism examined at the Highlands Hospital had a clinical picture resembling progressive supranuclear palsy.

It is suggested that neither on clinical nor pathological grounds is it justifiable to equate this disorder with known postencephalitic syndromes.

Are frontotemporal lobar degeneration, progressive supranuclear palsy and corticobasal degeneration distinct diseases?

New findings relating to the clinical, genetic and molecular bases of neurodegenerative disorders have led to a shift away from traditional nomenclatures of clinical syndromes. Historically, frontotemporal lobar degeneration (FTLD), corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP) were classified on the basis of distinct clinical and pathological features. In recent years, however, advances in molecular and genetic research have led clinicians to suggest that the similar etiologies of the three disorders warrant their amalgamation into a single disorder with three subtypes. In this Review, we consider the utility and validity of combining FTLD, CBD and PSP. The earliest reports of these disorders demonstrate their distinctiveness, whereas recent findings challenge traditional nomenclatures by showing etiological overlap. For example, tau inclusions have been confirmed in patients with CBD and those with PSP, and in some patients with FTLD, implying that all three disorders are 'tauopathies'. Furthermore, most patients with progressive nonfluent aphasia, a subtype of FTLD, show PSP or CBD post-mortem. Even tau-related cases of FTLD, CBD and PSP are distinguishable on the basis of other criteria, however, and many FTLD cases do not show tau pathology. We argue, therefore, that FTLD, CBD and PSP should be considered as pathologically similar but distinct syndromes. New research criteria for CBD and PSP should note that progressive nonfluent aphasia is often a precursor of these conditions.

Tauopathies: classification and clinical update on neurodegenerative diseases associated with microtubule-associated protein tau

The majority of neurodegenerative diseases are characterized by the deposition of insoluble protein in cells of the neuromuscular system. Advances in molecular neuropathology have allowed a classification system of neurodegenerative diseases based on this protein accumulation. Microtubule-associated tau is one protein that has important functions in healthy neurons, but forms insoluble deposits in diseases now known collectively as tauopathies. Tauopathies encompass more than 20 clinicopathological entities, including Alzheimer's disease, the most common tauopathy, progressive supranuclear palsy, Pick's disease, corticobasal degeneration and post-encephalitic parkinsonism. There are important clinical, pathological, biochemical and genetic similarities in the range of these diseases and they have helped to advance our understanding of the aetiological factors that initiate neurodegeneration and tau accumulation. This review examines the important clinical features of the most prevalent tauopathies and the molecular and pathological features that underpin the classification system.

Individual and regional variations of phospho-tau species in progressive supranuclear palsy

The purpose of this study was to learn about possible variations in phospho-tau profiles in terms of case-to-case differences, regional modifications and diversification of tau phosphorylation sites in five PSP cases with moderate to severe frontosubcortical dysfunction. Gel electrophoresis of sarkosyl-insoluble fractions and Western blotting with five anti-tau phospho-specific antibodies directed to phosphorylation sites Thr181, Ser202, Ser214, Ser396 and Ser422 were used to study four brain regions including frontal cortex, area 8, subcortical white matter of the frontal lobe, caudate/putamen: striatum, and basis pontis: pons. Although two bands of 66 and 62 kDa were observed in almost every region in each case, the intensity of the bands depends on the anti-tau phospho-specific antibody. More importantly, bands of 72, 50/55 and 37 kDa were commonly found in PSP brains, whereas other bands of about 60, 42, 33 and 29 kDa were irregularly observed. The pattern of bands differed slightly from one case to another and from one region to another. Moreover, the phospho-tau profile differed depending on the anti-tau phospho-specific antibody used. These data suggest that several species of tau are variably phosphorylated at a given time in a given region (and probably in a given cell), and that tau aggregates are composed of several phosphorylated truncated or cleaved tau molecules, in addition to phosphorylated complete tau isoforms.

Anatamopathological spectrum of tauopathies

The presence of tau-positive intraneuronal filamentous inclusions with or without additional inclusions in glial cells has been recognised as a major neuropathological feature in a significant group of neurodegenerative diseases, which are described as tauopathies. In one category of such diseases, the neuronal inclusions occur in association with extracellular deposition of a second aggregated protein (secondary tauopathies), whereas in another, the filamentous inclusions composed of tau are the sole neuropathological abnormality (primary tauopathies). Genetic studies of tauopathies in general, and in frontotemporal dementia with parkinsonism linked to chromosome 17 in particular, have significantly contributed to our knowledge about the pathogenesis not only of rare hereditary conditions but also of other more common diseases such as Alzheimer's disease and progressive supranuclear palsy.

Pathological, clinical and genetic heterogeneity in progressive supranuclear palsy

We have identified two groups of patients with clinically typical and atypical, pathologically diagnosed progressive supranuclear palsy (PSP), and investigated their genetic and molecular pathological characteristics. Those with clinically typical PSP are more likely to have the PSP susceptibility genotype and to have the deposition of PSP-type hyperphosphorylated tau protein. The clinically atypical PSP group contains a number of different clinical syndromes, including an L-dopa unresponsive bradykinetic syndrome and a clinical syndrome closely resembling idiopathic Parkinson's disease. The clinically atypical PSP group are less likely to have the PSP susceptibility genotype and often have the deposition of Alzheimer's disease paired helical filament type hyperphosphorylated tau. This study suggests that the tau PSP susceptibility genotype is most strongly associated with clinically typical PSP. Neurofibrillary tangle parkinsonian disorders, which pathologically resemble PSP but involve the deposition of Alzheimer's disease-type tau often without involvement of the tau susceptibility genotype, need to be distinguished for diagnostic and research purposes.

Neurodegenerative tauopathies

The defining neuropathological characteristics of Alzheimer's disease are abundant filamentous tau lesions and deposits of fibrillar amyloid beta peptides. Prominent filamentous tau inclusions and brain degeneration in the absence of beta-amyloid deposits are also hallmarks of neurodegenerative tauopathies exemplified by sporadic corticobasal degeneration, progressive supranuclear palsy, and Pick's disease, as well as by hereditary frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17). Because multiple tau gene mutations are pathogenic for FTDP-17 and tau polymorphisms appear to be genetic risk factors for sporadic progressive supranuclear palsy and corticobasal degeneration, tau abnormalities are linked directly to the etiology and pathogenesis of neurodegenerative disease. Indeed, emerging data support the hypothesis that different tau gene mutations are pathogenic because they impair tau functions, promote tau fibrillization, or perturb tau gene splicing, thereby leading to formation of biochemically and structurally distinct aggregates of tau. Nonetheless, different members of the same kindred often exhibit diverse FTDP-17 syndromes, which suggests that additional genetic or epigenetic factors influence the phenotypic manifestations of neurodegenerative tauopathies. Although these and other hypothetical mechanisms of neurodegenerative tauopathies remain to be tested and validated, transgenic models are increasingly available for this purpose, and they will accelerate discovery of more effective therapies for neurodegenerative tauopathies and related disorders, including Alzheimer's disease.

Progressive supranuclear palsy (Steele-Richardson-Olszewski disease)

Progressive supranuclear palsy is a neurodegenerative disease which affects the brainstem and basal ganglia. Patients present with disturbance of balance, a disorder of downward gaze and L-DOPA-unresponsive parkinsonism and usually develop progressive dysphagia and dysarthria leading to death from the complications of immobility and aspiration. Treatment remains largely supportive but, potentially, treatments based on cholinergic therapy may be useful. As in Alzheimer's disease, the neuronal degeneration is associated with the deposition of hyperphosphorylated tau protein as neurofibrillary tangles but there are important distinctions between the two diseases. Evidence from familial fronto-temporal dementia with parkinsonism linked to chromosome 17 suggests that tau protein deposition is a primary pathogenic event in some neurodegenerative diseases. The understanding of the mechanism of tau deposition in progressive supranuclear palsy is likely to be of importance in unravelling its aetiology.

Neuropathologic differentiation of progressive supranuclear palsy and corticobasal degeneration

Progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) are usually sporadic multi-system degenerations associated with filamentous tau inclusions in neurons and glia. As such they can be considered sporadic tauopathies in contrast to familial tauopathies linked to mutations in the tau gene. Mutations have not been found in the tau gene in either PSP or CBD. The clinical syndromes and neuroimaging of typical cases of PSP and CBD are distinct; however, atypical cases are described that have overlapping clinical and pathologic features. Both PSP and CBD have similar biochemical alterations in the tau protein, with the abnormal tau protein containing predominantly four-repeat tau. While there is overlap in the pathology in PSP and CBD, there are sufficient differences to continue the present day trend to consider these separate disorders. Several important pathologic features differentiate PSP from CBD. Ballooned neurons are frequent and nearly a sine qua non for CBD, but they are found in PSP at a frequency similar to that of other neurodegenerative diseases, such as Alzheimer's disease. Astrocytic lesions are different, with tufted astrocytes found in motor cortex and striatum in PSP and astrocytic plaques in focal atrophic cortices in CBD. The most characteristic neuronal tau pathology in CBD is wispy, fine filamentous inclusions within neuronal cell bodies, while affected neurons in PSP have compact, dense filamentous aggregates characteristic of globose neurofibrillary tangles. Thread-like processes in gray and white matter are much more numerous and widespread in CBD than in PSP. The brunt of the pathology in CBD is in the cerebrum, while the basal ganglia, diencephalon and brainstem are the targets of PSP. Further clinicopathologic studies will refine our understanding of these disorders and open the possibility that common etiologic factors may be identified for these unusual sporadic tauopathies.

Neurofibrillary tangle parkinsonian disorders--tau pathology and tau genetics

A number of related conditions, including progressive supranuclear palsy (PSP), corticobasal degeneration, Pick's disease, and the parkinsonism dementia complex of Guam, are characterized by the deposition of tau neurofibrillary tangles in the absence of amyloid pathology. These diseases share some overlap in their topography and clinical features but can be subdivided into three main groups according to the isoforms of the alternatively spliced tau gene that are deposited. The recent description of mutation in tau in frontotemporal dementia, and a common variant of tau that predisposes to PSP, and the relationship of these changes to the tau protein subgroups offers new insights into the pathogenesis of these disorders.

Progressive supranuclear palsy

Richardson observed an unusual clinical syndrome in the 1950s, which he later designated progressive supranuclear palsy (PSP). Over the past 25 years, although knowledge of this disorder has gradually improved, its cause is still unknown, pathogenesis is unclear, and there is still no definitive treatment for this disorder. This article reviews the epidemiology, clinical features, diagnostic criteria, neuropathology, neuroimaging, and treatment of PSP.

Regional quantitative analysis of tau-positive neurons in progressive supranuclear palsy: comparison with Alzheimer's disease

In patients with progressive supranuclear palsy (PSP), various tau-positive abnormal structures are found in the cerebral cortex as well as in the subcortical nuclei. Similar tau-positive abnormalities are also identified in cortico-basal degeneration (CBD). It is therefore questionable as to whether PSP can be neuropathologically differentiated from CBD. It also remains nuclear whether neurofibrillary tangles (NFT) in the cerebral cortex of PSP patients consist of PSP-NFT or concomitant Alzheimer's disease (AD)-NFT, although there have been some reports suggesting that PSP- and AD-NFT are different with respect to distribution pattern and biochemical character. In this study, a regional quantitative analysis of the distribution and antigenicity of tau-positive neurons (TPN) was performed in PSP cases and compared with that in AD cases. TPN consisted of NFT with tangle-formation and pretangle neurons (PN) without tangle-formation. In addition, NFT were subdivided into mature and immature NFT according to the difference of staining properties with anti-tau-related antibodies. The comparison of the TPN of the PSP cases with those of the AD cases revealed that the degree of tangle-formation in the TPN of AD was similar in all of the examined regions, while that in the TPN of PSP varied according to the region and case. Moreover, the NFT in the PSP and AD cases had different distributions according to the cortical layer and subnucleus, even in the common predilection sites of PSP and AD, suggesting that NFT in these regions of the PSP cases consist mainly of PSP-NFT. In addition, the PSP cases could be divided into two groups according to the difference of the tangle-formation of TPN; group I with typical PSP pathology and group II with atypical PSP pathology similar to CBD. This suggests that there is a continuity between PSP and CBD with respect to the distribution and antigenicity of TPN.

Epitope expression and hyperphosphorylation of tau protein in corticobasal degeneration: differentiation from progressive supranuclear palsy

Corticobasal degeneration (CBD) is a rare, progressive neurological disorder characterized by widespread neuronal and glial accumulation of abnormal tau protein. Using immunohistochemistry we analyzed tau epitope expression and phosphorylation state in CBD and compared them to cytoskeletal changes in Alzheimer's disease (AD) and progressive supranuclear palsy (PSP). Epitopes spanning the entire length of the tau protein were present in CBD inclusions. An antibody against the alternatively spliced exon 3 did not recognize cytoskeletal lesions in CBD, but did in AD and PSP. Tau epitopes from each region of the molecule were present in cytoskeletal inclusions in CBD, including gray matter astrocytic plaques, gray and white matter threads, and oligodendroglial inclusions. As in AD, tau from CBD was highly phosphorylated. Antibodies that recognized phosphorylated tau epitopes reacted with material from CBD in a highly phosphatase-dependent manner. Again, all types of inclusions contained phosphorylated epitopes. We conclude that abnormal tau protein in CBD comprises the entire tau molecule and is highly phosphorylated, but is distinguished from AD and PSP by the paucity of epitopes contained in the alternatively spliced exon 3.

Subcortical neurofibrillary degeneration presenting as Steele-Richardson-Olszewski and other related syndromes: a review of 90 pathologically verified cases

We have reviewed 90 patients from the literature with histopathological features compatible with currently accepted criteria for the diagnosis of the Steele-Richardson-Olszewski syndrome (SROS). Only 62 patients (69%) had clinically definite SROS based on the criteria of Maher and Lees. Neurofibrillary degeneration of subcortical structures with involvement of the internal pallidum, the subthalamic nucleus, and substantia nigra was considered essential for the pathological diagnosis. Thirty-six cases (40%) had neocortical neurofibrillary change that bore no clear relationship to the degree of cognitive impairment (chi 2 = 9.293; p < 0.4107). Grumose degeneration of the dentate nucleus was present in 25 cases (28%), and occasionally there were other, less usual, findings such as Pick bodies and Lewy bodies.

Neurofibrillary pathology in progressive supranuclear palsy (PSP)

In progressive supranuclear palsy (PSP), globose neurofibrillary tangles (NFT) are found in the subcortical areas and occasionally in the central cortex and spinal cord. An inverse relationship was found between the degree of neuronal loss and the presence of NFT. It has been postulated that NFT comes first and atrophy as a secondary event. Others authors have reported that the neurologic findings are associated with the presence of carcinomas and the CNS changes can be assessed as a paraneoplastic effect. In PSP the neuritic changes are mainly located in the basal ganglia and composed of straight filaments and tubules, different from the paired helical filaments found in the Alzheimer's disease, suggesting that they are formed of a new type of fibrous protein. In addition immunohistochemistry preparations using antibodies against tau and ubiquitin reveal an antigenic profile similar to early NFT in dementia of Alzheimer's type. These findings support the hypothesis that these changes may reflect different types of non-specific cytoskeletal disorganization.

Cortical tangles in progressive supranuclear palsy

Ten cases of PSP were examined for the presence of neocortical and hippocampal lesions. Samples from 10 cortical areas were stained by Bodian's method and by tau, ubiquitin and beta A4 immunocytochemistry. For the sake of comparison, 5 Alzheimer's cases were studied with the same techniques. Neocortical tangles, star-like tufts of fibers, and neuropil threads were seen in all the cases of PSP. They were stained by Bodian's technique and labelled by an anti-tau, but not by a polyclonal anti-ubiquitin antibody. Senile plaques (Bodian's technique), diffuse or focal amyloid deposits (beta-A4 immunohistochemistry) were rare or absent. The density of tangles was the highest in area 4 and the lowest in area 17. In area 4, the tangles were mainly located in layers V-VI. By contrast, the Alzheimer's tangles had a bimodal distribution (layers III and V-VI). These results favor the specificity of cortical alterations in PSP.

Neurofibrillary tangles in the neurons of spinal dorsal root ganglia of patients with progressive supranuclear palsy

Neurofibrillary tangles (NFTs) occur in neurons of human central nervous system (CNS) both in aged subjects and patients with several degenerative diseases, with a certain topographical predilection. In surveying the NFT distribution in nervous tissue of patients with progressive supranuclear palsy (PSP), we found silver-positive fibrillary tangles in the neurons of dorsal root ganglia (DRG) in two of five patients. By immunohistochemistry, these tangles were stained with antibodies to human tau protein, paired helical filaments (PHFs) and ubiquitin. Electron microscopy revealed that they were mainly composed of PHFs that were morphologically indistinguishable from PHFs in the NFTs of CNS typically seen in Alzheimer's disease brains. Our data demonstrate for the first time that the neurons of DRG produce NFTs in PSP and suggest that the pathological process(es) leading to tangle formation can occur in the neurons of the peripheral nervous system in this disease condition.

Immunohistochemical, ultrastructural and immunoelectron microscopic studies of spinal cord neurofibrillary tangles in progressive supranuclear palsy

Immunohistochemical, ultrastructural and immunoelectron microscopic studies of spinal cord neurofibrillary tangles (NFTs) in progressive supranuclear palsy (PSP) were performed. The spinal cord NFTs reacted with antibodies to tau protein (tau-2), ubiquitin and Alzheimer neurofibrillary tangles (ANTs, Ab 39). Ultrastructurally, the NFTs consisted of bundles of straight fibrils. In longitudinal sections, the individual NFT fibrils appeared as straight fibrils with a diameter of approximately 15 nm. In cross sections, circular structures approximately 15 nm in diameter were seen, and some had a central density. Electron microscopic examination of specimens stained with the antibodies and by the modified Bielschowsky method revealed the products of the tau, ubiquitin and ANTs immunoreactions and silver deposits on the NFT fibrils. This is the first demonstration of the ultrastructure of spinal cord NFTs in PSP.

Glial fibrillary tangles with straight tubules in the brains of patients with progressive supranuclear palsy

A recent report has described the appearance of silver positive, tau-immunoreactive astrocytes in the brains of patients with progressive supranuclear palsy (PSP) (Neurosci. Lett., 135 (1992) 99-102). In this study we confirmed this finding in two cases of PSP by using Bodian silver staining and immunohistochemistry with antibody to human tau protein. By electron microscopy we demonstrated that fibrillary masses present in these unique astrocytes were made up of straight tubules that were indistinguishable from those of neurofibrillary tangles of PSP. The term 'glial fibrillary tangle' was proposed for these structures.

Occurrence of 15-nm-wide straight tubules in neocortical neurons in progressive supranuclear palsy

Ultrastructural investigations were carried out on the cerebral neocortex in two cases of progressive supranuclear palsy. In both cases, characteristic 15-nm-wide straight tubules were observed in the neurons. The numbers of cells containing the straight tubules and of tubules in individual cells were small. However, the occurrence of the tubules strongly suggests that the cerebral neocortex is also exposed to the disease process in progressive supranuclear palsy.

Antigenic characteristics of neurofibrillary tangles in progressive supranuclear palsy

The antigenic components of neurofibrillary tangles in the basal forebrain and brainstem were studied in 4 cases of progressive supranuclear palsy (PSP) at the light and electron microscopic levels, using antibodies to neurofilaments (in the phosphorylated and non-phosphorylated forms); the high, middle and low molecular weight neurofilament subunits; ubiquitin; the microtubule associated proteins MAP1, MAP2 and tau; isolated Alzheimer paired helical filaments and to tubulin, in the tyrosinated and detyrosinated forms. Although PSP neurofibrillary tangles appear to have most antigenic sites in common with those of Alzheimer disease, PSP tangles share epitopes with tyrosinated and detyrosinated tubulin, which has not been demonstrated in Alzheimer neurofibrillary tangles.

Tau antisera recognize neurofibrillary tangles in a range of neurodegenerative disorders

Neurofibrillary tangles occur in a number of apparently distinct neurodegenerative diseases and in normal aging of the human brain. Antibodies raised against Alzheimer's disease paired helical filaments immunolabel the tangles seen in all other tangle-associated disorders examined to date. The neuronal microtubule-associated protein, tau, has recently been identified as an antigenic component of neurofibrillary tangles and senile plaque neurites in Alzheimer's disease. Three different polyclonal antibodies with strong tau immunoreactivity are examined in this study. These antibodies were found to immunostain tangles in normal aged brain and in brains affected by a range of neurodegenerative disorders, including Down's syndrome, Alzheimer's disease plus Parkinson's disease, progressive supranuclear palsy, and the parkinsonism-dementia complex of Guam, as well as Pick bodies in Pick's disease. The findings further illustrate the relative nonspecificity of neurofibrillary lesions in neurodegenerative disorders.

Neurofibrillary tangles in Alzheimer's disease and progressive supranuclear palsy: antigenic similarities and differences. Microtubule-associated protein tau antigenicity is prominent in all types of tangles

The antigenic profile of neurofibrillary tangles (NFT) in Alzheimer's disease (AD), senile dementia of Alzheimer type (SDAT), progressive supranuclear palsy (PSP) and in non-demented aged humans was investigated by light and electron microscopic immunocytochemistry using antisera and monoclonal antibodies to tubulin, microtubule-associated proteins (MAP1, MAP2 and tau), neurofilament proteins and determinants unique to Alzheimer paired helical filaments (PHF). Antibodies to tau proteins labeled NFT in all cases investigated (AD, SDAT, PSP and non-demented aged humans). However, one monoclonal antibody to PHF recognized numerous tangles in AD/SDAT, but only a small minority of the PSP tangles. Antibodies to tubulin, MAP1, MAP2 and neurofilament proteins did not selectively stain NFT. Whereas pretreatment of sections with phosphatase was required for the detection of tangles with Tau-1 monoclonal antibody, digestion of sections with either phosphatase or pronase had no significant effect on the staining pattern obtained with the other antibodies. Our studies show that, as previously described for AD/SDAT, phosphorylated tau polypeptides are also a major antigenic determinant of tangles in PSP, indicating that tangle formation may follow a common pathogenetic pathway in neurofibrillary degenerations. There is, however, at least one epitope in AD/SDAT tangles which seems to be absent on, or at least inaccessible in, the 15-nm straight fibrils of PSP.

Spinal cord lesions in progressive supranuclear palsy: some new observations

The spinal cord was examined in two cases of progressive supranuclear palsy. In both cases, cells with neurofibrillary tangles were seen in the anterior horn, posterior horn, lateral horn, Clark's column, and intermediate gray. The tangles were most frequently observed in the posterior horn. The results suggest that the spinal cord is involved in the pathological process of progressive supranuclear palsy.

Atypical presentation of progressive supranuclear palsy

Four pathologically documented cases of progressive supranuclear palsy are reported. Two patients exhibited severe dementia and 2 parkinsonism; none had the classic ophthalmoplegia. On retrospective analysis, clues to the diagnosis included early prominent gait disturbance, apraxia of eyelid opening in 1 patient, lack of tremor, poor response to levodopa-carbidopa, and severe rigidity with a posture of neck extension terminally in 1 patient. The clinical presentation of progressive supranuclear palsy, therefore, is not as stereotyped as previously thought, and the diagnosis can be overlooked if one adheres rigidly to the classic diagnostic criteria.

Progressive supranuclear palsy--20 years later

Reviewing the literature since recognition of progressive supranuclear palsy (PSP) as a clinicopathological entity 20 years ago, the present state of knowledge is delineated. The etiology of PSP is still unknown. The clinical hallmarks are supranuclear palsy of vertical gaze, axial dystonia in extension and pseudobulbar palsy with marked dysarthria and dysphagia. Accessory features include subcortical dementia, mental, extrapyramidal, pyramidal and cerebellar symptoms. PSP is a disease of the presenium (average age at onset, 59.6 years) with a male preponderance (60% men). The onset is insidious with vague complaints of dysequilibrium (60%), mental changes (46%) and disturbed vision (21%), often preceding abnormal neurological findings. The important borderland and main differential diagnosis is parkinsonism. However, in PSP, responsiveness to antiparkinsonian agents is poor and progression is rapid and fatal within few years (average survival time, 5.7 years). Promising diagnostic tools at present include CT-scanning and neuro-otologic and -ophthalmologic examination. Neuropathological findings, confined to specific diencephalic, brainstem and cerebellar nuclei, include neurofibrillary tangles (ultrastructurally different from those seen in other CNS disorders), neuron loss and gliosis. The importance of research on neurocytochemistry, brain ultrastructure and immunology in the current investigation of PSP is outlined.

Substructure of 20 nm filaments of progressive supranuclear palsy

In contrast to the ultrastructure of Alzheimer's neurofibrillary tangles (NFT), which has been well characterized as accumulations of paired helical 10-nm filaments (PHF) with 80-nm regular constrictions, the morphology of the neurofibrillary changes of PSP remains ill-defined. Until recently, the fine structure of PSP tangles was generally accepted as 15-nm straight filaments or tubules, although many reports describing different electron-microscopic findings have appeared in the literature. In this report, we present morphological data indicating a protofilamentous substructure present in straight filaments of PSP which has some points of similarity with the protofilamentous architectures which have been reported for paired helical filaments of Alzheimer's disease. The straight filaments were found to be composed of six or more helically symmetric 2-5-nm protofilaments. We conclude that despite the varied morphology of filaments in neurofibrillary tangles observed in PSP there may be some underlying identity at the molecular level with the PHF of neurofibrillary tangles of Alzheimer's disease.

An atypical case of progressive supranuclear palsy

We report a 59 year old woman who presented with double vision, nuchal pain and mild dementia. On neurological examination she demonstrated third, sixth and seventh nerve palsies and ataxia. Following intravenous ACTH and oral prednisone therapy she showed a remarkable recovery which left her with only a left facial weakness. She remained well for two years. She then developed bulbar palsy and profound dementia. Pathological examination revealed progressive supranuclear palsy (PSP). This patient demonstrated a greater variability in the course of PSP than has previously been recognized.

The locus coeruleus and its possible role in ageing and degenerative disease of the human central nervous system

The central noradrenergic pathways with the mammalian brain are principally based on that group of nerve cells within the reticular substance of the upper pons known as the locus coeruleus. The physiological role of these nerve cells appears to be one of maintaining homeostasis within the central nervous system, whatever adverse conditions prevail in the rest of the body, through governing the flow of blood through, and degree of water permeability of, the capillary bed. The extensive ramifications of these noradrenergic terminals mean that the atrophy and loss of nerve cells from locus coeruleus that occurs in old age, and especially so in degenerative diseases of the central nervous system such as Alzheimer's disease and other conditions, will have widespread repercussions for brain function. The chain of physiological disturbances set up as a result of this cell loss may mean a progressive failure of homeostasis within the brain, which in the extreme may culminate in that pattern of mental breakdown which is usually termed dementia.

Immunocytochemical comparison of neurofibrillary tangles in senile dementia of Alzheimer type, progressive supranuclear palsy, and postencephalitic parkinsonism

Antiserum raised against a two-cycle-purified human brain microtubule fraction that binds specifically to tangles of senile dementia of the Alzheimer type was tested on the subthalamus, basis pontis, and midbrain sections of two patients with progressive supranuclear palsy. Tangles composed of 15 nm straight fibers in these areas showed positive immunolabeling with the antiserum. The labeling tangles appeared as a fibrous meshwork in neuronal cell bodies and occasionally in short segments of axons. Corresponding sections of brains obtained from patients with idiopathic parkinsonism, striatonigral degeneration, and olivopontocerebellar atrophy treated with the same antiserum did not display peroxidase products. Only in the elderly subjects and patients with postencephalitic parkinsonism did the periaqueductal gray and median raphe show occasional cells that reacted positively with the antiserum. Tangles in the substantia nigra of patients with postencephalitic parkinsonism were also recognized by the antiserum. The results suggest that the two morphologically distinct neurofibrillary tangles share their immunological properties with components present in microtubule fractions of normal brain.

Unusual paired helical filaments in progressive supranuclear palsy

Unusual paired helical filaments (PHF) coexisting with single filaments were observed in neurofibrillary degeneration (NFD) in the globus pallidus, subthalamic nucleus, substantia nigra, and pontine tegmentum of a typical case of progressive supra-nuclear palsy (PSP). Each filament had a diameter of 10-12 nm and showed central low density and a smooth contour. The thickest portion of a pair was 22-24 nm in diameter. The periodicity of twist varied from 150 nm to 300 nm, but each PHF had regular periodicity. The present ultrastructural finding is unusual in the neurofibrillary pathology of PSP, and is also different from the PHF found in Alzheimer type NFD.

Frequency of Alzheimer's neurofibrillary tangle in the brains of progressive supranuclear palsy, postencephalitic parkinsonism, Alzheimer's disease, senile dementia and non-demented elderly person

The frequency and the distribution of Alzheimer's neurofibrillary tangles were examined in those cases of progressive supranuclear palsy (one case), postencephalitic parkinsonism (one case), Alzheimer's disease (two cases), senile dementia (two cases) and non-demented elderly person (three cases). The light microscopic pattern of Alzheimer's neurofibrillary tangles seen in progressive supranuclear palsy was similar to those in postencephalitic parkinsonism, Alzheimer's disease, senile dementia and non-demented elderly person. Some differences in the frequency and the distribution of Alzheimer's neurofibrillary tangles were demonstrated.

The fine structure of neurofibrillary tangles in a case of atypical presenile dementia

The neurofibrillary tangles in a case of atypical presenile dementia were studied by electron microscopy. The tangles consisted of 2 types of tubule: one straight, measuring about 15--20 nm in width, the other twisted. Both types of tubule appeared separately in each neuron; however, occasionally twisted tubules seemed to be distributed among the straight tubules. The implications of these findings are briefly discussed.

Neurofibrillary pathology in progressive supranuclear palsy

We describe the fine structure of the subcortical neurofibrillary tangles (NFT) in 2 cases of progressive supranuclear palsy (PSP). In case 1 (69-year-old man) about one half of the NFT in the midbrain and pons examined were composed of 13-16 nm straight filaments and the other were made up of paired helical filaments (PHF) of Alzheimer type. The NFT in case 2 consisted of straight tubules with infrequent segments of unusual twisted fibril of unknown nature. The simultaneous occurrence of straight and PHF in one of these cases suggests that the NFT in PSP may be similar to those of Alzheimer type occurring in various conditions.

Progressive supranuclear palsy: clinico-pathological and biochemical studies

Ten autopsy cases of Progressive Supranuclear Palsy (PSP) are reported. Age at onset ranged from 16 to 67 years and the duration of illness 3 to 24 years. The clinical features were aggressive mental retardation in 4 cases with early onset, paroxysmal dysequilibrium, ophthalmoplegia, rigidity and akinesia, pseudobulbar palsy and variable degrees of dementia. Neuropathology showed widespread neurofibrillary degeneration associated with system-bound neuronal loss and gliosis in subcortical areas, particularly affecting the subthalamic nucleus, substantia nigra, brainstem tegmentum and dentate nuclei, with no or little involvement of the cerebral cortex. The distribution of the lesions and the ultrastructure of the neurofibrillary tangles made of 15 nm straight filaments (seen in one case) in PSP are different from postencephalitic parkinsonism, Guam Parkinson-dementia complex and brainstem affection in (pre)senile dementia. Post-mortem biochemical analysis of two brains disclosed severe reduction of tyrosine hydroxylase, the key synthetic enzyme of the catecholamine pathway, not only in the nigrostriatal system as seen in Parkinson's disease, but in most areas of the brain-stem and limbic system. The implication and possible pathogenic and therapeutic significance of these biochemical findings are discussed. The etiology of PSP and its nosological position within the degenerative extrapyramidal disorders remain unknown.

Ultrastructure of neurofibrillary tangles in progressive supranuclear palsy

The fine structure of neurofibrillary tangles in the hippocampal gyrus, substantia nigra, pontine nuclei and locus coeruleus of the brain was postmortem studied in a case of progressive supranuclear palsy. Straight tubules and twisted tubules were observed in both the cortical and subcortical neurofibrillary tangles. Most tubules appeared separately in each neuron but a few straight tubules were mixed with the twisted tubules in the cortical tangles. The implication and possible significance of this findings are discussed.

The fine structure of subcortical neurofibrillary tangles in progressive supranuclear palsy

The fine structure of subcortical neurofibrillary tangles was investigated in pallidum, substantia nigra, periaqueductal gray, pontine reticular gray, and dentate nucleus of 5 autopsy cases of Progressive Supranuclear Palsy. Only tangles due to straight 150 A wide filaments have been detected. These findings, obtained from a large series of cases and areas examined, confirm previous observations on the fine structure of neurofibrillary tangles in Progressive Supranuclear Palsy and suggest that the association between tangles due to straight filaments and tangles due to twisted tubules, so far described in one case, is probably exceptional.

Neurofibrillary degeneration in a case of quadriplegia and myoclonic movement

A case of spastic quadriplegia with myoclonic movement was studied by both light and electron microscope. Argentophilic inclusions were found in a unique distribution involving the cerebral cortex, brain stem, cerebellum, and the spinal cord, including the motor neuron system. The fine structure of the inclusions consisted of accumulation of previously undescribed straight or wavy tubules approximately 120A wide devoid of periodic constriction.

Morphological investigations on axonal swellings and spheroids in various human diseases

Axonal swellings and spheroids in various human diseases were studied by light and electron microscopy. 4 cases of infantile neuroaxonal dystrophy, 2 of degenerative diseases, 2 brain tumors and 3 of cerebrovascular disease were examined. Ultrastructurally most spheroids in infantile neuroaxonal dystrophy consisted of interconnected tubules, stacked membranotubular profiles, alternating layered membranes and accumulations of neurofilaments. Combinations of these four constituents were seen only in infantile neuroaxonal dystrophy. "Torpedos" (fusiform swelling of the axon of a Purkinje cell) consisted exclusively of neurofilaments. Spheroids in case 6 (mental retardation) and 7 (atypical teratoma) consisted of interwoven skeins of neurofilaments and grouped mitochondria. Spheroids in case 8 (demyelination) and 9 (cerebrovascular disease) consisted of packed complex bodies and mitochondria. Spheroids in cases 10 and 11 (cerebrovascular disease) consisted of degenerating organelles only. The morphological differences between cases 9, 10 and 11 probably depends on the severity and timing of the cerebral injury. Most spheroids show similar histological and histochemical properties, but ultrastructural study may give some clue to the origin of the bodies.

Ultrastructure of neurofibrillary tangles in progressive supranuclear palsy

Ultrastructure of neurofibrillary tangles was investigated on the subcortical neurons of an autopsy case of progressive supranuclear palsy. The patient was a 64-year-old female and suffered from her illness for 9 years. Two kinds of ultrastructure were observed in the subcortical neurofibrillary tangles, i.e. that 150 A straight tubules and the 220 A twisted tubules. They appeared separately in each neuron and a transition between these two structures could not be remarked. Besides, a few particles with a paracrystalline hexagonal structure were observed in some subcortical neurons.

Frequency of Alzheimer's neurofibrillary tangles in the cerebral cortex in progressive supranuclear palsy (subcortical argyrophilic dystrophy)

The frequency of Alzheimer's neurofibrillary tangles was studied, employing large sections of the cerebral hemispheres, in the cerebral cortex in 2 cases of progressive supranuclear palsy. The majority of the neurofibrillary tangles were found in the smaller nerve cells of the third layer. The typical triangular form was rare, and most of them showed argyrophilic neurofibrillary filaments which coiled around the well-preserved nucleus. We concluded that their occurrence in the cerebral cortex is one of the morphological manifestations of the disease process.