The Experts below are selected from a list of 42 Experts worldwide ranked by ideXlab platform
José A. Armengol - One of the best experts on this subject based on the ideXlab platform.
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IPSILATERALLY LOCATED Olivocerebellar PROJECTION NEURONS OF THE CHICK
Neuroscience research, 1996Co-Authors: A. López-román, José A. ArmengolAbstract:AbsTract The use of horseradish peroxidase (HRP) and 1,1′-Dioctadecyl-3,3,3′,3′-tetramethyl-indocarbocyanine perchlorate (DiI) as retrograde tracers, applied in vitro within the Olivocerebellar Tract of both embryos (9 to 21 days old) and postnatal (3–60 days old) chickens, has allowed the observation of a small population of neurons located ipsilaterally to the placement of the tracer. These neurons, whose morphology indicated that they belong to the inferior olive rather than to the reticular formation or the raphe nuclei, followed the same developmental steps as normally placed inferior olivary neurons. Furthermore, pedunculotomy experiments made on 3-day-old chickens demonstrated that ipsilateral neurons sent their axons through the cerebellar peduncle. In contrast to the completely crossed arrangement of the Olivocerebellar projection, the present results show the existence, as in the rat, of a few ipsilateral inferior olivary neurons whose significance is unclear.
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Pattern of degeneration of the rat inferior olivary complex after the early postnatal axotomy of the Olivocerebellar projection
Histology and histopathology, 1996Co-Authors: José A. Armengol, A. López-románAbstract:Neuronal death of inferior olivary neurons after early axotomy of the Olivocerebellar Tract was studied in newborn (Pl) hemicerebellectomized rats during the first six days after lesion. The degeneration of the inferior olive showed a topographic pattem from one (P2) to six days after axotomy (P7), after which this complex had almost completely disappeared. The first degenerative changes were observed in the principal olive (P2), while the media1 accessory olive was the later-degenerated area (P5). The analysis of these degenerative changes provides a reference for future experimental studies. Furthermore, the topographic study of the degenerative process demonstrated that: i) the most vulnerable neurons were dorsolaterally located, whereas the most resistant ones occupied the media1 aspect of the inferior olivary complex, ii) the comparison between the topographical arrangement of the inferior olivary neurons according to their birth dates, and the rate of degenerative changes observed after hemicerebellectomy, open the possibility that the neurona1 generation date and the response to the axotomy of the inferior olivary neurons could be related.
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Morphological evidence for the presence of ipsilateral inferior olivary neurons during postnatal development of the Olivocerebellar projection in the rat.
The Journal of comparative neurology, 1994Co-Authors: A. López-román, José A. ArmengolAbstract:The presence of ipsilateral inferior olivary neurons during postnatal development of the Olivocerebellar projection in the rat was investigated by two in vitro axonal tracing methods and by the axotomy of one Olivocerebellar Tract. The experiments were carried out before (P1), during (P5–P10) and after (P20) the period of multiple innervation of Purkinje cells by climbing fibers. According to present results: (1) ipsilateral inferior olivary neurons are distributed, on all analyzed days, throughout the entire inferior olive; (2) cell counts after axotomy experiments demonstrated that they represent a small population of inferior olivary neurons, whose number oscillated between 271 ± 30 in young animlas (pedunculotomized at P1 and killed at P7) and 26 ± 12 in older ones (pedunculotomized at P20 and killed at P40). This experiment confirmed that most of these neurons are eliminated during the regressive events that take place during normal development of the Olivocerebellar projection; and (3) few ipsilateral inferior olivary neurons, however, survive at P40, but their significance is still unclear. © 1994 Wiley-Liss, Inc.
A. López-román - One of the best experts on this subject based on the ideXlab platform.
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IPSILATERALLY LOCATED Olivocerebellar PROJECTION NEURONS OF THE CHICK
Neuroscience research, 1996Co-Authors: A. López-román, José A. ArmengolAbstract:AbsTract The use of horseradish peroxidase (HRP) and 1,1′-Dioctadecyl-3,3,3′,3′-tetramethyl-indocarbocyanine perchlorate (DiI) as retrograde tracers, applied in vitro within the Olivocerebellar Tract of both embryos (9 to 21 days old) and postnatal (3–60 days old) chickens, has allowed the observation of a small population of neurons located ipsilaterally to the placement of the tracer. These neurons, whose morphology indicated that they belong to the inferior olive rather than to the reticular formation or the raphe nuclei, followed the same developmental steps as normally placed inferior olivary neurons. Furthermore, pedunculotomy experiments made on 3-day-old chickens demonstrated that ipsilateral neurons sent their axons through the cerebellar peduncle. In contrast to the completely crossed arrangement of the Olivocerebellar projection, the present results show the existence, as in the rat, of a few ipsilateral inferior olivary neurons whose significance is unclear.
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Pattern of degeneration of the rat inferior olivary complex after the early postnatal axotomy of the Olivocerebellar projection
Histology and histopathology, 1996Co-Authors: José A. Armengol, A. López-románAbstract:Neuronal death of inferior olivary neurons after early axotomy of the Olivocerebellar Tract was studied in newborn (Pl) hemicerebellectomized rats during the first six days after lesion. The degeneration of the inferior olive showed a topographic pattem from one (P2) to six days after axotomy (P7), after which this complex had almost completely disappeared. The first degenerative changes were observed in the principal olive (P2), while the media1 accessory olive was the later-degenerated area (P5). The analysis of these degenerative changes provides a reference for future experimental studies. Furthermore, the topographic study of the degenerative process demonstrated that: i) the most vulnerable neurons were dorsolaterally located, whereas the most resistant ones occupied the media1 aspect of the inferior olivary complex, ii) the comparison between the topographical arrangement of the inferior olivary neurons according to their birth dates, and the rate of degenerative changes observed after hemicerebellectomy, open the possibility that the neurona1 generation date and the response to the axotomy of the inferior olivary neurons could be related.
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Morphological evidence for the presence of ipsilateral inferior olivary neurons during postnatal development of the Olivocerebellar projection in the rat.
The Journal of comparative neurology, 1994Co-Authors: A. López-román, José A. ArmengolAbstract:The presence of ipsilateral inferior olivary neurons during postnatal development of the Olivocerebellar projection in the rat was investigated by two in vitro axonal tracing methods and by the axotomy of one Olivocerebellar Tract. The experiments were carried out before (P1), during (P5–P10) and after (P20) the period of multiple innervation of Purkinje cells by climbing fibers. According to present results: (1) ipsilateral inferior olivary neurons are distributed, on all analyzed days, throughout the entire inferior olive; (2) cell counts after axotomy experiments demonstrated that they represent a small population of inferior olivary neurons, whose number oscillated between 271 ± 30 in young animlas (pedunculotomized at P1 and killed at P7) and 26 ± 12 in older ones (pedunculotomized at P20 and killed at P40). This experiment confirmed that most of these neurons are eliminated during the regressive events that take place during normal development of the Olivocerebellar projection; and (3) few ipsilateral inferior olivary neurons, however, survive at P40, but their significance is still unclear. © 1994 Wiley-Liss, Inc.
Clifford R. Jack - One of the best experts on this subject based on the ideXlab platform.
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TDP-43 type C pathology and semantic dementia
2016Co-Authors: Neill R. Graff-radford, David S. Knopman, Bradley F. Boeve, Matthew L. Senjem, Rosa Rademakers, Clifford R. Jack, Ronald C. Petersen, Dennis W. DicksonAbstract:Four subtypes of frontotemporal lobar degeneration with TDP-43 immunoreactive inclusions have been described (types A–D). Of these four subtypes, motor neuron disease is more commonly associated with type B pathology, but has also been reported with type A pathology. We have noted, however, the unusual occurrence of cases of type C pathology having corticospinal Tract degeneration. We aimed to assess the severity of corticospinal Tract degeneration in a large cohort of cases with type C (n = 31). Pathological analysis included semi-quantitation of myelin loss of fibres of the corticospinal Tract and associated macrophage burden, as well as axonal loss, at the level of the medullary pyramids. We also assessed for motor cortex degeneration and fibre loss of the medial lemniscus/Olivocerebellar Tract. All cases were subdivided into three groups based on the degree of corti-cospinal Tract degeneration: (i) no corticospinal Tract degeneration; (ii) equivocal corticospinal Tract degeneration; and (iii) moderate to very severe corticospinal Tract degeneration. Clinical, genetic, pathological and imaging comparisons were per-formed across groups. Eight cases had no corticospinal Tract degeneration, and 14 cases had equivocal to mild corticospinal trac
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Corticospinal Tract degeneration associated with TDP-43 type C pathology and semantic dementia
Brain, 2013Co-Authors: Keith A. Josephs, Neill R. Graff-radford, David S. Knopman, Bradley F. Boeve, Matthew L. Senjem, Rosa Rademakers, Jennifer L. Whitwell, Melissa E. Murray, Joseph E. Parisi, Clifford R. JackAbstract:Four subtypes of frontotemporal lobar degeneration with TDP-43 immunoreactive inclusions have been described (types A–D). Of these four subtypes, motor neuron disease is more commonly associated with type B pathology, but has also been reported with type A pathology. We have noted, however, the unusual occurrence of cases of type C pathology having corticospinal Tract degeneration. We aimed to assess the severity of corticospinal Tract degeneration in a large cohort of cases with type C ( n = 31). Pathological analysis included semi-quantitation of myelin loss of fibres of the corticospinal Tract and associated macrophage burden, as well as axonal loss, at the level of the medullary pyramids. We also assessed for motor cortex degeneration and fibre loss of the medial lemniscus/Olivocerebellar Tract. All cases were subdivided into three groups based on the degree of corticospinal Tract degeneration: (i) no corticospinal Tract degeneration; (ii) equivocal corticospinal Tract degeneration; and (iii) moderate to very severe corticospinal Tract degeneration. Clinical, genetic, pathological and imaging comparisons were performed across groups. Eight cases had no corticospinal Tract degeneration, and 14 cases had equivocal to mild corticospinal Tract degeneration. Nine cases, however, had moderate to very severe corticospinal Tract degeneration with myelin and axonal loss. In these nine cases, there was degeneration of the motor cortex without lower motor neuron degeneration or involvement of other brainstem Tracts. These cases most commonly presented as semantic dementia, and they had longer disease duration (mean: 15.3 years) compared with the other two groups (10.8 and 9.9 years; P = 0.03). After adjusting for disease duration, severity of corticospinal Tract degeneration remained significantly different across groups. Only one case, without corticospinal Tract degeneration, was found to have a hexanucleotide repeat expansion in the C9ORF72 gene. All three groups were associated with anterior temporal lobe atrophy on MRI; however, the cases with moderate to severe corticospinal Tract degeneration showed right-sided temporal lobe asymmetry and greater involvement of the right temporal lobe and superior motor cortices than the other groups. In contrast, the cases with no or equivocal corticospinal Tract degeneration were more likely to show left-sided temporal lobe asymmetry. For comparison, the corticospinal Tract was assessed in 86 type A and B cases, and only two cases showed evidence of corticospinal Tract degeneration without lower motor neuron degeneration. These findings confirm that there exists a unique association between frontotemporal lobar degeneration with type C pathology and corticospinal Tract degeneration, with this entity showing a predilection to involve the right temporal lobe. * Abbreviations : CSTD : corticospinal Tract degeneration FTD : frontotemporal dementia FTLD : frontotemporal lobar degeneration MND : motor neuron degeneration
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Corticospinal Tract degeneration associated with TDP-43 type C pathology and semantic dementia.
Brain : a journal of neurology, 2013Co-Authors: Keith A. Josephs, Neill R. Graff-radford, David S. Knopman, Bradley F. Boeve, Matthew L. Senjem, Rosa Rademakers, Jennifer L. Whitwell, Melissa E. Murray, Joseph E. Parisi, Clifford R. JackAbstract:Four subtypes of frontotemporal lobar degeneration with TDP-43 immunoreactive inclusions have been described (types A-D). Of these four subtypes, motor neuron disease is more commonly associated with type B pathology, but has also been reported with type A pathology. We have noted, however, the unusual occurrence of cases of type C pathology having corticospinal Tract degeneration. We aimed to assess the severity of corticospinal Tract degeneration in a large cohort of cases with type C (n = 31). Pathological analysis included semi-quantitation of myelin loss of fibres of the corticospinal Tract and associated macrophage burden, as well as axonal loss, at the level of the medullary pyramids. We also assessed for motor cortex degeneration and fibre loss of the medial lemniscus/Olivocerebellar Tract. All cases were subdivided into three groups based on the degree of corticospinal Tract degeneration: (i) no corticospinal Tract degeneration; (ii) equivocal corticospinal Tract degeneration; and (iii) moderate to very severe corticospinal Tract degeneration. Clinical, genetic, pathological and imaging comparisons were performed across groups. Eight cases had no corticospinal Tract degeneration, and 14 cases had equivocal to mild corticospinal Tract degeneration. Nine cases, however, had moderate to very severe corticospinal Tract degeneration with myelin and axonal loss. In these nine cases, there was degeneration of the motor cortex without lower motor neuron degeneration or involvement of other brainstem Tracts. These cases most commonly presented as semantic dementia, and they had longer disease duration (mean: 15.3 years) compared with the other two groups (10.8 and 9.9 years; P = 0.03). After adjusting for disease duration, severity of corticospinal Tract degeneration remained significantly different across groups. Only one case, without corticospinal Tract degeneration, was found to have a hexanucleotide repeat expansion in the C9ORF72 gene. All three groups were associated with anterior temporal lobe atrophy on MRI; however, the cases with moderate to severe corticospinal Tract degeneration showed right-sided temporal lobe asymmetry and greater involvement of the right temporal lobe and superior motor cortices than the other groups. In contrast, the cases with no or equivocal corticospinal Tract degeneration were more likely to show left-sided temporal lobe asymmetry. For comparison, the corticospinal Tract was assessed in 86 type A and B cases, and only two cases showed evidence of corticospinal Tract degeneration without lower motor neuron degeneration. These findings confirm that there exists a unique association between frontotemporal lobar degeneration with type C pathology and corticospinal Tract degeneration, with this entity showing a predilection to involve the right temporal lobe.
Keith A. Josephs - One of the best experts on this subject based on the ideXlab platform.
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Corticospinal Tract degeneration associated with TDP-43 type C pathology and semantic dementia
Brain, 2013Co-Authors: Keith A. Josephs, Neill R. Graff-radford, David S. Knopman, Bradley F. Boeve, Matthew L. Senjem, Rosa Rademakers, Jennifer L. Whitwell, Melissa E. Murray, Joseph E. Parisi, Clifford R. JackAbstract:Four subtypes of frontotemporal lobar degeneration with TDP-43 immunoreactive inclusions have been described (types A–D). Of these four subtypes, motor neuron disease is more commonly associated with type B pathology, but has also been reported with type A pathology. We have noted, however, the unusual occurrence of cases of type C pathology having corticospinal Tract degeneration. We aimed to assess the severity of corticospinal Tract degeneration in a large cohort of cases with type C ( n = 31). Pathological analysis included semi-quantitation of myelin loss of fibres of the corticospinal Tract and associated macrophage burden, as well as axonal loss, at the level of the medullary pyramids. We also assessed for motor cortex degeneration and fibre loss of the medial lemniscus/Olivocerebellar Tract. All cases were subdivided into three groups based on the degree of corticospinal Tract degeneration: (i) no corticospinal Tract degeneration; (ii) equivocal corticospinal Tract degeneration; and (iii) moderate to very severe corticospinal Tract degeneration. Clinical, genetic, pathological and imaging comparisons were performed across groups. Eight cases had no corticospinal Tract degeneration, and 14 cases had equivocal to mild corticospinal Tract degeneration. Nine cases, however, had moderate to very severe corticospinal Tract degeneration with myelin and axonal loss. In these nine cases, there was degeneration of the motor cortex without lower motor neuron degeneration or involvement of other brainstem Tracts. These cases most commonly presented as semantic dementia, and they had longer disease duration (mean: 15.3 years) compared with the other two groups (10.8 and 9.9 years; P = 0.03). After adjusting for disease duration, severity of corticospinal Tract degeneration remained significantly different across groups. Only one case, without corticospinal Tract degeneration, was found to have a hexanucleotide repeat expansion in the C9ORF72 gene. All three groups were associated with anterior temporal lobe atrophy on MRI; however, the cases with moderate to severe corticospinal Tract degeneration showed right-sided temporal lobe asymmetry and greater involvement of the right temporal lobe and superior motor cortices than the other groups. In contrast, the cases with no or equivocal corticospinal Tract degeneration were more likely to show left-sided temporal lobe asymmetry. For comparison, the corticospinal Tract was assessed in 86 type A and B cases, and only two cases showed evidence of corticospinal Tract degeneration without lower motor neuron degeneration. These findings confirm that there exists a unique association between frontotemporal lobar degeneration with type C pathology and corticospinal Tract degeneration, with this entity showing a predilection to involve the right temporal lobe. * Abbreviations : CSTD : corticospinal Tract degeneration FTD : frontotemporal dementia FTLD : frontotemporal lobar degeneration MND : motor neuron degeneration
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Corticospinal Tract degeneration associated with TDP-43 type C pathology and semantic dementia.
Brain : a journal of neurology, 2013Co-Authors: Keith A. Josephs, Neill R. Graff-radford, David S. Knopman, Bradley F. Boeve, Matthew L. Senjem, Rosa Rademakers, Jennifer L. Whitwell, Melissa E. Murray, Joseph E. Parisi, Clifford R. JackAbstract:Four subtypes of frontotemporal lobar degeneration with TDP-43 immunoreactive inclusions have been described (types A-D). Of these four subtypes, motor neuron disease is more commonly associated with type B pathology, but has also been reported with type A pathology. We have noted, however, the unusual occurrence of cases of type C pathology having corticospinal Tract degeneration. We aimed to assess the severity of corticospinal Tract degeneration in a large cohort of cases with type C (n = 31). Pathological analysis included semi-quantitation of myelin loss of fibres of the corticospinal Tract and associated macrophage burden, as well as axonal loss, at the level of the medullary pyramids. We also assessed for motor cortex degeneration and fibre loss of the medial lemniscus/Olivocerebellar Tract. All cases were subdivided into three groups based on the degree of corticospinal Tract degeneration: (i) no corticospinal Tract degeneration; (ii) equivocal corticospinal Tract degeneration; and (iii) moderate to very severe corticospinal Tract degeneration. Clinical, genetic, pathological and imaging comparisons were performed across groups. Eight cases had no corticospinal Tract degeneration, and 14 cases had equivocal to mild corticospinal Tract degeneration. Nine cases, however, had moderate to very severe corticospinal Tract degeneration with myelin and axonal loss. In these nine cases, there was degeneration of the motor cortex without lower motor neuron degeneration or involvement of other brainstem Tracts. These cases most commonly presented as semantic dementia, and they had longer disease duration (mean: 15.3 years) compared with the other two groups (10.8 and 9.9 years; P = 0.03). After adjusting for disease duration, severity of corticospinal Tract degeneration remained significantly different across groups. Only one case, without corticospinal Tract degeneration, was found to have a hexanucleotide repeat expansion in the C9ORF72 gene. All three groups were associated with anterior temporal lobe atrophy on MRI; however, the cases with moderate to severe corticospinal Tract degeneration showed right-sided temporal lobe asymmetry and greater involvement of the right temporal lobe and superior motor cortices than the other groups. In contrast, the cases with no or equivocal corticospinal Tract degeneration were more likely to show left-sided temporal lobe asymmetry. For comparison, the corticospinal Tract was assessed in 86 type A and B cases, and only two cases showed evidence of corticospinal Tract degeneration without lower motor neuron degeneration. These findings confirm that there exists a unique association between frontotemporal lobar degeneration with type C pathology and corticospinal Tract degeneration, with this entity showing a predilection to involve the right temporal lobe.
Neill R. Graff-radford - One of the best experts on this subject based on the ideXlab platform.
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TDP-43 type C pathology and semantic dementia
2016Co-Authors: Neill R. Graff-radford, David S. Knopman, Bradley F. Boeve, Matthew L. Senjem, Rosa Rademakers, Clifford R. Jack, Ronald C. Petersen, Dennis W. DicksonAbstract:Four subtypes of frontotemporal lobar degeneration with TDP-43 immunoreactive inclusions have been described (types A–D). Of these four subtypes, motor neuron disease is more commonly associated with type B pathology, but has also been reported with type A pathology. We have noted, however, the unusual occurrence of cases of type C pathology having corticospinal Tract degeneration. We aimed to assess the severity of corticospinal Tract degeneration in a large cohort of cases with type C (n = 31). Pathological analysis included semi-quantitation of myelin loss of fibres of the corticospinal Tract and associated macrophage burden, as well as axonal loss, at the level of the medullary pyramids. We also assessed for motor cortex degeneration and fibre loss of the medial lemniscus/Olivocerebellar Tract. All cases were subdivided into three groups based on the degree of corti-cospinal Tract degeneration: (i) no corticospinal Tract degeneration; (ii) equivocal corticospinal Tract degeneration; and (iii) moderate to very severe corticospinal Tract degeneration. Clinical, genetic, pathological and imaging comparisons were per-formed across groups. Eight cases had no corticospinal Tract degeneration, and 14 cases had equivocal to mild corticospinal trac
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Corticospinal Tract degeneration associated with TDP-43 type C pathology and semantic dementia
Brain, 2013Co-Authors: Keith A. Josephs, Neill R. Graff-radford, David S. Knopman, Bradley F. Boeve, Matthew L. Senjem, Rosa Rademakers, Jennifer L. Whitwell, Melissa E. Murray, Joseph E. Parisi, Clifford R. JackAbstract:Four subtypes of frontotemporal lobar degeneration with TDP-43 immunoreactive inclusions have been described (types A–D). Of these four subtypes, motor neuron disease is more commonly associated with type B pathology, but has also been reported with type A pathology. We have noted, however, the unusual occurrence of cases of type C pathology having corticospinal Tract degeneration. We aimed to assess the severity of corticospinal Tract degeneration in a large cohort of cases with type C ( n = 31). Pathological analysis included semi-quantitation of myelin loss of fibres of the corticospinal Tract and associated macrophage burden, as well as axonal loss, at the level of the medullary pyramids. We also assessed for motor cortex degeneration and fibre loss of the medial lemniscus/Olivocerebellar Tract. All cases were subdivided into three groups based on the degree of corticospinal Tract degeneration: (i) no corticospinal Tract degeneration; (ii) equivocal corticospinal Tract degeneration; and (iii) moderate to very severe corticospinal Tract degeneration. Clinical, genetic, pathological and imaging comparisons were performed across groups. Eight cases had no corticospinal Tract degeneration, and 14 cases had equivocal to mild corticospinal Tract degeneration. Nine cases, however, had moderate to very severe corticospinal Tract degeneration with myelin and axonal loss. In these nine cases, there was degeneration of the motor cortex without lower motor neuron degeneration or involvement of other brainstem Tracts. These cases most commonly presented as semantic dementia, and they had longer disease duration (mean: 15.3 years) compared with the other two groups (10.8 and 9.9 years; P = 0.03). After adjusting for disease duration, severity of corticospinal Tract degeneration remained significantly different across groups. Only one case, without corticospinal Tract degeneration, was found to have a hexanucleotide repeat expansion in the C9ORF72 gene. All three groups were associated with anterior temporal lobe atrophy on MRI; however, the cases with moderate to severe corticospinal Tract degeneration showed right-sided temporal lobe asymmetry and greater involvement of the right temporal lobe and superior motor cortices than the other groups. In contrast, the cases with no or equivocal corticospinal Tract degeneration were more likely to show left-sided temporal lobe asymmetry. For comparison, the corticospinal Tract was assessed in 86 type A and B cases, and only two cases showed evidence of corticospinal Tract degeneration without lower motor neuron degeneration. These findings confirm that there exists a unique association between frontotemporal lobar degeneration with type C pathology and corticospinal Tract degeneration, with this entity showing a predilection to involve the right temporal lobe. * Abbreviations : CSTD : corticospinal Tract degeneration FTD : frontotemporal dementia FTLD : frontotemporal lobar degeneration MND : motor neuron degeneration
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Corticospinal Tract degeneration associated with TDP-43 type C pathology and semantic dementia.
Brain : a journal of neurology, 2013Co-Authors: Keith A. Josephs, Neill R. Graff-radford, David S. Knopman, Bradley F. Boeve, Matthew L. Senjem, Rosa Rademakers, Jennifer L. Whitwell, Melissa E. Murray, Joseph E. Parisi, Clifford R. JackAbstract:Four subtypes of frontotemporal lobar degeneration with TDP-43 immunoreactive inclusions have been described (types A-D). Of these four subtypes, motor neuron disease is more commonly associated with type B pathology, but has also been reported with type A pathology. We have noted, however, the unusual occurrence of cases of type C pathology having corticospinal Tract degeneration. We aimed to assess the severity of corticospinal Tract degeneration in a large cohort of cases with type C (n = 31). Pathological analysis included semi-quantitation of myelin loss of fibres of the corticospinal Tract and associated macrophage burden, as well as axonal loss, at the level of the medullary pyramids. We also assessed for motor cortex degeneration and fibre loss of the medial lemniscus/Olivocerebellar Tract. All cases were subdivided into three groups based on the degree of corticospinal Tract degeneration: (i) no corticospinal Tract degeneration; (ii) equivocal corticospinal Tract degeneration; and (iii) moderate to very severe corticospinal Tract degeneration. Clinical, genetic, pathological and imaging comparisons were performed across groups. Eight cases had no corticospinal Tract degeneration, and 14 cases had equivocal to mild corticospinal Tract degeneration. Nine cases, however, had moderate to very severe corticospinal Tract degeneration with myelin and axonal loss. In these nine cases, there was degeneration of the motor cortex without lower motor neuron degeneration or involvement of other brainstem Tracts. These cases most commonly presented as semantic dementia, and they had longer disease duration (mean: 15.3 years) compared with the other two groups (10.8 and 9.9 years; P = 0.03). After adjusting for disease duration, severity of corticospinal Tract degeneration remained significantly different across groups. Only one case, without corticospinal Tract degeneration, was found to have a hexanucleotide repeat expansion in the C9ORF72 gene. All three groups were associated with anterior temporal lobe atrophy on MRI; however, the cases with moderate to severe corticospinal Tract degeneration showed right-sided temporal lobe asymmetry and greater involvement of the right temporal lobe and superior motor cortices than the other groups. In contrast, the cases with no or equivocal corticospinal Tract degeneration were more likely to show left-sided temporal lobe asymmetry. For comparison, the corticospinal Tract was assessed in 86 type A and B cases, and only two cases showed evidence of corticospinal Tract degeneration without lower motor neuron degeneration. These findings confirm that there exists a unique association between frontotemporal lobar degeneration with type C pathology and corticospinal Tract degeneration, with this entity showing a predilection to involve the right temporal lobe.
