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Halawani AM, Tohyama S, Hung PSP, Behan B, Bernstein M, Kalia S, Zadeh G, Cusimano M, Schwartz M, Gentili F, Mikulis DJ, Laperriere NJ, Hodaie M. Correlation between Cranial Nerve Microstructural Characteristics and Vestibular Schwannoma Tumor Volume. AJNR. AMERICAN JOURNAL OF NEURORADIOLOGY 2021; 42:1853-1858. [PMID: 34615646 DOI: 10.3174/ajnr.a7257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 05/28/2021] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Vestibular schwannomas are common cerebellopontine angle tumors arising from the vestibulocochlear nerve and can result in cranial nerve dysfunction. Conventional MR imaging does not provide information that could correlate with cranial nerve compression symptoms of hearing loss or imbalance. We used multitensor tractography to evaluate the relationship between the WM microstructural properties of cranial nerves and tumor volume in a cohort of patients with vestibular schwannomas. MATERIALS AND METHODS A retrospective study was performed in 258 patients with vestibular schwannomas treated at the Gamma Knife clinic at Toronto Western Hospital between 2014 and 2018. 3T MR images were analyzed in 160 surgically naïve patients with unilateral vestibular schwannomas. Multitensor tractography was used to extract DTI-derived metrics (fractional anisotropy and radial, axial, and mean diffusivities of the bilateral facial and vestibulocochlear nerves [cranial nerves VII/VIII]). ROIs were placed in the transition between cisternal and intracanalicular segments, and images were analyzed using the eXtended Streamline Tractography reconstruction method. Diffusion metrics were correlated with 3D tumor volume derived from the Gamma Knife clinic. RESULTS DTI analyses revealed significantly higher fractional anisotropy values and a reduction in axial diffusivity, radial diffusivity, and mean diffusivity (all P < .001) within the affected cranial nerves VII and VIII compared with unaffected side. All specific diffusivities (axial, radial, and mean diffusivity) demonstrated an inverse correlation with tumor volume (axial, radial, and mean diffusivity, P < .01). CONCLUSIONS Multitensor tractography allows the quantification of cranial nerve VII and VIII WM microstructural alterations in patients with vestibular schwannomas. Our findings support the hypothesis that tumor volume may cause microstructural alterations of the affected cranial nerves VII and VIII. This type of advanced imaging may represent a possible avenue to correlate diffusivities with cranial nerve function.
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Affiliation(s)
- A M Halawani
- From the Division of Brain Imaging, and Behaviour-Systems Neuroscience (A.M.H., S.T., P.S.-P.H., D.J.M., M.H.), Krembil Research Institute, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada.,Department of Medical Imaging (A.M.H., D.J.M.), Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.,Division of Neuroradiology (A.M.H., D.J.M.), Joint Department of Medical Imaging, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - S Tohyama
- From the Division of Brain Imaging, and Behaviour-Systems Neuroscience (A.M.H., S.T., P.S.-P.H., D.J.M., M.H.), Krembil Research Institute, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada.,Institute of Medical Science, (S.T., P.S.-P.H., M.H.), Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - P S-P Hung
- From the Division of Brain Imaging, and Behaviour-Systems Neuroscience (A.M.H., S.T., P.S.-P.H., D.J.M., M.H.), Krembil Research Institute, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada.,Institute of Medical Science, (S.T., P.S.-P.H., M.H.), Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - B Behan
- Ontario Brain Institute (B.B.), Toronto, Ontario, Canada
| | - M Bernstein
- Department of Surgery (M.B., S.K., G.Z., M.C., F.G., M.H.), Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.,Division of Neurosurgery (M.B., S.K., F.G., M.H.), Krembil Neuroscience Centre, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - S Kalia
- Department of Surgery (M.B., S.K., G.Z., M.C., F.G., M.H.), Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.,Division of Neurosurgery (M.B., S.K., F.G., M.H.), Krembil Neuroscience Centre, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - G Zadeh
- Department of Surgery (M.B., S.K., G.Z., M.C., F.G., M.H.), Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.,The Arthur and Sonia Labatt Brain Tumor Research Centre (G.Z.), Hospital for Sick Children, Toronto, Ontario, Canada
| | - M Cusimano
- Department of Surgery (M.B., S.K., G.Z., M.C., F.G., M.H.), Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.,Division of Neurosurgery (M.C.), Saint Michael's Hospital, Toronto, Ontario, Canada
| | - M Schwartz
- Division of Neurosurgery (M.S.), Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
| | - F Gentili
- Department of Surgery (M.B., S.K., G.Z., M.C., F.G., M.H.), Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.,Division of Neurosurgery (M.B., S.K., F.G., M.H.), Krembil Neuroscience Centre, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - D J Mikulis
- From the Division of Brain Imaging, and Behaviour-Systems Neuroscience (A.M.H., S.T., P.S.-P.H., D.J.M., M.H.), Krembil Research Institute, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada.,Department of Medical Imaging (A.M.H., D.J.M.), Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.,Division of Neuroradiology (A.M.H., D.J.M.), Joint Department of Medical Imaging, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - N J Laperriere
- Department of Radiation Oncology (N.J.L.), University of Toronto, Toronto, Ontario, Canada.,Division of Radiation Oncology (N.J.L.), Princess Margaret Hospital, University Health Network, Toronto, Ontario, Canada
| | - M Hodaie
- From the Division of Brain Imaging, and Behaviour-Systems Neuroscience (A.M.H., S.T., P.S.-P.H., D.J.M., M.H.), Krembil Research Institute, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada .,Institute of Medical Science, (S.T., P.S.-P.H., M.H.), Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.,Department of Surgery (M.B., S.K., G.Z., M.C., F.G., M.H.), Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.,Division of Neurosurgery (M.B., S.K., F.G., M.H.), Krembil Neuroscience Centre, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
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2
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Colbert MK, Ho LC, van der Merwe Y, Yang X, McLellan GJ, Hurley SA, Field AS, Yun H, Du Y, Conner IP, Parra C, Faiq MA, Fingert JH, Wollstein G, Schuman JS, Chan KC. Diffusion Tensor Imaging of Visual Pathway Abnormalities in Five Glaucoma Animal Models. Invest Ophthalmol Vis Sci 2021; 62:21. [PMID: 34410298 PMCID: PMC8383913 DOI: 10.1167/iovs.62.10.21] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Purpose To characterize the visual pathway integrity of five glaucoma animal models using diffusion tensor imaging (DTI). Methods Two experimentally induced and three genetically determined models of glaucoma were evaluated. For inducible models, chronic IOP elevation was achieved via intracameral injection of microbeads or laser photocoagulation of the trabecular meshwork in adult rodent eyes. For genetic models, the DBA/2J mouse model of pigmentary glaucoma, the LTBP2 mutant feline model of congenital glaucoma, and the transgenic TBK1 mouse model of normotensive glaucoma were compared with their respective genetically matched healthy controls. DTI parameters, including fractional anisotropy, axial diffusivity, and radial diffusivity, were evaluated along the optic nerve and optic tract. Results Significantly elevated IOP relative to controls was observed in each animal model except for the transgenic TBK1 mice. Significantly lower fractional anisotropy and higher radial diffusivity were observed along the visual pathways of the microbead- and laser-induced rodent models, the DBA/2J mice, and the LTBP2-mutant cats compared with their respective healthy controls. The DBA/2J mice also exhibited lower axial diffusivity, which was not observed in the other models examined. No apparent DTI change was observed in the transgenic TBK1 mice compared with controls. Conclusions Chronic IOP elevation was accompanied by decreased fractional anisotropy and increased radial diffusivity along the optic nerve or optic tract, suggestive of disrupted microstructural integrity in both inducible and genetic glaucoma animal models. The effects on axial diffusivity differed between models, indicating that this DTI metric may represent different aspects of pathological changes over time and with severity.
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Affiliation(s)
- Max K Colbert
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, United States
| | - Leon C Ho
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Yolandi van der Merwe
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Xiaoling Yang
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Gillian J McLellan
- Department of Ophthalmology and Visual Sciences, University of Wisconsin - Madison, Madison, Wisconsin, United States.,McPherson Eye Research Institute, University of Wisconsin - Madison, Madison, Wisconsin, United States
| | - Samuel A Hurley
- Department of Radiology, University of Wisconsin - Madison, Madison, Wisconsin, United States
| | - Aaron S Field
- Department of Radiology, University of Wisconsin - Madison, Madison, Wisconsin, United States
| | - Hongmin Yun
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Yiqin Du
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Ian P Conner
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Carlos Parra
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, United States
| | - Muneeb A Faiq
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, United States
| | - John H Fingert
- Department of Ophthalmology and Visual Sciences, University of Iowa College of Medicine, Iowa City, Iowa, United States
| | - Gadi Wollstein
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, United States.,Center for Neural Science, College of Arts and Science, New York University, New York, New York, United States.,Department of Biomedical Engineering, New York University Tandon School of Engineering, Brooklyn, New York, United States
| | - Joel S Schuman
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, United States.,Center for Neural Science, College of Arts and Science, New York University, New York, New York, United States.,Department of Biomedical Engineering, New York University Tandon School of Engineering, Brooklyn, New York, United States.,Neuroscience Institute, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, United States
| | - Kevin C Chan
- Department of Ophthalmology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, United States.,Center for Neural Science, College of Arts and Science, New York University, New York, New York, United States.,Department of Biomedical Engineering, New York University Tandon School of Engineering, Brooklyn, New York, United States.,Neuroscience Institute, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, United States.,Department of Radiology, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, United States
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3
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Gao L, Huang M, Luo X, Song T, Wang X, Wang Z, Zhang W, Chen J, Lei H. Microstructure abnormity in the optic nerve of type 1 diabetic rats revealed by diffusion tensor imaging study. Magn Reson Imaging 2020; 71:105-114. [PMID: 32434010 DOI: 10.1016/j.mri.2020.05.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 05/08/2020] [Accepted: 05/11/2020] [Indexed: 02/06/2023]
Abstract
Diabetic retinopathy (DR) is one of a major complication of type 1 diabetes mellitus (T1DM) and a leading cause of blindness. Evidence of animal study has shown that it is not only a microvasucular lesion of the eye, but also a neurodegeneration disease of the visual system. However, the in vivo imaging evidence of axonal degeneration in the diabetic optic nerve is scarce. Diffusion tensor imaging (DTI) technique has been proved to be an effective tool to track the integrity of the nerve fibers in the central nervous system. In this study, type 1 diabetes was induced by intraperitoneally injecting a single dose of streptozotocin (STZ) into Sprague-Dawley rats. DTI combined with histological assessments was carried out on the optic nerve to clarify the microstructural alterations underlying DTI indices changes at 4 weeks (4 w), 8 weeks (8 w) and 12 weeks (12 w) after STZ induction. The retinal changes were analyzed by pathological evaluations at 4 weeks (4 w) and 12 weeks (12 w) after STZ induction. DTI results showed significantly decreased mean diffusivity (MD) and axial diffusivity (Da) in diabetic optic nerve compared to controls at 12 w. Atrophy in diabetic nerves was monitored by high resolution T2-weighted images. Axonal degeneration without myelin loss of the optic nerve was confirmed by histological examination. Moreover, there are positive correlations between decreased diffusivities (MD and Da) in the optic nerve and reduced total axolemmal area. The diabetic rats showed intense glial activity since 4 w and thinning of the thickness in inner plexiform layer and nerve fiber layer at 12 w in the retina. In conclusion, DTI could in vivo monitor the progression of optic nerve degeneration in diabetes and the findings in our study would help supply axonal protection for DR in preclinical practice.
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Affiliation(s)
- Lifeng Gao
- Department of Medical Imaging, School of Medicine, Jianghan University, Wuhan 430056, China
| | - Mingming Huang
- Department of Radiology, Affiliated Hospital of Guiyang Medical University, Guiyang 550008, China
| | - Xiaowen Luo
- Department of Medical Imaging, School of Medicine, Jianghan University, Wuhan 430056, China
| | - Tao Song
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Xuxia Wang
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Zhe Wang
- Department of Medical Imaging, School of Medicine, Jianghan University, Wuhan 430056, China
| | - Wei Zhang
- Department of Radiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; Hubei Key Laboratory of Molecular Imaging, Wuhan 430022, China.
| | - Jiangyuan Chen
- Department of Medical Imaging, School of Medicine, Jianghan University, Wuhan 430056, China.
| | - Hao Lei
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China.
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David G, Mohammadi S, Martin AR, Cohen-Adad J, Weiskopf N, Thompson A, Freund P. Traumatic and nontraumatic spinal cord injury: pathological insights from neuroimaging. Nat Rev Neurol 2019; 15:718-731. [PMID: 31673093 DOI: 10.1038/s41582-019-0270-5] [Citation(s) in RCA: 100] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/18/2019] [Indexed: 01/23/2023]
Abstract
Pathophysiological changes in the spinal cord white and grey matter resulting from injury can be observed with MRI techniques. These techniques provide sensitive markers of macrostructural and microstructural tissue integrity, which correlate with histological findings. Spinal cord MRI findings in traumatic spinal cord injury (tSCI) and nontraumatic spinal cord injury - the most common form of which is degenerative cervical myelopathy (DCM) - have provided important insights into the pathophysiological processes taking place not just at the focal injury site but also rostral and caudal to the spinal injury. Although tSCI and DCM have different aetiologies, they show similar degrees of spinal cord pathology remote from the injury site, suggesting the involvement of similar secondary degenerative mechanisms. Advanced quantitative MRI protocols that are sensitive to spinal cord pathology have the potential to improve diagnosis and, more importantly, predict outcomes in patients with tSCI or nontraumatic spinal cord injury. This Review describes the insights into tSCI and DCM that have been revealed by neuroimaging and outlines current activities and future directions for the field.
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Affiliation(s)
- Gergely David
- Spinal Cord Injury Center Balgrist, University Hospital Zurich, University of Zurich, Zurich, Switzerland.,Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Siawoosh Mohammadi
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,Wellcome Centre for Human Neuroimaging, UCL Institute of Neurology, London, UK
| | - Allan R Martin
- Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Julien Cohen-Adad
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, Quebec, Canada
| | - Nikolaus Weiskopf
- Wellcome Centre for Human Neuroimaging, UCL Institute of Neurology, London, UK.,Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Alan Thompson
- Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, London, UK
| | - Patrick Freund
- Spinal Cord Injury Center Balgrist, University Hospital Zurich, University of Zurich, Zurich, Switzerland. .,Wellcome Centre for Human Neuroimaging, UCL Institute of Neurology, London, UK. .,Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany. .,Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, London, UK. .,Department of Neurology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
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Developmental trajectory of the prefrontal cortex: a systematic review of diffusion tensor imaging studies. Brain Imaging Behav 2019; 12:1197-1210. [PMID: 28913594 DOI: 10.1007/s11682-017-9761-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Fluctuations in gray and white matter volumes in addition to the fibers' reorganization and refinement of synaptic connectivity apparently happen in a particular temporo-spatial sequence during the dynamic and prolonged process of cerebral maturation. These developmental events are associated with regional modifications of brain tissues and neural circuits, contributing to networks' specialization and enhanced cognitive processing. According to several studies, improvements in cognitive processes are possibly myelin-dependent and associated to white matter maturation. Of particular interest is the developmental pattern of the prefrontal cortex (PFC), more specifically the PFC white matter, due to its role in high-level executive processes such as attention, working memory and inhibitory control. A systematic review of the literature was conducted using the Web of Science, PubMed and Embase databases to analyze the development of PFC white matter using Diffusion Tensor Imaging (DTI), a widely used non-invasive technique to assess white matter maturation. Both the research and reporting of results were based on Cochrane's recommendations and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines. Information extracted from 27 published studies revealed an increased myelination, organization and integrity of frontal white matter with age, as revealed by DTI indexes (fractional anisotropy [FA], mean diffusivity [MD], radial diffusivity [RD] and axial diffusivity [AD]). These patterns highlight the extended developmental course of the frontal structural connectivity, which parallels the improvements in higher-level cognitive functions observed between adolescence and early adulthood.
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Ruff CA, Faulkner SD, Rumajogee P, Beldick S, Foltz W, Corrigan J, Basilious A, Jiang S, Thiyagalingam S, Yager JY, Fehlings MG. The extent of intrauterine growth restriction determines the severity of cerebral injury and neurobehavioural deficits in rodents. PLoS One 2017; 12:e0184653. [PMID: 28934247 PMCID: PMC5608203 DOI: 10.1371/journal.pone.0184653] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 08/28/2017] [Indexed: 12/16/2022] Open
Abstract
Background Cerebral Palsy (CP) is the most common physical pediatric neurodevelopmental disorder and spastic diplegic injury is its most frequent subtype. CP results in substantial neuromotor and cognitive impairments that have significant socioeconomic impact. Despite this, its underlying pathophysiological mechanisms and etiology remain incompletely understood. Furthermore, there is a need for clinically relevant injury models, which a) reflect the heterogeneity of the condition and b) can be used to evaluate new translational therapies. To address these key knowledge gaps, we characterized a chronic placental insufficiency (PI) model, using bilateral uterine artery ligation (BUAL) of dams. This injury model results in intrauterine growth restriction (IUGR) in pups, and animals recapitulate the human phenotype both in terms of neurobehavioural and anatomical deficits. Methods Effects of BUAL were studied using luxol fast blue (LFB)/hematoxylin & eosin (H&E) staining, immunohistochemistry, quantitative Magnetic Resonance Imaging (MRI), and Catwalk neurobehavioural tests. Results Neuroanatomical analysis revealed regional ventricular enlargement and corpus callosum thinning in IUGR animals, which was correlated with the extent of growth restriction. Olig2 staining revealed reductions in oligodendrocyte density in white and grey matter structures, including the corpus callosum, optic chiasm, and nucleus accumbens. The caudate nucleus, along with other brain structures such as the optic chiasm, internal capsule, septofimbrial and lateral septal nuclei, exhibited reduced size in animals with IUGR. The size of the pretectal nucleus was reduced only in moderately injured animals. MAG/NF200 staining demonstrated reduced myelination and axonal counts in the corpus callosum of IUGR animals. NeuN staining revealed changes in neuronal density in the hippocampus and in the thickness of hippocampal CA2 and CA3 regions. Diffusion weighted imaging (DWI) revealed regional white and grey matter changes at 3 weeks of age. Furthermore, neurobehavioural testing demonstrated neuromotor impairments in animals with IUGR in paw intensities, swing speed, relative print positions, and phase dispersions. Conclusions We have characterized a rodent model of IUGR and have demonstrated that the neuroanatomical and neurobehavioural deficits mirror the severity of the IUGR injury. This model has the potential to be applied to examine the pathobiology of and potential therapeutic strategies for IUGR-related brain injury. Thus, this work has potential translational relevance for the study of CP.
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Affiliation(s)
- Crystal A. Ruff
- Division of Genetics and Development, Krembil Research Institute, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Stuart D. Faulkner
- Division of Genetics and Development, Krembil Research Institute, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Prakasham Rumajogee
- Division of Genetics and Development, Krembil Research Institute, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Stephanie Beldick
- Division of Genetics and Development, Krembil Research Institute, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Warren Foltz
- STARR facility, Toronto Medical Discovery Tower, Toronto, Ontario, Canada
| | - Jennifer Corrigan
- Section of Pediatric Neurosciences, Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Alfred Basilious
- Division of Genetics and Development, Krembil Research Institute, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Shangjun Jiang
- Division of Genetics and Development, Krembil Research Institute, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Shanojan Thiyagalingam
- Division of Genetics and Development, Krembil Research Institute, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Jerome Y. Yager
- Section of Pediatric Neurosciences, Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Michael G. Fehlings
- Division of Genetics and Development, Krembil Research Institute, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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Quantitative assessment of optic nerve in patients with Leber’s hereditary optic neuropathy using reduced field-of-view diffusion tensor imaging. Eur J Radiol 2017; 93:24-29. [DOI: 10.1016/j.ejrad.2017.05.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 05/21/2017] [Indexed: 11/22/2022]
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8
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Sun SW, Nishioka C, Chung CF, Park J, Liang HF. Anterograde-propagation of axonal degeneration in the visual system of wlds mice characterized by diffusion tensor imaging. J Magn Reson Imaging 2016; 45:482-491. [PMID: 27373882 DOI: 10.1002/jmri.25368] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 06/17/2016] [Indexed: 12/28/2022] Open
Abstract
PURPOSE To evaluate the feasibility of using diffusion tensor imaging (DTI) to characterize the temporospatial profile of axonal degeneration and its relation to blood-brain barrier (BBB) permeability. MATERIALS AND METHODS Longitudinal DTI was performed in Wallerian degeneration slow (WldS) mice following retinal ischemia. In parallel, gadolinium (Gd)-enhanced T1 -weighted imaging (Gd-T1 WI) was performed to evaluate BBB permeability in white matter during axonal degeneration. To confirm the in vivo findings, immunohistochemistry using SMI-31 and myelin basic protein (MBP) was performed to examine the axons and myelin, respectively, and Evans blue was used to evaluate the permeability of the BBB. RESULTS Reduced axial diffusivity was found in the optic nerve (ON, -15%, P = 0.0063) 1 week and optic tact (OT, -18%, P = 0.0077) 2 weeks after retinal ischemia, which were respectively associated with an 11% (P = 0.0116) and 25% (P = 0.0001) axonal loss. Increased radial diffusivity was found 1-2 weeks after the colocated decrease of axial diffusivity (35% increase, P = 0.0388 in the ON at week 2 and an 80% increase, P = 0.0015 in the OT at week 4). No significant changes were observed using Gd-T1 WI (P = 0.13-0.75), although an approximately 1-fold increase in Evans blue staining intensity was found in the injured ON and OT starting 1 week after retinal ischemia. CONCLUSION We demonstrated the utility of DTI to characterize anterograde-propagating axonal degeneration through the ON and OT following retinal damage. Evans blue staining revealed serum albumin accumulation at injured sites, although there was no BBB leakage detectable using Gd-T1 WI. LEVEL OF EVIDENCE 2 J. Magn. Reson. Imaging 2017;45:482-491.
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Affiliation(s)
- Shu-Wei Sun
- Basic Sciences, School of Medicine, Loma Linda University, California, USA.,Radiation Medicine, School of Medicine, Loma Linda University, California, USA.,Pharmaceutical Science, School of Pharmacy, Loma Linda University, California, USA.,Neuroscience, University of California, Riverside, California, USA
| | | | - Chen-Fang Chung
- Basic Sciences, School of Medicine, Loma Linda University, California, USA
| | - JoAnn Park
- Basic Sciences, School of Medicine, Loma Linda University, California, USA
| | - Hsiao-Fang Liang
- Basic Sciences, School of Medicine, Loma Linda University, California, USA
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9
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Fan SM, Chen W, Xiong L, Xia Y, Xie YB, Chen J. Magnetic resonance diffusion tensor imaging study of rhesus optic nerve radiation injury caused by a single dose/fractionation scheme stereotactic radiosurgery at an early stage. J Neuroradiol 2015; 43:207-13. [PMID: 26726930 DOI: 10.1016/j.neurad.2015.10.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 10/10/2015] [Accepted: 10/24/2015] [Indexed: 02/05/2023]
Abstract
BACKGROUND AND PURPOSE Radiation-induced optic neuropathy (RION) is a devastating late complication of radiotherapy. However, research on the imaging performance of RION is not sufficient. The aim of this study was to investigate the performance of magnetic resonance diffusion tensor imaging (DTI) early after injury of the optic nerve of rhesus monkeys by a single-dose/fractionation-scheme of stereotactic radiosurgery (SRS). MATERIALS AND METHODS The intraorbital optic nerve contour of 5 rhesus monkeys was acquired by magnetic resonance imaging (MRI). Then, the unilateral intraorbital optic nerves of 5 rhesus monkeys were injured by gamma knife surgery (GKS) with a single-dose/fractionation scheme (marginal dose of 15Gy, 50% isodose curve). DTI was performed before the irradiation and 1week, 2weeks, 4weeks, and 24weeks after injury to obtain the cross-sectional area, and the fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD) and radial diffusivity (RD) values. RESULTS The cross-sectional area of the injured optic nerve exhibited significant atrophy 24weeks after SRS. FA declined 1week after injury; this value then increased slightly but remained lower than before injury (P<0.05). AD began to decline in the 2weeks after injury and gradually disappeared (P<0.05). CONCLUSION SRS with a single-dose/fractionation scheme (marginal dose of 15Gy, 50% isodose curve) on the unilateral intraorbital optic nerve can induce RION. DTI can detect RION at an early stage. FA and AD are useful indicators for RION diagnosis. In the early stage, the primary site of RION may be the vascular endothelium.
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Affiliation(s)
- Shuang Min Fan
- Department of Neurosurgery, Sichuan University, West China Hospital, Chengdu, Sichuan Province, PR China
| | - Wei Chen
- Department of Neurosurgery, Sichuan University, West China Hospital, Chengdu, Sichuan Province, PR China
| | - Li Xiong
- Department of Neurosurgery, Sichuan Provincial People's Hospital, Chengdu, Sichuan Province, PR China
| | - Yong Xia
- Department of Neurosurgery, Sichuan University, West China Hospital, Chengdu, Sichuan Province, PR China
| | - Yue Bin Xie
- Department of Neurosurgery, Sichuan University, West China Hospital, Chengdu, Sichuan Province, PR China
| | - Jing Chen
- Department of Neurosurgery, Sichuan University, West China Hospital, Chengdu, Sichuan Province, PR China.
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10
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Gray and white matter alterations in hereditary spastic paraplegia type SPG4 and clinical correlations. J Neurol 2015; 262:1961-71. [PMID: 26050637 DOI: 10.1007/s00415-015-7791-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 05/20/2015] [Accepted: 05/21/2015] [Indexed: 12/14/2022]
Abstract
Hereditary spastic paraplegias (HSP) are a group of clinically and genetically heterogeneous disorders with the hallmark of progressive spastic gait disturbance. We used advanced neuroimaging to identify brain regions involved in SPG4, the most common HSP genotype. Additionally, we analyzed correlations between imaging and clinical findings. We performed 3T MRI scans including isotropic high-resolution 3D T1, T2-FLAIR, and DTI sequences in 15 adult patients with genetically confirmed SPG4 and 15 age- and sex-matched healthy controls. Brain volume loss of gray and white matter was evaluated through voxel-based morphometry (VBM) for supra- and infratentorial regions separately. DTI maps of axial diffusivity (AD), radial diffusivity (RD), mean diffusivity (MD), fractional anisotropy (FA), and measured anisotropy (MA1) were analyzed through tract-based special statistics (TBSS). VBM and TBSS revealed a widespread affection of gray and white matter in SPG4 including the corpus callosum, medio-dorsal thalamus, parieto-occipital regions, upper brainstem, cerebellum, and corticospinal tract. Significant correlations with correlation coefficients r > 0.6 between clinical data and DTI findings could be demonstrated for disease duration and disease severity as assessed by the spastic paraplegia rating scale for the pontine crossing tract (AD) and the corpus callosum (RD and FA). Imaging also provided evidence that SPG4 underlies a primarily axonal rather than demyelinating damage in accordance with post-mortem data. DTI is an attractive tool to assess subclinical affection in SPG4. The correlation of imaging findings with disease duration and severity suggests AD, RD, and FA as potential progression markers in interventional studies.
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11
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Gess B, Röhr D, Lange E, Halfter H, Young P. Desmoplakin is involved in organization of an adhesion complex in peripheral nerve regeneration after injury. Exp Neurol 2014; 264:55-66. [PMID: 25496840 DOI: 10.1016/j.expneurol.2014.12.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 11/23/2014] [Accepted: 12/07/2014] [Indexed: 11/17/2022]
Abstract
Peripheral nerves have the unique capability to regenerate after injury. Insights into regeneration of peripheral nerves after injury may have implications for neurodegenerative diseases of the nervous system. In this study, we analyzed the expression and function of desmoplakin in peripheral nerve regeneration. Desmoplakin was upregulated in spinal cord motoneurons after sciatic nerve injury. Conditional ablation of desmoplakin in motoneurons demonstrated that desmoplakin is necessary for normal motor regeneration. SiRNA and desmoplakin deletion-constructs revealed a role of desmoplakin in neurite extension in vitro. A complex of N-cadherin, plakoglobin, desmoplakin and vimentin was shown in motoneuronal cell cultures and peripheral nerves after injury in vivo. Motor nerve fiber regeneration and localization of N-cadherin and vimentin to axonal growth fronts were reduced in conditionally desmoplakin-ablated mice. These data indicate a function of desmoplakin in motor nerve regeneration by linking N-cadherin to intermediate filaments in regenerating motor axons.
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Affiliation(s)
- B Gess
- Department of Sleep Medicine and Neuromuscular Disorders, University of Muenster, Germany.
| | - D Röhr
- Department of Sleep Medicine and Neuromuscular Disorders, University of Muenster, Germany
| | - E Lange
- Department of Sleep Medicine and Neuromuscular Disorders, University of Muenster, Germany
| | - H Halfter
- Department of Sleep Medicine and Neuromuscular Disorders, University of Muenster, Germany
| | - P Young
- Department of Sleep Medicine and Neuromuscular Disorders, University of Muenster, Germany
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12
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Aghakhanyan G, Martinuzzi A, Frijia F, Vavla M, Hlavata H, Baratto A, Martino N, Paparella G, Montanaro D. Brain white matter involvement in hereditary spastic paraplegias: analysis with multiple diffusion tensor indices. AJNR Am J Neuroradiol 2014; 35:1533-8. [PMID: 24788132 DOI: 10.3174/ajnr.a3897] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
BACKGROUND AND PURPOSE The hereditary spastic paraplegias are a group of genetically heterogeneous neurodegenerative disorders, characterized by progressive spasticity and weakness of the lower limbs. Although conventional brain MR imaging findings are normal in patients with pure hereditary spastic paraplegia, microstructural alteration in the cerebral WM can be revealed with DTI. Concomitant investigation of multiple intrinsic diffusivities may shed light on the neurobiologic substrate of the WM degeneration pattern in patients with pure hereditary spastic paraplegia across the whole brain. MATERIALS AND METHODS Tract-based spatial statistics analysis was performed to compare fractional anisotropy and mean, axial, and radial diffusivities of the WM skeleton in a group of 12 patients with pure hereditary spastic paraplegia and 12 healthy volunteers. Data were analyzed counting age and sex as nuisance covariates. The threshold-free cluster-enhancement option was applied, and the family-wise error rate was controlled by using permutation tests for nonparametric statistics. RESULTS In pure hereditary spastic paraplegia, group widespread fractional anisotropy decreases and radial diffusivity and mean diffusivity increases (P < .05, corrected) were found. No voxelwise difference was observed for the axial diffusivity map. Percentage of voxels within the WM skeleton that passed the significance threshold were 51%, 41.6%, and 11.9%, respectively, for radial diffusivity, fractional anisotropy, and mean diffusivity clusters. An anteroposterior pattern with preferential decrease of fractional anisotropy in the frontal circuitry was detected. CONCLUSIONS In patients with pure hereditary spastic paraplegia, alterations in multiple DTI indices were found. Radial diffusivity seems more sensitive to hereditary spastic paraplegia-related WM pathology and, in line with the lack of axial diffusivity changes, might indicate a widespread loss of myelin integrity. A decrease of fractional anisotropy alone in the frontal circuitry may reflect subtle disruption of the frontal connections.
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Affiliation(s)
- G Aghakhanyan
- From the Institute of Life Sciences (G.A.), Scuola Superiore Sant'Anna, Pisa, ItalyNeuroradiology Unit (G.A., F.F., H.H., D.M.), Fondazione CNR/Regione Toscana G. Monasterio, Pisa, Italy
| | - A Martinuzzi
- Medea Scientific Institute (A.M., M.V., G.P.), Conegliano and Bosisio Parini, Treviso, Italy
| | - F Frijia
- Neuroradiology Unit (G.A., F.F., H.H., D.M.), Fondazione CNR/Regione Toscana G. Monasterio, Pisa, Italy
| | - M Vavla
- Medea Scientific Institute (A.M., M.V., G.P.), Conegliano and Bosisio Parini, Treviso, Italy
| | - H Hlavata
- Neuroradiology Unit (G.A., F.F., H.H., D.M.), Fondazione CNR/Regione Toscana G. Monasterio, Pisa, Italy
| | - A Baratto
- Radiology Unit (A.B., N.M.), MRI Unit, ULSS7, Conegliano, Treviso, Italy
| | - N Martino
- Radiology Unit (A.B., N.M.), MRI Unit, ULSS7, Conegliano, Treviso, Italy
| | - G Paparella
- Medea Scientific Institute (A.M., M.V., G.P.), Conegliano and Bosisio Parini, Treviso, Italy
| | - D Montanaro
- Neuroradiology Unit (G.A., F.F., H.H., D.M.), Fondazione CNR/Regione Toscana G. Monasterio, Pisa, Italy
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13
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Versace A, Andreazza AC, Young LT, Fournier JC, Almeida JRC, Stiffler RS, Lockovich JC, Aslam HA, Pollock MH, Park H, Nimgaonkar VL, Kupfer DJ, Phillips ML. Elevated serum measures of lipid peroxidation and abnormal prefrontal white matter in euthymic bipolar adults: toward peripheral biomarkers of bipolar disorder. Mol Psychiatry 2014; 19:200-8. [PMID: 23358158 PMCID: PMC3640681 DOI: 10.1038/mp.2012.188] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 10/22/2012] [Accepted: 11/12/2012] [Indexed: 12/14/2022]
Abstract
Diffusion tensor imaging (DTI) studies consistently reported abnormalities in fractional anisotropy (FA) and radial diffusivity (RD), measures of the integrity of white matter (WM), in bipolar disorder (BD), that may reflect underlying pathophysiologic processes. There is, however, a pressing need to identify peripheral measures that are related to these WM measures, to help identify easily obtainable peripheral biomarkers of BD. Given the high lipid content of axonal membranes and myelin sheaths, and that elevated serum levels of lipid peroxidation are reported in BD, these serum measures may be promising peripheral biomarkers of underlying WM abnormalities in BD. We used DTI and probabilistic tractography to compare FA and RD in ten prefrontal-centered WM tracts, 8 of which are consistently shown to have abnormal FA (and/or RD) in BD, and also examined serum lipid peroxidation (lipid hydroperoxides, LPH and 4-hydroxy-2-nonenal, 4-HNE), in 24 currently euthymic BD adults (BDE) and 19 age- and gender-matched healthy adults (CONT). There was a significant effect of group upon FA in these a priori WM tracts (BDECONT: F[1,41]=10.3; P=0.003), and a significant between-group difference in LPH (BDE>CONT: t[40]=2.4; P=0.022), but not in 4-HNE. Multivariate multiple regression analyses revealed that LPH variance explained, respectively, 59 and 51% of the variance of FA and RD across all study participants. This is the first study to examine relationships between measures of WM integrity and peripheral measures of lipid peroxidation. Our findings suggest that serum LPH may be useful in the development of a clinically relevant, yet easily obtainable and inexpensive, peripheral biomarkers of BD.
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Affiliation(s)
- A Versace
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - A C Andreazza
- 1] Departments of Psychiatry and Pharmacology, University of Toronto, Toronto, Ontario, Canada [2] Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - L T Young
- 1] Departments of Psychiatry and Pharmacology, University of Toronto, Toronto, Ontario, Canada [2] Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - J C Fournier
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - J R C Almeida
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - R S Stiffler
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - J C Lockovich
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - H A Aslam
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - M H Pollock
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - H Park
- 1] Departments of Psychiatry and Pharmacology, University of Toronto, Toronto, Ontario, Canada [2] Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - V L Nimgaonkar
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - D J Kupfer
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - M L Phillips
- 1] Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA [2] Department of Psychological Medicine, Cardiff University School of Medicine, Cardiff, UK
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Aung WY, Mar S, Benzinger TL. Diffusion tensor MRI as a biomarker in axonal and myelin damage. ACTA ACUST UNITED AC 2013; 5:427-440. [PMID: 24795779 DOI: 10.2217/iim.13.49] [Citation(s) in RCA: 217] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Diffusion tensor imaging has been used extensively as a research tool to understand the structural changes associated with white matter pathology. Using water diffusion as the basis to construct anatomic details, diffusion tensor imaging offers the potential to identify structural and functional adaptations before gross anatomical changes, such as lesions and tumors, become apparent on conventional MRI. Over the past 10 years, further parameters, such as axial and radial diffusivity, have been developed to characterize white matter changes specific to axons and myelin. In this paper, the potential application and outstanding issues on the use of diffusion tensor imaging directional diffusivity as a biomarker in axonal and myelin damage in neurological disorders will be reviewed.
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Affiliation(s)
- Wint Yan Aung
- Department of Radiology, Washington University, School of Medicine, 510 South Kingshighway Boulevard, St Louis, MO 63110, USA
| | - Soe Mar
- Department of Pediatric & Developmental Neurology, Washington University School of Medicine, St Louis, MO, USA
| | - Tammie Ls Benzinger
- Department of Radiology, Washington University, School of Medicine, 510 South Kingshighway Boulevard, St Louis, MO 63110, USA ; Department of Neurological Surgery, Washington University School of Medicine, St Louis, MO, USA
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15
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Oguz KK, Haliloglu G, Temucin C, Gocmen R, Has AC, Doerschner K, Dolgun A, Alikasifoglu M. Assessment of whole-brain white matter by DTI in autosomal recessive spastic ataxia of Charlevoix-Saguenay. AJNR Am J Neuroradiol 2013; 34:1952-7. [PMID: 23598833 DOI: 10.3174/ajnr.a3488] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
BACKGROUND AND PURPOSE Extension and characteristics of WM involvement other than the brain stem remain inadequately investigated in ARSACS. The aim of this study was to investigate whole-brain WM alterations in patients with ARSACS. MATERIALS AND METHODS Nine Turkish unrelated patients with ARSACS and 9 sex- and age-matched healthy control participants underwent neurologic examination, molecular studies, electrophysiologic studies, and DTI of the brain. TBSS was used for whole-brain voxelwise analysis of FA, AD, RD, mean diffusivity of WM. Tractographies for the CST and TPF were also computed. RESULTS Molecular studies revealed 8 novel mutations (3 nonsense, 4 missense, and 1 frameshift insertion) and a missense variation in the SACS gene. Thick TPF displaced and compressed the CST in the pons. The TPF had increased FA, decreased RD, and increased AD, which may be attributed to hypertrophy and/or hypermyelination. Widespread decreased FA and increased RD, suggesting demyelination, was found in the limbic, commissural, and projection fibers. In addition to demyelination, CST coursing cranial and caudal to the pons also showed a marked decrease in AD, suggesting axonal degeneration. Electrophysiologic studies revealed findings that concur with demyelination and axonal involvement. CONCLUSIONS In addition to developmental changes of the TPF and their effects on the CST in the brain stem, axonal degeneration mainly along the pyramidal tracts and widespread demyelination in WM also occur in patients with ARSACS. Widespread tissue damage may be associated with extensive loss of sacsin protein in the brain and may explain a wide range of progressive neurologic abnormalities in patients with ARSACS.
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Affiliation(s)
- K K Oguz
- National Magnetic Resonance Research Center, Bilkent University, Bilkent, Ankara, Turkey
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16
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Zhu Y, Zhang L, Sasaki Y, Milbrandt J, Gidday JM. Protection of mouse retinal ganglion cell axons and soma from glaucomatous and ischemic injury by cytoplasmic overexpression of Nmnat1. Invest Ophthalmol Vis Sci 2013; 54:25-36. [PMID: 23211826 DOI: 10.1167/iovs.12-10861] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
PURPOSE The Wlds mutation affords protection of retinal ganglion cell (RGC) axons in retinal ischemia and in inducible and hereditary preclinical models of glaucoma. We undertook the present study to determine whether the Nmnat1 portion of the chimeric protein provides axonal and somatic protection of RGCs in models of ischemia and glaucoma, particularly when localized to nonnuclear regions of the cell. METHODS The survival and integrity of RGC axons and soma from transgenic mice with confirmed cytoplasmic overexpression of Nmnat1 in retina and optic nerve (cytNmnat1-Tg mice) were examined in the retina and postlaminar optic nerve 4 days following acute retinal ischemia, and 3 weeks following the chronic elevation of intraocular pressure. RESULTS Ischemia- and glaucoma-induced disruptions of proximal segments of RGC axons that comprise the nerve fiber layer in wild-type mice were both robustly abrogated in cytNmnat1-Tg mice. More distal portions of RGC axons within the optic nerve were also protected from glaucomatous disruption in the transgenic mice. In both disease models, Nmnat1 overexpression in extranuclear locations significantly enhanced the survival of RGC soma. CONCLUSIONS Overexpression of Nmnat1 in the cytoplasm and axons of RGCs robustly protected against both ischemic and glaucomatous loss of RGC axonal integrity, as well as loss of RGC soma. These findings reflect the more pan-cellular protection of CNS neurons that is realized by cytoplasmic Nmnat1 expression, and thus provide a therapeutic strategy for protecting against retinal neurodegeneration, and perhaps other CNS neurodegenerative diseases as well.
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Affiliation(s)
- Yanli Zhu
- Department of Neurosurgery, Washington University School of Medicine, St. Louis, MO 63110, USA
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17
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Structural insights into the rodent CNS via diffusion tensor imaging. Trends Neurosci 2012; 35:412-21. [PMID: 22651954 DOI: 10.1016/j.tins.2012.04.010] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2012] [Revised: 04/30/2012] [Accepted: 04/30/2012] [Indexed: 12/31/2022]
Abstract
Diffusion tensor imaging (DTI) is a useful tool for studying anatomy and pathology in the rodent central nervous system (CNS).The unique tissue contrasts provided by DTI are well suited for monitoring disease progression, studying brain development, and characterizing anatomical phenotypes. Recent technical developments have vastly improved the speed and resolution of rodent DTI. Ongoing research efforts exploring the microstructural basis of DTI signals have provided useful insights into its capabilities to delineate brain structures and detect neuropathology. Significant progress has also been made in combining DTI results with data acquired using other imaging modalities to enhance our understanding of the rodent CNS.
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