Special imaging yields SPG4 insights

Axonal damage measured

Axonal damage measured in the spinal cord in the neck and upper back regions in 12 people with SPG4 correlates with the degree of motor disability measured as the Spastic Paraplegia Rating Scale score.

Using a special type of MRI called Diffusion Tensor Imaging (DTI) axonal damage can be quantified by multiple means in specific structural locations (tracts) in the spinal cord at two different levels in the spine, namely the neck or cervical spine and the upper back (upper thoracic).

Background: SPG4 is a subtype of hereditary spastic paraplegia (HSP), an upper motor neuron disorder characterized by axonal degeneration of the corticospinal tracts and the fasciculus gracilis. The few neuroimaging studies that have focused on the spinal cord in HSP are based mainly on the analysis of structural characteristics.

Methods: We assessed diffusion-related characteristics of the spinal cord using diffusion tensor imaging (DTI), as well as structural and shape-related properties in 12 SPG4 patients and 14 controls. We used linear mixed effects models up to T3 in order to analyze the global effects of ‘group’ and ‘clinical data’ on structural and diffusion data. For DTI, we carried out a region of interest (ROI) analysis in native space for the whole spinal cord, the anterior and lateral funiculi, and the dorsal columns. We also performed a voxelwise analysis of the spinal cord to study local diffusion-related changes.

Results: A reduced cross-sectional area was observed in the cervical region of SPG4 patients, with significant anteroposterior flattening. DTI analyses revealed significantly decreased fractional anisotropy (FA) and increased radial diffusivity at all the cervical and thoracic levels, particularly in the lateral funiculi and dorsal columns. The FA changes in SPG4 patients were significantly related to disease severity, measured as the Spastic Paraplegia Rating Scale score.

Conclusions: Our results in SPG4 indicate tract-specific axonal damage at the level of the cervical and thoracic spinal cord. This finding is correlated with the degree of motor disability.

SOURCE:  J Neurol. 2022 Jan 9. doi: 10.1007/s00415-021-10933-8. Online ahead of print. PMID: 34999956 © 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.

Tract-specific damage at spinal cord level in pure hereditary spastic paraplegia type 4: a diffusion tensor imaging study

Francisco J Navas-Sánchez  1   2 Luis Marcos-Vidal  3   4   5 Daniel Martín de Blas  3   4   5 Alberto Fernández-Pena  3   4   5 Yasser Alemán-Gómez  6   7   8 Juan A Guzmán-de-Villoria  3   4   9 Julia Romero  4   9 Irene Catalina  4   10 Laura Lillo  11 José L Muñoz-Blanco  4   10 Andrés Ordoñez-Ugalde  12   13   14 Beatriz Quintáns  12   15   16 María-Jesús Sobrido  12   17 Susanna Carmona  3   4 Francisco Grandas #  4   10 Manuel Desco #  3   4   5   18

1. Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Dr Esquerdo 46, 28007, Madrid, Spain. [email protected]

2. Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain. [email protected]

3. Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Dr Esquerdo 46, 28007, Madrid, Spain.

4. Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain.

5. Departamento de Bioingeniería E Ingeniería Aeroespacial, Universidad Carlos III de Madrid, Madrid, Spain.

6. Department of Psychiatry, Centre Hospitalier Universitaire Vaudois, Prilly, Switzerland.

7. Department of Radiology, Centre Hospitalier Universitaire Vaudois (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland.

8. Medical Image Analysis Laboratory (MIAL), Centre d’Imagerie BioMédicale (CIBM), Lausanne, Switzerland.

9. Servicio de Radiodiagnóstico, Hospital General Universitario Gregorio Marañón, Madrid, Spain.

10. Servicio de Neurología, Hospital General Universitario Gregorio Marañón, Madrid, Spain.

11. Servicio de Neurología, Hospital Ruber Internacional, Madrid, Spain.

12. Instituto de Investigación Sanitaria, Hospital Clínico Universitario, Santiago de Compostela, Spain.

13. Laboratorio Biomolecular, Cuenca, Ecuador.

14. Unidad de Genética y Molecular, Hospital de Especialidades José Carrasco Arteaga, Cuenca, Ecuador.

15. Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER-U711), Madrid, Spain.

16. Fundación Pública Galega de Medicina Xenómica, Santiago de Compostela, Spain.

17. Instituto de Investigación Biomédica, Hospital Clínico Universitario de A Coruña, SERGAS, A Coruña, Spain.

18. Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain.

#. Contributed equally.

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