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Cereb Cortex. 2015 Sep;25(9):2670-82. doi: 10.1093/cercor/bhu065. Epub 2014 Apr 4.

The Corticospinal Tract in Huntington's Disease.

Author information

1
Clinical and Behavioral Neurology Department, Rome, Italy.
2
IRCCS Neuromed (Pozzilli), Pozzilli, Italy.
3
Radiology Department, IRCCS Santa Lucia Foundation, Rome, Italy.
4
Clinical and Behavioral Neurology Department, Rome, Italy Neuroscience Department, University of Rome 'Tor Vergata', Rome, Italy.
5
Clinical and Behavioral Neurology Department, Rome, Italy Department of Internal Medicine and Public Health, University of L'Aquila, Rome, Italy m.dipaola@hsantalucia.it.

Abstract

Huntington's disease (HD) is characterized by progressive motor impairment. Therefore, the connectivity of the corticospinal tract (CST), which is the main white matter (WM) pathway that conducts motor impulses from the primary motor cortex to the spinal cord, merits particular attention. WM abnormalities have already been shown in presymptomatic (Pre-HD) and symptomatic HD subjects using magnetic resonance imaging (MRI). In the present study, we examined CST microstructure using diffusion tensor imaging (DTI)-based tractography in 30-direction DTI data collected from 100 subjects: Pre-HD subjects (n = 25), HD patients (n = 25) and control subjects (n = 50), and T2*-weighted (iron sensitive) imaging. Results show decreased fractional anisotropy (FA) and increased axial (AD), and radial diffusivity (RD) in the bilateral CST of HD patients. Pre-HD subjects had elevated iron in the left CST, regionally localized between the brainstem and thalamus. CAG repeat length in conjunction with age, as well as motor (UHDRS) assessment were correlated with CST FA, AD, and RD both in Pre-HD and HD. In the presymptomatic phase, increased iron in the inferior portion supports the "dying back" hypothesis that axonal damage advances in a retrograde fashion. Furthermore, early iron alteration may cause a high level of toxicity, which may contribute to further damage.

KEYWORDS:

CAG repeats; DTI diffusion tensor imaging; Huntington's disease; corticospinal tract; structural connectivity; tractography

PMID:
24706734
DOI:
10.1093/cercor/bhu065
[Indexed for MEDLINE]

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