Tracking the neurodegenerative gradient after spinal cord injury
Michela Azzarito, Maryam Seif, Sreenath P. Kyathanahally, Armin Curt, Patrick Freund
Abstract
OBJECTIVE: To quantify neurodegenerative changes along the cervical spinal cord rostral to a spinal cord injury (SCI) by means of quantitative MRI (qMRI) and to determine its relationship with clinical impairment. METHODS: Thirty chronic SCI patients (15 tetraplegics and 15 paraplegics) and 23 healthy controls underwent a high-resolution T1-weighted and myelin-sensitive magnetization transfer (MT) MRI. We assessed macro- and microstructural changes along the cervical cord from levels C1 to C4, calculating cross-sectional spinal cord area, its anterior-posterior and left-right width and myelin content (i.e. MT). Regression analysis determined associations between qMRI parameters and clinical impairment. RESULTS: , p = 0.011), left-right width (by 0.36 mm, p = 0.03), and mean cord MT (by 0.13%, p = 0.04), but independant of lesion severity (p > 0.05). Higher lesion level was associated with greater magnitudes of neurodegeneration. Greater loss in myelin content in the dorsal columns and spinothalamic tract was associated with worse light touch (p = 0.016) and pin prick score (p = 0.024), respectively. CONCLUSIONS: A gradient of neurodegeneration is evident in the cervical cord remote from a SCI. Tract-specific associations with appropriate clinical outcomes highlight that remote neurodegenerative changes are clinically eloquent. Monitoring the neurodegenerative gradient could be used to track treatment effects of regenerative and neuroprotective agents, both in trials targeting cervical and thoracic SCI patients.