Relationship between brainstem neurodegeneration and clinical impairment in traumatic spinal cord injury

NeuroImage: Clinical, 2017 · DOI: http://dx.doi.org/10.1016/j.nicl.2017.05.026 · Published: June 1, 2017

Spinal Cord Injury Neuroimaging Neurology

Simple Explanation

This study investigates the relationship between damage to the brainstem and clinical impairment in patients with traumatic spinal cord injury (SCI). It uses quantitative MRI to assess neurodegeneration in major brainstem pathways and nuclei. Quantitative MRI data was acquired from 30 chronic traumatic SCI patients and 23 controls. The researchers measured myelin content (using MT and R1) and iron levels (using R2*) in different brainstem regions. The study found that SCI patients had volume loss in the corticospinal tracts and medial lemniscus, as well as myelin reductions in the periaqueductal grey (PAG) and other areas. The extent of myelin reductions was related to clinical impairment, such as pinprick sensation and functional independence.

Study Duration

August 2011 and May 2015

Participants

30 chronic traumatic SCI patients (15 tetraplegic, 15 paraplegic) and 23 controls

Evidence Level

Not specified

Key Findings

1
Volume loss was detected in the corticospinal tracts (CSTs) and in the medial lemniscus in SCI patients compared to healthy controls.
2
Myelin-sensitive MT and R1 were reduced in the periaqueductal grey (PAG), the CSTs, the dorsal medulla and pons in SCI patients.
3
Lower pinprick score related to more myelin reductions in the PAG, whereas lower functional independence was related to more myelin reductions in the vestibular and pontine nuclei.

Research Summary

The study revealed atrophy and myelin reductions within major brainstem pathways and nuclei involved in motor and sensory function in chronic traumatic SCI. Atrophy was observed in motor and sensory pathways, while myelin reductions occurred in areas containing brainstem nuclei. The magnitude of myelin reductions was related to the extent of motor and sensory impairment, suggesting these structural alterations could be potential biomarkers for monitoring impairment and treatment efficacy.

Practical Implications

Neuroimaging Biomarkers

Quantitative MRI protocols offer new targets that may be used as neuroimaging biomarkers in treatment trials for SCI.

Treatment Targets

The extrapyramidal system, in combination with advanced neuroimaging tools, might offer new treatment targets to increase levels of independence in activities of daily living by improving postural stability.

Understanding Pain Mechanisms

Multimodal studies, including direct readouts of nociceptive information flow and structural/functional MRI, are needed to understand the complex interaction of nociceptive processing in SCI patients.

Study Limitations

1
Patients were on average 7.8 years older than controls.
2
The scanner was upgraded during the study period.
3
The cross-sectional study design allows us to only assess diﬀerences in MRI readouts between SCI and healthy controls, but not the underlying trajectories of structural changes.

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