In vivo motion of the human cervical spinal cord in extension and flexion

Margulies, Susan S.; Meaney, David F.; Bilston, Lynne B.; Thibault, Lawrence E.; Campeau, Norbert G.; Riederer, Stephen J.

Acute spinal cord injury is a devastating form of trauma exhibiting a 40% mortality rate and occurring most commonly in motor vehicle accidents. During a traumatic spinal cord injury, tissue damage occurs when the neural and/or vascular components of the spinal cord are stretched beyond the threshold of functional or structural failure. Therefore, characterizing the motion and spatial deformation of the spinal cord during realistic loading is essential in understanding the pathomechanics of acute spinal cord injury.

The objective of this study was to use a motion tracking magnetic resonance imaging technique to measure the in-vivo quasi-static motion of the cervical spinal cord in human volunteers produced by varying degrees of flexion and extension. An initial preparation pulse consisting of a slice selective 180. pulse inverted the magnetization in a midsagittal section while the subject was in a neutral position. Before motion, tissue was tagged in multiple transverse planes using additional spatially selective radio frequency pulses. After the head-neck structure came to rest in its new position, a midsagittal magnetic resonance (MR) image was obtained which showed the movement of the tissue tag lines caused by the maneuver. A comparison of the tagged line pattern in MR images obtained with and without head movement revealed the distortion of the cervical spinal cord and its displacement relative to surrounding structures.

Results revealed the spinal cord moves and deforms considerably during the flexion and extension maneuvers within the normal range of motion. Flexion is characterized by a slight lengthening of the spinal cord relative to its neutral position length, with a variable displacement of the upper cervical cord and cephalad (towards the head) motion of the lower cord Conversely, extension causes a shortening and caudal (away from the head) movement of the spinal cord. These in-vivo motion measurements form the foundation for more sophisticated studies to elucidate the biomechanical mechanisms responsible for traumatic spinal cord injury.

Year

Entry

1972

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1990

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1971

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