University of Louisville
Assessing Sensory, Motor, and Propriospinal Recovery After Thoracic Spinal Cord Injury
Institution
University of Louisville
Faculty Advisor/ Mentor
Stephen Onifer
Abstract
There are about 11,000 spinal cord injuries in the United States each year. Spinal cord injury (SCI) results in damage of sensory and motor axonal pathways responsible for locomotion. Propriospinal axons involved in the coordination between upper and lower limbs during locomotion can also be damaged. Behavioral and electrophysiological assessments are critical for measuring and understanding dysfunctions and functional recovery after SCI. Using a clinically relevant adult rat SCI model, contusion injuries of 6.25 g=B7cm (n=3D1), 12.5 g=B7cm (n=3D1), 25 g=B7cm (n=3D1), 125 Kdyn (n=3D2), and 175 Kdyn (n=3D2) were produced at the T10 spinal cord segment. The extremes of SCIs showed a direct relationship to locomotion measured with the Basso, Beattie, Bresnahan (BBB) Open Field Locomotor Scale. TcMMEPs, an index of motor transmission through the ventral cord, were not recorded in any rat at any time post-SCI. SSEPs, an index of sensory transmission through the dorsal cord, were never recorded in the most severely injured rats. Interenlargement reflex responses were recorded in least severely injured rats whose BBB scores indicated that they had forelimb and hindlimb coordination. Histology revealed that the extent of damage to axons passing through the SCI site had a direct relationship to the behavioral and electrophysiological results. We conclude that behavioral, electrophysiological, and anatomical assessments after SCI allow for the evaluation of functioning and recovering axonal pathways. This novel study of interenlargement reflexes showed that they will be useful for assessing recovery of neurotransmission along propriospinal pathways after SCI.
Assessing Sensory, Motor, and Propriospinal Recovery After Thoracic Spinal Cord Injury
There are about 11,000 spinal cord injuries in the United States each year. Spinal cord injury (SCI) results in damage of sensory and motor axonal pathways responsible for locomotion. Propriospinal axons involved in the coordination between upper and lower limbs during locomotion can also be damaged. Behavioral and electrophysiological assessments are critical for measuring and understanding dysfunctions and functional recovery after SCI. Using a clinically relevant adult rat SCI model, contusion injuries of 6.25 g=B7cm (n=3D1), 12.5 g=B7cm (n=3D1), 25 g=B7cm (n=3D1), 125 Kdyn (n=3D2), and 175 Kdyn (n=3D2) were produced at the T10 spinal cord segment. The extremes of SCIs showed a direct relationship to locomotion measured with the Basso, Beattie, Bresnahan (BBB) Open Field Locomotor Scale. TcMMEPs, an index of motor transmission through the ventral cord, were not recorded in any rat at any time post-SCI. SSEPs, an index of sensory transmission through the dorsal cord, were never recorded in the most severely injured rats. Interenlargement reflex responses were recorded in least severely injured rats whose BBB scores indicated that they had forelimb and hindlimb coordination. Histology revealed that the extent of damage to axons passing through the SCI site had a direct relationship to the behavioral and electrophysiological results. We conclude that behavioral, electrophysiological, and anatomical assessments after SCI allow for the evaluation of functioning and recovering axonal pathways. This novel study of interenlargement reflexes showed that they will be useful for assessing recovery of neurotransmission along propriospinal pathways after SCI.