Characterization of graded multicenter animal spinal cord injury study contusion spinal cord injury using somatosensory-evoked potentials.
METHODS
Electrophysiological analysis using somatosensory-evoked potentials (SEPs) and behavioral assessment using Basso, Beattie, Bresnahan (BBB) scale were compared over time for graded Multicenter Animal Spinal Cord Injury Study (MASCIS) contusion spinal cord injury (SCI).


OBJECTIVE
To study the SEP responses across different contusion injury severities and to compare them with BBB scores.


BACKGROUND
For any SCI therapy evaluation, it is important to accurately and objectively standardize the injury model. The graded MASCIS contusion injuries on dorsal spine have been standardized using BBB, which is subjective and prone to human errors. Furthermore, dorsal pathway disruption does not always produce locomotor deficits. SEP monitoring provides an advantage of providing a reliable and objective assessment of the functional integrity of dorsal sensory pathways.


METHODS
Four groups of Fischer rats received contusion at T8 using New York University (NYU)-MASCIS impactor from impact heights of 6.25 mm (mild), 12.5 mm (moderate), 25 mm (severe), or 50 mm (very severe). The control group underwent laminectomy only. SEP and BBB recordings were performed once before injury, and then weekly for up to 7 weeks.


RESULTS
Graded levels of injury produced concomitant attenuations in hindlimb SEP amplitudes. Following injury, 25 and 50 mm groups together differed significantly from 12.5 and 6.25 mm groups (P < 0.01). From week 5, differences between 12.5 and 6.25 mm groups also became apparent (P < 0.01), which showed significant electrophysiological improvement. However, no significant differences were observed between 25 and 50 mm groups, which showed negligible electrophysiological recovery. Although comparable differences between different groups were also detected by BBB after injury (P < 0.001), BBB was less sensitive in detecting any improvement in 6.25 and 12.5 mm groups.


CONCLUSIONS
SEP amplitudes and BBB scores decrease corresponding to increase in injury severity, however, these show different temporal patterns of recovery. These results demonstrate the utility of SEPs in conjunction with BBB, to monitor therapeutic interventions in SCI research.
Agrawal
Gracee
G
Department of Biomedical Engineering, Johns Hopkins University School of Medicine, 720 Rutland Avenue, Baltimore, MD 21205, USA.
Kerr
Candace
C
Thakor
Nitish V
NV
All
Angelo H
AH
D000704:Analysis of Variance; D000818:Animals; D002540:Cerebral Cortex / Q000503:physiopathology*; D003288:Contusions / Q000503:physiopathology*; D004567:Electrodes, Implanted; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006614:Hindlimb / Q000503:physiopathology; D009043:Motor Activity / Q000502:physiology; D051381:Rats; D011916:Rats, Inbred F344; D020127:Recovery of Function / Q000502:physiology; D012720:Severity of Illness Index; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D013904:Thoracic Vertebrae / Q000503:physiopathology