Characterization of Graded MASCIS Contusion Spinal Cord Injury using Somatosensory Evoked Potentials

Study Design—Electrophysiological analysis using somatosensory evoked potentials (SEPs) and behavioral assessment using Basso-Beattie-Bresnahan (BBB) scale were compared over time for graded MASCIS contusion spinal cord injury (SCI). Objective—To study SEP responses across different contusion injury severities and to compare them with BBB scores. Summary of Background Data—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 NYU-MASCIS impactor from impact heights of 6.25 (mild), 12.5 (moderate), 25 (severe), or 50 mm (very severe). The control group underwent laminectomy only. SEP and BBB recordings were performed once prior to 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. While 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. Correspondence: Dr. Angelo All, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, 720 Rutland Avenue, Traylor 701C, Baltimore, MD 21205, Tel: (410) 502-5393, [email protected]. Protocol Approval: Institutional Animal Care and Use Committee (IACUC), Johns Hopkins University NIH Public Access Author Manuscript Spine (Phila Pa 1976). Author manuscript; available in PMC 2011 May 15. Published in final edited form as: Spine (Phila Pa 1976). 2010 May 15; 35(11): 1122–1127. doi:10.1097/BRS.0b013e3181be5fa7. N IH PA Athor M anscript N IH PA Athor M anscript N IH PA Athor M anscript Conclusion—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.