A NEW METHOD OF QUANTIFYING THE EXTENT OF TISSUE LOSS FOLLOWING SPINAL-CORD INJURY IN THE RAT

Many agents are being tested for their ability to limit the developmen t of secondary tissue damage following trauma to the spinal cord by co mparing the extent of trauma-induced tissue destruction between groups of animals receiving different treatments. However, the changes that occur following spinal concussion result in initial swelling of the co rd and then progressive shrinkage. It is therefore impossible to deter mine the preinjury cross-sectional area of cord once it has been damag ed, making accurate calculation of the extent of tissue destruction di fficult. To overcome this problem, a method for predicting the preinju ry cross-sectional area of damaged spinal cord was developed in the ra t by establishing correction factors that related the cross-sectional area of a reference transverse section to the area of sections at othe r points along the cord. This method was used to calculate the volume of tissue destruction in groups of rats 48 h, 4 days, and 4 weeks afte r photochemically induced cord injury. The results were compared with the volume of tissue destruction obtained when calculated from measure d rather than predicted cord area. One month following photochemically induced injury, the spinal cord had shrunk significantly. This result ed in significant underestimation of the lesion volume when calculated from the measured area of injured cord. This demonstrates that the pr einjury area of the cord must be established in order to calculate the full extent of tissue destruction and that it can be estimated accura tely using the method described in this study. (C) 1996 Academic Press , Inc.