A SENSITIVE AND RELIABLE LOCOMOTOR RATING-SCALE FOR OPEN-FIELD TESTING IN RATS

Behavioral assessment after spinal cord contusion has long focused on open field locomotion using modifications of a rating scale developed by Tarlov and Klinger (1954). However, on-going modifications by sever al groups have made interlaboratory comparison of locomotor outcome me asures difficult. The purpose of the present study was to develop an e fficient, expanded, and unambiguous locomotor rating scale to standard ize locomotor outcome measures across laboratories. Adult rats (n = 85 ) were contused at T7-9 cord level with an electromagnetic or weight d rop device. Locomotor behavior was evaluated before injury, on the fir st or second postoperative day, and then for up to 10 weeks. Scoring c ategories and attributes were identified, operationally defined, and r anked based on the observed sequence of locomotor recovery patterns. T hese categories formed the Basso, Beattie, Bresnahan (BBB) Locomotor R ating Scale. The data indicate that the BBB scale is a valid and predi ctive measure of locomotor recovery able to distinguish behavioral out comes due to different injuries and to predict anatomical alterations at the lesion center. Interrater reliability tests indicate that exami ners with widely varying behavioral testing experience can apply the s cale consistently and obtain similar scores. The BBB Locomotor Rating Scale offers investigators a more discriminating measure of behavioral outcome to evaluate treatments after spinal cord injury.