[Water tank scale: a reliable method for assessing motor function after spinal cord injury in rats]

To analyze the reliability of the Water Tank Scale for assessing recovery of motor function after spinal cord injury (SCI) in rats.

Thirty-six adult female SD rats were randomly divided into SCI and sham-operated groups (n= 18). The recovery of the hind limb motor function was assessed using Water Tank scoring, BBB scoring, and motor-evoked potentials (MEP) at 1, 3, 5, 7, 14 and 21 days after SCI. MEP was used as the gold standard for analyzing and comparing differences between the two scoring methods.

The Water Tank scores of the rats were significantly higher than the BBB scores on day 3 (0.22±0.43 vs 0, P < 0.05) and also on days 5, 7 and 14 after SCI (0.67±0.49 vs 0.11±0.32, 4.33±1.19 vs 2.83±1.04, 8.61± 1.20 vs 7.06±1.0, P < 0.01). On day 21 after SCI, the scores of the Water Tank Scale of the rats did not significantly differ from the BBB scores (14.78±1.06 vs 14.50±1.47, P>0.05). Neurophysiological monitoring showed that both the Water Tank score and BBB score were significantly correlated with MEP latency, but the Water Tank score had a greater correlation coefficient with MEP latency (r=-0.90).

Compared with the BBB scale, Water Tank scoring allows more objective and accurate assessment of functional recovery of the spinal cord in early stages following SCI in rats, and can thus be used as a reliable method for assessing functional recovery of the hind limbs in rat models of acute SCI.