Fig. 7.

Swallow rate differs between hindlimb-and forelimb-affected LCN-SOD1 mice. Although the data distribution for swallow rate (a) was not statistically different between LCN-SOD1 mice with predominant hindlimb (b) versus forelimb (c) paralysis, there was a trend for forelimb-affected mice to have slower swallow rates compared to hindlimb-affected mice. Specifically, forelimb-affected mice had relatively tight clustering of the data, which spanned only half the distribution range of hindlimb-affected mice. This finding suggests additional phenotype classifications may exist beyond the basic dichotomy used in this preliminary study. Radiographic images from two different mice are shown in (b, c)—one with hindlimb paralysis (b) and the other with forelimb paralysis (c). Radiographic images from a single control mouse (d, e) are shown for comparison. Boney structures are labeled for the hindlimbs (F femur, f fibula, t tibia, hp hindpaw), forelimbs (H humerus, r radius, u ulna, fp forepaw), and tail. Note the caudally extended hindlimbs and inverted hindpaws (i.e., soles facing upward) in the hindlimb-affected mouse (b). In the forelimb-affected mouse (c), one forepaw is curled under and the other is inverted (i.e., palm facing upward), with both forepaws located in close proximity to the hindpaws. Also note the “dropped” head and torso, which demonstrates the reduced weight-bearing capacity of the forelimbs in this mouse. Sample size (n) = 5 mice per group; ns nonsignificant (p = 0.340); X mean