Skin topographical methods for quantifying pharmacodynamic parameters of a paralytic effect of a Clostridial toxin, such as a botulinum toxin upon a muscle, such as a frontalis muscle. The methods are effective in determining the potency of a Clostridial toxin, and in comparing toxins. For example, wrinkle reduction effects caused by one or more neurotoxins may be monitored, and differences in effects correspond to differences of neurotoxins.