Figure 2.

Measurement of mechanical hyperalgesia. Touch of a 22-gauge spinal needle to the plantar surface of the hind paw may elicit a prolonged lifting, shaking, and chewing of the paw. This is rare in control animals and those having sham surgery to expose but not cut the spinal nerves. However, after spinal nerve ligation (SNL), there is an ipsilateral (circles) increase in incidence of this behavior when tested 4, 11, and 18 days after baseline (BL). # – different from baseline; * – different from contralateral (squares). From Hogan et al (35), with permission.