Femoral and obturator neuropathies.

The femoral and obturator nerves both arise from the L2, L3, and L4 spinal nerve roots and descend into the pelvis before emerging in the lower limbs. The femoral nerve's primary function is knee extension and hip flexion, along with some sensory innervation to the leg. The obturator nerve's primary function is thigh adduction and sensory innervation to a small area of the medial thigh. Each may be injured by a variety of potential causes, many of them iatrogenic. Here, we review the anatomy of the femoral and obturator nerves and the clinical features and potential etiologies of femoral and obturator neuropathies. Their necessary investigations, including electrodiagnostic studies and imaging, their prognosis, and potential treatments, are discussed in this chapter.

Using the Mouse Grimace Scale to reevaluate the efficacy of postoperative analgesics in laboratory mice.

Postoperative pain management in animals is complicated greatly by the inability to recognize pain. As a result, the choice of analgesics and their doses has been based on extrapolation from greatly differing pain models or the use of measures with unclear relevance to pain. We recently developed the Mouse Grimace Scale (MGS), a facial-expression-based pain coding system adapted directly from scales used in nonverbal human populations. The MGS has shown to be a reliable, highly accurate measure of spontaneous pain of moderate duration, and therefore is particularly useful in the quantification of postoperative pain. In the present study, we quantified the relative intensity and duration of postoperative pain after a sham ventral ovariectomy (laparotomy) in outbred mice. In addition, we compiled dose-response data for 4 commonly used analgesics: buprenorphine, carprofen, ketoprofen, and acetaminophen. We found that postoperative pain in mice, as defined by facial grimacing, lasts for 36 to 48 h, and appears to show relative exacerbation during the early dark (active) photophase. We find that buprenorphine was highly effective in inhibiting postoperative pain-induced facial grimacing in mice at doses equal to or lower than current recommendations, that carprofen and ketoprofen are effective only at doses markedly higher than those currently recommended, and that acetaminophen was ineffective at any dose used. We suggest the revision of practices for postoperative pain management in mice in light of these findings.

The Rat Grimace Scale: a partially automated method for quantifying pain in the laboratory rat via facial expressions.

We recently demonstrated the utility of quantifying spontaneous pain in mice via the blinded coding of facial expressions. As the majority of preclinical pain research is in fact performed in the laboratory rat, we attempted to modify the scale for use in this species. We present herein the Rat Grimace Scale, and show its reliability, accuracy, and ability to quantify the time course of spontaneous pain in the intraplantar complete Freund's adjuvant, intraarticular kaolin-carrageenan, and laparotomy (post-operative pain) assays. The scale's ability to demonstrate the dose-dependent analgesic efficacy of morphine is also shown. In addition, we have developed software, Rodent Face Finder®, which successfully automates the most labor-intensive step in the process. Given the known mechanistic dissociations between spontaneous and evoked pain, and the primacy of the former as a clinical problem, we believe that widespread adoption of spontaneous pain measures such as the Rat Grimace Scale might lead to more successful translation of basic science findings into clinical application.