Lasegue's sign


sciatica

 [si-at´ĭ-kah] neuralgia" >neuralgia along the course of the sciatic nerve; the term is popularly used to describe a number of disorders directly or indirectly affecting the nerve. Because of its length, the sciatic nerve is exposed to many different kinds of injury, and inflammation of the nerve or injury to it causes pain that travels down from the back or thigh along its course through the lower limb into the foot and toes. Certain leg muscles may be partly or completely paralyzed by such a disorder.

True sciatic neuritis is rare; it can be caused by a toxic substance such as lead or alcohol, and occasionally by other factors. Sciatic pain, however, can also be produced by conditions other than inflammation of the nerve. Probably the most common cause is a herniated disk. A back injury, irritation from arthritis of the spine, or pressure on the nerve from certain types of exertion may also be the cause. Occasionally diseases such as diabetes mellitus, gout, or vitamin deficiencies may be the inciting factor. In rare cases, pain may be referred over connected nerve pathways to the sciatic nerve from a disorder in another part of the body. Finally, some cases are idiopathic. Because of the long, painful, and disabling course of severe sciatica, the underlying cause should be investigated and corrected when possible.Radiation of sciatic nerve pain. From Frazier et al., 2000.

Lasegue's sign

A clinical sign of pressure on nerve roots in the lumbar region in SCIATICA. With the patient lying on his or her back there is limitation of thigh bending (flexion) on the affected side, on attempts to raise the straight leg. The sign can also be elicited by attempting to flex the ankle with the straight leg raised. This causes pain. (Charles Ernest Lasegue, 1816–83, French neurologist).