What is Referring Pain? Referred pain (also known as reflective pain and referring pain) is pain that you feel in one section of your body that actually originates in another section of the body. It may seem like a strange concept to consider - pain jumping from one region of the body to another, but all the parts of the body are interconnected, especially the structures of the nervous system. The individual nerves of the nervous system may travel a long way from the spinal cord, all the way to the top of the head and the tips of the fingers and toes. An injury to one region of the nerve may result in all the structures that nerve supplies from being affected. This is one of the reasons for referred pain.
Another example of referred pain is pain felt in one or more extremities - most commonly the left arm - as a result of a myocardial infarction (heart attack). In this case, the ischemia (lack of blood flow) results in pain in that arm or leg as a result of a lack of blood flow to those tissues. When cardiovascular issues arise, the distal (furthest from the point of attachment) parts of the arms and legs are the parts most likely to suffer, because the body has more trouble sending oxygen and returning carbon dioxide from those distant locations.
Referred pain is an interesting condition in that patients may not feel pain in the area of injury where it originates. Referred pain is somewhat different from radiating pain. In an injury that involves radiating pain, a person would experience pain at the location of structural injury, as well as pain that radiates away from this site in all directions, or in one direction - such as down one arm or leg. An example of a referred pain pattern, one the other hand, may occur when the S1 nerve root - located at the base of the spine - is pressed upon by a bulging or herniated disc, resulting in pain and dysfunction in the lower leg and foot. Unlike a radiating pain pattern, the S1 nerve root compression does not result in pain that travels from the leg and all the way through the upper and lower leg.
The most common types of referring pain pattern injuries associated with the back involve compression of the nerve roots where they pass through openings in the spine. These openings include the intervertebral foramina in the vertebral spine and the sacral foramina in the sacrum. In the vertebral spine, the foramen is located between the posterior section of the vertebral bodies and the superior and inferior articular processes. The intervertebral foramina are composed superior vertebral notch above and the inferior vertebral notch below. Together, these foramina allows for enough space for the passage of the nerve roots, blood vessels, and connective tissues. The size of these openings for the passage of the spinal nerves may be occluded by a thickening of the bone, development of osteophytes on the bone, and other arthritic degenerative changes that irritate the nerve or constrict it. Other disease conditions that may involve the encroachment of other materials into these openings include spinal disc herniations and tumors.
Nerve signals are interconnected with others and spread everywhere, making it hard to find the exact source of pain. Pain travels. A single lumbar spinal nerve supplies the facet joint, the muscles and skin over the back, and the muscles, bone, and skin of the leg. When the nerve is squeezed (aka - nerve root compression) at the opening in the spine, a signal is sent down the nerve reporting an injury. Any structure that is associated with this nerve may suffer from lost functioning or referring pain.
The two most common back pain injuries that involved referred pain in the feet are spinal disc herniations of the L5 nerve root and the S1 nerve root.