By Ben Benjamin, PhD
By Ben Benjamin, PhD
Question: If a client feels pain that radiates down the arm or leg, that usually indicates a disc injury. True or False?
Answer: False. This is a common misconception. The phenomenon of feeling pain in an area outside the lesion that's causing it is called referred pain. While referred pain can be caused by an injured disc, it can also result from damage to a ligament, tendon, muscle or joint -- which occurs much more frequently.
No matter where it originates, referred pain follows four basic guidelines in orthopedic medicine:
- Pain refers distally. Injuries generally refer pain from the midline to the periphery, not the other way around.
- Referred pain does not cross the midline. For instance, an injury on the right side of the low back can refer pain into the right buttock and leg, but not into the left buttock and leg.
If a client reports pain that travels from one side of the low back to the other, this means there are injuries present on both sides.
- Pain is referred within a dermatome. Each spinal nerve innervates a specific region of the body, which is known as a dermatome. Referred pain experienced within one of these dermatomes is sometimes caused by compression of the innervating nerve. However, this pain is more commonly caused by an injury to a muscle, tendon, or ligament elsewhere in the dermatome.
- The severity of an injury is directly proportional to the distance the pain refers. For instance, a severe cervical injury might refer pain to the hand, while a less severe injury might refer pain only to the upper arm.
Referred pain creates confusion for many health care practitioners. However, once you learn about the specific patterns in which particular injuries refer pain, the confusion quickly diminishes. For example, the sacrotuberous ligament in the pelvis refers pain down the back of the thigh and calf and into the heel, the gluteus medius muscle refers pain to the lateral calf, and the TP7 ligament (intertransverse ligament at C7) refers pain down one side of the lower neck to the medial border of the scapula.