Nerve root compression

Cases studies Activation of pain transmission nerves Muscle contraction Inflammation Nerve root compression

Compression of a nerve root may produce pain. When this occurs, the patient feels pain at the site where sensitivity is picked up by the root, and not at the compressed site. For example, when a lumbar disc herniation compresses a sciatic nerve root, patients feel leg pain, but feel no pain where the root is being compressed (usually around the intervertebral foramen). This type of pain is called "radiated" pain and it follows the compressed nerve pathway and is associated with other signs of compression, such as sensitivity, and strength or reflex changes.

Not all types of pain felt in the arms or legs come from radiated pain. Sometimes, back pain itself causes a reflex pain at these sites without the presence of nerve compression. In this case, pain is due to a reflex process of the spinal cord, and not to nerve compression. It is called "referred" pain and does not specifically follow any nerve pathway, nor is it accompanied by signs of compression.

Referred pain is of no importance and does not require any treatment changes. However, radiated pain transmits nerve compression and, therefore, a certain degree of neurologic suffering. The most generally accepted criterion is that if radiated pain worsens or is maintained for more than 6 weeks with signs of root compression, treatment should be changed and the possibility of surgery should be evaluated, provided there is certainty about what is compressing the nerve.

A nerve may be compressed and generate no pain. An example would be when the compressed nerve is one that controls a muscle and is no longer able to transmit sensitivity. In this case, pain may not be present even though the nerve is damaged, and patients only notice a great or total loss of strength in the related muscle. Although the muscle itself may be in good condition, it does not receive the stimuli ordering it to contract. If this occurs, it is a sign of relevant nerve compression, and it is usually necessary to treat it quickly.