At every level of the spine, nerve roots branch off the spinal cord and exit the spinal column through small canals. Each of these canals is called an intervertebral foramen or foraminal canal, and foraminal stenosis is a narrowing of this canal.
Causes of foraminal stenosis
Constriction of the nerve roots leaving the spine in the foraminal canal is typically caused by bone spurs, a herniated or bulging disc, arthritis or ligament thickening. Foraminal stenosis can also be caused by enlargement of a joint (the uncinate process of a vertebra) in the spinal canal.
Foraminal stenosis symptoms
Radicular pain results from compression, inflammation and/or injury to a spinal nerve root. Foraminal stenosis can elicit radicular pain, or pain that radiates through the peripheral nerve system into an extremity (including the thigh, calf and possibly the foot) directly along the course of a specific spinal nerve root. The pain is often deep, steady and reproducible with certain activities such as sitting or walking, and follows the involved area of distribution covered by the specific nerve. Traveling pain caused by foraminal stenosis can be accompanied by numbness and tingling, muscle weakness and loss of specific reflexes.
The most usual cause of radicular pain is sciatica (pain that radiates along the sciatic nerve that runs down the buttocks, along the back of the thigh and calf and into the foot).