The precise cause of LSS is unclear. Narrowing of spinal structures in the spinal cord such as the central canal, the lateral recesses, or the intervertebral foramen (the opening where a spinal nerve root passes) must be present, but are not sufficient to cause LSS alone. Many people who undergo MRI imaging are found to have such changes but have no symptoms. These changes are commonly seen in people who suffer from spinal degeneration that occurs with aging (e.g., spinal disc herniation). LSS may also be caused by osteophytes, osteoporosis, a tumor, trauma, or various skeletal dysplasias, such as with pseudoachondroplasia and achondroplasia.