Spinal canal narrowing with signal change in the cord is indicative of the beginnings of myelopathy. This causes dysfunction of the spinal cord and is associated with multiple signs and symptoms. Signs are findings on physical examination such as increased reflexes and imbalance with testing. Symptoms of course are what you would complain of. See the section regarding myelopathy on the website for a full explanation of these symptoms.
Not only is myelopathy a concern but acute injury to the cord is also possible. The spinal canal changes in diameter with flexion and extension. Extension or bending the neck backwards narrows the canal even further. This action can cause pinching of the cord and a resultant spine cord injury called a central cord syndrome. The potential for this injury increases with patients involved in activity that can cause falls onto the head. Biking, water and snow skiing, horseback riding among other activities fall into this category.
Normally on physical examination, the reflexes on both sides will be increased with the presence of myelopathy. There are rare presentations of injury to the cord that are only one-sided that can caused asymmetric hyper-reflexia. See Brown-Sequard syndrome of the website to explain this phenomenon.
Some of your symptoms could originate from the lumbar spine.
If you have developed the beginnings of myelopathy, surgery is generally recommended.