Another condition that could cause spinal cord compression is OPLL:
Ossification (calcifying, or turning to bone) of Posterior Longitudinal Ligament
The Posterior Longitudinal Ligament (PLL) lines the back side of the vertebral body, and is at the front side of the spinal canal. This ligament rests right against the front part of the dura, which is the sac that contains the spinal fluid and the spinal cord.
In the diagram to the right, the PLL is illustrated by the purple line.
In these cross section views on MRI studies, the thick black line behind the vertebral bodies, which in this case is composed of calcified tissue, looks black on the MRI scan. The presence of the OPLL here contributes to the compression on the spinal cord. At the areas of compression, there is no white fluid around the spinal cord as there is above and below.
In the images below, which are from CT scans, the ligament tissue which has ossified (turned to bone) shows up white.
The clinical significance of OPLL is that, while in most cases, the spinal cord can be decompressed most directly from the front approach (as illustrated here), in cases with OPLL, usually the decompression has to be done from the backside, or what is called a posterior approach, such as with laminoplasty or laminectomy. The bony change of OPLL often causes the bone to become adherent to the dura (the sac containing the spinal fluid), so that operating from the front has a higher chance of having a spinal fluid leak.
Some symptoms go along with a cervical (neck) degeneration (wearing out) condition, like neck pain and numbness/tingling, but with spinal cord compression, the findings might be more subtle.
Often, patient with pure myelopathy (spinal cord compression, as distinct from nerve root compression) might not have much pain, but present more with balance problems and trouble with fine motor movements, like buttoning clothing, or opening a jar. On exam, there may be abnormal reflexes, balance, or other findings.
Myelopathy tends to be progressive and in most cases, a serious discussion of the options, in many cases including a discussion of surgical decompression, needs to occur.