We’ve previously published a blog on the lumbar spine years ago. “Understanding your MRI of the Lumbar Spine”. The cervical sequel is late but at least it showed up to the party.
Cervical spine arthritic degeneration results from increased mechanical stressors passing through the cervical spinal column, resulting in bone spur formation (uncovertebral spurring) and secondary degenerative changes in surrounding structures. This includes loss of height and water content in the discs, and enlargement of the facet joints and ligaments. Evidence of these degenerative changes are even found in asymptomatic adults, including 25% under the age of 40, 50% over the age of 40, and 85% over the age of 60. The most common evidence of degeneration is found at C5-6 followed by C6-7 and C4-5, as these levels are the most naturally mobile in the neck.
That’s right, as we all get into our 20’s, our cervical and lumbar spine starts to develop arthritis. This isn’t a disease just for your grandparents. While modern medicine fixes many problems, our bodies simply weren’t made to live this long. King Tut died around the age of 19, which was common in that era, yet those Egyptian spines weren’t evolutionarily much different than ours today.
Fortunately, many people are completely asymptomatic. Unfortunately, others can develop neck pain, regional shoulder pain, or develop neurologic deficits from pressure on the spinal cord and/or nerves.
Cervical spine degeneration can be mistaken with other conditions, like muscle strains or shoulder problems. Not every patient experiences the same symptoms or signs, so evaluating your individual condition may best be achieved by talking to a specialist, and not just comparing complaints with a friend or family.
Just as is the low back, most people (approximately 70%) get better with just rest, time and over-the-counter medications. If after four to six weeks of symptoms without improvement, some therapy or basic imaging, like an x-ray, may be beneficial.
Advanced imaging, like a cervical MRI, is reasonable when symptoms have been persistent after about 6 weeks of conservative management, or there is an abnormal neurologic exam suggesting nerve compression.
It’s pretty common nowadays for patients to receive their MRI report and most people read these reports and try to understand what is wrong. With the ease of internet access, self-diagnosis is very common, but there’s a reason Google is free and a medical education is hundreds of thousands of dollars. What’s important to remember is that the report is made by a radiologist (a physician specifically trained to review these images) who must report everything they see. Now radiologists may miss certain findings too, while doing their best. But the radiologist makes this report often without any consideration of patient’s symptoms. This is why, usually, radiologists are not the physicians calling patients about their report. Therefore the MRI may mention many different findings or abnormalities, making patients feel like everything is wrong with their spine. However all, none or some of these findings may explain the symptoms. Additionally, the severity of findings is very subjective and may vary between different physicians or radiologists. What is “severe” to one physician, may not appear so bad to another. It’s imperative that you discuss the MRI report with a spine specialist to see which, if any, of these findings are important and need to be addressed. The spine specialist should review the actual images with you and answer any questions you have about your report. If surgery eventually is required, surgery is intended to only fix the issues causing the symptoms and not to make your spine or MRI look perfect.
Normal Anatomy of the Cervical Spine
Before deciphering the abnormalities listed in the cervical MRI report, it’s important to understand the normal anatomy.
The cervical spine consists of bones (usually 7 vertebral bodies) stacked on top of each other and separated by 6 discs. There is no disc between the first and second cervical vertebrae. The vertebral bodies are usually labeled 1 through 7, and the discs are named by the bones above and below. Therefore the C4 and C5 vertebral bodies are separated by the C4-5 disc. The back side of the spine is more bone called the lamina and spinous process. This normal configuration is reported in the MRI report as both sagittal and axial depictions. The sagittal view is a profile picture. The axial view is a cross-section.
The viewpoint is similar to the lumbar spine.
Just behind the column of bones and discs is the sac which holds the spinal cord, nerve roots and fluid, called cerebral spinal fluid (CSF). Now this is different from the lumbar spine. The spinal cord itself, which is considered part of the “central nervous system” and cannot necessary be repaired if injured, spans from the brain to the ~ T12 or L1 or L2 level. Therefore the cervical spine encases the spinal cord, whereas most of the lumbar spine encases peripheral spinal nerves, called the cauda equina.
The normal cervical spine canal should be between 10-14 millimeters. Some report even larger, up to 16 millimeters. Sometimes this measurement is included in a report. The spinal cord itself extends through the entire cervical spine. At each disc level, a nerve exits the spine and goes to a specific region of the arm.
Some patients are born with smaller-than-normal cervical canals. This is termed a, “congenitally narrow canal” or “congenital stenosis”. Often, congenital stenosis can be quickly recognized when the facets axial length spans or exceeds the sagittal diameter of the canal. With a “smaller” canal at baseline, these patients may be more susceptible to spinal cord compression with more minimal changes in the discs, bone spurs or ligaments, than one with a more standard canal. However congenital narrowing may also be a finding without any clinical significance. This does not mean any intervention is required.
Pressure on the spinal cord itself may cause symptoms in the arms or legs because all the nerves heading to the lumbar spine have to pass through the cervical spine first. However the nerve roots go to specific regions of just the arms. A cervical nerve root compression would not explain leg symptoms. The C5 nerve tends to go the shoulder, or deltoid muscle. The C6 to the bicep. The C7 to the tricep. The C8 and T1 usually to the hand. There is also a branch of the cervical nerve that extends to the muscles between the shoulder blades. Spasm in the interscapular region sometimes originate from the neck, but are mistaken to feel like a problem with the thoracic spine.
Just as in the lumbar spine, the cervical disc is composed of two parts. These are microscopic and cannot exactly be differentiated on an MRI. The central softer part of the disc is the nucleus and the out layer is the annulus. Normally, the annulus holds the nucleus in the center and there is no contact with the nerve roots.
Problems in the Cervical Spine
As we get older, changes occur naturally in the spine. The discs tend to lose their water content (desiccate). The annulus of the disc may bulge, protrude or extrude/ herniate. The bones may develop bone spurs (osteophytes). The ligamentum flavum may enlarge (hypertrophy). The facet joints may enlarge (hypertrophy). The joints attached to the vertebral body (uncovertebral joints/ Luschka joints) may enlarge The bones may slip on one another (subluxation or spondylolisthesis). The result of these changes may narrow the place where the nerve exits the spine (foraminal stenosis). These changes may narrow the canal where the spinal cord resides in the spine (central stenosis). Each of these things may happen and not cause any symptoms. On the other hand, these problems may start pressing on the spinal cord/ nerves causing pain, weakness, numbness, balance problems or “myelopathy”. Listed are some commonly occurring changes, which may be described in a cervical MRI report. The most common levels affected at C4-5, C5-6 and C6-7 as these are the most mobile levels in the cervical spine.
This term is very broad and can be used to describe any arthritis in the cervical spine.
Also called “loss of disc height” or “dark discs”. Disc desiccation is a nonspecific term which describes natural “aging” of the discs. When we are young, the discs have a lot of water or cushioning in them. As we get older, the disc naturally loses its water and essentially shrinks. This can lead to “narrowing of the disc space”, “disc flattening” or “bone on bone” changes, however, this occurs in every person and this is not necessarily a cause of any symptoms.
Disc Bulge/ Disc Protrusion/ Disc Extrusion or Herniation etc…
These terms are variations of the same concept. A normal cervical disc has a smooth concave (arch) shape over the spinal canal. Typically a bulge just means the annulus is weaker and deviates towards the nerve sac. Bulges are extremely common and rarely cause any pain or symptoms. Many people have them at multiple levels in their spine. Protrusion is a slight progression in which the disc now MAY focally direct towards the cord or nerve. An extrusion or herniation occurs when a piece of the nucleus now has exited the disc and is possibly pressing on a nerve or the spinal cord.
It is difficult to understand, but the coverings of the spinal nerves (dura) have minimal pain receptors. The spinal cord itself also lacks pain receptors. It’s the part of the cervical spinal nerve, called the dorsal root ganglion, which typically mediates pain. What this insinuates is that central disc bulges, protrusions, or even herniations, often may not cause pain. This is true even when the bulge, protrusion, or even herniation may deform the cord or its sac. It usually is when the herniation, bone spur, or facet compresses the nerve root’s dorsal ganglion when pain symptoms develop.
There is also a sequence on cervical MRI, called the gradient echo, which can help your treating provider know if the herniation is new or old. Newer disc changes appear whiter while chronic appear darker.
Also called “bone spurs.” Osteophytes are bony changes that occur with natural aging. They are commonly associated with other findings such as disc bulges. The bony edges, that attach to the discs, can enlarge as the discs bulge and may or may not compress the nerves. This is commonly referred to as “uncovertebral hypertrophy” Just as with disc bulges, these are very common. However if the uncovertebral hypertrophy is significant enough, it could compress the nerves and cause symptoms.
In the cervical spine, anterior osteophytes may also occur. As these bone spurs form in front of the spine, they will not press on any nerves or cause neurologic problems. However in very rare cases, they may become so large they could compress the esophagus and cause swallowing problems.
The facets are the joints in the back that help the spine move. The spine is essentially a three-legged table. The disc is the largest leg in the front. The two facets are the two back legs.
As we age, the facets can become larger and may, or may not, press into the nerves. This may, or may not, cause pain in the neck or arms.
The ligamentum flavum is a tissue just behind the nerve sac. As we age, this ligament can get bigger or hypertrophy. Depending on how much it enlarges, it could press on the nerves and potentially cause symptoms. Usually, the ligamentum hypertrophies in combination with a disc bulge.
These two terms refer to the vertebral bodies slipping over one another. Everywhere in the spine the bones should be aligned. As we age, the ligaments holding the bones in place can loosen and allow the bones to slip. This can also occur from a fracture. In either case, this condition may or may not be symptomatic.
Stenosis refers to a situation in which a space is made smaller. It’s a very general term. The central canal, where the spinal cord resides, can become smaller, causing central stenosis. The foramen where the nerves exit the spine can become smaller, causing foraminal stenosis. Anything from a disc bulge to an osteophyte to ligamentum hypertrophy to facet hypertrophy to spondylolisthesis can cause central or foraminal stenosis. Whether or not this causes symptoms depends on the degree of stenosis and if the stenosis is causing inflammation of the nerves. Surprisingly, severe central or foraminal stenosis can be asymptomatic, if inflammation does not follow.
Cysts may form around the cervical nerve roots. These are typically called “perineural cysts”. These are fairly common and do not appear to cause symptoms.
On the other hand, cysts may form from the facet joint, called “synovial cysts”. These may be compressive and could cause symptoms.
In summary, the MRI findings do not determine whether or not symptoms are occurring. A person’s MRI can appear fairly normal and they can be in terrible pain with many symptoms. On the other hand, a person can be asymptomatic with an MRI showing awful disc extrusion, hypertrophies and spondylolisthesis. The way we accurately treat patients is by correlating their symptoms to specific changes in their MRI. The puzzle pieces must fit together.
It is imperative that the patient understands the cause of their symptoms and the treatment options. If you have an MRI showing changes, it is recommended you meet with a spine specialist to see if these changes can explain your symptoms. If it does not appear they explain your clinical picture, that does not mean you are crazy or anyone is questioning your pain. There are many causes for neck and arm symptoms, and only some are explained by a cervical spine structural change.