by Christopher Graves, MD
Although as an orthopaedic spine surgeon I am terribly biased, I think that the cervical spine is one of the most interesting and complex structures in the human body. It has several very important functions, which at time seem like they are at odds with each other! The cervical spine is tasked with protecting the very important (and fragile) spinal cord, which requires it to be stiff and strong like a suit of armor. At the same time we ask the cervical spine to allow for an incredible amount of motion so that we can turn our heads in all sorts of directions to be able to see, hear, and otherwise use our senses in the most optimal position. This results in a beautifully complex structure that in most cases does its job unfailingly for decades.
The cervical spine is made up of 7 specially shaped bones called vertebrae. These bones are connected together by a series of complex joints, ligments, muscles and special shock absorbing structures called discs. We number the vertebrae C1 (directly underneath the skull) through C7. The first two vertebrae (C1 and C2) are extra special to allow the great range of movement of the human head. Subsequently, are shaped differently from the other vertebrae and have special names. The first cervical vertebrae (C1) is called the “atlas” because it holds the skull up like the mythological Atlas held up the earth. The second vertebrae is called the “axis” because it has a bony process on which the “atlas” rotates called the dens. Together the atlas and the axis account for more than 50% of the motion of the cervical spine.
The vertebrae below the axis are referred to as the “sub axial” cervical spine. These bones all look similar to one another, and serve similar functions to the axis and atlas. Each bone of the sub-axial spine is connected to the surrounding bones by no less than 4 joints! In addition to these joints, a shock absorber called the intervertebral disc acts to cushion the bones of the spine as we run and walk, and allow for even more freedom of motion between the vertebrae. Through the middle of these structures lies the intricate, fragile spinal cord. More than just a cable connecting the brain to the limbs and rest of the body, the spinal cord is a complex and delicate organ, with its own blood supply.
When we are born, the spinal cord is perfectly mated to the hollow area inside of the vertebral of our neck, even including a nice cushion of “extra” space to allow for movement. Unfortunately, as we age, some of these amazing structures that protect our spinal cord begin to lose their shape due to wear and tear. The intervertebral disc begins to deteriorate, and the smooth substance inside the joints (called cartilage) dries out and also deteriorates with age. This process of age related degenerative change is called arthritis when it happens elsewhere in the body. In the spine, we have a special name for this wear and tear — spondylosis.
Spondylosis is a normal process, and this process occurs in everyone as we age. Discs lose their height as they begin to dry out, and begin to “bulge” outward, including backward towards the spinal cord. As the discs lose height, the body responds by forming extra bone (“bone spurs”) in an attempt to become stiffer and protect the spinal cord. Sometimes people are born with less space in their spine, and this process of stiffening the spine for protection works against itself, causing the spinal cord to not have enough room to function properly. We call this process of spinal cord dysfunction “myelopathy”. Myelopathy can be caused by several different things including problems with the discs called “herniations”. If you think about the intervertebral disk like a jelly donut, the jelly-like nucleus pulposis is on the inside, while the tough, outer layer (the donut) on the outside is called the annulus fibrosis. A herniation happens when the nucleus pulposis pushes through the annulus fibrosis (the jelly squirts out of the donut). This can put pressure on the spinal cord and cause myelopathic symptoms as well. By far the most common cause of myelopathy in humans however is pinching caused by arthritis in the cervical spine. Therefore, this condition is known as Cervical Spondylitic Myelopathy(or CSM for short).
As we said earlier, the spinal cord is a very fragile structure, and it is extremely sensitive to pressure. It can become injured very easily, and unfortunately once it is injured there is not much we can do about it. Spinal cord injury is one of the most well funded and well researched areas in spine surgery, and although there have been many promising discoveries, there is currently no way in modern medicine to repair an injured spinal cord. Because of this, physicians go to great lengths to encourage people to protect their spinal cords from injury by doing things such as wearing seatbelts while driving. Early recognition and treatment of CSM is another important strategy of mitigating preventable cervical spine injury and dysfunction.
The most common symptoms of cervical spondylosis (neck arthritis) include neck pain and headaches.
The symptoms of myelopathy caused by CSM, however are even more subtle, and can often be overlooked, especially in elderly patients.
Patients with CSM will often report trouble with standing balance or walking. This is often noticed by family members rather than the patients themselves. Patients will describe feelings of weakness in their arms or legs which never goes away despite rest or exercise. Another one of the most tell-tale signs of CSM is difficulty with fine motor tasks or changes in their handwriting. Much of the literature that was written on myelopathy comes from Japan, and one of the classic signs of myelopathy in the Japanese Orthopaedic Association (JOA) scale is difficulty with using chopsticks. This may be less applicable however in central Illinois, as most of us tend to use easier to handle forks and spoons!
The first step in evaluating a patient for myelopathy is a history and physical examination performed by a physician who is trained to evaluate for the signs and symptoms of this type of spinal cord dysfunction. If there is clinical concern for myelopathy, your physician will likely order more tests such as x-rays and possibly an MRI scan of your spine to determine if there is enough space for your spinal cord, to see if it is showing signs of being pinched on imaging.
Treatment of cervical spondylitic myelopathy is different from treatment of most other spine pathology. If left untreated, most patients will progress as the arthritic changes worsen and the space for the spinal cord becomes less and less. The neurologic changes associated with CSM are often sudden and severe—with worsening and decline occurring in a “stepwise” fashion without warning. The story is usually “I was doing perfectly fine until one day I woke up and had trouble walking, buttoning my shirt, or signing my name”. While most problems in the spine warrant a conservative approach, the permanent and unfixable nature of injury to the cervical spinal cord means that many surgeons recommend operative treatment of CSM early in its course to prevent permanent neurologic damage.
The good news is that the surgical option most often recommended to decompress the spinal cord is one of the most successful operations in spine surgery – the Anterior Cervical Discectomy and Fusion (ACDF). This minimally invasive surgery is performed through a small incision in the front of the neck. The arthritic bone spurs compressing the spinal cord are removed, and the arthritic joints are fused together to prevent recurrence of compression. Often times this procedure can be done as an outpatient or with as little as a one overnight stay in the hospital. Many times, the symptoms are alleviated as soon as the patient wakes up after surgery.
Cervical spondylitic myelopathy is a disease that if diagnosed and treated early has an excellent prognosis. If you believe you or a family member is suffering from CSM, you should discuss this with your family physician or orthopedic surgeon. All of the physicians at the Orthopedic Center of Illinois are trained in evaluating for the signs and symptoms of cervical spondylitic myelopathy. We will be happy to help you get the right diagnosis and treatment. Call 217-547-9100 to schedule an appointment today!