Normal Anatomy
There are 33 bones that make up the spinal column. There are 7 bones in the neck (cervical spine), 12 in the trunk (thoracic spine), 5 in the low back (lumbar spine), 5 fused bones that attach the spine to the pelvis (sacrum) and 3 fused bones form the “tail bone” (coccyx).
The cervical spine three two main functions:
- House and protect the spinal cord
- Support the weight of the head
- Allow motion in the neck so that the head can turn
The spinal cord is attached to the brain and is similar to a large electrical cable. It conducts information between the brain and the arms and legs. Approximately 60 smaller nerves exit the spinal cord (30 to the right and 30 to the left) along its path from top (base of the brain) to bottom (the spinal cord generally ends at the disc between the first and second lumbar vertebrae). Each nerve exits from a “hole” that is formed where two vertebrae meet (called the “neural foramen”) and is thus named (eg the nerve that exits adjacent to the 5th cervical bone is called the C5 nerve root).
These nerve roots go to different parts of the body (arms, trunk, legs, bowel and bladder) and transmit information to and from those regions (eg the C5 nerve root carries sensation from the outside of the arm and shoulder region and allows you to raise your shoulder to the side). When thinking about the function of the spinal cord, I like to use the following analogy:
The spinal cord is like a major interstate (I-95) that runs in a north/south direction (from the brain towards the lower back). Just as the interstate has multiple exits that allow traffic to enter and leave, the spinal cord has nerves that branch off and function similarly to these exits by allowing information (about motor and sensory function) to get to and from the spinal cord and on to the brain. There are conditions that can affect the interstate (spinal cord), the exits (nerves) or both; these are discussed later in this handout.
The bones of the spine (vertebrae) are stacked on top of each other with soft cushioning discs located in between them (intervertebral discs). These discs are very similar to a jelly doughnut. The outer portion of the disc (called the annulus fibrosus) is like the dough of a jelly doughnut and the inner portion (nucleus pulposus) is similar to the jelly inside the doughnut. In a normal disc, all the nucleus pulposus remains inside the annulus fibrosus.
However, if there is a full thickness tear in the annulus fibrosus, the nucleus pulposus will leak out of that tear. This is similar to a full thickness tear in the dough of the jelly doughnut with the jelly inside it leaking out through that tear. The leaked part of the nucleus/jelly is referred to as a “disc herniation.” It is also commonly referred to as a herniated disc, disc extrusion, or a slipped disc. The leaked portion of the disc enters the space where the nerve resides and causes compression of the nerve &/or the spinal cord. This compression leads to irritation of the nerve and the subsequent pain, numbness, tingling, paresthesias (feeling of “pins and needles”), temperature changes, etc. Compression of the spinal cord can frequently present with or without pain but be associated with numbness/tingling/paresthesias in the arms &/or legs, balance problems, clumsiness of the hands, etc.
MRI of the neck demonstrating a disc herniation and bone spurs causing spinal cord & nerve root compression.
NECK PAIN
While problems with the cervical spine frequently lead to “neck pain,” they can also present with pain/numbness/tingling/etc. in the shoulder area and/or the upper extremity (arm, forearm or hand). Most episodes of “neck pain” are caused by relatively harmless conditions. The most common of these conditions include: muscle strain (“pulled muscle”), weak neck extensors (muscles that hold up the head), degenerative discs (Figure 1), arthritic facets (Figure 2), spinal instability (spondylolisthesis- slipping of the bones) and cervical kyphosis (Figure 1). Neck pain affects a significant portion of the population at some point in their lifetime. The muscular causes of neck pain occur with an acute injury (ie whip lash) when there is a muscle strain (“pulled muscle”) or from chronic conditions such as weakness and subsequent fatigue of muscles that support the cervical spine (generally due to weakness or being overworked due to cervical malalignment).
The most common reason for neck pain is due to the normal aging process of the discs in the cervical spine. This wear is a combination of biomechanical changes that occur in the disc (determined by one’s genetic program) as well the mechanical effects of absorbing both weight and allowing motion to occur between the bones as they move against the disc. This mechanical wear is very similar to the wearing of a car tire of the sole of a shoe over time. When these discs reach a critical level where they can no longer absorb shock efficiently, this can result in neck pain (Figure 1).
Figure 1. MRI demonstrating normal degenerative discs at every level except at L5-S1 where the disc has degenerated (“worn out”). Note how the other discs are tall and have the white core (hydrated “jelly” inside a donut) whereas the L5-S1 disc is dark and has no white core in it. Thus, the L5-S1 disc has lost its ability to absorb shock and may lead to pain during a “flare up.” This patient had back pain of the “discogenic” pattern. Xray demonstrating degenerative discs.
Figure 2 CT scan demonstrating a degenerative facet joint. Normal facet joints have a smooth surface made of cartilage that slides against each other. One of the facet joints is more worn out (right side of this page) than the other facet joint. This can lead to neck pain as two rough surfaces (“bone on bone”) move against each other.
This common form of neck pain is usually worse when a patient spends an excessive amount of time in a “fixed” position (ie looking down at paper work, starring at a computer screen, etc). The person may note that they are often stiff and sore in the morning after waking. This is not a dangerous condition and treatment is based on the severity of the pain. Improving your aerobic conditioning and strengthening the neck extensor muscles can help in the long term management of this condition. Even if aerobic activity causes neck pain, it should be pursued. No long term harm will result in exercising through the neck pain.
If the pain is mild and you are able to cope with it using the occasional anti-inflammatory medication, then that is okay. For those whose pain is more severe and persistent, physical therapy can be helpful. For those who have persistent pain and fail both medical management and physical therapy, epidural steroid injections (ie “cortisone” injections) may be effective. While most patients do not need surgery for this condition, some patients who have failed all other treatment modalities and continue to suffer from severe pain, may benefit from surgery.
ARM PAIN, NUMBNESS & TINGLING
Pain, numbness, tingling or burning can occur together or independently in the arm, forearm or hand due to one, or a combination of several different problems. These symptoms are most commonly due to a pinched nerve in the neck but can also be caused due to problems of the shoulder joint (eg: rotator cuff tear, shoulder arthritis, etc), elbow problems (pinched nerve at the elbow) or wrist/hand (carpal tunnel syndrome). The site of the problem (neck versus shoulder) is easily determined with a good physical exam.
Why does a “neck” problem cause symptoms in the arm and hand? Because the nerves in the arm, forearm and hand originate in the neck. Thus, when they get pinched in the neck the pain radiates to or presents along the course of that nerve. A nerve root usually gets pinched when the jelly from the doughnut leaks out and puts pressure on that nerve root as it exits the spine (please look at the Normal Anatomy section for /images to better understand this statement). Nerves can also get pinched when bone spurs grow into and decrease the size of the hole where the nerve exits the spinal column.
The severity of the symptoms can range from mild to very severe. For a lightly pinched nerve, the symptoms are generally on the milder side while for a significantly pinched nerve, the symptoms can be very severe. For example, if I were to lightly squeeze your index finger it may not bother you much. However, if I put all my might into it and squeezed the same finger as hard as it could, it would probably hurt more. Similarly, the symptoms of a “pinched” nerve aresomewhat determined by how “hard” the nerve is being squeezed. If the symptoms (pain, numbness, tingling, burning, etc) are mild and you are able to cope with them using the occasional anti-inflammatory medication, then that is okay. For those whose symptoms are more severe and persistent, physical therapy can be helpful. For those who have persistent symptoms and fail both medical management and physical therapy, epidural steroid injections (ie “cortisone” injections) may be indicated.
The goal of epidural steroid injections is to try to decrease the inflammation around the nerve the thus help decrease the pain. They are generally not very effective for other symptoms of pinched nerves such as numbness, tingling, and burning. Their effectiveness can range from being completely unhelpful to completely resolving your pain. For the majority of cases, they provide partial relief of the pain for a certain period of time (ranging from hours to months) before the pain returns as the injected steroid “wears out.” I generally think that if you do not attain substantial relief with an epidural steroid injection, it is better to try a different approach.
For patients who have failed all other treatment modalities or want immediate, complete relief of their symptoms, surgery can be very effective. In fact, surgery of the cervical spine (neck) for pinched nerves is one of the most successful surgeries we perform. The gist of the surgery is to remove the herniated disc and/or bone spurs that are compressing the nerve root and causing your symptoms (we “UNpinch” the nerve root). The overwhelming majority of patients have immediate resolution of their symptoms upon awakening from surgery. If you have had a pinched nerve for a long time before you proceed with surgery, you may be left with somenumbness; however, this is generally mild, not bothersome and resolves over the course of several days to weeks. A very small percentage of patients are left with a small patch of permanent numbness which is due to “nerve damage” that can happen if a nerve is “pinched” for a long time before surgery. There are different types of surgery that can be performed depending on your specific condition, symptoms, anatomy, etc. I will discuss this with you individually if and when we reach this point in your treatment. For educational purposes, a brief description and /images of the different types of surgical procedures is included.
CERVICAL STENOSIS
Cervical stenosis means narrowing of the spinal canal in the cervical spine (neck region). The symptoms begin slowly over time and are characterized by neck pain and/or stiffness, shoulder and/or arm pain, hand numbness/tingling/weakness/clumsiness, leg stiffness/weakness and overall balance problems with walking. There are three main causes of cervical stenosis and they can occur individually or in combination:
- Degenerative discs: The “wear and tear” of the discs in between the bones of the cervical spine leads to bulging and herniation of the disc and arthritic bone spurs into the spinal canal, thus narrowing the diameter of that canal. As the diameter of the canal decreases, there is less space for the spinal cord and nerves, thus leading their compression.
- Facet degeneration: The “wear and tear” of the facet joints leads to over growth of those joints and the protrusion of the resulting bone spurs into the spinal canal.
- Thickening of the ligamentum flavum: With the wear and tear of the spine, this membrane connecting the individual bones in the back of the neck gets thicker and “buckles” into the spinal canal, thus causing canal narrowing.
Treatment
The treatment of cervical stenosis depends not only on the symptoms but also whether there is presence of spinal cord compression. Most symptoms of cervical stenosis can be treated non-operatively with medications, physical therapy and regular neck exercises. However, if the narrowing of the spinal canal is severe enough where there is spinal cord compression, surgery maybe recommended. Spinal cord compression is a significant issue because the spinal cord is the super highway of information transmission to and from the brain to the arms and legs. When there is pressure on and thus squeezing of the spinal cord, the messages to and from the brain cannot get through efficiently past this block and could be lost. As the wear and tear accumulates over the years, this squeezing of the spinal cord can get worse and lead to worsening of the symptoms and profound balance and manual dexterity problems. It is important to understand the difference between spinal cord compression and nerve root compression. A compressed nerve root can be treated non-operatively if the symptoms are tolerable for the patient and there is NO muscle weakness. I like to use the following analogy when thinking about the implications of spinal cord and/or nerve root compression:
The spinal cord is like the Mississippi river with the nerve roots being the tributaries that take off from the river. A patient can have blockage of the Mississippi river itself (spinal cord compression) or one of the tributaries (nerve root compression). As you may imagine, blockage of one of the tributaries is a lot less significant than the blockage of the river itself! This problem is fairly common and its presentation and treatment is discussed later in this publication.
Spinal cord compression is interesting in that it can be painless and is usually suspected during the physical exam and confirmed with an MRI (or a CT scan if a patient cannot undergo an MRI). Depending on the severity of the compression and your symptoms (balance problems, hand/arm numbness/tingling/burning, leg/foot numbness/tingling/burning, weakness, spasticity, etc), treatment recommendations are made.
ANTERIOR CERVICAL SPINAL SURGERY
Anterior Cervical Discectomy & Fusion (ACDF)
A small (around 1 inch) incision is made over the affected disc space of the cervical spine in the front of the neck. I use a microscope to provide the best visualization and minimize the size of the incision and amount of soft tissue injury. The intervertebral disc space between the two vertebrae is identified. With the use of a microscope and specialized tools, the entire “bad” disc is removed and the pressure on the nerve root &/or spinal cord is relieved. Any additional bone spurs or arthritic joints causing additional compression at that level are also removed. Specialized tools are then used to contour the vertebral endplates so that there is good fit between the bone graft. The bone graft is the material (patient’s own hip bone, plastic cage, or cadaver bone) that will replace the removed intervertebral disc space and “jack open” the previously collapsed space. After the graft is placed in the disc space, a plate with screws is applied for additional stability in most cases. This plate is very small and the patient is not able to feel its presence.
Patients are allowed to get out of bed and walk independently within a couple of hours of the operation. Whether patients stay overnight or go home the same day is decided on an individual basis before the operation. Patients who undergo a one-level ACDF usually elect to go home several hours after the operation (outpatient). Patients who undergo an ACDF of three or more levels are usually admitted overnight and go home the following day. Those patients undergoing a two-level ACDF can go home the same day or be admitted depending on their comfort level. The overwhelming majority of patients experience significant, if not complete relief of their arm pain, numbness, tingling, etc. There is mild pain at the incision site and some pain in the back of the neck but it is generally well controlled with pain medication; most patients are off all pain medications in a few days. Immediately following the operation, patients are allowed to resume all activities (expect high impact ones for 3 months) without restrictions.
ACDF is one of the most successful operations in terms of maximizing patient outcomes and minimizing associated complications. The results of this operation are generally very good and patients with symptoms in the upper extremity (pain/numbness/tingling/etc.) have immediate relief upon awakening after surgery. The critical factor for good outcomes with this type of surgery is the accuracy of diagnosis and, needless to say, meticulous surgical technique. The better the correlation between your symptoms, examination findings and imaging studies, the better the chance of surgery eliminating your symptoms.
Patient File- One Level ACDF
Figure: MRI (at the top of the page) demonstrates a very large disc herniation causing severe spinal cord compression. Interestingly, this patient did not have much pain but had numbness, tingling and burning sensation in her arms and fingers.
Patient File 2- One Level ACDF
A 54 year old woman with long standing mild to moderate neck pain came into my office with complaints of worsening neck pain and new onset pain, numbness and tingling in her right arm.
Figure: X-rays of the neck do not show any abnormalities other than a slightly degenerative disc at C6-7 (note that the height there is slightly diminished compared to the discs above it)…which is not unusual given that this patient was 54 years old.
My suspicion was that she had a disc herniation which was accounting for her new onset arm symptoms. The neck pain was attributed to weak neck extensor muscles and some “age appropriate wear and tear” (AKA degenerative discs). Because her pain and other symptoms were mild and tolerable, we started with physical therapy & NSAIDs. Unfortunately, the therapy did not work and her symptoms persisted. An MRI of the neck was ordered and she returned to see me after the MRI was done.
In the mean time, her symptoms did not resolve and were bothersome enough where she decided to undergo surgery (a C6-7 ACDF).
These are the post-operative X-rays after the patient underwent a C6-7 ACDF. The surgery lasted 30 minutes and the patient had immediate relief from all her arm symptoms upon awakening after surgery. She had some mild neck soreness due to the surgery. However, her surgery related pain was not severe enough to prevent her from going home a few hours after surgery.
Patient File 3- Two Level ACDF
Figure: This MRI was done after the surgery and it demonstrates how the pressure that was on the spinal cord and nerves before the surgery has been relieved.
Figure: Post-operative X-ray of the patient after undergoing an anterior discectomy and fusion from C4-6 (also called a C4-6 ACDF).
Anterior Cervical Corpectomy & Fusion
This procedure is very similar to the ACDF except that either a part or all of the vertebral bone is removed along with the discs next to it. This procedure is required if the disc herniation has migrated behind the bone or there are bone spurs behind the vertebral bone that cannot be reached and removed by doing a discectomy alone. This procedure is also necessary in cases of severe cervical kyphosis where doing discectomy alone will not restore normal alignment.
CASE- Vertebral body facture
The patient was a 28 year old man who fell from a height of 8 feet. He had a fracture of the C3 vertebral body (RED arrow on the X-ray marked “A” and BLUE arrow on the CT scan). An attempt was made to treat him without surgery in a halo; however, the fracture was too unstable and could not be aligned in an acceptable position. Thus, he underwent a C3 corpectomy (where the fractured bone was removed) and C2-4 fusion. In place of the fractured bone, a piece of hip bone was inserted. He went on to heal without complications. The X-ray marked C was performed at 6 weeks after surgery and shows the hip bone was being not at “white” at the C2 and C4 bones because it has not mended (or “fused”) with those bones yet. An X-ray done at 6 months after surgery (marked D) shows how the hip bone is of the same density (“whiteness”) as the C2 and C4 bones and has woven together with those bones.
POSTERIOR CERVICAL SPINAL SURGERY
Cervical Laminectomy
A one inch (or longer for extensive stenosis) incision is made in the back of the neck over the effected region of the spine. The muscles over the bone are moved aside until the lamina is visualized. The correct level is then identified again. With the use of a microscope and specialized tools, the lamina is removed and the spinal cord and nerves are decompressed (released so that they are no longer pinched). All the unnecessary bone spurs and thickened ligaments that compress the nerves are also removed. This is a very safe operation which is usually performed in a short period of time (30 minutes to 120 minutes depending of the extent of stenosis) without any significant complications (I will discuss individual complications with you). Depending on the extent of surgery, the patient maybe able to go home after surgery or stay in the hospital for a couple of days. Patients who only require one level of laminectomy and do not have any instability (malalignment or “slipped bones”) generally do not require a fusion and do not lose any motion. Patients who undergo several levels of laminectomy are generally fused so that they do not develop malalignment (and associated pain) that requires additional surgery in the future.
Cervical Laminectomy & Fusion
Patients with multi-level spinal cord compression due to spondylosis (severe arthritis of the spine), spondylolisthesis (abnormally slippage between bones), or scoliosis (curvature of the spine) may require a fusion with or without the placement of screws and rods. While this is also a very safe procedure, it does add slightly more operative time and is generally associated with a slightly longer recovery. I generally do not fuse after a laminectomy unless it is absolutely necessary because of the aforementioned reasons &/or to prevent a future surgery. There is some loss of motion after a fusion; the extent of motion loss depends on the amount of surgery and the number of levels being fused. For example, a one level fusion will generally result in a negligible amount of motion loss while a multilevel (eg. C4-T1 laminectomy and fusion) fusion could result in significantly more (the exact amount depends on your specific problem and will vary between individuals). In those with pre-existing motion loss due to ankylosed joints (“worn out” joints that don’t move normally), there is generally not any increase in motion loss after a laminectomy in fusion.
Patient File 4
Figure: These radiographs are of a patient who underwent a cervical laminectomy and fusion. This procedure is done through a incision on the back of the neck. This patient had a fracture which was causing spinal cord and nerve compression.
Laminoplasty
This is a procedure that allows the surgeon to remove the pressure off the spinal cord without fusion. It is unlike a laminectomy in that NO bone is removed. Instead the volume of and the space in the spinal canal is increased by “repositioning” the lamina. Unfortunately, because this is a procedure that is performed from the back of the neck, there is more post-operative pain than procedures performed from the front of the neck. Also, this procedure is used for a specific set of problems and the patient needs to meet several criteria to be a candidate for this procedure.
Patient File 5
Figure: This is a patient with multilevel cervical stenosis and spinal cord compression as demonstrated on the MRI. He underwent a “laminoplasty” to create more space around the spinal cord, thus relieving the pressure off and “unpinching” the spinal cord. The intraoperative radiograph on the right shows the small laminoplasty plates which are holding open the lamina and creating the space around the spinal cord.
Patient File 6
This radiograph demonstrates loss of the normal curvature of the spine due to degenerative (“worn out”) discs. Due to the degeneration, the vertebrae (bones of the spine) start collapsing on each other resulting in a forward lean of the head and neck. This is associated with neck and shoulder pain as the muscles on the neck have to work harder to hold up the head & prevent it from falling forward. There is also stretching (and pain) of these posterior neck muscles as the alignment worsens.
While the white line represents normal spinal alignment (what the spine should look like), the red line demonstrates the current malalignment (the curve of the spine is in the opposite direction of normal) known as "cervical kyphosis."
MRI of the same patient demonstrates multiple degenerative discs with herniation and bone spurs that cause nerve compression and account for the pain and numbness in her neck and arms.
The patient’s pain did not improve with NON-operative treatment and she underwent a C4-7 anterior cervical discectomy and fusion. The radiograph on the left shows her spinal alignment before the surgery and the one on the right shows her spine after surgery. Note the improvement in alignment and the placement of bone in space vacated by the degenerative discs. Also note that the bone placed where the disc was removed has mended with her own bone and thus “fusion” has occurred. She was in the hospital overnight and went home the following day. The pain in her neck, numbness and tingling in her neck and arms completely resolved.
