History of the Herniated Disc
The history is the patient’s story: how the symptoms began, where the symptoms are located, what is the interference in the quality of life, what relieves and what aggravates. A back disc herniation commonly causes leg pain because the herniation compresses a nerve in the spinal canal and that nerve ultimately carries information to the leg. However, the nerve compression may only cause numbness, or weakness instead of pain or may cause all or some of those symptoms in a leg. (numbness, weakness, pain). Occasionally, a central disc herniation causes symptoms in both legs through direct pressure on the nerves in the dural sac (fluid filled bag containing the nerves).

Physical Exam of the Disc Herniation
The physical exam is performed by the doctor to determine the effects of herniation. An examination of the function of the nerves in the legs determines if there is any weakness, numbness, or reflex change. An examination of the movement of the back may cause pain to radiate from the back into the effected leg. Raising the leg with the patient lying on his/her back may produce pain in the leg from compression of the nerve.

Diagnostic Studies of the Disc Herniation
The purpose of diagnostic studies is to answer the question, “where on the electrical diagram is the interruption that explains the patient’s clinical situation.” (history and physical exam) Diagnostic studies are designed to produce a picture of the interruption (MRI, Myelogram, C.A.T. scan, Discogram, etc.) or to indicate which nerve may be electrically interfered with (EMG or SSEP). The diagnostic studies must correlate with (explain) the patient’s history and physical exam to be meaningful. Many tests show age related changes that exist in people who do not have pain. (there are people who have herniated discs who do not have any symptoms and degenerative changes are common in the spine as patients mature). Therefore, the diagnostic studies must be carefully reviewed to determine if any findings on the tests are relevant to the partiular patient.Treatment of the Disc Herniation

Natural History
The natural history is the rate that nature cures a particular condition. Nature has been curing things for 3 billion years and a certain percentage of patients with a particular diagnosis are going to be healed by nature. For disc herniations, nature does a good job of relieving symptoms.
Approximately 80% of patients with a pinched back nerve will improve without surgery. Why do people with herniations pressing on a spinal nerve improve? The problem is a 3-dimensional equation between the degree of tension on the nerve and space available for the nerve. The people who improve have a favorable combination of the space available for the nerve and the degree of tension on the nerve. Nature adequately adapts the nerve to its environment in 80% of patients.

Conservative Care
The purpose of conservative care is to relieve symptoms and improve function. Conservative Treatment does not always “cure” but often it “relieves.” The laundry list of potential treatments for the herniated disc includes: physical therapy, injections, medications, etc.

Surgery
The goal of surgery is to take the pressure off the nerve by removing the herniated disc and providing adequate room for the nerve which nature failed to do. The herniation causes the symptoms in the leg, and freeing the nerve allows the potential for the nerve to reverse its “injury state” from compression. Surgery improves specific symptoms in the leg more than other symptoms. (e.g. surgery is very effective for leg pain but less effective for numbness.)

The herniated disc means part of the nucleus (N) pushes through the outer ring of the disc (A = Annulus). Herniation means displacement from its original location. The diagram shows the herniation in red. Compare the diagram on the left (normal disc) to the diagram on the right (herniated disc). In the normal disc, the nucleus (N) is completely surrounded by intact ring called the annulus (A). In the diagram on the right (herniated disc), the outer ring is torn, allowing the displacement of the nucleus.



The image above is a schematic of a top down view of the disc in the normal anatomic arrangement. Notice that immediately behind the disc is the dura (black ring) (dura = sack that contains spinal fluid and the nerves) and the nerve roots themselves (black arrows). If a disc herniates (pushes through the ring of the disc, the annulus), the nerves are easily effected because they are just behind the normal disc structure. The herniation usually occur towards the back of the disc because the wall of the ring (annulus) is thinner and the front side of the ring (annulus) is bordered by the strongest ligament in the spine. (the anterior longitudinal ligament)

The herniated disc has several anatomic forms: contained, extruded, and free fragment (sequestered disc). These descriptions serve to explain the relationship of the herniation to the the disc located between the vertebral bodies. The diagrams above show the different types of herniation. A Contained Disc Herniation (1) stretches the outer wall (black semicircle) but is still bound by the outer wall. An Extruded Disc Herniation (2) breaks through the outer wall and ligament but is in contact with the disc space. A Free Fragment (3) breaks through the outer wall and ligament and is completely separated from the disc.

The spinal nerve originates in the spinal cord and terminates in an extremity. A degree of slack allows the full movement of the nerve. If a disc herniation occupies space underneath the nerve, then the nerve can be stretched over the herniation and also compressed by the herniation. The nerve carries electrical signals between its origin and its destination. If the nerve is distorted and its function interrupted from stretch or compression, then the signals may be completely or partially interrupted. The loss or partial interruption of the signals is recognized as a particular symptom or symptoms

The nerve is a two way street carrying information from its origin (spinal cord) to its destination (extremity, such as leg or arm) and from its destination to its origin (spinal cord). The nerve is essentially a telephone cable with fibers inside carrying specific information, (red and black lines in the diagram above). Specific information includes skin sensation, muscle movement, atrophy, reflex, pain, and temperature sensation. If a nerve is compressed, some or all these functions may be interrupted.

The nerves originate in the spinal cord and exit the spine at different intervals. A specific nerve controls specific sensation, muscle function, pain territory and reflex. The nerve exits at the corresponding disc level in the cervical spine so that a C4-C5 level disc would effect the C5 nerve. The blue rings are the pedicles, which serve as columns of bone projecting from the floor of the spinal canal to hold up the roof. The pedicles are shown cut across the base of the floor in this diagram. The spinal nerve anatomy is essentially an electrical wiring diagram. From a patient with a herniated disc, assessment of the symptoms, physical exam, and diagnostic studies can lead to an understanding of the location of interruption in the wiring diagram. The drawing above demonstrates the nerves on the right side of the spine. The same color coded nerve organization would exist on the left side of the diagram so that each spinal level has a matched pair of nerves but are not shown in this schematic to avoid confusion.

The herniated disc may migrate down from the disc space where it originates. The diagram above shows the disc herniation has moved down the spinal canal below the original disc space (origin of the herniated disc) and is located behind the vertebral body.

Normal Anatomy
The spinal cord and spinal nerves fit in a three dimensional box: a roof, a floor and side walls. Compromise of the three dimensional box can produce pressure on the spinal cord, the spinal nerves or both.



Central Herniated Disc
A central disc herniation (black) is located in the center of the spinal canal and can compress the spinal cord. Depending on the size of the herniation, and the degree of compression and level of location in the neck, the arms and legs may be affected. Occasionally, the function of the bowel and bladder will be disturbed.



Posterolateral Herniated Disc
A posterolateral herniation is located to one side of the spinal canal and compresses the spinal nerve exiting to go down the arm at that level of the neck. The herniation (black) will usually effect one nerve going down the arm.



Foraminal Herniated Disc
A foraminal disc herniation (black) is located further to the side of the spinal canal underneath the nerve and is in the bony tunnel in which the nerve exits the spine. After the nerve leaves the spine, it travels into the arm to perform its intended function. Compression of the nerve in the foramen (bony tunnel) causes symptoms in one arm in the distribution of that particular nerve.



Foraminal Narrowing (Foraminal Stenosis)
Foraminal narrowing (red from above and yellow from below) is the zone in which the spinal nerve leaves the bony spinal canal to go down the arm. Compression of the nerve in the foramen (bony tunnel) causes symptoms in the arm due to compression of the nerve supplying that arm.



Uncinate Spur
Uncinate spurring (yellow) can compress the spinal nerve and produce symptoms in the arm supplied by that specific nerve. This is pressure from the floor of the spinal canal on the nerve.



Facet Spur
Facet spurring (red) can compress the spinal nerve and produce symptoms in the arm supplied by that specific nerve. This is pressure from the roof of the spinal canal on the nerve.



The natural history of the cervical herniated disc compressing the spinal nerve is controlled by essentially two factors: space available for the nerve and degree of tension on the nerve. These factors are not predictable from viewing an MRI scan.The clinical course of the patient reveals the improtance of these two factors. Why do some people with cervical nerve root compression improve without surgery? The reason is that the space available and degree of tenison factors are favorable.

Normal Cervical Spinal Canal with the boundaries of the floor and roof.



Normal Cervical Spinal Canal with spinal cord and nerve root added in. This diagram shows the floor on the left and the roof on the right. (just the opposite of the first diagram in this series)



The herniated disc may be also viewed from the side. The front of the spine (floor) consists of the vertebra and the disc space located between the vertebra. The disc space contains the disc itself consisting of the nucleus and the annulus. The back (roof) of the spine consists of the spinous process and the lamina. Between the roof and floor of the spine is the spinal canal where the nerves are located. The diagram above shows a herniated disc displaced into the spinal canal at the level of the disc space.



The herniated disc may migrate up from the disc space where it originates. The diagram above shows the disc herniation has moved up the spinal canal above the original disc space and is located behind the vertebral body.



The herniated disc may migrate down from the disc space where it originates. The diagram above shows the disc herniation has moved down the spinal canal below the original disc space and is located behind the vertebral body.