Surgery for a ruptured or herniated cervical disk is the most commonly performed surgical procedure for neck pain that usually includes pain radiating into an arm.

Anatomy

• The normal cervical spine is composed of seven building blocks called vertebrae (labeled C1 through C7) that sit on the thoracic (chest) spine (Figure 1)
  1. At the upper end of the cervical spine sits the head. The cervical spine allows one to bend the head forward (flex) and backward (extend) and tilt and twist the head to the left and right
  2. Each vertebrae is constructed of a body, lamina, and pedicles which surround an opening, the spinal canal (Figures 2 and 4)
  3. On each side of a cervical vertebra lie the facets, the portion of the vertebra that forms the joints between two vertebrae (Figure 3)
  4. Through the spinal canal passes the spinal cord. Nerve roots form at each level and exit the spine through holes (foramina) formed by two adjacent vertebrae. The spinal cord and the part of the nerve roots within the spinal canal are enclosed in a fibrous sac called the dura. The nerve roots eventually form into nerves that go to the arms
  5. The spinal cord and roots float in fluid (cerebrospinal fluid) and are contained within the dura
• Separating any two vertebral bodies is a soft elastic material called a disk. The disk is composed of two parts, a soft center called the nucleus and a tough outer band called the annulus
  1. Lining the surface of the disk space of the two vertebrae on top and bottom are thin plates of cartilage
  2. There are seven cervical disks beginning below C2 and extending below C7. There is no disk between C1 and C2

Figure 1 - Seven cervical vertebrae as seen from the front.	Figure 2 - Cervical vertebra and disk seen from below.

Figure 3 - Cervical vertebrae seen from the side.	Figure 4 - Cut section through two vertebrae showing a normal disk. (ant. long. lig. = anterior longitudinal ligament, post. long. lig. = posterior longitudinal ligament).© T. Graves

Pathology

A common cause of pain in the neck and arm is a ruptured or herniated disk.

• With sudden stress such as seen following an accident or most often by gradually wearing out, the annulus of the disk may tear and allow the soft nucleus to squeeze out through the annulus like toothpaste (Figure 5 and 6)
• The nucleus may then press on a nerve root or the spinal canal. Though the injury is in the neck, the brain frequently interprets the pain as if it was in the shoulder, arm or hand

Figure 5 - Ruptured disk seen from below. Nucleus has herniated through the annulus and compresses the spinal cord and/or nerve root.	Figure 6 - Same view as figure 4 showing ruptured disk. © T. Graves

History and Examination

• The medical history and the examination allows the doctor to determine which muscles and reflexes are effected, as well as which part of the arm or hand may have decreased feeling. This information allows the doctor to diagnose whether the ruptured disk presses on the spinal cord or which nerve root the ruptured disk is pinching
• A ruptured disk between C4 and C5 produces weakness in the deltoid muscle, which elevates the arm at the shoulder, and numbness at the top of the shoulder
• A ruptured disk between C5 and C6 produces weakness of the biceps muscle, which bends the elbow, and numbness along the outside of the upper and lower arm
• A ruptured disk between C6 and C7 produces weakness of the triceps muscle, which straightens the elbow, and numbness in the thumb and first finger, the adjacent palm of the hand and lower forearm
• A ruptured disk between the C7 and first thoracic vertebrae produces weakness in the muscles of the hand and numbness in the fourth and fifth fingers of the hand and adjacent palm

Non-surgical Therapy

Unless the neck and arm pain from a ruptured disk is excruciating or there is significant muscle weakness, a trial of non-surgical therapy is indicated. This includes:

• Medication for the relief of pain and muscle spasm
• Cervical traction at home
• Physical therapy that may include deep heat and message, ultrasound and traction
• Neck muscle strengthening exercises

Special Testing

Various tests help decide whether surgery is needed and to determine the exact location of the ruptured disk. Some of the tests are:

• An x-ray of the cervical. The x-ray may show narrowing of the disk space, bony overgrowth of bone or evidence of instability of the spine,
• An electromyogram or EMG, which measures nerve function. This is accomplished by placing small needles in the muscles and recording the result on a special machine
• A CT (computerized tomography) scan or MRI (magnetic resonance imaging). These scans produce detailed computer generated images of your ruptured disk and surrounding bone and other tissues. These tests may also rule out other causes of pain and weakness in your arm or hand
• A myelogram followed by a CT scan. A myelogram is an invasive test. Though invasive, a myelogram is probably the most accurate test. An iodine containing dye, which shows-up on x-rays is injected into the cerebrospinal fluid in the lumbar spine. The dye is then positioned in the cervical spine and X-rays followed by a CT scan are taken. Leakage of cerebrospinal fluid following the procedure may cause subsequent headaches which usually does not last more that a couple of days

Indications for Surgery

• Significant weakness in the hand or arm
• Failure to improve on medication and physical therapy
• The various tests confirm the presence of a ruptured disk

Surgical Procedure

The surgery is designed to remove the ruptured portion of the disk away from the injured nerve root. This usually results in relief of the neck and arm pain and may allow the muscles that are weak to regain their strength. There are two ways to remove a ruptured cervical disk.

• Cervical laminectomy and microdiscectomy. This is performed through the back of the neck. The procedure is similar to that used for a lumbar ruptured disk. (See Ruptured lumbar disk)
  1. A small incision in the skin at the back of the neck over the area of the ruptured disk. Then the muscle is moved away from the lamina of the vertebrae above and below the area of the ruptured disk
  2. Using an air drill or special bone instruments, a little bit of the lamina and adjacent facet is removed to gain access to the disk. The main part of the surgery is then carried out using an operating microscope or special magnifying lenses
  3. Using special instruments, some of the ligament under the bone is removed and the nerve root carefully moved (Figure 7 A-C)
  4. The ruptured disk is then found and removed from in front of the nerve root. Bleeding is controlled, the wound is sutured together and a sterile dressing applied

Figure 7a - Removal of the ruptured disk from the back of the neck by laminectomy. A small amount of lamina and the adjacent facet is removed using a bone biting rongeur. © T. Graves	Figure 7b - The nerve root (covered by dura) is elevated off the ruptured disk. © T. Graves

Figure 7c - A grasping rongeur is used to remove the ruptured disk. © T. Graves

• Anterior cervical discectomy and fusion. This is performed through the front of the neck. (Figures 8A-D)
  1. A small incision is made in a crease of the neck on one side or the other and directly in front of the disc to be removed. The tissues between the skin and the front of the vertebrae are dissected apart in a plane between the carotid artery and jugular vein, laterally, and the strap muscles, medially, that overly the thyroid gland beneath which is the recurrent laryngeal nerve. (Figures 8A and 8B ) The recurrent laryngeal nerve is the nerve to the vocal cords
  2. To fully expose the front of the disk and adjacent vertebra, a pair of muscles (longus colli) are elevated to each side and the blades of a retractor inserted into the underbelly of the muscles. This also displaces the thyroid gland medially (Figures 8C and 8D)
  3. The annulus is cut and the soft nucleus is removed. The annulus at the back of the disk is also cut as well the thicker ligament lying directly behind. This is carried out under the operating microscope or with special magnifying lenses called loupes (Figures 8E and 8F)
  4. Next, the part of the ruptured disc that lay against the nerve root is removed, taking the pressure off the nerve root
  5. The plates of cartilage that line the bone are removed otherwise the fusion will not occur and then the surface of the bone reshaped (Figure 8G)
  6. In order to maintain the normal height of the disk space, it is necessary to separate the two vertebrae using a bone graft. A piece of bone (bone graft) taken from the fuse together patient's iliac crest (hip bone), or more often cadaver iliac crest bone or cadaver fibular (lower leg) bone is used for the fusion. (Cadaver bone is removed from a cadaver, specially processed and sterilized.) (Figure 8H) More recently titanium and plastic prostheses have been used to maintain disk height and through which bone bridges the vertebra. The fusion between the two vertebrae takes four to twelve months to complete
  7. Some surgeons also place a titanium plate between the two vertebrae to be fused. The plate is attached to the two vertebrae using titanium screws. However, there is no evidence that inclusion of a plate is necessary. A titanium plate may be desirable if, in addition to the ruptured disk, there is instability between the two vertebrae or there is a history of smoking

Figure 8a - view from in front, and B, cross-section through the neck at the C7 level, showing the dissection along the plane between the carotid artery and strap muscles overlying the thyroid gland. RLN = recurrent laryngeal nerve. © T. Graves	Figure 8b - © T. Graves
Figure 8c - C and D. Tissues are held apart by retractor blades inserted into the elevated longus colli muscles. Note that the thyroid gland and recurrent laryngeal nerve are displaced by the retractor against the trachea, which is made more rigid by the tube inserted for anesthesia (not shown). © T. Graves	Figure 8d - © T. Graves

Figure 8e - Same view as figure 6 showing a ruptured disk. © T. Graves	Figure 8f - The ruptured disk has been removed from in front and a curette removes the cartilage.. © T. Graves
Figure 8g - A bur is used to shape the surfaces of the bone to receive the bone. © T. Graves	Figure 8h - A bone graft is inserted between the two vertebral bodies and demineralized bone matrix gel placed about the graft.. © T. Graves

Complications

• No surgery is absolutely safe and free of complications. Some of the possible complications of cervical disk surgery are:
• Negative effects of anesthesia (See Anesthesia)
• Bleeding or hemorrhage with the possible need for blood transfusions
• Nerve root or spinal cord injury that could result in paralysis, loss of feeling, or loss of bowel and bladder control
• Infection
• Tear in the covering of the nerves with leaking of cerebrospinal fluid
• Injury to blood vessels
• Vocal cord paralysis due to compression of the recurrent laryngeal nerve during anterior cervical discectomy by even a properly placed retractor (Figure 8H)
• Injury to the various structures in the neck such as the carotid artery, jugular vein, trachea and esophagus, etc
• Failure of the fusion to take place (Figure 9a and b)
  
• The possibility of unforeseen complications
  
• Fracture of a plate (Figure 9a and b)

Figure 9a - Three level fusion with plate. Neck in flexion (neck bent forward). Note the fractured plate with ends touching.	Figure 9b - Neck in extension (neck bent backward). Upper levels are fused (small arrows). At the lowest level the plate segments separate showing that there is no fusion at this level (large arrow).

Care after Surgery

• Most patients are discharged from hospital on the first post-operative day. Many can be discharged the same day as surgery
• Elderly patients may require additional hospital stay
• A collar may be prescribed
• Any drainage from the wound should be reported to the doctor
• Do not expect that the removal of the ruptured disk guarantees that there will never be a neck problem in the future. A neck that has suffered a ruptured disk is evidence of a predisposition for problems. Occasional neck pain from time to time is not unusual