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Cervical Laminectomy
Removal of the posterior aspect of the spine in the neck

Until the 1950’s, virtually the only operation for taking pressure off of the cervical (neck) spinal cord was cervical laminectomy. This review of cervical laminectomy is primarily for the treatment of cervical spondylotic myelopathy, a disease in which the cervical spinal cord is compressed by overgrown bone and soft tissues, usually as a result of degenerative arthritis. Cervical laminectomy for ruptured disc is reviewed under discectomy for cervical ruptured disc. Cervical laminoplasty is another operation that takes the pressure off the spinal cord but retains the lamina and spinous processes.

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)
  • At the upper end of the cervical spine sits the head. The cervical spine allows the head to bend forward (flex) and backward (extend) and tilt and twist the head to the left and right
  • Each vertebrae is constructed of a body, lamina, and pedicles which surround an opening, the spinal canal (Figure 2)
  • On each side of a cervical vertebra lie the facets, the portion of the vertebra that forms the joints between two vertebrae (Figure 3). The bone lying between the upper and lower facets of a vertebra is called the lateral mass
  • Through the spinal canal passes the spinal cord. The spinal cord is made up of many nerve tracts that run the length of the cord and carry electrical impulses from the brain to the nerve roots at every level and from the nerve roots to the brain. The major tracts that control movement are in the front (anterior) part of the cord. The major tracts that carry sensation to the brain are in the back (posterior) part of the cord
  • Nerve roots are present at each level and exit the spine through holes (foramina) formed by two adjacent vertebrae. The nerve roots eventually form into nerves that go to the arms. The spinal cord and roots float in fluid (cerebrospinal fluid) and are contained within a fibrous sac called 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. Lining the surface of the disk space of the two vertebrae on top and bottom are thin plates of cartilage. There are seven cervical disks beginning below C2 and extending below C7. There is no disk between C1 and C2
  • 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)
Figure 1 - Cervical spine as seen from the back. Figure 2 - Cervical spine as seen in cross-section.
 

Figure 3 - Cervical spine as seen from the side.

Through the spinal canal passes the spinal cord.  Nerve roots are present at each level and exit the spine through holes (foramina) formed by two adjacent vertebrae.  The nerve roots eventually form into nerves that go to the arms. The spinal cord and roots float in fluid (cerebrospinal fluid) and are contained within a fibrous sac called 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. Lining the surface of the disk space of the two vertebrae on top and bottom are thin plates of cartilage. There are seven cervical disks beginning below C2 and extending below C7. There is no disk between C1 and C2.

The spinal cord is made up of many nerve tracts that run the length of the cord and carry electrical impulses from the brain to the nerve roots at every level and from the nerve roots to the brain. The major tracts that control movement are in the front (anterior) part of the cord. The major tracts that carry sensation to the brain are in the back (posterior) part of the cord.

Pathology

Some individuals have a congenital narrowing of the spinal canal (spinal stenosis) that causes spinal cord compression when young.  With advancing age, injury or surgical removal of a disk, several changes occur in the bone, disk, joints and ligaments of the cervical spine that can produce neck and arm pain as a result of a nerve root being compressed or weakness and loss of feeling in the arm and legs because the spinal cord is compressed (Figure 4).

Figure 4 - MRI through the center of the cervical spine showing a spondylolesthesis of C3 on C4 causing compression of the spinal cord (between arrows) as indicated by a change in signal (lighter area between asterisks).
  • Bones. With aging, bones tend to lose water and become less dense, a condition called spondylolsis. These degenerative changes near the disk may cause an overgrowth of bone producing bony spurs (osteophytes) that can compress the spinal cord (Figure 5)
Figure 5 - CT scan through the C6 vertebra showing a bony spur that compresses the spinal canal. (Same patient as in figure 4)
  • Disk - The disks also lose water and shrink thus narrowing the disk space.  As the disk becomes thinner the space between the vertebrae likewise narrows which narrows the foramina causing nerve root compression and pain. As the disk space narrows, the annulus tends to bulge and mushroom out causing pressure on the spinal cord
  • Joints - Along with the other degenerative changes, there can develop a degenerative arthritis of the facet joints that causes the joints to enlarge. Sometimes the lining of the joint (synovium) enlarges or becomes like a cyst.  This combination of events results in narrowing of the spinal canal and increasing stiffness of the spine. If the joints degenerate such that one vertebra slips over the one below (called spondylolesthesis) the spine may become unstable resulting in pain and the spinal cord may be compressed
  • Ligaments - With advancing age the ligaments tend to stretch and thicken. This may cause instability between vertebrae, as well as result in pressure on the spinal cord and nerve roots
  • Spinal cord - Myelopathy (malfunction of the spinal cord) occurs due to compression of the spinal cord. Motion of the spine rubbing on the cord may also contribute to the myelopathy. Furthermore compression of the spinal cord may lead to a compromise of the blood vessels feeding the spinal cord, which further aggravates the myelopathy. This myelopathy caused by overgrowth of bone and supporting tissues in the neck is called cervical spondylotic myelopathy (Figure 4)
Making the Diagnosis

Because of the variety of ways the degenerative process in the cervical spine may cause compression of the cord, the medical picture (syndrome) that a patient with cervical spondylotic myelopathy presents to the physician may vary in degree and position of pain, numbness, paresthesias (tingly sensations), weakness, loss coordination in the arms and weakness or unsteadiness in walking.

  • When all the nerve tracts are involved, the patient presents with weakness in the arms and legs and inability to normally feel pain and touch
  • The patient may present only with weakness. Sometimes this may occur only in the legs or only in the arms
  • There may be pain in the arms similar to that presented by a person with a ruptured cervical disk (discectomy for cervical ruptured disc) combined with weakness in the legs
  • The patient may present with weakness on one side of the body and numbness on the other side (Brown-Sequard syndrome)
  • Weakness in the hands and forearms
Special Testing

You may need certain tests to help your doctor decide whether you need surgery, and to determine the exact location of the cervical spinal stenosis. Some of these tests are:

  • X-ray of the cervical spine. 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 the bony spine (CT) and spinal cord and surrounding tissues (MRI). These tests may also rule out other causes of pain and weakness (Figures 4 & 5)
  • A myelogram followed by a CT scan. A myelogram is an invasive test. Though invasive, a myelogram is probably the most accurate test for determining the degree of spinal stenosis (narrowing). 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

Non-operative Treatment

Non-operative treatment is recommended for those individuals who have

  • only mild or moderate complaints and are not disabled
  • advanced cervical spondylotic myelopathy with nerve deficits that cannot be changed with surgery
  • advanced age or medical conditions that pose a considerable risk for surgery
Non-operative treatment includes
  • the use of a firm collar
  • cervical traction - this usually can be done at home 2-3 times a day
  • anti-inflammatory medication such as motrin
  • physical therapy
  • epidural steroid injection (injection into the cervical spine between the covering of the spinal cord and the bone) to control symptoms in those individuals who are poor surgical risks in order to control complaints
Indications for Cervical Laminectomy
  • The most common reason is cervical spondylotic myelopathy particularly when there is
    1. acute or progressive muscle weakness
    2. disabling loss of sensation
    3. difficulty in walking
  • Cervical laminectomy is also used for
    1. tumors within and outside the spinal cord
    2. trauma to the cervical spine
    3. congenital stenosis (narrowing from birth) of the spine
  • Disease at one or more spinal levels
  • Carrying out the surgery from in front is difficult because of
    1. failure of prior surgery
    2. obesity, particularly with a short, stout neck
  • Factors that make the surgery less risky
    1. decrease in operative time
    2. older patients tolerate laminectomy better than surgery from in front 3. better exposure of the nerve roots
  • The need to fuse the spine from behind
  • The presence of a tracheostomy (opening into the windpipe) or other obstruction to an approach from in front
Relative contraindications for decompressing the cervical spinal cord
  • Elderly patient particularly combined with osteoporosis
  • Severe lung disease
  • Severe heart disease
  • Loss of the normal curve of the cervical spine
  • Instability because of inadequate structures in the anterior parts of the cervical spine 
The Operative Procedure
  • There are two procedures for decompressing the cervical spine
    1. Cervical laminectomy in which the lamina and spinous processes are removed to expose the dura covering the spinal cord
    2. Cervical laminoplasty in which the lamina are lifted off of the dura but not removed (Figure 6)
Figure 6 - CT scan through a cervical vertebrae showing a laminoplasty using a bone graft and titanium miniplate. (Same patient as in Figure 4)
  • With cervical spondylotic myelopathy, the patient is positioned on the operating table with the head and neck in a neutral position since undue flexion or extension of the neck may cause pressure on the spinal cord
  • Because placing a tube in the airway (endotracheal tube) may result in excessive extension of the neck, the tube is frequently inserted with the patient awake
  • Steroid medication may be given to help in protecting the spinal cord
  • In some instances the surgeon may monitor the ability of the spinal cord to transmit impulses (somatosensory evoked potentials). Such monitoring is more often used when the laminectomy is used for the removal of a spinal cord tumor
  • The patient is placed prone (face down)on the operating table with the head held firmly by pins by a special headrest
  • After the skin is cleaned and disinfected and sterilely draped, an incision is made in the skin of the back of the neck
  • The muscles are elevated and the spinous processes, lamina and facets are exposed
  • Cervical laminectomy (Animation A)
    1. Usually the lamina and spinous processes are removed from 3 or 4 vertebral levels
    2. Using a small burr, a cut is made through the lamina at their junctions with the facets at each level
    3. The ligament lining the inner surface of the spinal canal (ligamentum flavum) is cut and the lamina are removed
    4. If there is any evidence of instability or anterior angulation of the cervical spine, fusion from behind is usually indicated. Fusion is frequently accomplished using titanium plates secured over the facets
    5. All bleeding is controlled and the muscles, fascia and skin are brought together in layers
Click image to view animation
Animation A -Cervical laminectomy of C4, C5 and C6 as seen from behind. The upper two lamina have already been cut through. The lamina of C6 are shown being cut and then the lamina of these vertebra are removed to expose the dura over the spinal cord.
  • Cervical laminoplasty (Figure 7 and Animation B)
    1. As in a cervical laminectomy, a small burr is used to make a cut through the lamina at their junctions with the facets. On one side the cut is complete while on the other, the cut is made almost through the lamina
    2. On the side where the lamina is cut, the ligamentum flavum is likewise cut
    3. The lamina are then elevated from the cut side in the manner of a "trap door"
    4. The open side of the lamina is held open with a strut of bone and secured in place with a small titanium plate
    5. The canal is thus made wider which decompresses the spinal cord
    6. All bleeding is controlled and the muscles, fascia and skin are brought together in layers

      

    Click image to view animation

    Figure 7 - Cervical spine X-ray taken from the side (Same patient as in Figure 4). Titanium plates are used to stabilize the unstable spondylolesthesis by fusing C3 to C4. The miniplates are part of a laminoplasty to widen the cervical canal at C4, C5 and C6.

    Animation B - Cervical laminoplasty as seen in cross-section. The lamina on each side are cut and the lamina elevated one on side like a trap door. The lamina are held away from the spinal cord by a small bone graft and secured with a titanium miniplate and screws.
  • Posterior cervical fusion (Figure 7)
    1. Used with cervical laminectomy or laminoplasty when there is instability of the vertebra at any level
    2. The cartilage is removed from the facet joints to be fused. Then small pieces of bone (usually taken from the removed lamina and spinous processes) are placed into the facet joints
    3. To keep the vertebrae supported while fusion takes place (like a cast on a broken leg), titanium screws are inserted on both sides into the lateral masses of the vertebrae to be fused. The screws secure titanium plates or rods that bridge the vertebrae
Complications
  • Worsening of the neurologic condition such as increased paralysis or loss of sensation
  • Bleeding
  • Forward bending of the cervical spine (kyphosis)
  • Air embolus- air entering the blood stream and causing clotting of blood in the heart
  • Tear in the dura covering the spinal cord
  • Injury to nerve roots
  • Leaking of the fluid surrounding the cord (cerebrospinal fluid) through to the skin
  • Injury to the nerves going to the arms (brachial plexus)
  • Infection
  • Postoperative instability of the spine
Postoperative Care
  • Following surgery, the patient may wear a collar for several months
  • Unless there is weakness or paralysis the patient may be discharged in 2-4 days
  • If there is weakness or paralysis the patient may go to a rehabilitation unit
  • Pain medication is given as necessary
  • After discharge, the patient is seen in the surgeon’s office in one to three weeks
  • Follow up X-rays, CTs or MRIs may be obtained as required by the surgeon