MIS Treatment of Herniated Discs
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About Herniated Discs
A herniated disc (intervertebral disc) is a common cause of neck and back pain. Intervertebral discs are the spine's shock absorbers and are located in between the bones of the vertebral bodies. Each disc is made up of a tire-like outer band (annulus fibrosus) that surrounds and protects the gel-like cushion (nucleus pulposus).
When a disc herniates through the annular wall, the gel-like nucleus and disc fragments can compress fragile nerves or the spinal cord, as illustrated below. In addition, the broken intervertebral disc releases a chemical irritant causing nerve inflammation, pain and other symptoms.
Where symptoms develop depends on where the disc ruptures.
- Cervical (neck) herniation: Dull or sharp pain in the neck or between the shoulder blades. Movement may intensify pain. Pain, numbness, and tingling spreads (radiates) down the arm, hand, and into the fingers (radiculopathy).
- Lumbar (low back) herniation: Low back and leg pain (sciatica) is common. Bending, coughing, sneezing, or other movement may intensify symptoms. Muscle spasm or cramping may develop, as well as leg weakness or loss of leg function.
Important to a proper diagnosis is the patient's medical history, physical and neurological examination, and diagnostic test results (i.e. MRI). The examination and diagnostic tests may differ depending on the location of the herniation (i.e. cervical, lumbar)
- Medical history includes symptoms, their severity, and treatments already tried.
- Physical and neurological examination includes evaluating movement limitations, balance problems, pain, extremity reflexes, muscle weakness, and sensation. The exam may include a series of movements such as turning the head from side to side and forward and backward, bending sideways, forward and backward at the waist, and walking.
- Diagnostic tests may include x-rays, CT scan, or MRI. Discography, myelography or electrodiagnostic studies (i.e. nerve conduction test) may be necessary.
When MIS is Recommended
Although the indications for surgery vary, MIS may be recommended if:
- Pain and other symptoms worsen
- Pain and symptoms are unresponsive to nonoperative treatment
- Neurologic problems develop, such as weakness, poor coordination, severe pain, or bowel or bladder dysfunction
- Imaging tests demonstrate spinal instability
Surgical goals include:
- Decompress the spinal cord and / or nerves (relieve pressure)
- Stabilize the spine
MIS may include procedures to decompress and stabilize the spine.
- Decompression procedures relieve pressure on spinal nerves. Discectomy (disc removal), laminotomy, laminectomy, and foraminotomy are common procedures. Laminotomy (partial removal) and laminectomy (complete removal) involve removing the vertebral body?s lamina to increase the size of the spinal canal. The lamina is a section of bone near each facet joint covering access to the spinal canal. Foraminotomy expands the foramen or spinal nerve passageways.
- Most MIS surgery avoids spinal fusion, but if there is deformity or spinal mal-alignment, a fusion may be the best option. Specialized MIS fusion instruments are available if fusion is needed.
Minimally spine surgery procedures approach the spine from the front (anterior), back (posterior), side (lateral), or back and side (posterolateral). In the treatment of disc herniation, your MIS surgeon may perform the following:
- Muscle-sparing Anterior Cervical Discectomy and Fusion (ACDF)
Muscle-sparing tubular retractors gently dilate and separate muscle and soft tissue. As the soft tissues are expanded, the operative field is revealed (i.e. spine). A microdiscectomy is performed using microscopic visualization and small specialized instruments passed through the retractor. The cervical disc is removed (microdiscectomy); the disc space is packed with bone graft or an interbody device (i.e. cage) is implanted, and / or the spinal level is stabilized using a cervical plate and screws.
- Anterior Cervical Discectomy and Uncovertebrectomy
Similar to the muscle-sparing cervical discectomy and fusion, this procedure includes removal of one or more uncovertebral joints (or Luschka's joints). The uncovertebral joints are found at C3 through C7 and are susceptible to degenerative changes. These fibrous joints are formed by the bony processes at the sides of the cervical vertebrae previously mentioned. Although technically more difficult, this procedure can avoid a fusion.
- Cervical Posterior MIS Tubular Microdiscectomy
This cervical procedure is similar to the muscle-sparing cervical discectomy,except surgery is performed from behind (posterior) and fusion is not usually necessary.
- Cervical Disc Replacement
Similar to muscle-sparing cervical discectomy and fusion, cervical disc replacement involves removal of the diseased disc and herniation. Instead of inserting a spacer (i.e. interbody device, cage) to obtain a fusion, a motion device, similar to a total knee replacement device, is implanted. The benefit of cervical disc replacement is it maintains motion of the cervical spine at that segment. However, a cervical disc replacement procedure cannot correct deformities and is not appropriate for use in severely diseased spines. Disc replacement is a relatively new technology and was approved by the FDA for single-level surgery in 2008.
- Lumbar Endoscopic Discectomy
An endoscope is a thin telescope-like instrument with a lighted tube and camera attachment. Through a small incision, the endoscope is passed between muscle and soft tissue to the spine. Surgery is performed by passing instruments through the endoscope to the operative field. The light illuminates the field and the camera transmits images to a monitor in the operating room. Through the endoscope, the discectomy is performed using lasers, bipolar probes, and other specialized instruments.
- Lumbar Tubular Microdiscectomy
This procedure is similar to the muscle-sparing cervical discectomy and fusion, except it is performed in the lumbar spine. It uses the microscope to relieve pressure on the nerves and remove herniated disc fragments and bone spurs. Fusion is usually not necessary.
- Use of Lasers During MIS
Lasers are one of many specialized tools needed during minimally invasive spine surgery. A laser is used during endoscopic spinal surgery to remove hard disc herniations and bone spurs. During endoscopic spine surgery, additional tools, such as flexible bipolar electrocautery, graspers, rongeurs, and currettes are needed to perform the procedure. Lasers are not used during minimally invasive fusion surgery to treat disorders such as spondylolisthesis or degenerative scoliosis, since larger areas of diseased disc and bone must be treated.
Risks and Complications
No patients are identical and risks and complications vary. Your surgeon will explain possible risks and complications related to your specific MIS procedure.