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Lumbar Discectomy
For lumbar ruptured disk

Lumbar disk surgery for a ruptured or herniated disk is the most commonly performed surgical procedure for low back pain with pain radiating into a leg. A satisfactory result from lumbar disk surgery is as much dependent on proper patient selection as the actual performance of the surgery. A patient whose symptoms, examination and tests do not point to a specific ruptured disk may not improve with surgery.

Anatomy

  • The lumbar spine and pelvis (the low back) supports the entire upper body
  • The lumbar spine allows bending forward and back and to twist at the waist
  • The normal lumbar spine is composed of five building blocks called vertebrae that sit on the sacrum, which is the back part of the pelvic bone (Figure 1)
  • Each vertebra is constructed of a body, lamina and pedicles, which surround an opening, the spinal canal (Figure 2)
  • Through the spinal canal pass the nerve roots that emerge from the end of the spinal cord and go to form the nerves to the legs. The roots float in fluid (cerebrospinal fluid) and are contained within a fibrous sac called the dura (Figure 3)
  • 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. (Figure 4) There are five lumbar disks that are designated by the number of the lumbar vertebra just above the disk
Figure 1 Figure 2
Figure 3 Figure 4

Pathology

  • A common cause of pain in the back and leg is a ruptured or herniated disk
  • With sudden stress such as with lifting a heavy object or by gradually wearing out, the annulus of the disk may tear and allow the soft nucleus to squeeze out through the annulus like toothpaste
  • The most common place for a disk to rupture is just to the right or left of the midline. (Figure 5A) In about 5% of ruptured disks, the disk ruptures lateral (away from the midline) to the facet (Figure 5B)
  • The ruptured nucleus may then presses on a nerve root
  • Though the injury is in your back, your brain interprets the pain as if it was in your foot or leg
Figure 5a Figure 5b

History and Examination

  • The history and examination allows the doctor to determine which muscles and reflexes are effected, as well as which part of you leg may be have decreased feeling
  • This information allows your doctor to diagnose which nerve root is being pinched by the ruptured disk
  • The fifth lumbar vertebra is the disk that most commonly ruptures and compresses the first sacral nerve root (S1)
    1. Pain is usually along the back of the thigh and calf towards the outside of the foot and there may be numbness in the same area
    2. There is weakness in pushing the foot down
    3. The ankle reflex is decreased or absent
  • The second most common ruptured disk is at L4 and compresses the fifth lumbar (L5) root. The L5 root causes:
    1. Pain along the front of the lower leg going toward the big toe
    2. Weakness on elevating the big toe and in some cases a foot drop
    3. Numbness over the top inside part of the foot
  • Occasionally the L3 may rupture to compress the L4 root
    1. The pain and any numbness is usually along the anterior thigh and over the cap of the knee
    2. There is weakness in extending (straightening) the knee
    3. The knee reflex is decreased or absent
  • L1 and L2 ruptured disks are uncommon
  • Lateral disk rupture causes signs and symptoms referred to the same root level (an lateral ruptured disc at L4 causes L4 signs and symptoms)

Testing

  • An x-ray of the lumbar 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 scan or MRI. 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 the legs
  • A myelogram followed by a CT scan. A myelogram is an invasive test. Though invasive, a myelogram may be needed if the non-invasive tests are negative. An iodine containing dye which shows-up on x-rays is injected into the fluid surrounding the lumbar nerve roots. Leakage of cerebrospinal fluid following the procedure may cause subsequent headaches which usually does not last more that a couple of days

Non-surgical Therapy

Unless the back and leg 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
  • Bed rest in a comfortable position such as with two pillows under the head and two under the knees
  • Physical therapy that may include deep heat and message, ultrasound and traction
  • Stretching exercises

Indications

Surgery is indicated for removal of a ruptured disk when there is:

  • Significant weakness
  • Severe pain
  • The various tests confirm the presence of a ruptured disk that matches the side and vertebral level of your examination, and there is no improvement on medication and physical therapy

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 back and leg pain and may allow the muscles that are weak to regain their strength (Animation)
Animation -
Animation
  • A small incision is made in the skin over the area of the ruptured disk
  • The muscle is moved away from the lamina of the vertebra above and below the level of the ruptured disk
  • Using an air drill or special bone instruments a little bit of the lamina 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
  • Using special instruments, some of the ligament under the bone is removed and the nerve root carefully moved.
  • The ruptured disk is then found and removed from in front of the nerve root. The disk space may then be entered and additional loose disk material removed
  • Bleeding is controlled, the wound is sutured together and a sterile dressing applied
  • When the disk ruptures lateral to the facet, the incision is made more laterally so that the disk rupture can be approached more directly (Figure 6, red arrow)
Figure 6

Minimally Invasive Discectomy

  • This procedure is very much like the standard microdiscectomy except that a smaller incision (less than one inch) is made
  • The muscle is separated and narrow retractors or a tubular retractor ¾ to one inch in diameter is inserted (Figure 7A)
  • Either the operating microscope or an endoscope is used to visualize the surgery
  • The ruptured (herniated) disc may be removed with usual microdiscectomy instruments or similar instruments modified for use through the tubular retractor (Figure 7B)
Figure 7a - A tubular retractor is inserted through a small skin incision to expose the area of the ruptured disc. Courtesy Dr. M. Perez-Cruet Figure 7b - The disc removal is aided by the lighted endoscope. Dr. M. Perez-Cruet

Complications

  • No surgery is absolutely safe and free of complications
  • Some of the possible complications of lumbar disk surgery are:
    1. Untoward effects of anesthesia
    2. Bleeding or hemorrhage with the possible need for blood transfusions
    3. Nerve root injury that could result in paralysis, loss of feeling, or loss of bowel and bladder control
    4. Infection
    5. Tear in the covering of the nerves with leaking of cerebrospinal fluid
    6. Injury to blood vessels
    7. Injury to bowel or ureters
    8. The possibility of unforeseen complications
  • A ruptured disk may recur in five to ten percent of cases

After Surgery

  • The doctor will give instructions until seen in the office
  • Contact the doctor if there is any:
  • Redness of the wound
  • Any discharge from the wound
  • Fever
  • Weakness or numbness in the legs
  • Trouble with urination
  • Most patients are discharged from hospital on the first post-operative day
  • Many patients can be discharged the same day as surgery
  • Elderly patients may require additional hospital stay
  • Do not expect that removal of the ruptured disk will guarantee that there will never have a back problem in the future
  • No back that has suffered a ruptured disk is normal
  • After surgery it is important to learn to live with the 'bad' back. One must learn to always remember that he/she has had a bad back and must learn to move and bend correctly

Other Forms of Rupture Disk Surgery

  • Chemonucleolysis. A chemical, chymopapain, is injected into the disk space through a needle. The chymopapain dissolves the nucleus of the disk. This procedure has lost its initial enthusiasm because of occasional severe allergic reaction and rare but disastrous episodes of transverse myelitis, a severe inflammation of the spinal cord causing paralysis.
  • Automated Percutaneous Discectomy (APD). A two millimeter diameter probe is inserted into the disk space. Suction and a rotary blade is applied through a side port at the end of the probe. This removes some of the center of the disk, but does not directly affect the portion of the disk that is ruptured. This procedure has not been shown to be effective in relieving the symptoms of a ruptured disc and is NOT recommended.
  • Percutaneous Laser Discectomy (PLD). This procedure is similar to APD except that a laser fiber is inserted into the disk space through a needle. The laser vaporizes some of the disk nucleus, which is removed by suction. Like APD, this procedure has not been shown to be effective and is NOT recommended.
  • SpineCATH Intradiscal ElectroThermal Catheter: This is a newer procedure that is similar to APD and PLD. A small catheter that contains a heating element is inserted into the disk space. The heating element is positioned near the posterior aspect of the disk space near the annulus. Heating of the element is said to cause contraction and thickening of the annulus and thus relieve back pain. Since this procedure is similar to APD and PLD and there is no independent validation of the procedure, it is, therefore, NOT recommended.
  • Lumbar Foramenoscopic Microdiscectomy. A needle is inserted about 3 inches off the midline and under Xray control toward the appropriate disk. A wire is inserted through the needle, the needle removed and a cannula (special large needle) is inserted towards the intervertebral foramen (the 'hole' between two vertebrae through which the nerve exits the spinal canal) of the involved nerve root. An endoscope about 4.5 mm. (3/16 inch) in diameter is passed through the cannula. Under visualization through the optics of the endoscope the scope is passed through the intervertebral foramen to the ruptured fragment of disk, which is then removed through the working channel of the scope with a grasping forceps. The technique can be used only in select cases of ruptured lumbar disk. The technique is said to reduce postoperative scarring.