Category: Spine Surgery

Lumbar Microdiscectomy Explained

Lumbar Microdiscectomy is one of the most common neurosurgical procedures performed in the United States each year.  This surgical procedure is a often performed to remove a herniated lumbar disc, which is a common condition.  Most of the time, a lumbar herniated disc causes severe shooting pain into the leg, often called lumbar radiculopathy.

The best way to understand this operation is to consider a recent case.

A middle aged patient presented to the office with moderate low back pain and severe pain shooting down the back of the thigh and around the knee.  It was severe and shooting in nature.  The patient said it was 7 out of 10 in severity, even while taking narcotic medications, which they received after an ER visit.

The first step in diagnosis of a herniated disc is clinical suspicion.  This is usually followed by an MRI or other imaging study to confirm the diagnosis.  In most cases, a

Axial T2 MRI. This image shows the right L2-3 disc herniation. When viewing MRI in the axial plane, the patient’s RIGHT side is on the left side of the screen.

CT Myelogram or MRI study is sufficient to identify a herniated disc.  If it explains the patient’s symptoms then surgery can be considered.

After the diagnosis of a herniated disc the patient usually has a trial of conservative (non-operative) treatment.  This may include physical therapy, chiropractic manipulation, steroids, other anti-inflammatories, gabapentin, or other medications.  If these treatments alleviate the patients’s pain then they may not require surgery.

If the patient has continued pain surgery may be considered.  Typically, surgery to remove a herniated disc is called a “lumbar hemilaminotomy and microdisectomy.”  This surgery is performed on the back.  A small incision is made over the spinal levels of interest (this is confirmed with x-ray or fluoroscopy at the start of surgery).  After making an midline incision, we dissect down to expose the lamina, or part of the bone overlying the dura.  This is done on the left or right side (it is done on the side that corresponds to the patient’s pain and side of disc herniation), at the level of the herniated disc.  A small window of bone is then removed with a drill to expose the ligament underneath.  Once the ligament is removed, we can see dura, or sac containing the lumbar nerve roots.  The models below show the location of this patient’s disc herniation and the planned lamina that will be removed.

Normal Lumbar Spine Model. The lumbar vertebrae are labeled L1 through L5.
Lumbar Spine Model, with red circle at the approximate location of the right L2-3 herniated disc, as seen on this patient’s MRI (above MRI images).
The yellow area is the planned area of bone removal (called a hemilaminotomy) to expose the dura and herniated disc.

In the images below we can see the view through the microscope during this microdiscectomy surgery.  We have exposed the dura, gently retract it medially, and then remove the herniated disc material.

Microscope View. For reference, the feet are on the left, the head is to the right, the top of the image is the midline, and the patient’s right is the bottom of the image. Here, we have removed the lamina and ligament, and the dura is in view. One can see a small amount of herniated disc material off to the right side of the dura, in the lateral gutter.
Microscope View. For reference, the feet are on the left, the head is to the right, the top of the image is the midline, and the patient’s right is the bottom of the image. Here, we have gently pushed the dura towards the midline to get a better view of the herniated disc material.
Microscope View. For reference, the feet are on the left, the head is to the right, the top of the image is the midline, and the patient’s right is the bottom of the image. Here, we have gently pulled a large fragment of disc up and out of the lateral gutter. It is sitting on top of the dura just prior to removal.

After removing the disc material, any bleeding is controlled with bipolar electrocautery.  The wound is irrigated out with an antibiotic saline solution, and the dura is covered with gelfoam.  The retractors are removed and the wound is closed.

This image shows the disc material removed in this particular surgery.

In this case, we were able to remove a large amount of herniated disc material.  The patient did quite well, with resolution of the leg pain shortly after surgery.

Complex Cervical Spine Surgery

Although Dr. Lawson specializes in cerebrovascular surgery & endovascular neurosurgery, he also performs complex cervical and lumbar spine surgery. Roughly 45% of his practice is related to brain tumor surgery and cerebrovascular/endovascular neurosurgery (brain aneurysms, stroke, AVMs, and carotid disease).  The other 55% is general neurosurgery, including complex cervical and lumbar spine surgery.  In fact, Dr. Lawson performs much of the complex cervical spine surgery at TMH.

CT scan showing C4 burst fracture.

Recently, a young man presented as a trauma alert to the hospital with a suspected spinal cord injury.  He was involved in an accident and was unable to use his arms or legs.  His initial CT scan of the cervical spine demonstrated a C4 burst fracture with central canal compromise.  This is a complex fracture that resulted in a spinal cord injury.

An MRI was performed, which confirmed the degree of spinal cord compression and injury.  It was felt that surgery was his most reasonable treatment option.  Surgery would involve two procedures: an anterior cervical corpectomy and a posterior cervical stabilization.

CT Scan (axial image) showing C4 burst fracture, lamina fracture, and central canal compromise.
MRI Showing compression of the spinal cord and spinal cord edema.

In the images to the left, we can see the axial CT scan, which shows the C4 burst fracture, a lamina fracture, and central canal compromise.

 

 

The MRI image seen to the left (below the axial CT scan), shows some central spinal stenosis with edema of the spinal cord.  The spinal cord is the gray structure in the middle of the image, running from top to bottom.  There is white, haziness noted in the cord, which is spinal cord edema (this is indicative of a spinal cord injury).  One can also appreciate how the fractured bone pushes into the spinal cord.

Clinically, this patient had a severe spinal cord injury, with the inability to move his arms or legs upon arrival to the hospital.

After the MRI study, he was taken to the operating room for surgery.  This consisted of two stages, anterior and posterior.  In the anterior stage, a small incision made on the front of the neck and a C4 corpectomy was performed.  In this procedure, the fractured vertebral body is removed, along with the disc above and below the fracture.  This is done to take all of the pressure off of the front of the spinal cord and remove the fractured bone.  Next, a bone strut (cadaver bone — fibula strut graft) is placed in the defect to reconstruct the spinal column and allow the neck to bear weight.  A

Post OP CT showing the bone strut and anterior cervical plate after the C4 corpectomy.

cervical plate is then placed from C3 to C5 to hold the strut in place.

Next, the patient was flipped into the prone position (face down) so that the second phase of the procedure can be performed on the back of the neck.  A posterior cervical stabilization with lateral mass screws and rods was performed from C3 to C6.  In addition, a cervical laminectomy was performed at C3 to C5 to ensure decompression of the spinal cord.

The final result is the x-ray seen below.  In this x-ray you can see that the C4 fracture has been removed, a bone strut is in its place, there is an anterior cervical plate (on the front of the spine) as well as posterior screws & rods (on the back of the spine).

Post OP lateral x-ray, showing all hardware in place.

This patient did very well after surgery, and regained partial use of the right arm and leg.  He was transitioned to rehabilitation.  Clearly, he has a long road of rehabilitation in front of him for his spinal cord injury, and we are excited to see how he is doing at the six month interval.

Dr. Lawson performs numerous cervical spine procedures, including:

  • ACDF (Anterior Cervical Discectomy and Fusion) – a common procedure for treatment of herniated cervical discs, typically causing neck and arm pain.
  • Posterior Cervical Laminectomy and Fusion – for treatment of cervical stenosis and cervical myelopathy.
  • C1-2 Stabilization – for instability, fracture, or compression at C1 or C2.  Most commonly, this is for treatment of C2 fractures or rheumatoid arthritis with compression of the spinal cord at C1-2.
  • O-C Stabilization – for instability, fracture, or compression at the craniocervical junction.
  • Complex cervical spine procedures (such as the C4 corpectomy and posterior stabilization described above) for the treatment of deformity or fracture.

Neck pain?  Cervical spine fracture?  Click here to contact Dr. Lawson and make an office appointment.