Use of MR Neurography for Diagnosis of Routine and Unusual Spinal Pathologies

Animation: Adiculopathy exacerbated by lumbar spine instrumented fusion.

(A) 59-year-old woman with persistent severe left S1 radiculopathy exacerbated by lumbar spine instrumented fusion and not relieved by subsequent removal of the instrumentation. The image demonstrates perforation of the left S1 root by the course of the pedicle screw (ps). No further surgical treatment was recommended.

(B) Persistent sciatica after a fall with no improvement after discectomy. The image demonstrates inflammation around the nerve (S1) consistent with a sacral fracture (fx) abutting the foramen.

(C) The MR Neurography imaging protocol results in an MR myelogram as well as Neurographic images of the exiting nerve roots.

Post-Discectomy Nerve Root Inflammation

Animation: Post-discectomy radiculitis.

Two fascicles in the right S1 root are hyperintense as they descend from the root sleeve (A) and traverse the sacrum (B,C, D & E arrows).

The contralateral S1 root is normal in appearance. The patient experienced focal pain in the calf despite relief of other symptoms by microdiscectomy. There was no recurrent disc.

The symptoms resolved with a short course of dexamethasone.

Post-Discectomy Nerve Root Inflammation

Animation: Post-discectomy radiculitis.

Two fascicles in the right S1 root are hyperintense as they descend from the root sleeve (A) and traverse the sacrum (B,C, D & E arrows).

The contralateral S1 root is normal in appearance. The patient experienced focal pain in the calf despite relief of other symptoms by microdiscectomy. There was no recurrent disc.

The symptoms resolved with a short course of dexamethasone.

Minimal Access Spinal Technologies

When spine problems develop due to injury, aging, wear and tear, or deformity, treatment options should focus on the actual source of the problem with the least amount of interruption to a patients life. Medication, physical therapy, bracing or lifestyle changes may successfully treat problems caused by slipped discs, slipped vertebrae or curvature of the spine. For many people, though, surgery may be the best option to treat pain or deformity.

Open Surgery: The most beneficial aspect of traditional open surgery is the ability to see and access the spine easily. This type of surgery, however, involves long incisions, cutting and removal of muscle from the spine, and considerable post-surgical pain. Due to the large incisions and significant damage to the muscle, open surgery patients may experience hospital stays, recovery periods, scarring and pain that make this type of surgery daunting and exhaustive. Developing procedures that significantly reduce these effects through minimally invasive methods may allow patients to return to regular, active lives with less interruption and pain.
MAST: Minimally invasive procedures made possible by Minimal Access Spinal Technologies (MAST) potentially allow surgeons to successfully treat back pain and deformity with the least amount of interruption while achieving the same surgical objectives as open surgeries. These technologies have been developed out of the advances made in the field of orthopedic minimal access surgeries over the past two decades. Video cameras, x-rays, detailed anatomy imaging, computer-assisted navigation, specially designed instruments and precise diagnostic tools provide alternatives to conventional open spine surgery that may minimize patient recovery time and pain.

MAST procedures mean surgeons may achieve the same results and objectives of traditional surgery with imaging systems, tiny cameras and skin incisions no longer than thumbnails. Muscle is left intact and only separated, or split, along natural divisions to reach the affected area. Special live-action x-ray machines guide surgeons to exact locations on the spine, rendering moot any need to open the site for clear visualization and location of the spinal problem. MAST products provide surgeons the ability to work precisely in smaller surgical fields with significantly less tissue trauma. The potential patient benefits of MAST procedures can offer patients physical, psychological, emotional and aesthetic advantages that make surgery less daunting.

Potential patient benefits of MAST procedures:

• Quicker return to normal activities

• Less post-operative pain

• Less damage to muscle and skin

• Easier rehabilitation

• Smaller scars

• Less blood loss

• Outpatient surgery for some patients

CD HORIZON® SEXTANT Spinal System: The CD HORIZON® SEXTANT Spinal System allows surgeons to deliver and apply screw and rod implants to the posterior aspect of the spine without the major muscle and tissue disruption encountered with traditional spinal fusion surgeries. This minimally invasive technique potentially allows significant patient benefits.

• Shorter hospital stays one to three days vs. up to a week with open surgery

• Smaller scars one-inch scars vs. six- to eight-inch scars

• Shorter recovery periods

• Less post-operative pain no muscle cutting or stripping

Spinal Fusion: Spinal fusion is a process using bone graft to cause two opposing vertebrae to grow, or weld, together. To ensure position and rigid alignment while fusion takes place, surgeons apply spinal instruments, or implants, such as screws and rods to the spine. These implants are joined together to maintain spinal stability and are rarely removed. Spinal fusion and implants are used to restore stability to the spine, correct deformity and bridge spaces created by the removal of damaged spinal elements such as discs.

The Traditional Spinal Fusion Procedure with Implants: Traditionally, implants are applied directly to the spine through an open approach requiring incisions up and down the middle of the back. Large bands of back muscles are stripped free from the spine and pulled off (retracted) to each side for visualization of the spine and easy access to the bones for instrument implantation. This stripping and retraction can cause considerable back pain, and the muscles, to some degree, are permanently scarred and damaged.

How CD HORIZON SEXTANT System Works

• Using a special live action x-ray machine called a fluoroscope to visualize the spine, the surgeon determines screw insertion points.

• A stiff guidewire is inserted through skin and muscle to the screw insertion point on one vertebra.

• METRx System dilating tubes are slowly passed down over the guide wire, creating tunnels through the muscle to the target screw placement area.

• A screw, attached to a screw extender, is delivered through the muscle to the vertebra and secured.

• The process is repeated for the second screw placement.

• The protruding shafts of the extenders are rotated until the screw heads are aligned for rod insertion.

• After rotation, the protruding extenders are joined and secured so the swinging arm rod inserter may be connected.

• A pre-cut rod is attached to the end of the curved arm of the rod inserter.

• The rod inserter swings down and drives the small rod through the skin and muscle, precisely inserting the rod though the heads of the aligned screws.

• The screw extenders and rod inserter are removed.

• The separated muscle flows back together, and the skin incisions are closed, leaving only thumbnail-sized skin incisions.

Who Can Benefit From CD HORIZON SEXTANT

• An estimated 190,000 lumbar spinal fusion surgeries will be performed in 2002.

• By the age of 50, 85 percent of the population will show evidence of disc degeneration.

• Disc degeneration affects about 12 million people in the United States.

Clinical Experience: While still a new technology, several preliminary studies have indicated the potential accuracy and reliability of the CD HORIZON SEXTANT Spinal System. A recent study [J Neurosurgery: Spine 2002; 97:7-12] followed 12 patients who underwent pedicle screw fixation using the CD HORIZON SEXTANT Spinal System. The system was used in each case to accomplish an instrumented posterior spinal fusion. After completing the surgery, the patients were followed for an average of 13.8 months. Results were classified according to modified McNab criteria, which measure surgical outcomes on a poor to excellent scale. The study results include:

• Six patients were rated with excellent results (no pain; non-restricted mobility; and normal work and activity levels), five patients with good results (occasional non-radicular pain; relief of presenting symptoms; modified work activity), and one with a poor result (continued objective symptoms of root involvement; additional surgery required). A second surgery was performed on the patient with a poor result, and the patient achieved a good clinical result with solid fusion.

• In all patients solid fusion across the involved levels was achieved.

• Six patients were discharged in one to two days after surgery, and the rest by post-operative day three.

METRx MicroDiscectomy System: The unique, muscle-splitting METRx MicroDiscectomy System provides access to the spine with less tissue trauma than associated with traditional surgeries to relieve pressure on nerves. Posterior approach procedures with this system offer significant potential benefits.

• Shorter hospital stays outpatient surgery vs. two to three days with open surgery

• Smaller scars one inch vs. up to four inches

• Quicker return to work and normal activities

• Avoidance of general anesthetic

• Less post-operative pain no muscle cutting or stripping

Discectomy: A discectomy removes a disc herniation (bulging disc) to relieve pressure on an adjoining nerve.

A traditional open discectomy requires a large (up to four inches) incision down the middle of the back with extensive stripping of muscle from the spine to get to the affected disc. Though using one-inch skin incisions, newer microsurgery discectomies still involve cutting muscle and scraping it from the spine to access the disc. The muscle damage of these surgeries contributes to most post-operative pain and longer, more difficult rehabilitation periods

The METRx MicroDiscectomy System is composed of bayoneted surgical tools with various-sized metal tubes used to create and maintain openings to spinal elements. Fundamental to this system are specially designed metal tubes, called dilators, which progressively increase in diameter size. These dilators are inserted sequentially smaller to larger through the muscle to gradually separate, or split, and open the muscle to create an opening large enough for surgical tools to be used. The systems retractor tubes maintain the opening while the surgeon uses specially designed surgical tools to reach and remove spinal elements that are causing pain.

The Minimally Invasive Approach with the METRx
Surgeons are able to precisely locate, see and remove herniated discs in the spine through tunnels created by tubes that split back muscle, much like a sewing needle splits the weave of fabric, along natural divisions. No muscle fiber is cut, only separated. This unique muscle-splitting approach allows surgeons to access the spine with a posterior approach without cutting or removing muscle from the spine. How it works:

• Using a special live-action x-ray called a fluoroscope to visualize the spine, the surgeon precisely locates the herniated disc.

• Guided by the fluoroscope, a small needle is inserted through the skin and muscle to the affected area.

• The needle is withdrawn, a 1 to 2-inch skin incision is made, and dilators are inserted, one around the other, to gradually split the weave of the muscle until a 3 to 4-inch tunnel to the disc is created.

• The retractor holds the tunnel open to allow for the microscope (or endoscope), surgical tools and instruments to be inserted.

• While viewing the herniated disc through the microscope, the surgeon uses special instruments to remove the herniated disc.

• Once the procedure is completed, the tube is withdrawn, and the separated muscle fibers flow back together.

• A small adhesive bandage is applied to cover the incision.

Who can Benefit from METRx MicroDiscectomy System

• Lumbar discectomy is the #1 procedure performed on the spine in the United States each year.

• About 250,000 Americans have surgery to relieve herniated discs annually.

• 70 percent to 80 percent of patients requiring herniated disc surgery are candidates for this procedure.

Clinical Experience: The METRx System represents a new area in spine surgery, and the results of surgeries performed with this system have yet to be fully studied. However, in a preliminary study of 26 patients who had a lumbar discectomy with the METRx System, all reported very high levels of satisfaction with the procedure. In addition, patients in one study stayed in the hospital for an average of 12.1 hours, with a range of two hours to 48 hours. This compares favorably to the two to four days needed for open procedures.

In terms of relief of symptoms related to unpinching the nerve root, surgical outcomes using the METRx System are comparable to open procedures. However, since the METRx System allows the surgeon to unpinch the root without cutting or stripping muscle, patients are offered several advantages in terms of post-operative pain, recovery period, rehabilitation and cosmetic results.

Complex Spine Surgery

Modern treatment for degenerative spine disease, spine tumors, infections, spine fractures and instabilities is considered to be complex spine surgery. Surgical treatment for these conditions may include minimally invasive microsurgical anterior and posterior approaches to the entire spine and often require fusion with titanium devices, bone grafts, pedicle screws, plates and rods.

With the use of the advantageous Stealth neuronavigation system surgeons  are able to place titanium instrumentation devices with unparalleled accuracy.

This revolutionary technology and surgical skill offers patients faster recovery and minimizes postoperative pain and complications.