The Procedure | Proper Candidate | Surgery Timing | Research | Open Discectomy | Microdiscectomy | History of Herniation & Discectomy | Surgery Position | Picking vs. Sequestrectomy | Endoscopic Discectomy
When a lumbar disc herniation occurs, it usually happens in the posterolateral region of the disc, which in turn irritates the traversing nerve root and causes not only back pain, but also a terrible radiating, burning pain down the lower extremity—usually into the foot (i.e., sciatica).
How does it work? In the grand scheme of things, the surgeon's mission is to surgically remove (excise) the herniated portion of the disc – the part that is pinching/irritating/inflaming the nerve root and making the patient's life quite miserable. By removing the disc herniation, the pressure is in turn removed from the nerve root, which usually rapidly diminishes the leg pain greater than back pain.
So who is a proper candidate? A proper candidate can be defined as the patient who has (1) imaging evidence (MRI, CT myelography, and/or CT discography) of a herniation that matches the neurological deficit on exam; (2) nerve root tension signs (i.e., a positive straight leg raise or reverse straight leg raise test); and (3) subjective complaints that match the former and latter criteria.
Who are mandatory candidates? the short answer is this: (1) cauda equina syndrome; (2) severe progressive neurological findings; and (3) severe intractable pain. let's talk about them:
Sometime the disc herniation is so large and so compressive that the nerves that control the bowel and bladder become dysfunctional to the point voluntary control is lost-- this is called cauda equina syndrome. More specifically, the patient will lose control and start accidentally urinating and/or defecating in their under-garments. This horrible syndrome is often preceded by a numbness, tingling, burning in a saddle-like distribution over the anus and genitalia (i.e., the perineal area) (THIS IS A MEDICAL EMERGENCY and is something that must be addressed immediately or risk suffering permanent loss of control to the structures.
The American Academy of Orthopedic Surgeons and Alf Nachemson – who was the number one spine researcher in the world (18) -- recommends the following conditions be met before decompressive surgery is offered:
The Short answer is that you should only fool around with true disc herniation-induced sciatica for three or four months--if it ain't better by then, and you meet the above criteria, then you should seriously consider having open/microdiscectomy surgery.
The following is a chart I made regarding the outcomes of investigations into this important topic. As you can see, based on the medical literature, you shouldn't wait more than four months--one year maximum, for after that time, the chances of affording a successful discectomy are drastically diminished (although that certainly doesn't mean that with the passage of time you won't get better--in fact, you will probably achieve about the same outcome as if you were to have surgery; although, it may take years (so surgery is a quicker fix) .
Also keep in mind that researchers consider a "surgical success" to be defined as a 50% improvement in patient VAS scores--so if your VAS drops from an 8 to a 4, you are considered to have had a successful surgery. It's certainly the minority of patients who get 100% better following surgery.
Let's prove it sometime works:
THE RESEARCH: What Are My Chances for Success Following Discectomies?
[Is it my "research corner," for a whole bunch more studies].
Subsequent modifications, however, created the very successful procedure for the treatment disc herniation-induced sciatica [1, 13] that we have today. These included the usage of a minimal laminotomy in place of laminectomy  (they no longer took the whole lamina out, which minimized scar tissue formation and helped maintain stability of the motion segment) and minimal flavectomy (they saved as much of ligamentum flavum as possible, which again helps with stability and minimizes scar tissue formation).
Grafton Love, a surgeon at the Mayo Clinic, put his twist on the open discectomy technique in 1939, using what he called a "key hole" laminotomy to access the epidural space--microdiscectomy was born .
In 1977, Yasargil  and Caspar  independently described the addition of a powerful operating microscope to the open discectomy procedure that resulted in a much more minimally invasive procedure. That is, the microscope greatly increased the physician's vision, which in turn resulted in smaller and cleaner dissections down to the disc herniation. Arguably, this precision results in less soft tissue damage and less postsurgical scarring (epidural fibrosis and perineural fibrosis), which in turn yields better patient outcomes when compared to traditional open discectomy. And that superiority is just what the first outcome study on microdiscectomy demonstrated . Current studies, however, are not so persuasive (see below).
So the touted advantages of microdiscectomy by some proponents include a cosmetic advantage (smaller skin incision); shorter hospital stay; and less blood loss during surgery. The big disadvantage, which has been extensively reported upon,is that the smaller operating field may make some fragments of disc herniations more difficult to retrieve or even completely missed [20, 21].
If the space between the lamina of the vertebra above and the lamina below is wide enough (like at L5/S1, which by the way is called the interlaminar space), then usually only the ligamentum flavum is all that needs to be removed; however, usually some degree of laminotomy (a piece of the lamina is removed) is needed, as is a limited medial facetectomy. The tools needed to perform this are typically rongeurs and Kerrison punches.
As a side note it should be noted that epidural fibrosis/perineural fibrosis (scar tissue) is the bane of every surgeon and patient, for it is the leading cause of failed back surgical syndrome (a surgery that not only didn't work, it made the patient worse) [6, 7].
In general, there are two types of tables used to perform micro/open discectomy procedures: the Relton-Hall table (which yields a more prone patient position) and the Andrews table (which yields a knee-chest position). *Sometimes these are called frames instead of tables.
So which one is best? The research shows that both tables are about the same and afford the best possible position for surgery.
How do you know that? The research:
In this study a total of 30 patients ready for single level lumbar microdiscectomy had their intra-abdominal pressure measured through a urinary bladder catheter together with airway pressure. Several different positions were tested in the patients, who were randomly assign these positions. the bottom line of the investigation was that there was no statistical difference with regard to the more prone position of the Relton-Hall table, versus the more knee-chest position of the Andrews-type table .
There are also other frames commonly used, such as the Jackson frame.
One of the major complications with microdiscectomy or open discectomy is recurrent disc herniations (i.e., the herniation was surgically removed, but it returned again--through the same annular tear). More specifically, the incidence of such reherniations is, depending on the source, between 1 and 11% [23-25].
In order to reduce those percentages, surgeons perform either type of discectomy via two methodologies: to only remove the herniated material that is outside of the confines of the annulus fibrosis (this type of surgery is called a sequestrectomy); or to explore the annular tear (inside the disc) and remove any fragments of nuclear material (I call this camp "the picking technique") that may be lurking about. The latter methodology is the norm.
You see, many surgeons believe that aggressive removal of nuclear fragments within the annulus will prevent further reherniation simply because there will be less nuclear material to herniate.
However, there is scientific research that contradicts this general belief. An especially scientifically strong randomized controlled trial  of 84 patients demonstrated that sequestrectomy resulted in fewer reherniation at the one year time point . However, those same researchers found no difference between the two techniques in subsequent investigations at a two-year follow-up [22, 23].
Bottom line: the research says when it comes to open versus microdiscectomy there is really no difference between sequestrectomy and traditional "picking technique."
As a side note, there is a third school of thought that not only performs a sequestrectomy and "picking" of the annular tear, but also uses a special dye to stain the walls of the annular tear for pre-fragment / degenerated tissue, which in turn is removed. There is virtually no research on this form of treatment, so the jury is still out on whether or not it is efficacious.
It was Foley and Smith whom more recently reported on the latest innovation of endoscopic discectomy. [31, 32]. This approach is a hybrid between a percutaneous flavor of discectomy and open microdiscectomy. They named this procedure microendoscopic discectomy (MED). More specifically, this procedure uses a K-wire to get down to the lamina on the side of the herniation. Once in its proper position, A series of dilators (METRx-MED system)--the first is very small and the others are added in increasing Order of diameter--are placed over the K-wire, which have the effect to push the paraspinal musculature off the lamina. The working channel of the endoscope is placed over the final dilator and finally the endoscope is attached. Then a standard microdiscectomy is performed which includes a hemi-laminotomy and sometime a medial facetectomy, followed by a removal of part of ligamentum flavum, then retraction of the thecal sac and nerve root--this exposes the disc herniation, which is then removed. If the surgeon so desires, he can attach a standard microscope to the system instead of an endoscope.
One touted strength of this METRx-MED system over minimally invasive endoscopic techniques for disc herniation removal is that it has the capability of addressing bony stenotic conditions, sequestrations, as well as small contained disc herniations. Observational studies have demonstrated the procedures short term efficacy  and long-term efficacy .
While the jury is still out on the efficacy of endoscopic microdiscectomy, there is some evidence hinting at their superiority to open discectomy and even microdiscectomy. More specifically, in 2002 German investigators Schick et al. published the results of their study that pitted open discectomy against endoscopic discectomy. They were specifically interested in whether or not use of the endoscope mitigated stress/injury to the dura and nerve roots when they are retracted out of the way during discectomy. To accomplish this, they monitored the lumbosacral nerve roots electromyographically during the operations of 15 patients who underwent open discectomy and 15 patients who underwent endoscopic discectomy. The results indicated that the endoscopic technique afforded less nerve root irritation (as confirmed by EMG) when compared to the open procedure .
We shall keep an eye on this technique and report any further studies showing its superiority.
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