sciatic nerve에 대한 이해

[문형철]

좌골신경에 대해 한번도 진지하게 고민해본적이 없는거 같다.

그냥 mixed nerve, 허리디스크로, 이상근 때문에 자주 아프다. 이것 말고는

panic brid.......

Anatomy | Dermatome Connection | Dermatome Research | Dermatome Map | The Causes | A Cure? | MRI False Positives | Treatment | The Odds | Risk Factors | Will I Recover? | The Outcome Studies|

“Thou cold sciatica, cripple our senators, that their limbs may halt as lamely as their manners.” – William Shakespeare 1564.

As you can see from the Shakespearian quote above, sciatica has been torturing mankind for hundreds if not thousands of years. In fact, there has even been biblical mention of this disease! (6) I can certainly attest to the horror, frustration, and true evil of this awful affliction!

Sciatica is a term which refers to a burning, stinging, and/or numbing pain that is felt in the buttock, thigh, leg, and/or foot; it may or may not be associated with low back pain.

In layman's terms, sciatica is caused by a pinching and/or irritation of one of the three lowest lumbar nerve roots that make up the giant sciatic nerve. Any pinching / irritation of these delicate nerve roots may not only may cause lower back pain but may also ignite the entire sciatica nerve into a pain state!

Fig.#1 shows the general location of the giant sciatica nerve (yellow) which is the thickest and longest nerve in the human body. When this nerve gets aggravated (red), there is often a lot of pain involved over a large portion of the body (the lower limb). Note that there are three main 'spinal nerve roots' (within the lower back) that leave the spine and blend together within the pelvis and form the sciatic nerve. These are labeled L4, L5, and S1.

Not all lower extremity pain is classified as 'true sciatica': Sciatic pain may be classified as radicular pain (true sciatica) - pain radiating from the low back, past the knee, and into the dermatome (L4, L5, and/or S1) of the affected lumbar nerve root; or as non-radicular pain - pain radiating in the lower limb in a non-dermatomal pattern (29). Bogduk defines radicular pain as a burning and/or numbing pain that presents in a band-like dermatomal pattern below the knee (7).

Now, if you already know the anatomy and understand what dermatomes are, you may jump over the anatomy lessons and continue here : The Causes of Sciatica

QUICK ANATOMY LESSION: The Formation of the Sciatic Nerve.

Fig.#2 Illustrates the anatomy of the origin of the sciatica nerve in greater detail; the backs of the vertebrae (posterior ring) have been cut away in order to see how the sciatic nerve is formed.

Spinal Nerve Roots: one motor root and one sensory root, leave the cauda equina and course towards their respective intervertebral foramen (IVF). As they 'transverse' towards the IVF, they come in close contact with the posterior surface of the intervertebral disc. Herniations of the disc can directly compress the passing spinal nerve root and cause back pain and sciatica.

Within the IVF the two spinal nerve roots blend into one larger nerve; this nerve is now called the 'Spinal Nerve'. The Spinal nerve quickly splits into a 'Ventral Rami', and 'Dorsal Rami'. The Dorsal Rami courses to the skin and muscle of the lower back and butt, the Ventral Rami courses downward to form the Sciatica nerve.

The only thing you really need to understand is that the L4, L5, and S1 Spinal Nerve Roots make up the sciatica nerve. Irritation to anyone of these nerve roots may ignite sciatica. For a better lesson and picture of real nerve roots, go to my 'Disc Anatomy' page and click the tab 'Real Nerve Anatomy'.

DERMATOMES & RADICULAR PAIN: Which Flavor of Sciatica do you have?

The first order of business is to clear-up some terminology issues: The terms Sciatica, Radicular Pain, Radiculopathy, Radiculopathic Pain, and Root Pain are all synonymous (mean the same). I prefer the term 'Radicular Pain' since it more accurately denotes that the patients 'pain' is coming from the spinal root level ('radic' indicates spinal nerve root) as opposed to a referred pain from a facet joint, SI joint, or other spinal structure. The term 'sciatica' is not very specific and only indicates that the patient has lower limb pain, which may or may not be caused from nerve root compression/irritation.

Since there are three possible nerve roots to irritate, and each of these nerve roots are connected to different regions of the 'skin' (sensory) and 'muscle' (motor) in the lower limbs, sciatica come in 'three different flavors': S1 radicular pain, L5 radicular pain, or L4 radicular pain (fairly rare). L3, L2, and L1 radicular pains (aka: radiculopathy) are also possible with high lumbar disc herniations; however, since these are not nearly as common and DON'T involve the sciatic nerve, they will not be discussed here.

Dermatome Research:

Did you know that most of the dermatome charts floating around the internet and on the walls of doctors' offices were based on investigations made over 35 years ago at best (31), and over 90 years ago at worst (30). Heck, some investigation date back to the 1800s (32)! Although in 1948 Keegan et al. had the right idea for developing dermatome charts (33), in that he studies and mapped the effects of disc herniations on the skin in the extremities, his results still couldn't confirm‎ any of the prior work!

Nitta et al: Finally, Nitta et al. published the first investigation that was of high scientific design (2)! In 1992, this group of investigators successfully mapped the sensory-dermatomal distribution of the L4, L5, and S1 nerve roots. They gathered 71 patients, who were suffering disc herniation-associated radicular pain, and 'blocked' (anesthetized) their problematic nerve root with Xylocain; this was done under fluoroscopy to ensure the correct nerve roots were blocked. Next they carefully marked (aka: mapped) the areas on the patients skin that were numbed by the Xylocain nerve blocks. The results were tabulated and are shown below; however, the bottom line is this: "The L4 nerve root innervates (connects, gives-life-to) the medial side (inside) of the lower leg in 88% of the patients tested. The L5 nerve root innervates the side of the first digit (big toe) on the dorsum (top) of the foot in 82% of the patients. The S1 nerve root innervates the side of the fifth digit of the foot in 83% of the individuals." (2) I've based all of my dermatome maps on this investigation. (see below)

Although the majority of patients seem to share the same 'nerve root dermatomal distributions' (wiring), this investigation has clearly demonstrated that the neural anatomy of the lumbar spine does have some degree of variation, i.e., some 20% of the patients did NOT have the typical 'nerve root dermatomal distributions'. For example, in some patients, a L5 nerve root block would result in numbness of the S1 dermatome and not the anticipated L5 dermatome (2).

Kortelainen et al: In another giant study of radicular pain patterns, Kortelainen et al. also found that spinal nerve root irritation (via disc herniation) did NOT always project pain into the classic dermatomal regions; this was especially true of the S1 dermatome (1). After studying the radicular pain patterns of 403 disc herniation-induced radicular pain patients - all of whom eventually underwent discectomy surgery - they found the following:

Level of disc rupture	Number of patients	L4 Dermatome	L5 Dermatome	S1 Dermatome	No specific dermatome
L2 Disc	3 (0.7%)	(0%)	1 (0.6%)	2 (1%)
L3 Disc	7 (1.7%)	1 (9%)	3 (1.8%)	3 (1.5%)
L4 Disc	229 (57%)	7 (64%)	136 (79%)	66 (34%)	20 (74%)
L5 Disc	164 (41%)	3 (27%)	31 (18%)	123 (63%)	7 (26%)
Total	403	11 (3%)	171 (42%)	194 (48%)	27 (7%)

In summary, sciatic pain projection into the L5 dermatome (top of the foot) was caused by the anticipated L4 disc herniation in 79% of the cases; by the unexpected L5 disc herniation in 18% of the cases; and by the really unexpected L3 disc herniation in 1.8% of the cases.
Pain project in into the S1 dermatome was caused by the anticipated L5 disc herniation in only 63% of the cases, and by a unexpected L4 disc herniation in 34% of the cases! As you can see by these results, S1 dermatomal pain (pain on the side of the foot) is not very accurate at predicting the level of nerve root compression/irritation (1) (I would note that the Kortelainen study was not as 'scientific' as the Nitta study, and we can only assume that the disc herniations all caused compression of the descending nerve root and NOT the transcending root. There was no mention of this very important factor in the paper!)

So, I hope I didn't loose too many of you in that last discussion! The bottom line is that you can't always trust the presence of pain in a dermatome to indicate which disc has herniated in the spine, although its still a moderately accurate method.

Let's go over where patients typically feel nerve root pain.

Dermatome Mapping:

Without question, Nitta et al. has published the highest quality investigation on dermatomes (2); therefore, only his work will be reflected on the following dermatome maps:

S1 RADICULAR PAIN:

If the L5 disc herniates into the 'lateral recess' (which is where it usually does) and compresses / irritates the descending S1 nerve root, the patient may suffer an S1 radicular pain (aka: S1 root-pain, or S1 Sciatica). Fig.#4 shows the regions in the lower limb where the patient will most likely suffer the symptoms of S1 sciatica (2). As you can see, the majority of patients (75%) suffer the burning, stinging, and numbing pain of sciatica in the lateral foot, posterolateral leg, thigh, and butt, as well as, the bottom, outer 1/2 of the foot. These pains are the result of damage and irritation to the 'sensory portion' (portion of the nerve root which connects to skin) of the nerve root.

If the 'motor portion' (portion of the nerve root which connects to muscle) of the S1 nerve root is damaged or irritated by the disc herniation, the patient my suffer weakness and/or atrophy in the Gastrocnemius muscle (the calf), the peroneal muscles (foot evertors), and/or the muscles which flex or curl the 'big toe'. The Achilles' Reflex and Plantar Reflex may also be diminished or absent. If severe, the patient will be unable to do 'calf raises' with the effected foot. Calf raising is the 'gold standard' muscle test for S1.

L5 RADICULAR PAIN:

If the L4 disc herniates into the 'lateral recess' (which is where it usually does) and compresses / irritates the descending L5 nerve root, the patient may suffer an L5 radicular pain (aka: L5 root-pain, or L5 Sciatica). Fig. # 5 shows the regions in the lower limb where the patient will most likely suffer the symptoms of L5 sciatica (2). As you can see, the majority of patients (75%) suffer the burning, stinging, and numbing pain of sciatica in the top and inner surface (dorsum) of the foot, the outer-front of the leg, and the bottom of the big toe. These pains are the result of damage and irritation to the 'sensory portion' (portion of the nerve root which connects to skin) of the nerve root.

If the 'motor portion' (portion of the nerve root which connects to muscle) of the L5 nerve root is damaged or irritated by the disc herniation, the patient my suffer weakness in the Extensor Hallusis Longus muscle (muscle that lifts the big toe - classic finding) or the muscles that dorsi-flex the foot (lift the foot up) upward. If severe, the patient will be unable to 'walk on their heals' with their toes and ball-of-the-foot off the ground. There is no reliable reflex test for this nerve root.

L4 RADICULAR PAIN:

If the L3 disc herniates into the 'lateral recess' (which is where it usually does) and compresses / irritates the descending L4 nerve root, the patient may suffer an L4 radicular pain (aka: L4 root-pain, or L4 Sciatica). Fig. # 6 shows the regions in the lower limb where the patient will most likely suffer the symptoms of L4 sciatica (2). As you can see, the majority of patients (75%) suffer the burning, stinging, and numbing pain of sciatica in the top and inner surface (dorsum) of the foot, the outer-front of the leg, and the bottom of the big toe. These pains are the result of damage and irritation to the 'sensory portion' (portion of the nerve root which connects to skin) of the nerve root.

If the 'motor portion' (portion of the nerve root which connects to muscle) of the L4 nerve root is damaged or irritated by the disc herniation, the patient my suffer weakness in the quadriceps muscle (muscle that extend the knee). If severe, the patient will be unable to perform a squat or get out of a chair because. If the problem is severe, the patient will often have a diminished or absent Patellar Reflex (aka: knee jerk).

THE CAUSES OF SCIATICA: [ | Disc Herniation | The Conundrum | Discogenic Sciatica | Chemical Radiculopathy | Autoimmune Attack | ]

Now that we know what sciatica is, it's time to try and explain why it occurs--a task easier said than done!

As I see it, there are three possible "causes" of acute sciatica--excluding the more exotic forms: (1) disc herniation induced sciatica; that is, the posterior of the disc herniates into the adjacent sciatica nerve root, which in turn physically compresses and irritates that nerve root into a painful state; (2) grade V annular tear induced sciatica; that is, the disc rips open and allows biochemical (cytokines) to leak out and soak the adjacent sciatica nerve root(s), which in turn inflammes the sciatica nerve root into a painful state; and (3) discogenic sciatica; that is, the patient may experience a "referred" pain (that often is dermatomal) down the lower limb from severe irritation of the tiny sensory nerve fibers (sinuvertebral nerve) that live within the outer 1/3 of the annulus of the disc. This is NOT an irritation of the actual sciatica nerve but simply the patient's preception of sciatic nerve irritation--like the left arm pain felt by someone suffering a heart attack.

In a general sense, disc herniation (25, 70) and/or stenosis are by far the most frequent causes of compressive sciatica (67-70), there are, however, other more exotic causes of sciatica; such as, Spondylolisthesis, Piriformis Syndrome, Obturator Syndrome, Far-Out Syndrome, Synovial Cysts, Hypertrophied Epidural Vessels, Gas-containing Ganglion cysts, and Tumors. These rare causes are beyond the scope of this paper.

And before we dig deeping into the phenomenon of sciatica, here is another important fact that need be remembered: the mechanism of lower limb pain (sciatica) is most likely VERY complex and is not nearly as simple as the disc herniates, pinches the nerve, and you get pain. There are many other factors (some of which that are still unknown) that contribute to the pain of sciatica. In fact, recently we have learned from the work of Karppinen et al. that neither the amount of nerve root compression nor the size of the disc displacement (posterior outpouching of the disc) relates to the amount of pain (VAS) or disability (Oswestry) the patient suffers (70). Those 'other factors' are still being debated within the research community, but proinflammatory cytokines (especially TNF-alpha) are certainly involved (96-99). Pain 'referred' directly from the disc may also have a role in the sensation of sciatica (11,12).

Let talk a moment about the number one cause of sciatica: The disc herniation.

The Lumbar Disc Herniation:

It has been known for years and is generally accepted that a compressive lumbar disc herniation is a common cause of sciatica (25,70), and the patients symptoms will usually depend upon which spinal nerve root is involved. Since 95% of lumbar disc herniations occurs at either the L4 or L5 disc level (290), it's not at all surprising that sciatica is so very commonly. This high frequency of L4 and L5 disc herniation is also the reason why most EMG-confirmed radiculopathy occurs in the L5 or S1 root (290).

I'm not going to go into the mechanism of disc herniation on this page since it has been covered in depth on the 'Disc Herniation Page'. But, figure #3 depicts how this mechanism works:

Fig. #3 demonstrates a paracentral herniation (pink) of the L5 disc that is located within a region called the lateral recess. The herniation is compressing the right S1 nerve root which may cause 'radicular pain' in this patient's S1 dermatome (right lateral foot). This patient may also have a loss of 'motor function' in the right lower limb. More explicitly, a loss of muscle strength in gastrocnemius (calf), and peroneal muscles. There might also be a lost Achilles' reflex.

THE SCIATICA-HERNIATION CONUNDRUM:

So you think you've got this sciatica thing figured out? It's easy right: the disc herniates, pinches the sciatica nerve root, and pain occurs in the distribution of the sciatica nerve. NOT SO FAST!

Although disc hernation-induced sciatica certainly does occur, it's common knowledge that not all disc herniations cause sciatica. Some people have severe sciatica without any evidence of compressive disc herniation at all!

In a recent investigation by Karppinen et al. [Karppinen], it was demonstrated that 20% of severely acute sciatica patients had no compressive disc herniation on MRI; all MRI images were negative for protrusion, extrusion, and/or sequestration, yet these patients were suffering from severe back and leg pain! (70) These researchers concluded that the severity of sciatica and back pain are NOT related to the amount of the disc displacement (size of the herniation) or the amount of spinal nerve root compression! VAS and Oswestry scores were virtually the same for both disc herniations patients (disc herniation = protrusion, extrusion, & sequestration) as they were for disc bulge or normal disc patients! (I would add that patients who were applying for early retirement were removed from this study which enhances its validity). (70)

So, if its not a compressive disc herniation that's causing the suffering, then what it?

One possible explanation was put forth by both Ohnmeiss et al. (619,620) and Milette et al. (621) These investigators experimentally demonstrated that disruptions within the substance of the disc (anular tears) not only caused low back pain but also caused ‘referred pain’ into the lower limb; we may call this referred lower limb pain ‘discogenic sciatica’.   [Ohnmeiss Paper & Milette Paper]

Another explanation is based upon the investigations of Olmarker et al.   This group has repeatedly demonstrated that the application of nucleus pulposus upon the spinal nerve root can create marked morphological change (axon damage) and functional change (decreased conduction speed) to the micro-anatomy of that nerve root, as well as cause ‘pain-related behaviors’ to occur within the test animals (790-795).  

Therefore, if this nucleus pulposus get ‘loose’ in the epidural space (most likely from a grade 5 posterior anular disc tear), it may well cause the pathological spinal nerve root changes described by Olmarker (790-795) and result in a painful sciatica syndrome without nerve root compression.   Researchers have termed this phenomenon “Chemical Radiculopathy” (788,789).

The final theory on non-compression induced sciatica implicates the activation of the patients own immune system against the nucleus pulposus-soaked nerve root (800,801). This ‘auto-immune’ type reaction may help perpetuate the syndrome of chronic sciatic pain.

Whatever the cause, it is clear that non-compressive disc defects (bulges and contained herniations) are just as painful and disabling as the classic large compressive disc herniation.   Therefore the symptoms of sciatic patients without disc herniation in MRI should not be dismissed by the doctor.  

DISC HERNIATIONS IN NORMAL ASYMPTOMATIC PEOPLE:

It's common knowledge that not all compressive disc herniations (as seen on MRI and CT scan) will result in back pain and/or sciatica and are commonly found in completely asymptomatic people (40-47). I've got a page on the phenomenon of disc herniations in asymptomatic people ( here: Abnormal MRI in Pain-Free People ) , but would like to give you all an example and then the 'bottom line' of my research into MRI false positives:

The Bottom-line on the 'False Positives' of MRI:

If I were to gather a group of middle age folks (45 average age) who have NEVER had back pain before and shoot MRIs on them all, here's what we would find: 38% would have disc bulges, 37% disc protrusions (aka: contained herniations), 11% disc extrusions (aka: non-contained herniations), 0% disc sequestrations (aka: free fragments) and 4% nerve root compression by the disc herniation. (40-43)

Here's a recap of the main investigations of accuracy of MRI: See the full page here: (Abnormal MRI in pain-free people)

The below chart shows the percentages of false positive MRI readings for each type of disc herniations (bulge, protrusion, or extrusion) and for nerve root compression for a disc herniation. Remember, none of the below patients had ever had lower back pain before yet about 3/4 of them had some type of abnormal disc presentation:

Investigation:	Disc Bulge	Disc Protrusion	Disc Extrusion	Disc Pathology (Bulge, Protrusion,extrusion, sequestration)	Root Deviation or Compression
Boden et al.		20%		NA
Jensen et al.	52%	27%	1%	80%
Boos et al.		63%	13%	76%	4%
Weishaupt et al.	24%	40%	18%	82%	4%
AVERAGES:	38%	37%	11%	79%	4%

And finally, another well known conundrum: the fact that patients radicular symptoms, clinical neurological presentation, and pain presentation do NOT always match the level of disc herniation (291)!

So you see, when it comes to diagnosing the cause of disc herniation-associated sciatica, sometimes things are not always so 'black and white'!

Discogenic Sciatica: Referred pain from the Disc mimics radicular pain.

Recently, we have learned that the intervertebral disc itself may ‘refer’ pain down into the lower limbs in a dermatomal like pain pattern (11, 621). The theory of Discogenic Sciatica is complex and still controversial but can be explained as follows: just as a person who is having a heart attack will often suffer a 'referred pain' down the left arm, a person with massive pain generation within a disrupted and/or diseased lumbar disc may also suffer a referred pain down into the leg, often in a dermatomal-like pain pattern. Ohnmeiss et al. has extensively investigated this theory and has done a good job at proving its existence (11). This phenomenon can make it very difficult to ascertain just exactly what is causing a patient’s sciatica: Is it from a disc herniation compressing the adjacent nerve-root, or from a severely internally disrupted disc referring pain, or a combination of both? This ‘referred pain’ from the disc into the lower back and/or lower limbs is called ‘Discogenic Pain’ or as I like to call it, ‘Discogenic Sciatica’.

Milette et al. has also investigated the phenomenon of discogenic referred pain and demonstrated that disruptions within the disc can indeed refer pain into the back and down the leg. Read the full paper here: (Milette - 1995: Discogenic Sciatica)

I will be devoting an entire page to this theory in the near future and will be presenting some real cases of 'Discogenic Sciatica' from an upcoming investigation that I will be writing with Dr. Jinfu Lin of Taiwan China.

Chemical Radiculopathy: A leaking disc may result in radicular pain.

Another possible cause of sciatica is called Chemical Radiculopathy (257,258). This is believed to occur when the disc rips open and leaks without disc bulge or herniation.   It has been proposed that certain biochemicals (especially proinflammatory cytokines) may ‘leak’ from a completely disrupted disc (a disc with a hole in it), soak the adjacent nerve root and cause a 'Biochemical irritation' to that nerve root, hence inducing radicular pain(153,155.550). Again we have a situation where radicular pain may occur without the presence of a disc herniation!

Although this theory is relatively new, I'm convinced that it happens all the time. Not only have I seen this time and time again in my own clinical practice, I've just recently seen it occur in two of our local medical doctors who I personally know (one's a neurosurgeon and the other's a neurologist). Both had come down with real root-related sciatica (confirmed by EMG) despite having a completely normal looking MRI!

Numerous animal investigations has confirmed that the presence of nucleus pulposus on spine nerve roots is a 'bad thing'(551,553-558,560)! Nucleus pulposus and the biochemical Tumor Necrosis Factor - alpha have been linked to some truly damaging effects on spinal nerve-roots, such as: Wallerian degeneration of the axons within the nerve root; a characteristic myelin injury to the axon (551,553-555); a local increase in vascular permeability with the nerve root (556,557); intravascular coagulation within the nerve root (551,558); reduced intraneural blood flow within the nerve root(560); leukotaxis (558); macrophage recruitment within the nerve root; and a splitting of the myelin sheath from the axon (140, 141).

AUTOIMMUNE ATTACK:

The final theory on non-compression induced sciatica implicates the activation of the patients own immune system against the nucleus pulposus-soaked nerve root (800,801). This ‘auto-immune’ type reaction may help perpetuate the syndrome of chronic sciatic pain. Again, this is a very complex subject, and I will be devoting an entire page to it in the near future.

RISK FACTORS FOR THE DEVELOPMENT OF SCIATICA:

Beside having bad genetics for disc building material, which is probably the number-one risk factor for disc herniation-associated sciatica, the line of work that you choose may significantly increase or decrease your livelihood of developing disc herniation-associated sciatica. Research has indicated that 'heavy manual labor' and 'sedimentary work' are the two types of employment most frequently associated with the development of sciatica (195). More explicitly, investigations have demonstrated that frequent heavy lifting, (193,194) frequent twisting and bending, (193,194) exposure to vibration,(192,193) and sedentary activity (192,195) [190] all increase the risk of developing sciatica.

It seems the 'safest' type of work (the work in which less people develop sciatica) is that which combines a combination of sitting standing and physical activity (195).

A CURE FOR SCIATICA? INFLIXIMAB & ETANERCEPT (False hope: 2005 update )

It is currently believed by some investigators that the cytokine 'Tumor Necrosis Factor - alpha' (TNF-a) is one of the "smoking guns" of sciatica as it has been shown to be directly involved in nucleus pulposus-induced nerve root damage (4). It has been experimentally demonstrated in both the animal and human that the chimeric antibody 'Infliximab' stops and minimizes nerve root damage after the application of nucleus pulposus upon a nerve root (animal studies) and significantly decreases the lower limb pain in acute sciatica sufferers (140). Although the use for Infliximab looks promising to combat sciatica, a larger randomized study is desperately needed to confirm‎ the results of Karppinen's initial pilot study of 2003 (140) and recent 2005 one year follow-up on these 10 patients (900).

Although Infliximab has already been proven safe and effective for the treatment of other diseases of the body, such as rheumatoid arthritis (144,145), plaque-type psoriasis (146), active ankylosing spondylitis (147), and Crohn’s disease (148), further investigation is needed before sciatica can be added to the list of indications for the drug Infliximab (140).

UPDATE (2005) Unfortunately, It would now appear that Infliximab is no more effective than placebo for the treatment of disc herniation related sciatica. In a larger randomized controlled investigation, Karppinen et al. discovered that patients given placebo (fake) injections obtained just as much sciatic pain releif as those who got the injection of the "ultra-expensive" infliximab:

Korhonen T, Karppinen J, et al. "The treatment of disc herniation-induced sciatica with infliximab: results of a randomized, controlled, 3-month follow-up study." Spine 2005 Dec 15;30(24):2724-8.

Department of Physical Medicine and Rehabilitation, Oulu University Hospital, Oulu, Finland.

STUDY DESIGN: A randomized controlled trial. OBJECTIVES: To eval‎uate the efficacy of infliximab, a monoclonal antibody against tumor necrosis factor (TNF)-alpha in a randomized controlled setting. SUMMARY OF BACKGROUND DATA: Recently, we obtained encouraging results in an open-label study of infliximab in patients with disc herniation-induced sciatica. Furthermore, the results of experimental studies support the use of infliximab in sciatica. Therefore, we initiated a randomized, controlled trial (FIRST II, Finnish Infliximab Related STudy) to confirm‎ the efficacy of a single infusion of infliximab for sciatic pain. METHODS: Inclusion criteria were unilateral moderate to severe sciatic pain with an MRI-confirmed disc herniation concordant with the symptoms and signs of radicular pain. Patients had to be candidates for discectomy, as eval‎uated by an independent orthopedic surgeon. Forty patients were allocated to a single intravenous infusion of either infliximab 5 mg/kg or placebo. Assessments at baseline and various time points included clinical examination with measurement of straight leg raising restriction; questionnaires related to subjective symptoms (leg and back pain by 100-mm visual analog scale, Oswestry disability); sick leaves; number of discectomies; and adverse effects possibly related to treatment. The primary endpoint was a reduction in leg pain from baseline to 12 weeks, which was analyzed using a Mann-Whitney U test and repeated-measures analysis. RESULTS: A significant reduction in leg pain was observed in both groups, with no significant difference between treatment regimens. Similar efficacy was observed between treatment groups for secondary endpoints. Seven patients in each group required surgery. No adverse effects related to treatment were encountered. CONCLUSIONS: The results of this randomized trial do not support the use of infliximab for lumbar radicular pain in patients with disc herniation-induced sciatica.

UPDATE 2007:

Now, Etanercept, another TNF-a inhibitor (a fusion protein) has been shot down by a grade "A" randomized placebo-controlled double blind trial. In 2007, John Hopkins School of Medicine's SP Cohen, et al published the results of their investigation into the off-lable use of Etanercept for the treatment of sciatica. Unfortunately, they discovered that this very expensive treatment is no better than that of a placebo (suger pill). They concluded, "A single low dose of intradiscal etanercept does not seem to be an effective treatment for chronic radicular or discogenic low back pain."

TREATMENT OPTIONS: [Surgery Timing | Surgery Indications | Treatment Guidelines ]

Warning: These recommendations are for educational purposes ONLY and should never be substituted nor could nerve take the place of an examination by your medical doctor! Do NOT implement any of these courses of treatment without the approval of your medical doctor.

Without question, the best treatment for non-complicated sciatica is passage of TIME. Even the worst cases of sciatica may spontaneously resolve with time, and even some very large disc extrusions may completely be reabsorbed by the body (23), hence decompressing the nerve root naturally. BUT, if you are a candidate for surgery and are not improving with care at all, then delaying the surgery seems to decrease your chances for a successful surgical out come (305).

FOUR INDICATIONS FOR SURGERY:

The American Academy of Orthopedic Surgeons and Alf Nachemson – who is the number one spine researcher in the world - (18) recommends the following conditions be met before decompressive surgery is offered:

#1	Functional incapacitating pain in the leg, extending below the knee with a nerve root distribution.
#2	Nerve root tension signs (positive straight leg raising test) with or without neurologic abnormalities, fitting the radiculopathy.
#3	Failure of clinical improvement after 4-8 weeks of conservative treatment,
#4	Confirm‎ing imaging study: abnormal myelogram, computed tomogram (CT), or magnetic resonance imaging (MRI) correlated to the physical signs and distribution of the pain.

The only ABSOLUTE indication for surgical intervention, however, is if the patient develops a loss of bowl or bladder control (cauda equina syndrome); if the patient develops severe progressive motor loss in the lower limbs, such as foot-drop; or if the patients has severe debilitating pain.  

Several high quality outcome assessment investigations have shown that even patients with confirmed radiculopathy (nerve root damage) that meet the 'four criteria' for surgery often do 'well' with non-surgical treatment (77 - Saal & Saal); furthermore, although patients who undergo discectomy seem to get better faster (rarely 100% better), in the long-run (4 to 7 years) the non-surgical patients obtain nearly the same improvement in terms of pain relief and functional outcome. (78 - Weber)

SURGERY TIMING: When to "Pull the Trigger" and Try Surgery?

It is generally agreed upon, assuming the patient is NOT improving, that one should not wait too long before undergoing decompression via discectomy. The the experts can't seem to agree upon is how long the patient should be allowed to suffer. The forthcoming investigations all yield different opinions on when surgery should be performed; however, they all agree that a suffering patient should not wait longer than one year. The average time is currently 4.6 months, so waiting longer than this might decrease your chances of having a successful discectomy. I would seem to be living proof of this, i.e., I waited 15 months and my surgery failed miserably.

Research papers:	Year (foot note)	Length of conservative care:
Postacchini F.	1999 (14)	6 months
Dvorak J, et al.	1988 (11)	4 months
Hurme M. & Alaranta H.	1987 (12)	2 months
Rothoerl RD , et al.	2002 (26)	2 months
Ng LC & Sell P	2004 (66)	< 12 months
Dauch WA , et al.	1994 (10)	6 weeks
Average suffering periods for all investigations: After this time, your chances of discectomy success may drop.		4.6 months

Treatment Guide-lines:

I’ve read a tremendous amount of research and picked-the-brain of many a doctor during my own battle with sciatica. Based on my research and personal experience I've developed some recommendations for the treatment of sciatica:

Start anti-inflammatory medication such as Naproxen, Ibuprofen, and Celebrex, as soon as possible. The sciatic-inflamation associating is becoming stronger and stronger, so anti-inflammatory measures are a must.

Take ½ aspirin per day to thin the blood. This may help prevent clotting and venous stasis within the of microvasculatory system within the delicate nerve root. It is believed that damage to this micro-circulatory system within the delicate nerve may lead to permanently axon death, scaring within the nerve root, chronic hypersensitivity of the nerve root and chronic pain. (Remember to check with your MD first!)

Get at least one transforaminal epidural steroid injection (aka: TFESI) performed under done under fluoroscopy at all suspected root levels. Don't monkey around with nerve root blocks UNLESS they administer the steroid immediately afterwards.

Start conservative care promptly:this may include physical therapy, exercise, swimming, traction and/or Chiropractic care. Try and stay as active as possible without aggravating your pain. Home traction devices and/or a slant board are also worth trying.

Try a 14 day course of oral steroids (prednisone) to help reduce inflammation that might be occurring in an area that was not reached by the epidural injections.

At the three-month-mark, if you’re NOT IMPROVING, get an immediate neurosurgical opinion!   You absolutely do NOT want to wait too long for an indicated surgery.   Numerous research papers have found that your chances for a successful surgery decrease with the passage of time after the 3 or 4 month mark (301-309).

WHAT ARE MY CHANCES OF GETTING SCIATICA?

For the answer to this question, we must turn the giant population based survey studies which are mostly flawed with respect to sciatica, for they don’t differentiate between true root related sciatica, and fake sciatica (referred lower limb pains from the SI joint, intraspinal ligaments, and/or facet joints etc).

From these less specific studies we have learned that the life-time chance (preval‎ence) for developing ‘generic sciatica’ (sciatica of unknown cause) is about 35%; this number has been pretty well substantiated in other investigations as well (181,183-186).   Over the course of each year, about 1% of the North American population will suffer an attack of sciatica (9); that equates to about 4.9 MILLION cases per year!

Only two groups of investigators has had the intelligence to address the life-time preval‎ence of true root-related sciatica: Heliovaara et al. found that 5% of men and 4% of women will develop nerve root-related sciatica at some point in there life (181).   These numbers were later confirmed by Manninen P, et al in 1995 (182).  

The differentiation between the life-time chances of generic sciatica (35%) and true root-related sciatica (5%) demonstrates that true root-based sciatica is a relatively rare phenomenon.  (Don’t we feel special?)

There are no studies that have investigated the preval‎ence for ‘discogenic pain/sciatica’ in the population, but I’m guessing it to be around 1% or 2%.

WILL I RECOVER FROM SCIATICA? [ Pertinent Research outcome ]

The short answer: probably not 100% if your sciatica is a true radiculopathy confirmed by EMG and/ or severe.

Unlike lower back pain, sciatica has a more prolonged and less certain recovery period. For the general non-radiculopathic sciatica, 40% to 50% of those affected will completely recovery within 4 weeks (19,20), and 88% will recovery within 6 months (8); however, 5% to 10% will not recover and require surgical decompression (9).

For us patients with 'real' disc herniation-associated radicular pain (radiculopathy), the outcome is less favorable, as has been demonstrated by several well-written investigations: Only 37% will completely recovery from there radicular pain (sciatica) by 3.5 years! This number was derived by averaging out all the complete recovery patient from the major five outcome studies of our time. (here)

The Outcome Studies:

The Saal Study:

The Saal brothers’ 1989 outcome study is undoubtedly the best paper to date on the recovery-rates for radiculopathy-related sciatica:   the Saals followed 58 patients who had confirmed disc herniation-induced radiculopathy (via MRI & EMG). They had all failed ‘passive conservative care’ and were put through the authors aggressive conservative care program, which included special exercises, medications, epidural steroid injection and physical therapy.   After 2 ½ years, only 30% of the patients reported a full recovery and 10% were lost to surgery.   The good news - if you’re not an athlete - is that 90% of the patients returned to their original work and recovered enough to at least be able to perform some limited recreational activities (77).

The Atlas Study:

Atlas et al. followed 220 patients that were treated surgically for disc herniation-induced sciatica and 183 patients who were non-surgically treated for the same. At five years only 28% of the surgically treated patients reported that their pains were completely gone. The conservatively treated group faired even worse, in that only 12% reported a complete resolution of their symptoms (15).

The Nykvist Study:

Another outcome study by Nykvist et al. found that after five years of either surgical or non-surgical treatment; 82% of the non-surgically treated group and 62% of the surgically treated group still suffered with at least some degree of sciatica (17)!

The Weber Study #1:

Weber et al. studied the outcome for a group of 208 non-surgically treated patients, all of whom had “root symptoms” associated with sciatica. After one year, 30% of the patients had reduced capacity in work, and restrictions of leisure activity and only 50% reported no pain at work or leisure (19).

The Volvo Award Winning Weber Study:

In the only quality ‘randomized’ outcome study to date, Henrik Weber followed a group of 126 sciatica patients who were ‘randomly’ assigned to either surgery or non-surgical care. All of these patients were considered ‘boarder-line’ surgical candidates and were followed for over 10 years. Over that 10 year period, only 5% of the patients were lose, which gives this Volvo Award Winning study excellent predictive value. At four years post ‘treatment’, only 66% of the surgical patients were “completely satisfied” with their outcomes, versus only 52% of the conservatively treated group. At 10 years, only 58% of the surgical group were completely satisfied (some had worsened), and 56% of the conservative group were completely satisfied. At 10 years only 2% of both groups reported residual lower limb pains (sciatica), which was greatly improved from the 37% and 23% residual sciatica reported sciatica at 4 years (16).

The Balague Study of 1999: (126) This group of Swiss and American investigators study the outcomes of 82 'severe sciatica patients' - patients were hospitalized because of the severity of their sciatica. 33% of the patients were lost during the one year follow-up period to surgery, although they were still followed up. As for the recovery of this cohort, the authors stated the following, "...a substantial percentage of patients with acute severe sciatica had not recovered by 1 year after discharge." More explicitly, only 21 (29%) of the all 82 patients were "essentially" pain free at one year. Interestingly, only 74% of these patients had disc herniation on MRI, and only 62% had a positive EMG!

The Bottom Line:

Radiculopathy Outcome Studies:	Complete Recovery or Completely Satisfied with Outcome:
Saal & Saal. 1989 (77)	30% (conservative) @ 2 ½ years
Atlas et al. 2001 (15)	28% (surgical) 12% (conservative) @ 5 years
Nykvist et al. 1989 (17)	38% (surgical) 18% (conservative) @ 5 years
Weber et al. 1993 (19)	54% (conservative) @ 1 year
Weber. 1983 volvo award (16)	66% (surgical) 52% (conservative) @ 4 years
Balague et al. 1999 (126)	29% (surgical & conservative) @ 1 year.
Average % of Complete Recovery: (I took the average from all 6 investigations, also averaged surgical & conservative, when applicable, into one number before computing final number.)	ONLY 37% of sciatica patients, with or without surgery, recover completely or near completely (33% from conservative care and 40% from surgical care).

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