• Dr. Brian Abelson DC

Sciatica Part 1 – Many Different Causes

Updated: Nov 2

Sciatica can indeed be a pain in the butt! It’s also a pain with which I am familiar, both as a practitioner and patient. Over twenty years ago, I ruptured a lumbar disc (L5/S1) in my own back. One minute I was running marathons, the next minute, I could barely walk. It was a brutal experience, but it also taught me a great deal about this condition and how to get it under control. In my case, surgery in combination with manual therapy and exercise was the best option for a resolution. The good news for me was that, within a year, I was back to competing in Ironman races.

Fortunately, most cases of Sciatica do NOT require surgery. While severe cases of sciatica may require surgery, most other cases will achieve excellent results by combing conservative manual therapy with exercise.



Sciatica refers to pain that radiates down, along the pathway of the sciatic nerve.

The sciatic nerve:

  • Arises from the Sacral Plexus from the nerve roots of L4-S3.

  • Runs through the buttocks down to the knee where it bifurcates to form the tibial and peroneal nerves.

The Sciatic nerve is the longest and widest single nerve in the body and can be about the width of your thumb in its thickest section.

True Sciatica is different from what is often referred to as Sciatica. From a medical perspective, Sciatica describes leg pain limited to a specific distribution of lumbosacral nerve roots (a dermatomal pattern, most commonly L4-S2).

Often patients with low back and leg pain will not show this dermatomal pain pattern, but the problem is still diagnosed as Sciatica. A more accurate diagnosis for patients who DO NOT exhibit lumbosacral pain in a nerve root pattern (dermatomal pattern) would be “nonspecific radicular pain”.

Note: Dermatomal inconsistencies are common. Dermatomal patterns only give you general information on sensory changes. There is a lack of consensus between authors on dermatomal sensory patterns. There is also a considerable crossover between spinal nerve levels, and there are differences found between individuals (9).



Symptoms of sciatica can be caused by disc herniation, foraminal stenosis, spinal stenosis, or entrapment of the sciatic nerve anywhere along its path. In this blog, I will review Sciatic type symptoms that are caused by Disc Herniation and entrapment of the Sciatic Nerve along its pathway.

Sciatica Caused by Disc Herniation

A herniated disc is basically a dislocation of disc material (nucleus pulposus or annulus fibrosis) outside of the intervertebral disc space. The greatest occurrence of lumbar disc herniation occurs between the ages of 30 to 50 years old, with males having twice the number of disc herniations as compared to females (2).

When we discuss the subject of lumbar Disc Herniation, we need to talk about the difference between disc protrusions, disc prolapses and disc extrusions.

  • A disc protrusion (also known as a disc bulge) occurs when the inner material of the disc starts to push out through the outer wall of the disc, creating a bulge in the disc. You may be surprised to note that most cases of a disc bulge are completely symptom-less, they cause no pain or lack of function. In fact, most individuals over the age of forty have disc bulges (3). Problems occur when disc protrusions start to fragment or tear. A herniated disc occurs when the inner material of the disc (the nucleus pulposus) starts to push through the outer fibers of the disc (the annulus fibrosus). Most disc herniation's occur at the lower levels of the spinal column (L5/S1).

  • When the outer layers of the disc rupture, the inner centre of the disc may move out and press upon a nerve root. This condition is known as disc prolapse or protruding disc.

  • Along with disc prolapse, the material inside the disc can sometimes extrude into the vertebral (spinal) canal. When this occurs, the extruded piece of disc can interfere with the function of the nearby nerve roots. This condition is called a sequestered disc. A sequestered disc requires surgical intervention if it is causing neurological dysfunction; this is a problem that CANNOT be resolved with manual therapy.

Note: It is important to note that radio-graphical indications of disc herniation do not consistently predict the level of low back pain in the future (the patients prognosis), or even correlate with current symptoms (4). Asymptomatic patients can have a full blown disc herniation (10).

Fortunately, the majority of cases of sciatica that are caused by disc herniation DO NOT require surgical intervention. There are many cases where there is no major neurological dysfunction caused by disc herniation. On the other hand, it is important to know that when “Red Flags” are present an appropriate referral is critical


Below are examples of red flags that require immediate emergency medical care. The patient should seek immediate emergency care if they are experiencing:

  • Severe muscular wasting and atrophy.

  • Recent onset of bowel or bladder incontinence.

  • Saddle anesthesia where there is a loss of sensation in the area of the buttocks and perineum (the area between the anus and scrotum in males, and between the anus and vulva in females). This can be a symptom of Cauda Equina Syndrome – a neurosurgical emergency – caused by compression of the nerve roots below the level of the spinal cord, and sometimes as a result of a prolapsed disc.

  • Severe sciatica after a fall or other trauma, this could indicate a possible spinal fracture.



It is important to note that changes to the intervertebral disc (IVD) that take place during normal aging and the changes that take place during Degenerative Disc Disease (DDD) are NOT the same. Consider these fundamental differences (11,12).

During Normal Aging:

  • The IVD preserves its normal height (it does not collapse)

  • Dehydration of the disc does usually occurs by age 40.

  • The aging process occurs from the inside out, these changes occur over many years.

  • With aging there is less of a distinction between the centre of the disc and outer fibers (Nucleus Pulposus & Annulus Fibrosus)

  • Changes to the disc can be seen on MRI as a darkening of the disc.

Degenerative Joint Disease

  • There is a faster degeneration of the IVD compared to normal aging.

  • The IVD can collapse.

  • The DDD process occurs from the outside in.

  • Tears of the Annulus Fibrosus can enable growth of nerves and blood vessels (these can become a generator of chronic pain). This can occur in patients with no symptoms.

  • There is degeneration of the vertebral end plates.

  • There is also osseous degeneration, degeneration of the subchrondal bone.



So far, the discussion on disc bulges and protrusions sounds rather ominous. For this reason, I would like to mention two myths that we should consider:

The first myth is that the presence of a large disc protrusion – often seen on MRI or CAT scan images – is an indication that this problem cannot be resolved with conservative care (non- surgical care).

Yes, surgical treatment can provide faster relief from back pain symptoms in many patients with lumbar disc herniations, but what is interesting to note is that surgery does "not show a benefit over conservative treatment in midterm and long-term follow-ups". (14)

The second myth is that the extruded and sequestered disc fragments are less likely to resolve than the contained protrusions. In actuality, the migrating fragments actually resolve more frequently and faster than the contained protrusions. (6,7) The reason for this; the larger the disc protrusion, the greater the degree of inflammation around the protrusion. Once the disc fragments have broken off and inflammation has decreased around the fragments, with accompanying decreases in disc bulging, then the body is able to reabsorb the fragments. (8)

Key Point: Whether or not surgery is needed immediately would depend on whether neurological dysfunction is present (red flags).



Symptoms of sciatica can be caused by disc herniation, foraminal stenosis, spinal stenosis, or entrapment of the sciatic nerve. Most individuals over the age of forty have disc bulges. Most of these cases of a disc bulge are completely asymptomatic, causing no pain or lack of function. Most disc herniation's can be treated with conservative therapy first, as long as no red flags are present.

Some Key Points: The majority of people in our society have disc bulges. These bulges may never progress into a major problem. On the other hand, Degenerative Spinal Conditions are progressive and should be monitored. Over a period time damage to the disc could progress to the point of rupturing with sequestration (depending on multiple factors).

It is important to remember that what starts out as a minor problem, that resolves quickly, could progress into into a much more complex issue. Often these more serious problems take years to develop. Therefore, a disc herniation may be the the final sequelae (the final straw) in a long history of degeneration that started out as what is perceived as a minor event.

"Disc herniation is the result of an ongoing process!" It is rare to go from a healthy disc to disc herniation with the exception of severe trauma such as a motor vehicle accident. (13)

In part two “Sciatica – Causes and Diagnosis” we will discuss non-discogenic causes of Sciatic. This includes fibrous band tethering and direct compression. We will also include a section on physical examination tests that we use to evaluate cases of Sciatica.

Sciatica Part 1 – What Are You Dealing With

Sciatica Part 2 – Causes & Diagnosis

Sciatica Part 3 – Treatment - Logic & Recommendations

Sciatica Part 4 – Exercise & Activities of Daily Living



  1. Argoff CE, Wheeler AH. Backonja MM, ed. Spinal and radicular pain syndromes. Philadelphia, WB Saunders: Neurologic Clinics; 1998:833-45.

  2. Fardon DF, Milette PC. Nomenclature and classification of lumbar disc pathology: recommendations of the Combined Task Forces of the North American Spine Society, American Society of Spine Radiology, and American Society of Neuroradiology. Spine 2001;26:E93–E113.

  3. Maureen C. Jensen, Michael N. Brant-Zawadzki, Nancy Obuchowski, Michael T. Modic, Dennis Malkasian, and Jeffrey S. Ross Magnetic Resonance Imaging of the Lumbar Spine in People without Back Pain, N Engl J Med 1994; 331:69-73.

  4. Borenstein DG, O'Mara JW Jr, Boden SD, et al. The value of magnetic resonance imaging of the lumbar spine to predict low-back pain in asymptomatic subjects. J Bone Joint Surg Am 2001;83-A:1306–1311.

  5. Dullerud R, Nakstad PH. CT CHANGES AFTER CONSERVATIVE TREATMENT FOR LUMBAR DISC HERNIATION. Acta Radiologica, 1994;35:415-419.

  6. Komori H, Shinomiya K, Nakai O, Yamaura I, Takeda S, Furuya K. THE NATURAL HISTORY OF HERNIATED NUCLEUS PULPOSUS WITH RADICULOPATHY. Spine, 1996;21:225-229.

  7. Ikeda T, Nakamura T Kikuchi T, Senda H, Tagagi K. Pathomechanism Of Spontaneous Regression Of The Herniated Lumbar Disc: Histologic And Immunohistochemical Study. J Spinal Disord, 1996;9:136-140.

  8. Maigne J-Y, Deligne L. Computed Tomographic Follow-up Study Of 21 Cases Of Nonoperatively Treated Cervical Intervertebral Soft Disc Herniation. Spine, 1994;19:189-191.

  9. Taylor CS, Coxon AJ, Watson PC, Greenough CG. Do L5 and s1 nerve root compressions produce radicular pain in a dermatomal pattern? Spine (Phila Pa 1976). 2013 May 20;38(12):995-8.

  10. Brinjikji W, Luetmer PH, Comstock B, Bresnahan BW, Chen LE, Deyo RA, Halabi S, Turner JA, Avins AL, James K, Wald JT, Kallmes DF, Jarvik JG. Systematic literature review of imaging features of spinal degeneration in asymptomatic populations. AJNR Am J Neuroradiol. 2015 Apr;36(4):811-6. doi: 10.3174/ajnr.A4173. Epub 2014 Nov 27.

  11. William Mark Erwin,Leroi DeSouza, Martha Funabashi, Greg Kawchuk, Muhammad Zia Karim, Sarah Kim, StefanieMӓdler, Ajay Matta, Xiaomei Wang. K. Arne Mehrkens The biological basis of degenerative disc disease: proteomic and biomechanical analysis of the canine intervertebral disc Arthritis Research & Therapy201517:240

  12. Rade, Marinko; Pesonen, Janne; Könönen, Mervi; Marttila, Jarkko; Shacklock, Michael; Vanninen, Ritva; Kankaanpää, Markku; Airaksinen, OlaviReduced Spinal Cord Movement With the Straight Leg Raise Test in Patients With Lumbar Intervertebral Disc Herniation Spine, Volume 42, Number 15, 1 August 2017, pp. 1117-1124(8)

  13. Dr. Shawn Thistle - RRS Education - Chiropractic Care for Disc Patients April 28th 2019

  14. Marinella Gugliotta, Bruno R da Costa, Essam Dabis, Robert Theiler, Peter Jüni, Stephan Reichenbach, Hans Landolt and Paul Hasler BMJ Open. 2016; 6(12): e012938. Surgical versus conservative treatment for lumbar disc herniation: a prospective cohort study



Dr. Abelson believes in running an Evidence Based Practice (EBP). EBP's strive to adhere to the best research evidence available, while combining their clinical expertise with the specific values of each patient.

Dr. Abelson is the developer of Motion Specific Release (MSR) Treatment Systems. His clinical practice in is located in Calgary, Alberta (Kinetic Health). He has recently authored his 10th publications which will be available later this year.


Make Your Appointment Today!

Make an appointment with our incredible team at Kinetic Health in NW Calgary, Alberta. Call Kinetic Health at 403-241-3772 to make an appointment today, or just click the MSR logo to right. We look forward to seeing you!


#Sciatica #WhatisSciatica #WhatCausesSciatica #DiscHerniation #discprotrusion #discprolapse #sequesteredisc #BrianAbelson #KineticHealth #MotionSpeciifcRelease #MSR #calgarychiropractor #chiropractic #nwcalgary #backpain

1,861 views0 comments

Recent Posts

See All