Disk herniations account for 5-10% of diagnoses that people receive who are experiencing mechanical low back pain – that is, low back pain due to issues in the spine, disks, or soft tissue (i.e. muscles, tendons, nerves, ligaments, etc.) around the spine.1 But what exactly is a herniated disk?
A lumbar disk is located between each vertebra (bone of the spine). Its main job is to separate the vertebrae and help distribute any loads applied to the spine. The central part of the disk is called the nucleus pulposus, and 70-90% of it is composed of water. The nucleus pulposus is surrounded by the annulus fibrosus, which is made up of collagen and has a lower concentration of water than the nucleus pulposus. With normal aging or degenerative processes as well as poor biomechanics, we can develop fissures radiating from the nucleus pulposus. The amount of water in your body also decreases with age, which means that the amount of water in the lumbar disks decreases.2
A disk herniation occurs when parts of the annulus fibrosus tear, which allows the nucleus pulposus to move (often posteriorly or posterolaterally). This can cause a “bulge” of the annulus fibrosus or even an extrusion of the nucleus pulposus, which results in a true disk herniation. Disk herniations can happen due to degenerative processes or traumatically.2 The most common sites of disk herniations are L5-S1 and L4-L5, which means that they occur in the disks between the fifth lumbar vertebra and first sacral vertebra, and the fourth lumbar vertebra and fifth lumbar vertebra, respectively.
It is important to note that herniated disks do not always cause symptoms of pain. In fact, many studies have been conducted on the use of MRIs on people without any back pain. One study found that in 98 people without low back pain, only 36% of the people had normal disks.3 However, if you do have pain due to a herniated disk, the severity of the disk herniation can affect the symptoms that you feel. Common symptoms of disk herniations include low back pain, muscle weakness, changes in sensation, and changes in your reflexes.
Sciatica, or lumbar radicular pain, refers to symptoms of radiating pain in one leg, at times accompanied by changes in sensation, reflexes, and motor strength. Most people feel pain in the back of their leg and below their knee.4 Some, but not all, people feel back pain as well.
The nerve roots from the fourth and fifth lumbar vertebrae as well as the first two sacral vertebrae join together to form the sciatic nerve, which is the largest nerve in the body. The sciatic nerve travels down each leg and branches into smaller and smaller nerves. 85% of sciatica cases are due to nerve issues (commonly L4-L5 and L5-S1). However, sciatica may be due to issues outside of the spine, such as pelvic and gynecologic conditions, piriformis syndrome, pregnancy and delivery, and shingles.5
Sciatica has a lifetime incidence rate of 13-40%.6 Most people experience a reduction in symptoms within eight weeks after their pain started,7 but more than 50% of people report relapses of their sciatica over time.6 Sciatica is usually treated conservatively (with physical therapy), as “the international consensus has been that surgery should be offered only if symptoms persist after a period of conservative treatment.”7
How Are They Treated Conservatively?
Conservative treatment can effectively help reduce the size of a disk herniation and even completely resolve your symptoms. The recommended treatment course for low back pain with sciatica is conservative treatment, and two typical treatment methods are physical therapy and epidural steroid injections.
Physical therapy commonly includes manual therapy, education on proper posture and ergonomics, exercise therapy targeting the spinal stabilizing muscles, and exercises to move your back in certain directions to reduce your pain.
One type of epidural steroid injection is a therapeutic selective nerve root block (SNRB), which involves injecting a corticosteroid and an anesthetic into the low back to help manage pain. Oftentimes, patients who receive an SNRB are referred for PT directly afterward to capitalize on their decreased pain levels while rehabilitating their low back.6
What Types of Surgeries Are Offered?
The most common type of surgery to address a disk herniation and/or sciatica is a microdiscectomy, which involves a surgeon using a microscope to view the herniated disk and nerves and remove the herniated disk material. At times, the surgeon will also perform a laminectomy, which involves removing a small piece of the vertebra to see the herniated disk more easily.8
A large recent study published in the New England Journal of Medicine compared patients who received early surgery (within two weeks of joining the study) versus conservative therapy for their disk herniation. The study found that although the patients who received early surgery experienced faster relief of symptoms, there was no difference in recovery rates after one year, including leg pain.7
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- Will JS, Bury DC, Miller JA. Mechanical Low Back Pain. American Family Physician. 2018;98(7):421-428.
- Beattie P. The Relationship Between Symptoms and Abnormal Magnetic Resonance Images of Lumbar Intervertebral Disks. Physical Therapy. 1996;76(6):601-608. doi:10.1093/ptj/76.6.601.
- Jensen MC, Brant-Zawadzki MN, Obuchowski N, Modic MT, Malkasian D, Ross JS. Magnetic Resonance Imaging of the Lumbar Spine in People Without Back Pain. New England Journal of Medicine. 1994;331(2):69-73. doi:10.1056/NEJM199407143310201.
- Jensen RK, Kongsted A, Kjaer P, Koes B. Diagnosis and treatment of sciatica. Bmj. November 2019:l6273. doi:10.1136/bmj.l6273.
- Ropper AH, Zafonte RD. Sciatica. The New England Journal of Medicine. 2015;372(13):1240-1248. doi:10.1056/NEJMra1410151.
- Thackeray A, Fritz JM, Brennan GP, Zaman FM, Willick SE. A Pilot Study Examining the Effectiveness of Physical Therapy as an Adjunct to Selective Nerve Root Block in the Treatment of Lumbar Radicular Pain From Disk Herniation: A Randomized Controlled Trial. Physical Therapy. 2010;90(12):1717-1729. doi:10.2522/ptj.20090260.
- Peul WC, Houwelingen HCV, Hout WBVD, et al. Surgery versus Prolonged Conservative Treatment for Sciatica. New England Journal of Medicine. 2007;356(22):2245-2256. doi:10.1056/nejmoa064039.
- University of Wisconsin Hospitals and Clinics Authority. Health Information. UW Health. https://www.uwhealth.org/health/topic/surgicaldetail/discectomy-or-microdiscectomy-for-a-lumbar-herniated-disc/hw218424.html. Published June 26, 2019. Accessed May 28, 2020.