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Basics ⬇

Author: JinChoi, DO

Description

  • Any disease process that alters the normal anatomy of the discs between the vertebral bodies, causing various musculoskeletal and/or neurologic symptoms (low back pain, radiculopathy, urinary/bowel incontinence, etc.)
  • It represents a broad spectrum of pathology, including disc herniations, disc space narrowing, disc desiccation, discogenic pain, and sclerosis of the end plates as well as many other lumbar spine abnormalities with various etiologies.
  • Most commonly, the term refers to lumbar disc herniation, and this topic most specifically addresses lumbar disc herniation.
  • Lumbar disc herniations are the most common cause of sciatica although not the only cause (1).
  • Per North American Spine Society, disc herniation is defined as a localized displacement of disc material beyond the normal margins of the intervertebral disc space resulting in pain, weakness or numbness in myotomal, or dermatomal distribution (2).

Epidemiology

Incidence

  • Approximately 3:1 male to female ratio
  • Peak incidence is between the 4th and 6th decades of life (ages 30s to 50s).

Etiology and Pathophysiology

  • Compromise in the integrity of the annulus fibrosus may allow herniation of the nucleus pulposus (3,4).
  • Herniation of the nucleus pulposus of the disc may compress and irritate the adjacent nerve root.
  • The disc herniates when the pressure within the nucleus pulposus increases from a torsional strain or compression, and it pushes against the outside ring of the annulus fibrosis and overcomes its tensile strength (3,4).
  • Most common location of herniation is paracentral (posterior longitudinal ligament is the weakest at this location), followed by foraminal (lateral), and then central.
  • Different stages of herniation include protrusion, extrusion, and sequestration.
  • Due to vertical anatomy of lumbar nerve roots, paracentral and foraminal disc herniation will affect different nerve roots.
  • Most common site of herniation is L5–S1, affecting the S1 nerve root with a paracentral herniation and the L5 nerve root with a foraminal herniation (4).
  • Second most common site of herniation is L4–L5, affecting the L5 nerve root with a paracentral herniation and the L4 nerve root with a foraminal herniation (4).
  • Central herniation may present with back pain only, but the clinician should take caution for other possible red flags, such as cauda equina syndrome (see below).

Risk-Factors

  • Lifestyle risks, such as sedentary occupations, physical inactivity, and smoking
  • Family history of acquired spinal disorders, such as ankylosing spondylitis and degenerative arthritis
  • Prior low back injuries or surgeries
  • Increased height and weight

Diagnosis ⬆ ⬇

History

  • Often presents with history of multiple episodes of back pain that vary in severity and duration:
    • This accumulated recurrent back pain can lead to disc herniation.
    • May present following an acute lifting or twisting injury
    • Often worsened by coughing, sneezing, and Valsalva maneuver
  • May present with sciatic pain, which is pain originating in the low back and radiating to the buttock and down the posterior or lateral thigh to the ankle or foot:
    • Patients may have a difficult time finding a position of comfort.
  • Sciatica has a high sensitivity for lumbar disc herniation but low specificity (1):
    • More specific for disc herniation if the pain is greater in the leg than in the back or if the pain is worse with Valsalva maneuver
  • Can present with back pain that does not radiate, but patient may note motor or sensory deficits
  • Red flag symptoms that may indicate an alternative diagnosis, including cauda equina syndrome, infection, or neoplasm:
    • Fecal incontinence
    • Loss of motor function
    • Perianal numbness
    • Radicular symptoms lasting >6 wk
    • Saddle anesthesia
    • Urinary retention or incontinence
    • Unexplained fever
    • Unintentional weight loss
    • No improvement with >6 wk of conservative management

Physical Exam

  • A full physical exam of the back, pelvis, and lower extremities should be done, including a detailed neurologic exam:
    • Visual exam of the lower back and lower extremities and gait exam
    • Palpation of lower back, sacrum, and hips
    • Range of motion of lower back and lower extremities
    • Lower extremity strength, sensation, and reflex
  • Provocative tests should include a straight-leg raise (SLR) test, the most sensitive test for lumbar disc herniation (1):
    • SLR: can be done seated or supine, although for lumbar disc herniation supine test has higher sensitivity (1)
    • Crossed SLR: highly specific for lumbar nerve root entrapment, including that caused by lumbar disc herniation (1)
    • Lasègue sign, which is SLR aggravated by forced ankle dorsiflexion, is also helpful to increase sensitivity and specificity.
  • Other less commonly used provocative tests:
    • Bowstring sign: SLR aggravated by compression on popliteal fossa
    • Kernig test: pain reproduced with neck flexion, hip flexion, and leg extension
    • Naffziger test: pain reproduced by coughing, which is instigated by lying patient supine and applying pressure on the neck veins
    • Milgram test: pain reproduced with straight-leg elevation for 30 sec in the supine position
  • Other findings may include:
    • Decreased or loss of sensation:
      • Medial lower leg and foot, including plantar aspect of 1st toe (L3–L4 involvement)
      • Anterior lower leg, dorsum of the foot, and 1st dorsal web space (L4–L5 involvement)
      • Lateral foot and posterior heel (S1–S2 involvement)
    • Tendon reflex changes:
      • Diminished or lost patellar tendon reflex (L4 involvement)
      • Diminished or lost Achilles tendon reflex (S1 involvement)
      • No L1, L2, L3, or L5 tendon reflexes
    • Motor finding (often late findings):
      • Weak knee extension or hip flexion (L3–L4 involvement)
      • Weak ankle dorsiflexion (L4 involvement)
      • Weak 1st toe extension (extensor hallucis longus [EHL]) or hip abduction (L5 involvement)
      • Weak ankle plantarflexion (S1 involvement)
  • Waddell signs: to assess for possible nonorganic cause of back pain (psychological, socioeconomic, secondary gain, etc.):
    • Tenderness:
      • Superficial tenderness with light palpation or tenderness on deep palpation but nonanatomic over a large area
    • Simulated tests:
      • Axial loading causes low back pain, or rotation of the hips and shoulders together causes low back pain.
    • Distraction:
      • Formal straight-leg raise is positive but when distracted, straight-leg raise does not produce pain.
    • Regional sensory or motor changes:
      • Glove and stocking sensation loss or non-anatomic muscular weakness (various muscles innervated by different nerve roots)
    • Overreaction:
      • Exaggerated response or emotions

Differential Diagnosis

Diagnostic Tests & Interpretation

  • Magnetic resonance imaging (MRI) is the preferred imaging modality; however, in the absence of red flag symptoms, MRI should be delayed for a 6-wk trial of conservative treatment. If symptoms persist beyond 6 wk, MRI may then be considered (1)[A]:
    • Important to note that imaging evidence of degenerative disc disease in asymptomatic individuals is very common and its prevalence increases with age (5).
  • Emergent imaging may be considered for red flag symptoms such as urinary retention, fecal incontinence, saddle anesthesia, progressive neurologic changes, and intractable pain.
  • Plain radiographs may be beneficial to rule out osseous abnormalities (such as metastatic disease or fractures); in addition, they may demonstrate age-related degenerative changes.
  • Computed tomography (CT) is also useful in evaluating osseous abnormalities and for those whom an MRI is contraindicated.
  • CT-myelogram can be useful for patient with contraindications for MRI or with history of prior back surgeries (instrumentation can cause artifacts on MRI) (5).

Treatment ⬆ ⬇

General Measures

  • Clinicians should advise patients that most acute low back pain with or without sciatic symptoms resolves within the 1st month, and it generally has a very favorable prognosis.
  • Given that most patients with acute or subacute low back pain improve over time regardless of treatment, clinicians and patients should select nonpharmacologic treatment with superficial heat (moderate-quality evidence), massage, acupuncture, or spinal manipulation (low-quality evidence) (grade: strong recommendation per American College of Physicians [ACP] grading system) (6).
  • If pharmacologic treatment is desired, clinicians and patients should select nonsteroidal anti-inflammatory drugs (NSAIDs) or skeletal muscle relaxants (moderate-quality evidence) (grade: strong recommendation per ACP grading system) (6).

Medication

First Line

  • NSAIDs, acetaminophen, and muscle relaxants may be effective for nonspecific low back pain, but studies for lumbar disc herniation are limited (1)[B].
  • In the treatment of pain associated with lumbar disc herniation, systemic steroids are no better than placebo (1)[A].
  • Opioid medications and opioid agonists, such as tramadol, are often included as a standard component in the conservative treatment of patients with severe pain, although their use has not been extensively studied.

Second Line

Epidural steroid injections can improve pain in the short term (2 to 4 wk) but do not provide long-term relief (1,2)[A].

Surgery/Other Procedures

  • Common surgical techniques include:
    • Open discectomy.
    • Microdiscectomy.
  • Immediate indications for surgery include:
    • Cauda equina syndrome.
    • Acute myelopathy.
    • Severe motor deficits.
    • Intractable pain.
  • In addition, surgery may be considered with the failure of conservative therapy to provide relief within 6 to 12 wk (1)[A].
  • Discectomy is suggested to provide more effective symptom relief than medical/interventional care for patients with lumbar disc herniation with radiculopathy whose symptoms warrant surgical intervention. In patients with less severe symptoms, surgery or medical/interventional care appear to be effective for both short- and long-term relief (2)[B].
  • In comparison to conservative management, surgical discectomy has been shown to provide quicker and better relief of pain associated with lumbar disc herniation in the first 4 yr:
    • The performance of surgical decompression is suggested to provide better medium-term (1 to 4 yr) symptom relief as compared with medical/interventional management of patients with radiculopathy from lumbar disc herniation whose symptoms are severe enough to warrant surgery, but there is inconsistent evidence for long-term (>4 yr) symptom relief (2)[B].

COMPLEMENTARY & ALTERNATIVE MEDICINE

  • Physical therapy is often incorporated as a component of conservative therapy; however, there is insufficient data to make recommendation for or against the use of physical therapy or structured exercise regimen as stand-alone treatment for lumbar disc disease (2)[C].
  • Modalities such as ultrasound and transcutaneous electrical nerve stimulation (TENS) do not have enough quality evidence to clearly assess their effectiveness (2)[C], although they may provide some short-term benefit.
  • Traction produces conflicting evidence, and systemic reviews indicate that the results are inconsistent (2)[C].
  • Aerobic conditioning and trunk muscle strengthening are important for good outcomes and preventing future injuries.

Additional Reading ⬆ ⬇

  • Brinjikji W, Luetmer PH, Comstock B, et al. Systematic literature review of imaging features of spinal degeneration in asymptomatic populations. AJNR Am J Neuroradiol. 2015;36(4):811–816.
  • Greer S, Chambliss L, Mackler L, et al. Clinical inquiries. What physical exam techniques are useful to detect malingering?J Fam Pract. 2005;54(8):719–722.
  • Jarvik JG, Deyo RA. Diagnostic evaluation of low back pain with emphasis on imaging. Ann Intern Med. 2002;137(7):586–597.
  • Kerr RS, Cadoux-Hudson TA, Adams CB. The value of accurate clinical assessment in the surgical management of the lumbar disc protrusion. J Neurol Neurosurg Psychiatry. 1988;51(2):169–173.
  • Peul WC, van Houwelingen HC, van den Hout WB, et al. Surgery versus prolonged conservative treatment for sciatica. N Engl J Med. 2007;356(22):2245–2256.
  • Weinstein JN, Lurie JD, Tosteson TD, et al. Surgical vs nonoperative treatment for lumbar disk herniation: the Spine Patient Outcomes Research Trial (SPORT) observational cohort. JAMA. 2006;296(20):2451–2459.

References ⬆ ⬇

  1. Gregory DS, Seto CK, Wortley GC, et al. Acute lumbar disk pain: navigating evaluation and treatment choices. Am Fam Physician. 2008;78(7):835–842.
  2. Kreiner DS, Hwang SW, Easa JE, et al. An evidence-based clinical guideline for the diagnosis and treatment of lumbar disc herniation with radiculopathy. Spine J. 2014;14(1):180–191.
  3. Amin RM, Andrade NS, Neuman BJ, et al. Lumbar disc herniation. Curr Rev Musculoskelet Med. 2017;10(4):507–516.
  4. Humphreys SC, Eck JC. Clinical evaluation and treatment options for herniated lumbar disc. Am Fam Physician. 1999;59(3):575–582, 587–588.
  5. Hoeffner EG, Mukherji SK, Srinivasan A, et al. Neuroradiology back to the future: spine imaging. AJNR Am J Neuroradiol. 2012;33(6):999–1006.
  6. Qaseem A, Wilt TJ, McLean RM, et al. Noninvasive treatments for acute, subacute, and chronic low back pain: a clinical practice guideline from the American College of Physicians. Ann Intern Med. 2017;166(7):514–530.

Clinical Pearls ⬆

  • Obtaining detailed and careful history and physical exam is the key for making proper diagnosis and treatment plan for any lumbar disc disease etiology.
  • Although the specificity is low, the straight-leg raise test in supine position is the most sensitive physical exam test for lumbar disc herniation.
  • In the absence of red flag symptoms, conservative management may be attempted for 6 wk prior to obtaining diagnostic imaging such as MRI.
  • Conservative management may include NSAIDs, acetaminophen, muscle relaxants, and opioid analgesics for severe pain:
    • Oral steroids have not been shown to be beneficial compared to placebo.
  • There is insufficient data to make recommendation for or against the use of physical therapy or structured exercise regimen for symptoms associated with lumbar disc herniation.
  • Epidural steroids may provide short-term relief but have not been shown to provide long-term relief.
  • Although surgery offers better improvement of pain in the first 4 yr compared to conservative management, there is no difference in outcome beyond 4 yr.