Spinal Stenosis

General Information

Description:

  • Narrowing of spinal canal which may be asymptomatic, or may cause back pain, buttock pain, or lower extremity pain
    • Pain syndromes usually radicular or neurogenic claudication
    • May be associated with numbness, weakness, and impaired walking
  • This topic primarily covers degenerative or acquired lumbar spinal stenosis


Also called:

  • Pseudoclaudication
  • Spinal claudication


Definitions:

  • Clinical syndrome of lumbar spinal stenosis (LSS) requires both
    • Characteristic clinical presentation of neurogenic claudication and/or radicular pain
    • Radiographic or anatomic LSS
  • Radiographic lumbar spinal stenosis defined as narrowing found on cross-sectional imaging
    • Central canal stenosis – narrowing between medial edges of 2 zygapophysial (facet) joints
    • Lateral recess or subarticular stenosis – narrowing between medial edge of zygapophysial (facet) joint and medial pedicle border
    • Neuroforaminal stenosis – narrowing of neural foramina defined by medial and lateral pedicle borders
    • Relative lumbar spinal stenosis – narrowing ≤ 12 mm diameter of spinal canal
    • Absolute lumbar spinal stenosis – narrowing ≤ 10 mm diameter of spinal canal
  • Anatomic lumbar spinal stenosis – spinal canal narrowing identified intraoperatively
  • Neurogenic claudication defined as pain that
    • Radiates beyond spine into lower extremity (1 or both legs)
    • Worsens with walking or prolonged standing
    • Is relieved with sitting or lumbar flexion
    • May involve gait changes, lower extremity weakness, sensory loss, or fatigue
  • Radicular pain defined as pain that
    • Radiates within a dermatomal distribution
    • Occurs unrelated to activity


Who is most affected:

  • Older adults – typical onset of neurogenic claudication after age 60


Incidence/Prevalence:

  • Incidence and prevalence of symptomatic lumbar spinal stenosis unknown
  • Estimated prevalence of radiographic lumbar stenosis in asymptomatic adults > 55 years old
    • 21%-30% for moderate stenosis
    • 6%-7% for severe stenosis
  • About 30% of adults may have radiographic spinal stenosis
    • Based on cross-sectional study
    • 191 adults (mean age 53 years) from Framingham Heart Study having abdominal and chest computed tomography for assessment of coronary and aortic calcification were also evaluated for radiographic spinal stenosis and prevalence of persistent low back pain (including lower extremity symptoms) lasting ≥ 1 month during previous year
    • 32% of patients had radiographic lumbar spinal stenosis regardless of symptoms
    • 19.4% reported persistent low back pain (76% of these patients reported ≥ 1 distal symptom with low back pain)
    • Among patients reporting persistent low back pain
      • 29.7% had radiographic relative lumbar spinal stenosis (≤ 12 mm diameter of spinal canal)
      • 18.9% had radiographic absolute lumbar spinal stenosis (≤ 10 mm diameter of spinal canal)
    • Reference – Spine J 2009 Jul;9(7):545


Causes and Risk Factors

Causes:

  • Lumbar spinal stenosis most often caused by age-associated spinal degeneration
  • Idiopathic congenitally shortened pedicles typically accelerate degenerative processes leading to spinal stenosis


Pathogenesis:

  • Age-related degenerative changes in spinal structures result in constriction of space in central canal or neural foramina; several processes may be involved
    • Disc and facet joint degeneration lead to loss of disc height, bulging of disk material, and infolding of ligamentum Flavum
    • Facet osteoarthritis and hypertrophy may lead to osteophyte formation and thickening of joint capsule
    • In advanced osteoarthritis, facet joint synovial cysts may protrude into spinal canal
  • Postulated mechanisms of pain and neurologic symptoms include
    • Nerve root compression leading to radicular pain, weakness, and sensory deficits
    • Neurogenic claudication extension of lumbar spine (such as with walking or standing) further reduces cross-sectional area of canal and impairs blood flow of venules resulting in venule engorgement and further compression of nerve roots; symptoms reversed when lumbar spine returns to flexion (seated, bent forward)
  • Pain syndromes anecdotally linked to specific locations of stenosis (neurogenic pain with central stenosis, radicular pain with lateral stenosis), but varied clinical presentations can be seen in patients with similar imaging findings


Likely risk factors:

  • Conditions that increase risk for spinal stenosis include
    • Degenerative spondylolisthesis or prior spondylolysis
    • Prior back surgery (for example, after laminectomy)
    • Trauma
    • Corticosteroid excess (iatrogenic or endogenous [for example, Cushing disease])
    • Paget disease of bone
    • Achondroplastic dwarfism (onset of symptoms at age 20-40 years)
    • Acromegaly


Complications and Associated Conditions

Complications:

  • Cauda Equina syndrome
  • Peripheral or focal neuropathy
  • Neurogenic bladder
  • Neuropathic arthropathy


Associated conditions:

  • Degenerative joint disease of the low back
  • Spondylolisthesis
  • Herniated disc
  • Degenerative disc disease


History and Physical

History:

Chief concern (CC):

  • Radiating buttock or lower extremity pain, burning, or discomfort
  • Often accompanied by low back pain, impairment of walking, sensory loss, paraesthesias, or muscle weakness(


History of present illness (HPI):

  • Neurogenic claudication
    • Typically, pain, or burning sensation that
      • Radiates down buttocks, thighs, lower legs, or feet
      • Worsens with lumbar extension, as in walking, or prolonged standing
      • Improves with lumbar flexion, as in sitting, or bending forward
      • May or may not originate in low back (leg pain often more bothersome)
    • More subtle presentation possible, including
      • Abnormal weakness or fatigue in lower extremities
      • Numbness in lower extremities or perineal region
  • Radicular pain
    • Unilateral or bilateral radiating pain in ≥ 1 dermatomes
    • May occur alone or concurrent with neurogenic claudication
    • Not typically provoked by lumbar extension
  • In patients with lower extremity or back pain, symptoms that may predict lumbar spinal stenosis include burning sensation around buttocks, intermittent priapism with walking, urinary disturbance, or improvement of pain when bending forward (level 2 [mid-level] evidence)
    • Based on systematic review limited by clinical heterogeneity
    • Systematic review of 4 diagnostic cohort studies evaluating accuracy of history and physical exam findings in 741 patients with pain in lower extremities and/or low back
    • Clinical heterogeneity included differences between studies in
      • Reference standards (different combinations of expert physicians, history, physical exam findings, x-rays, magnetic resonance imaging, computed tomography, or myelography used)
      • Clinical settings (2 studies in specialty care only; 2 studies with primary care patients)
    • Mean age of study patients 64-65 years in 3 studies; age of patients in 1 study not reported
    • Prevalence of clinical lumbar stenosis 44%-49%
    • Findings with positive likelihood ratio (LR) > 5 reported in 1 high quality study of 469 patients
      • Burning sensation around buttocks, intermittent priapism with walking, or both (LR 7.2)
      • Urinary disturbance (LR 6.9)
      • Improvement when bending forward (LR 6.4)
    • Findings with positive LR > 5 reported in lower quality studies
      • Bilateral buttock or leg pain (LR 6.3) in 1 study of 179 patients
      • No pain when seated (LR 7.3) in 1 study of 93 patients
    • Reference – JAMA 2010 Dec 15;304(23):2628(1)
  • 47% of older adults with pain or numbness in lower extremities may have lumbar spinal stenosis
    • Based on cohort study of 468 adults (mean age 65 years) with primary symptoms of pain or numbness in lower extremities
    • Prevalence of lumbar spinal stenosis (diagnosed by clinical exam and radiographic findings)
      • 47% overall
      • 15% in patients < 60 years old
      • 25% in patients aged 60-70 years
      • 64% in patients > 70 years old
    • Reference – Eur Spine J 2007 Nov;16(11):1951
  • Other symptoms may include
    • Changes in nighttime urination frequency
    • Bilateral plantar numbness
    • Abnormal gait or poor balance

Past medical history (PMH):

  • Ask about prior back surgery
  • Check for history of relevant degenerative or congenital conditions, including
    • Osteoarthritis
    • Degenerative disc disease
    • Spondylolisthesis
    • Excess of corticosteroids (endogenous as in Cushing syndrome or iatrogenic)
    • Paget disease of bone
    • See other conditions in Rule out section


Physical
:

Back:

  • Lumbar extension may provoke symptoms of spinal stenosis

Extremities:

  • Check distal pulses to rule out peripheral arterial disease (PAD)
  • Other signs of PAD include
    • Distal hair loss
    • Trophic skin changes
    • Hypertrophic nails

Neuro:

  • In patients with lower extremity or back pain, wide-based gait may predict lumbar spinal stenosis (level 2 [mid-level] evidence)
    • Based on systematic review limited by clinical heterogeneity
    • Systematic review of 4 diagnostic cohort studies evaluating accuracy of history and physical exam items in 741 patients with pain in lower extremities and/or low back
    • Clinical heterogeneity included differences between studies in
      • Reference standards (different combinations of expert physicians, history, physical exam findings, x-rays, magnetic resonance imaging, computed tomography, or myelography used)
      • clinical settings (2 studies in specialty care only; 2 studies with primary care patients)
    • Mean age of study patients 64-65 years in 3 studies; age of patients in 1 study not reported
    • Prevalence of clinical lumbar stenosis 44%-49%
    • Neurologic exam findings associated with lumbar spinal stenosis
      • Wide-based gait (likelihood ratio [LR] 13)
      • Abnormal Romberg (positive LR 4.2)
      • Vibration deficit (LR 2.8)
      • Pinprick deficit (LR 2.5)
      • Absent Achilles reflex (LR 2.1)
      • Motor weakness (LR 2.1)

 


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