lumbar spinal stenosis

Introduction

A narrowing of the lumbar spinal canal.

Etiology

• spondylosis, or degenerative arthritis affecting the spine (most common)
• progressive disc degeneration due to aging, trauma, or other factors
• facet osteophytes, ligamentum flavum hypertrophy, & disc bulging can encroach on the central canal & neural foramina
• spondylolithesis can exacerbate spinal stenosis
• space-occupying lesions
  • lipoma, synovial cysts, neural cysts, other neoplasms
• metastatic calcification
• traumic & post-surgical, fibrosis
• skeletal disease
  • Paget's disease of bone
  • ankylosis spondylitis,
  • rheumatoid arthritis
  • diffuse idiopathic skeletal hyperostosis (DISH)
• developmental causes
  • dwarfism: achondroplasia, Morquio's syndrome
  • spinal dysraphism: spina bifida, spondylolithesis, myelomeningocele

Epidemiology

• common in the elderly (> 60 years of age)

Pathology

• mechanical compression & ischemia of nerve roots
• pathology is largely bony & unlikely to improve spontaneously
• role of inflammation is uncertain
• may coexist with spinal pathology in thoracic spine
• most commonly L3-L4, L4-L5

Clinical manifestations

• pain that radiates to the buttocks & proximal legs, or pain may begin distally (calf) & ascend
• pain is induced by walking & relieved by rest
• pain takes several minutes to resolve when induced by walking*
• thigh pain induced after 30 seconds of lumbar extension
• pain is relieved by spinal flexion
  • increases the spinal canal space
  • stooping, bending forward, sitting, lying in a flexed position, climbing a hill
  • no pain when sitting (LR=1.9-30)
  • relief of pain at night by flexion of hip & knee
• pain is aggravated by extension of the spine
  • further narrows the spinal canal space
  • standing, walking, & descending hills or walking up or down stairs
• burning sensation around the buttocks (LR=1.6-32)
• intermittent priapism associated with walking (LR=1.6-32)
• wide-based gait (LR=1.9-95)
• abnormal Romberg test (LR=1.4-13)
• neuromuscular deficits of the lower extremity
  • weakness of L4-S1 innervated muscles
    • hallux extensors, hip abductors, hip extensors
• deep tendon reflexes may be absent at the ankles, but normal at the knees
• neurologic exam may be normal if the patient is rested

* in contrast, pain due to peripheral vascular diseases resolves promptly

Diagnostic procedures

• electromyography & nerve conduction testing generally not required - absent H-reflex is a subtle manifestaiotn of S1 nerve involvement
• exercise tolerance testing (ETT) does not have a specific role, but can be useful
• ankle-brachial index (ABI) if vascular disease suspected

Radiology

• magnetic resonance imaging (MRI) of the lumbar spine
  • lumbar spinal stenosis may coexist with spinal pathology in the thoracic spine
  • include thoracic spine in MRI if clinical manifestations do not fit lumbar spinal stenosis
• lumbar spinal stenosis may be incidentally detected in patients who have imaging for another reason
• the degree of stenosis does not predict severity of symptoms
• X-rays of the knees & hips if osteoarthritis suspect

Complications

• cauda equina syndrome

• disease interaction(s) of lumbar spinal stenosis with urinary incontinence

Differential diagnosis

• peripheral vascular disease (intermittent claudication)
• osteoarthritis of the spine, hips, knees
• distal polyneuropathy generally without postural or activity effects
• inflammatory conditions involving lumbosacral nerve roots or cauda equina are generally without neurogenic claudication
• vertebral compression fracture of the lumbar spine

Management

• conservative management
  • physical therapy*
    • evidence-based support is lacking
    • as effective as surgery
    • no randomized controlled trials demonstrate effectiveness (GRS11)
  • stretching, strengthening, aerobic fitness
  • weight loss in overweight patients
  • abdominal corsets controversial
• pharmaceutical pain management:
  • NSAIDs
  • opiates
• epidural glucocorticoids &/or anesthetics of limited benefit
  • glucocorticoid-lidocaine no better than lidocaine alone
  • prednisone of no benefit (see low back pain)
• surgery (laminectomy)*
  • urgent surgery indicated for
    • rapidly progressive neurological symptoms
    • onset of bladder dysfunction
  • outcomes better than conservative management because pathology is largely bony & unlikely to change spontaneously
  • outcome predictors for surgery
    • positive: male, younger, better ability to walk, less comorbidity, more pronounced canal stenosis
    • negative: depression, cardiovascular disease, scolisis
    • outcomes for octogenarians similiar to outcomes for younger patients (mean age 64 years)
  • consider spinal cord stimulation if persistent pain after surgery
  • microdecompression is as effective as the more invasive open laminectomy
  • adding fusion surgery to decompression surgery of little to no benefit & is associated with longer hospitalization & increased costs

* laminectomy correct choice vs physical therapy per GRS8, GRS11

More general terms

• spinal stenosis

Additional terms

• 1st sacral spinal nerve (S1)
• 4th lumbar spinal nerve (L4)
• 5th lumbar spinal nerve (L5)
• neurogenic claudication; pseudoclaudication

Patient information

lumbar spinal stenosis patient information