Can constipation be a symptom of spinal stenosis?

Identifying Constipation Related to Spinal Stenosis

Constipation can indeed be a symptom of spinal stenosis, particularly when the stenosis affects the lower spine and impacts neurological function controlling bowel movements.

Distinguishing Features of Spinal Stenosis-Related Constipation

Neurological Symptoms

• Constipation accompanied by other neurological symptoms strongly suggests spinal stenosis as the cause 1, 2:
  • Lower extremity pain, numbness, or weakness
  • Back pain that worsens with extension and improves with flexion
  • Neurogenic claudication (leg pain with walking that improves with rest)
  • Saddle anesthesia (numbness in the perineal/genital region) 3
  • Urinary hesitancy or retention occurring alongside constipation

Bowel Dysfunction Patterns

• Specific characteristics of constipation related to spinal stenosis:
  • Often accompanied by reduced rectal sensation 4
  • May present with incomplete evacuation feeling
  • Typically worse in patients with higher-level spinal lesions (tetraplegics have higher prevalence than paraplegics) 4
  • May require manual evacuation methods 4
  • Often resistant to standard laxative treatments

Physical Examination Findings

• Key findings that suggest spinal stenosis as the cause of constipation:
  • Abnormal anal sphincter tone on digital rectal examination 1
  • Decreased perineal sensation 1
  • Positive straight leg raise test
  • Neurological deficits in lower extremities
  • Pain with lumbar extension that improves with flexion 2

Diagnostic Approach

Initial Assessment

• Perform a thorough history focusing on:
  • Timing of constipation relative to back pain onset
  • Pattern of bowel movements and consistency 1
  • Need for digital manipulation to assist evacuation 1
  • Presence of fecal incontinence 1
  • Other neurological symptoms

Physical Examination

• Digital rectal examination to assess:
  • Anal sphincter tone (may be lax with colonic hypotonia) 1
  • Rectal sensation (may be diminished) 1
  • Presence of impacted stool 1
  • Ability to contract and relax pelvic floor muscles

Imaging Studies

• MRI of the lumbar spine without IV contrast is the preferred imaging study 1:
  • Evaluates for cauda equina compression
  • Assesses severity of spinal canal narrowing
  • Rules out other causes of symptoms

Management Considerations

When to Suspect Cauda Equina Syndrome

• Constipation with any of these red flags requires urgent MRI 1:
  • New urinary retention or incontinence
  • Saddle anesthesia
  • Bilateral leg weakness
  • Fecal incontinence

Treatment Approach

• For constipation related to spinal stenosis:
  1. First-line treatment: Polyethylene glycol (PEG) 17g daily 5
  2. Consider adding stimulant laxatives like bisacodyl if PEG alone is insufficient 1, 5
  3. Avoid bulk-forming laxatives (psyllium) as they may be ineffective in neurogenic constipation 5
  4. Consider biofeedback therapy for defecatory disorders 1

Surgical Consideration

• Surgical decompression should be considered when:
  • Conservative management fails
  • Progressive neurological deficits occur
  • Bowel/bladder dysfunction is severe 2

Clinical Pearls and Pitfalls

Pearls

• Constipation that develops concurrently with back and leg pain should raise suspicion for spinal stenosis
• Improvement in bowel function has been reported after surgical decompression in appropriate cases 3
• A case report showed cisapride improved small intestinal motility and relieved constipation in a patient with cervical spinal stenosis 6

Pitfalls

• Don't attribute constipation solely to medication effects without considering structural causes
• Avoid missing cauda equina syndrome, which requires urgent surgical intervention
• Don't assume all constipation in patients with back pain is related to spinal stenosis; rule out other common causes 1

Remember that timely diagnosis and appropriate management of spinal stenosis not only addresses constipation but can prevent long-term sequelae of pain, numbness, weakness, and bowel or bladder dysfunction 1.