Back Pain and Related Symptoms (e.g., Sciatica)

Introduction

Back pain is one of the most common reasons for primary care visits in Canada. For the MCCQE1, the focus is rarely on diagnosing the exact anatomical lesion in mechanical back pain, but rather on differentiating mechanical pain from serious pathology (Red Flags) and identifying psychosocial barriers to recovery (Yellow Flags).

Understanding the CanMEDS roles is crucial here:

• Medical Expert: Differentiating cauda equina syndrome from benign lumbago.
• Communicator: Explaining that “hurt does not equal harm” and encouraging activity.
• Resource Steward: Adhering to Choosing Wisely Canada guidelines regarding imaging.

Epidemiology in Canada

• Prevalence: Approximately 80% of Canadians will experience at least one episode of low back pain (LBP) in their lifetime.
• Prognosis: Most cases (85-90%) of acute mechanical LBP resolve within 4-6 weeks regardless of treatment.
• Chronicity: A small percentage of patients develop chronic pain, which accounts for the majority of healthcare costs and disability associated with back pain.

Etiology and Classification

For MCCQE1 preparation, classify back pain into three main categories.

Clinical Evaluation

History: The Search for Flags

The history is the most important tool. You must actively rule out Red Flags (serious pathology) and assess Yellow Flags (psychosocial barriers).

Red Flags (TUNA FISH Mnemonic)

Yellow Flags (Psychosocial)

• Belief that pain is harmful or disabling.
• “Fear-avoidance” behavior (avoiding movement).
• Low mood or social withdrawal.
• Expectation that passive treatments (massage, drugs) will fit it rather than active participation.

Physical Examination

Perform a focused neurological exam to localize lesions.

Investigations

Choosing Wisely Canada Guidelines

A key component of the MCCQE1 is Resource Stewardship.

“Don’t imagine the lower spine for low back pain within the first six weeks unless red flags are present.”

1. Plain X-rays:

   • Generally NOT indicated for routine acute LBP.
   • Indications: History of significant trauma, suspicion of compression fracture (osteoporosis, steroid use), age >70.

2. MRI (Magnetic Resonance Imaging):

   • Indications: Cauda equina syndrome (Emergency), suspicion of malignancy or infection, progressive neurological deficits.
   • Note: MRI is generally not indicated for simple disc herniation unless symptoms persist >6 weeks despite conservative therapy and surgery is being considered.

3. Laboratory Studies:

   • CBC, ESR/CRP only if infection or malignancy is suspected.

Management

Acute Low Back Pain (<4 weeks)

The goal is symptom relief and return to function.

1. Education & Reassurance:
   • Reassure that prognosis is good.
   • Activity: Advise to stay active and continue daily activities as tolerated. Bed rest is contraindicated (worsens outcomes).
2. Pharmacotherapy:
   • First-line: NSAIDs (Naproxen, Ibuprofen) if no contraindications.
   • Note on Acetaminophen: Recent guidelines suggest it is less effective for LBP, but it remains an option if NSAIDs are contraindicated.
   • Muscle Relaxants: (e.g., Cyclobenzaprine) Short-term use only (<1 week) for muscle spasm. Caution regarding sedation.
   • Opioids: Generally avoided. Only for severe pain, short duration (<3 days).

Subacute/Chronic Low Back Pain (>12 weeks)

1. Non-Pharmacologic (Mainstay):
   • Physiotherapy (exercise therapy is superior to passive modalities).
   • Cognitive Behavioral Therapy (CBT) for chronic pain.
   • Spinal manipulation (Chiropractic/Osteopathic) - evidence exists for short-term benefit.
2. Pharmacologic:
   • NSAIDs.
   • Tricyclic Antidepressants (TCAs) or SNRI (Duloxetine) for neuropathic component.

Management of Sciatica (Radiculopathy)

• Most cases resolve spontaneously.
• Management is similar to acute LBP (NSAIDs, activity).
• Systemic Steroids: Not recommended.
• Epidural Steroid Injections: May provide short-term relief but do not alter long-term prognosis.
• Surgery: Considered if severe unremitting pain >6-12 weeks or progressive neurological deficit.

Key Points to Remember for MCCQE1

• Do not image acute back pain without red flags.
• Cauda Equina Syndrome requires immediate MRI and surgical decompression.
• Ankylosing Spondylitis: Consider in young males (<40) with morning stiffness that improves with exercise. Look for sacroiliitis on X-ray.
• Spinal Stenosis: “Pseudoclaudication” - leg pain worsens with walking/extension, improves with sitting/flexion (shopping cart sign).
• Bed rest is incorrect management; encourage activity.

Canadian Guidelines

• TOP (Toward Optimized Practice) Alberta Guidelines: Widely cited in Canadian medical education for LBP management. Emphasizes the “Yellow Flags” and returning to work.
• Choosing Wisely Canada: Specifically targets the reduction of unnecessary lumbar spine imaging (X-rays, CT, MRI) in primary care.

Sample Question

Case Presentation

A 48-year-old male presents to the emergency department with a 2-day history of severe lower back pain after lifting a heavy box in his garage. He reports the pain radiates down his right leg to his foot. On review of systems, he mentions he has been unable to void urine for the past 12 hours despite feeling the urge. He has no history of cancer or fever. Vital signs are stable. Physical examination reveals decreased sensation in the perianal region and weakness in right ankle plantar flexion.

Question

Which one of the following is the most appropriate next step in the management of this patient?

• A. Prescribe NSAIDs and advise bed rest for 2 days
• B. Order a lumbosacral spine X-ray
• C. Refer for urgent physiotherapy
• D. Obtain an emergent MRI of the lumbosacral spine
• E. Perform a post-void residual bladder scan and discharge with catheter

Explanation

The correct answer is:

• D. Obtain an emergent MRI of the lumbosacral spine

Explanation: This patient presents with classic signs of Cauda Equina Syndrome (CES), a neurosurgical emergency. The key features in the stem are:

1. Urinary retention: This is the most sensitive symptom for CES (90% sensitivity).
2. Saddle anesthesia: Decreased sensation in the perianal region.
3. Motor weakness: Weakness in ankle plantar flexion (S1 nerve root).

Why D is correct: The definitive investigation to confirm compression of the cauda equina is an emergent MRI. If confirmed, immediate surgical decompression is required to prevent permanent bladder/bowel dysfunction and paralysis.

Why other options are incorrect:

• A: Bed rest is contraindicated in back pain generally, but more importantly, this ignores the red flags of CES.
• B: X-rays show bone but cannot visualize the neural compression causing CES.
• C: Physiotherapy is inappropriate for an acute surgical emergency.
• E: While a bladder scan might confirm retention, discharging a patient with suspected CES without ruling out the compression is negligence.

References

1. Toward Optimized Practice (TOP). (2015). Guideline for the Evidence-Informed Primary Care Management of Low Back Pain. Alberta Medical Association.
2. Choosing Wisely Canada. (2023). Family Medicine: Imaging for lower back pain.
3. Medical Council of Canada. (2023). MCCQE Part I Clinical Decision-Making and Multiple-Choice Question Guidelines.
4. RxTx (e-Therapeutics). (2024). Low Back Pain. Canadian Pharmacists Association.
5. Toronto Notes. (2024). Neurosurgery & Orthopedics Sections.