What is the recommended examination approach for a patient with a prolapsed intervertebral disc (ID)?

Examination for Prolapsed Intervertebral Disc

The examination must immediately focus on identifying red flag features—particularly cauda equina syndrome—through assessment of urinary retention, perineal sensation, anal tone, bilateral radiculopathy, and progressive motor weakness, as these findings mandate emergency MRI and potential surgical intervention within 12 hours. 1, 2

Critical Red Flag Assessment (Perform First)

Cauda Equina Syndrome Screening

• Check for urinary retention (90% sensitivity for cauda equina syndrome—this is the single most important finding) 1
• Assess perineal sensation bilaterally using light touch and pinprick in the saddle distribution 1, 2
• Perform digital rectal examination to evaluate anal sphincter tone 1
• Ask specifically about fecal incontinence and new-onset bowel dysfunction 1
• Evaluate for bilateral leg symptoms rather than unilateral radiculopathy 2

Critical Pitfall: If urinary symptoms are present, do NOT catheterize the patient before surgical assessment, as this obscures whether progression to retention CES has occurred and prevents optimal surgical timing decisions. 2

Progressive Neurologic Deficit Assessment

• Test motor strength at multiple levels to identify multifocal deficits 1
• Document any rapidly progressive weakness over hours to days 1
• Assess for weakness in lower limbs bilaterally 1

Focused Neurologic Examination for Radiculopathy

Nerve Root-Specific Testing (L4-S1)

Since >90% of symptomatic lumbar disc herniations occur at L4/L5 and L5/S1 levels, focus examination here: 1

• L4 nerve root: Test knee extension strength and patellar reflex 1
• L5 nerve root: Test great toe dorsiflexion and foot dorsiflexion strength 1
• S1 nerve root: Test foot plantarflexion and ankle (Achilles) reflex 1
• Map sensory distribution of symptoms along the affected dermatome 1

Provocative Testing

• Straight-leg-raise test: Perform with patient supine, elevate leg 30-70 degrees; positive if reproduces patient's sciatica (91% sensitivity, 26% specificity for herniated disc) 1
• Crossed straight-leg-raise test: Elevate contralateral leg; positive if reproduces ipsilateral sciatica (29% sensitivity, 88% specificity—more specific but less sensitive) 1

Additional History Elements

Cancer Risk Stratification

• History of cancer (increases probability from 0.7% to 9%) 1
• Unexplained weight loss 1
• Age >50 years 1
• Failure to improve after 1 month of conservative treatment 1

Infection Risk Factors

• Fever 1
• Intravenous drug use 1
• Recent infection 1

Compression Fracture Risk

• Older age 1
• History of osteoporosis 1
• Corticosteroid use 1

Imaging Decision Algorithm

Immediate MRI Indications (Do Not Delay)

Order urgent MRI lumbar spine without IV contrast if: 1, 2

• Urinary retention or new urinary symptoms with back pain/sciatica
• Subjective perineal sensory loss
• Bilateral radiculopathy
• Progressive or severe motor weakness
• Fecal incontinence
• Absent anal sphincter tone

Routine Imaging (NOT Indicated Initially)

Do NOT order imaging in the first 4 weeks if: 1, 2

• Uncomplicated radiculopathy without red flags
• No progressive neurologic deficits
• Patient can be managed conservatively

Rationale: Natural history favors spontaneous improvement within 4 weeks, and early imaging does not change outcomes or management. 1, 2

Documentation Priorities

Document the following to guide management decisions:

• Timing of symptom onset (acute vs. chronic) 2
• Presence or absence of back pain (minimal back pain with marked nerve root compression predicts better surgical outcomes) 2
• Correlation between clinical findings and expected anatomic level 2
• Response to initial conservative measures if already attempted 2

Key Point: Patients with marked nerve root compression, minimal back pain, short symptom duration, and clinical-radiologic correlation have superior surgical outcomes if conservative management fails after 2 months. 2