What are the clinical presentations of cauda equina syndrome?

Clinical Presentation of Cauda Equina Syndrome

Cauda equina syndrome (CES) is characterized primarily by urinary retention (90% sensitivity), along with saddle anesthesia, bilateral radiculopathy, and bowel/bladder dysfunction. 1

Core Clinical Features

Early Warning Signs ("Red Flags")

• Bilateral radiculopathy (bilateral radicular pain, sensory disturbance, or motor weakness) 1
• New changes in bladder function with preserved control (hesitancy, poor stream, urgency) 1
• Subjective or objective loss of perineal sensation 1
• Low back pain with or without radicular symptoms 1

Progressive Symptoms

• Urinary retention (most frequent and sensitive finding - 90% sensitivity) 1
• Saddle anesthesia (numbness in perineal/genital region) 1, 2
• Sensory changes or numbness in lower limbs 1
• Motor weakness in lower extremities 1
• Absent lower limb reflexes 1

Advanced Manifestations ("White Flags")

• Urinary incontinence 1
• Fecal incontinence 1
• Complete perineal anesthesia 1
• Patulous anus (decreased rectal tone) 1, 2
• Sexual dysfunction 3

Clinical Classification

CES can be categorized into progressive stages that affect prognosis 3:

1. Preclinical CES: Low back pain with only bulbocavernosus and ischiocavernosus reflex abnormalities 3
2. Early CES: Saddle sensory disturbance and bilateral sciatica 3
3. Middle CES: Saddle sensory disturbance, bowel/bladder dysfunction, motor weakness, reduced sexual function 3
4. Late CES: Absence of saddle sensation, sexual function, and uncontrolled bowel function 3

Diagnostic Considerations

Prevalence and Etiology

• CES is rare, with an estimated prevalence of 0.04% among patients with low back pain 1
• Most commonly caused by massive midline disc herniation at L4-L5 and L5-S1 levels 1, 2
• Other causes include neoplasm, infection/inflammation, spinal stenosis, and hemorrhage 1, 4

Assessment Challenges

• No single symptom or sign has high positive predictive value in isolation 1
• Sensory testing is subjective; subtle impairment of perineal sensation can be easily missed 1
• Anal tone assessment has low interobserver reliability, especially among inexperienced clinicians 1
• Atypical presentations may occur with isolated bladder/bowel dysfunction without motor weakness 5

Clinical Pitfalls to Avoid

• Delayed diagnosis: In patients without urinary retention, the probability of CES is approximately 1 in 10,000, but this should not lead to complacency 1
• Overlooking subtle symptoms: Early signs of CES may be attributed to common postoperative findings in spine surgery patients 2
• Missing atypical presentations: Some patients present with isolated bladder/bowel dysfunction without lower limb weakness, leading to delayed diagnosis 5
• Inadequate assessment: Digital rectal examination findings have low interobserver reliability and should be interpreted cautiously 1
• Late recognition: By the time "white flag" symptoms appear (complete incontinence, perineal anesthesia), permanent damage may have occurred 1

Management Implications

When CES is suspected based on clinical presentation, urgent MRI is required for definitive diagnosis 1. The treatment is urgent surgical decompression, with better outcomes achieved when intervention occurs at preclinical or early stages 2, 3, 6.