What are the clinical findings of Cauda Equina syndrome and autonomic dysreflexia?

Clinical Findings of Cauda Equina Syndrome and Autonomic Dysreflexia

Cauda Equina Syndrome: Clinical Findings

The most critical clinical finding in established cauda equina syndrome is urinary retention, which has 90% sensitivity and is present in the vast majority of confirmed cases. 1, 2

Early Warning Signs ("Red Flags")

These findings indicate impending cauda equina syndrome and require immediate MRI and neurosurgical consultation:

• Bilateral radiculopathy: Bilateral radicular pain and/or bilateral sensory disturbance or motor weakness in the legs 2, 3, 4
• New changes in bladder function with preserved control: Any new difficulty with micturition, even if the patient can still void 2, 3
• Subjective or objective loss of perineal sensation: Numbness in the saddle distribution, though this is easily missed on examination due to its subjective nature 3, 4
• Progressive neurological deficits in the lower extremities: Worsening motor weakness or sensory loss 2, 3

Late Signs ("White Flags")

These findings indicate established cauda equina syndrome with likely irreversible damage:

• Urinary retention or incontinence: Especially painless retention, which is the most sensitive single finding at 90% 1, 2, 3
• Complete perineal anesthesia: Loss of sensation in the saddle/perianal region 2, 3, 4
• Fecal incontinence: Loss of bowel control 2, 3
• Patulous anus with reduced voluntary rectal tone: Though anal tone assessment has low interobserver reliability, especially among inexperienced clinicians 3
• Absent bulbocavernosus reflex: A neurological sign of sacral nerve root dysfunction 3

Additional Clinical Features

• Low back pain with sciatica: Back and leg pain in a typical lumbar nerve root distribution 1, 4
• Sexual dysfunction: Loss of sexual function or genital numbness, reported in 53% of long-term follow-up patients 5
• Motor weakness: Variable lower extremity weakness, which may be bilateral 6, 7

Critical Diagnostic Pitfall

In patients without urinary retention, the probability of cauda equina syndrome drops to approximately 1 in 10,000, making delayed diagnosis common in this population. 1 However, waiting for urinary retention before referral is a major error, as this represents a late sign associated with permanent neurological damage. 2, 3

Physical Examination Findings

The combination of normal bulbocavernosus reflex, normal voluntary rectal tone, and intact perianal sensation effectively rules out cauda equina syndrome. 3 Conversely, abnormal findings in any of these areas—loss of perineal sensation, reduced voluntary rectal tone, or absent bulbocavernosus reflex—requires immediate MRI. 3

Prevalence and Context

Cauda equina syndrome occurs in approximately 0.04% of patients presenting with low back pain and in approximately 2% of cases of herniated lumbar discs. 1, 7 It is most commonly associated with massive midline disc herniation, typically at L4-L5 and L5-S1 levels. 1, 2, 4

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Autonomic Dysreflexia: Clinical Findings

Note: The provided evidence does not contain information about autonomic dysreflexia. This is a distinct condition from cauda equina syndrome that occurs in patients with spinal cord injuries at T6 or above, not in cauda equina syndrome. The evidence focuses exclusively on cauda equina syndrome, which involves compression of nerve roots below the spinal cord terminus, not spinal cord injury itself.

Based on general medical knowledge, autonomic dysreflexia presents with:

• Severe hypertension: Often with systolic blood pressure >200 mmHg
• Pounding headache: Due to acute hypertension
• Profuse sweating above the level of injury: Particularly facial and neck sweating
• Flushing of skin above the level of injury: Red, warm skin
• Piloerection (goosebumps): Especially above the injury level
• Bradycardia or tachycardia: Paradoxical heart rate changes
• Nasal congestion
• Blurred vision
• Anxiety or sense of impending doom

This condition is triggered by noxious stimuli below the level of spinal cord injury (most commonly bladder distension or fecal impaction) and represents a medical emergency requiring immediate intervention to prevent stroke, seizures, or death.