Written by Alex Chen
Cauda equina is a disabling, potentially reversible, time-sensitive diagnosis. Here are pearls to keep you from missing it.
Why does this matter?
Cauda equina is a devastating disease that causes significant patient morbidity. It also requires significant resources to diagnose. This article is here to tell you that your history and physical exam findings may not be enough to rule this out, and you should be moving towards MRI when you are concerned.
Protect the horse tail
History and physical exam in isolation had poor sensitivity for the identification of cauda equina syndrome (CES).
Risk factors include: obesity, female gender, pre-existing spinal disease (e.g. spinal stenosis, thickened ligamentum flavum).
One study found that 89% of patients with CES had acute worsening within the past 24h; however, it may present gradually over weeks as well.
CES is most commonly caused by a large central disk herniation/prolapse at L4-5 or L5-S1.
Exam findings consistent with CES included: bilateral sciatica, reduced perineal sensation, urinary retention, loss of anal tone, loss of sexual function, motor/sensory changes in lower extremities, and diminished patellar and Achilles reflexes.
Post-void residual > 500ml had OR of 4.0, which increased to 48.0 when combined with two of the three following symptoms: bilateral sciatica, subjective urinary retention, or rectal incontinence.
The gold standard for diagnosis is MRI. CT myelography may be used when MRI is contraindicated.
Management requires emergent neurosurgical evaluation.
High-risk features include bladder dysfunction and rapid onset.
Evaluation and management of cauda equina syndrome in the emergency department. Am J Emerg Med. 2019 Aug 20:158402. doi: 10.1016/j.ajem.2019.158402. [Epub ahead of print]
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