Cauda Equina Syndrome Diagnosis and Imaging

Introduction to Cauda Equina Syndrome

The British journal of neurosurgery recommends that CES is fundamentally a clinical diagnosis based on symptoms and signs such as urinary retention, saddle anesthesia, bilateral radiculopathy, and bowel/sexual dysfunction—not an imaging diagnosis 1, 2, 3
The American College of Radiology suggests that MRI's role is to identify which patients with "red flag" clinical features have significant compression of the cauda equina nerve roots that requires urgent surgical decompression 1, 2, 3
No patient with potentially relevant symptoms can be definitively ruled out for CES without MRI to exclude significant compression of the cauda equina nerve roots, as stated by the British journal of neurosurgery 1, 2, 3

The American College of Radiology recommends that MRI lumbar spine without IV contrast is the imaging study of choice because it accurately depicts soft-tissue pathology, assesses vertebral marrow, and evaluates spinal canal patency with 96% sensitivity and 94% specificity for spine pathology 4, 5
MRI visualizes the anatomical compression of cauda equina nerve roots from disc herniation (most common at L4-L5 and L5-S1), neoplasm, infection, spinal stenosis, or hemorrhage, according to the Journal of the American College of Radiology 7, 6
The American College of Radiology suggests that MRI without and with IV contrast may be helpful when underlying malignancy, infection, or inflammation is clinically suspected as the etiology 4, 5

The American College of Radiology recommends that CT lumbar spine without IV contrast can answer whether cauda equina compression is present, though it is inferior to MRI for soft-tissue characterization 4, 5
CT with ≥50% thecal sac effacement predicts significant spinal stenosis with 98% sensitivity and 99% negative predictive value, while <50% thecal sac effacement reliably excludes cauda equina impingement, as stated by the Journal of the American College of Radiology 4, 5

The British journal of neurosurgery recommends that emergency MRI must be available for all patients with "red flag" symptoms—urinary retention, new-onset urinary symptoms with low back pain/sciatica, saddle anesthesia, bilateral radiculopathy, or progressive neurologic deficits 1, 2, 4, 5
The American College of Radiology suggests that urgent MRI assessment is recommended for all patients presenting with new-onset urinary symptoms in the context of low back pain or sciatica 4, 5, 6