What are the diagnostic criteria for cauda equina syndrome (CES)?

From the Guidelines

Cauda equina syndrome is diagnosed through a combination of clinical evaluation and imaging studies, with urgent magnetic resonance imaging (MRI) of the lumbar spine being the gold standard diagnostic test, as recommended by the most recent study 1. The diagnosis begins with a thorough history and physical examination, focusing on symptoms such as:

• Bilateral sciatica
• Saddle anesthesia (numbness in the groin and buttock areas)
• Bowel or bladder dysfunction (retention or incontinence)
• Lower extremity weakness The physical exam should include assessment of:
• Lower extremity strength
• Sensation (particularly in the perineal region)
• Reflexes
• Rectal tone A recent study 1 recommends urgent MRI assessment in all patients who present with new-onset urinary symptoms in the context of low back pain or sciatica. If MRI is unavailable, computed tomography (CT) myelography can be used as an alternative, as it can assess the patency of the spinal canal/thecal sac and of the subarticular recesses and neural foramen 1. Laboratory tests including complete blood count, erythrocyte sedimentation rate, and C-reactive protein may help identify infectious causes. Urinary retention with post-void residual volume greater than 100-200 mL supports the diagnosis, as it is a common finding in cauda equina syndrome, with a sensitivity of 90% 1. Cauda equina syndrome represents a medical emergency requiring prompt diagnosis and surgical intervention, typically within 48 hours of symptom onset, to prevent permanent neurological damage. The most common cause is a large central lumbar disc herniation, though tumors, infections, trauma, or spinal stenosis can also be responsible.

From the Research

Diagnosis of Cauda Equina Syndrome

To diagnose cauda equina syndrome, the following steps can be taken:

• A thorough history and physical exam is essential, as noted in 2, 3, 4
• Red flags and findings consistent with cauda equina syndrome include:
  • Bilateral neurogenic sciatica
  • Reduced perineal sensation
  • Altered bladder function leading to painless urinary retention
  • Loss of anal tone
  • Loss of sexual function, as mentioned in 2, 3, 4
• Postvoid bladder volume assessments can assist in the evaluation, as stated in 2
• Imaging studies, such as magnetic resonance imaging (MRI) or computed tomography myelography, are typically used to aid in diagnosis, as noted in 2, 3, 4, 5
• Urgent MRI assessment is recommended in all patients who present with new onset urinary symptoms in the context of lumbar back pain or sciatica, as suggested in 5

Clinical Assessment and MRI Scanning

The correlation between clinical assessment and MRI scanning in cauda equina syndrome is as follows:

• The diagnostic accuracy of urinary retention, urinary frequency, urinary incontinence, altered urinary sensation, and altered perineal sensation were found to be 0.57,0.65,0.61,0.65, and 0.60 respectively, as reported in 5
• MRI was normal in 43% of patients, and a disc prolapse causing cauda equina distortion was present in 22% of patients, as found in 5
• It is impossible to exclude the diagnosis of prolapsed intervertebral disc in a significant proportion of patients, highlighting the importance of urgent MRI assessment, as noted in 5

Treatment and Management

Treatment and management of cauda equina syndrome rely on:

• Surgical consultation and operative intervention for decompression, as stated in 2, 3, 4
• Emergent spinal surgery referral and urgent decompression, as recommended in 4
• Early intervention has been shown to portend a greater chance of neurologic recovery, as noted in 4