From the Guidelines
No, an MRI without contrast is the preferred initial imaging study for suspected cauda equina syndrome, as it can accurately depict soft-tissue pathology, assess vertebral marrow, and assess the spinal canal patency. According to the American College of Radiology Appropriateness Criteria, MRI lumbar spine without IV contrast is most useful in the evaluation of suspected cauda equina syndrome, multifocal deficit, or progressive neurologic deficit 1. This is because MRI without contrast can provide sufficient information to diagnose or rule out cauda equina compression, and it is a more efficient and rapid imaging protocol.
Some key points to consider when evaluating suspected cauda equina syndrome include:
- The most common cause of cauda equina syndrome is lumbar disc herniation at the L4-L5 and L5-S1 levels 1
- Other etiologies include neoplasm, infection/inflammation, spinal stenosis, and hemorrhage 1
- MRI lumbar spine without IV contrast can accurately depict soft-tissue pathology, assess vertebral marrow, and assess the spinal canal patency 1
- A prospective cohort study recommends urgent MRI assessment in all patients who present with new-onset urinary symptoms in the context of low back pain or sciatica 1
However, MRI lumbar spine with IV contrast may be helpful in certain situations, such as when underlying malignancy, infection, or inflammation is clinically suspected. In these cases, the use of contrast can help delineate the etiology of cauda equina syndrome and guide further management 1. Ultimately, the choice of imaging study should be based on the individual patient's clinical presentation and suspected underlying cause of their symptoms.
From the Research
Cauda Equina Syndrome Diagnosis
- Cauda equina syndrome is a rare but emergent condition associated with back pain, which can result in severe morbidity 2.
- The diagnosis of cauda equina syndrome often involves magnetic resonance imaging (MRI) or computed tomography myelography if MRI is not available 2.
- 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, and loss of sexual function 2, 3.
MRI with Contrast for Cauda Equina Syndrome
- There is no specific mention of the need for an MRI with contrast for cauda equina syndrome in the provided studies.
- However, it is recommended that MRI should be carried out on an urgent basis in cases of suspected cauda equina syndrome, with the presence of red flag findings 3.
- Urgent MRI assessment is also recommended in all patients who present with new onset urinary symptoms in the context of lumbar back pain or sciatica 4.
Importance of Early Diagnosis and Treatment
- Early diagnosis and treatment of cauda equina syndrome are crucial to prevent significant patient morbidity 2, 3.
- The treatment of cauda equina syndrome relies upon surgical consultation and operative intervention for decompression 5, 2.
- Timing to surgical decompression, severity of symptoms at time of onset, and involvement of bladder dysfunction are prognostic indicators of cauda equina syndrome 6.