From the Guidelines
MRI for cauda equina syndrome is typically performed without IV contrast as the initial study, but may be followed by MRI with IV contrast if underlying malignancy, infection, or inflammation is clinically suspected. The initial non-contrast MRI provides excellent visualization of the spinal canal, nerve roots, and any compressive lesions such as disc herniations or masses, as recommended by the American College of Radiology 1. This approach is supported by a prospective cohort study by Bell et al 1, which recommends urgent MRI assessment in all patients who present with new-onset urinary symptoms in the context of low back pain or sciatica.
When evaluating suspected cauda equina syndrome, the key considerations include:
- The ability of MRI to accurately depict soft-tissue pathology, assess vertebral marrow, and assess the spinal canal patency 1
- The use of a single 3-D heavily T2-weighted fat-saturated sequence protocol as a rapid and highly sensitive tool for evaluating cauda equina syndrome in the emergency department 1
- The potential need for contrast enhancement to better characterize potential causes of cauda equina syndrome, such as inflammation, infection, or tumors 1
In emergency situations where cauda equina syndrome is strongly suspected, a non-contrast MRI may be performed first for rapid assessment, with contrast added if the initial findings are equivocal or if more detailed characterization is needed 1. The combination of both techniques provides the most comprehensive evaluation, allowing for prompt diagnosis of this neurosurgical emergency that requires immediate intervention to prevent permanent neurological damage.
From the Research
MRI for Cauda Equina Syndrome
- The use of MRI in diagnosing cauda equina syndrome is a crucial aspect of its assessment, as it provides detailed images of the spinal cord and nerve roots 2, 3, 4, 5, 6.
- MRI can be used to identify the underlying cause of cauda equina syndrome, such as a herniated disc or spinal stenosis, and to guide treatment decisions 3, 5.
- The studies do not specifically mention whether MRI is done with or without contrast to demonstrate cauda equina syndrome, but they do emphasize the importance of urgent MRI assessment in patients with suspected cauda equina syndrome 3, 4, 5.
- The diagnostic accuracy of MRI in confirming cauda equina syndrome is high, but the sensitivity and specificity of red flags used to identify potential cauda equina syndrome vary, emphasizing the need for prompt diagnostic workup when these red flags are present 6.
Red Flags for Cauda Equina Syndrome
- Red flags for cauda equina syndrome include perianal/perineal/saddle sensory disturbance, bladder or bowel dysfunction, radicular/sciatic pain, new motor weakness, and decreased rectal tone 4, 6.
- These red flags can be used to identify patients who require urgent MRI assessment and potential surgical intervention 4, 5.
- The presence of these red flags should prompt a thorough history and physical exam, followed by magnetic resonance or computed tomography imaging myelogram to aid in diagnosis and treatment 5.