Neurologic Imaging

What Imaging Is Best for Acute Onset Myelopathy? An ACR-Guided Workflow

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What Imaging Is Best for Acute Onset Myelopathy? An ACR-Guided Workflow

A 45-year-old patient presents to the emergency department with rapidly progressing bilateral leg weakness and a new sensory level at the umbilicus that developed over the past 12 hours. They report no recent trauma. You suspect an acute process affecting the spinal cord—a myelopathy—and recognize the need for urgent imaging to guide management. The critical question is which study to order first to evaluate the spinal cord parenchyma and surrounding structures effectively and safely. This article provides a deep-dive workflow for this specific scenario, based on the American College of Radiology (ACR) Appropriateness Criteria, which rates ‘MRI spine area of interest without and with IV contrast’ as Usually Appropriate.

Who Fits This Clinical Scenario?

This guidance applies specifically to patients presenting with acute onset myelopathy, where symptoms have developed over hours to a few days. The clinical picture is defined by signs and symptoms localizing to the spinal cord, such as:

  • Bilateral motor weakness, often in the lower extremities.
  • A distinct sensory level, below which sensation is diminished or altered.
  • Bowel, bladder, or sexual dysfunction of new onset.
  • Upper motor neuron signs like hyperreflexia, spasticity, or a positive Babinski sign.

This workflow is intended for initial, non-traumatic presentations. It is crucial to distinguish this scenario from others that may appear similar but require a different diagnostic approach:

  • Chronic or Progressive Myelopathy: If the patient’s symptoms have developed insidiously over weeks, months, or years, they fit the chronic myelopathy scenario, which has a different differential diagnosis and imaging considerations.
  • Acute Trauma: If the patient has a history of significant, recent trauma, the primary concern is vertebral fracture and spinal instability. This presentation is covered under separate ACR guidelines for spine trauma, where CT is often the first-line modality.
  • Isolated Radiculopathy: If symptoms are confined to a single nerve root distribution (e.g., unilateral arm pain and weakness in a C6 pattern) without signs of spinal cord involvement, the workup is for radiculopathy, not myelopathy.

What Diagnoses Are You Working Up in Acute Myelopathy?

In acute myelopathy, the differential diagnosis is broad and includes several time-sensitive conditions. The choice of imaging is driven by the need to differentiate between these potential causes, which require vastly different treatments.

Compressive Myelopathy: This is often the most urgent consideration. An extrinsic process is physically compressing the spinal cord, which can lead to irreversible damage if not relieved quickly. Common causes include a spinal epidural abscess, an epidural hematoma (which can be spontaneous, especially in anticoagulated patients), a rapidly expanding metastatic tumor, or a large acute disc herniation.

Transverse Myelitis: This is an inflammatory condition causing focal inflammation across one or more segments of the spinal cord. It can be idiopathic or associated with systemic autoimmune diseases, infections, or post-vaccination phenomena. Identifying the characteristic cord enhancement on imaging is key to the diagnosis.

Spinal Cord Infarction: A vascular catastrophe, often called a “spinal stroke,” caused by occlusion of the anterior spinal artery or other feeding vessels. The presentation is typically hyperacute. While less common than cerebral stroke, it is a critical diagnosis to consider, as the imaging findings can be subtle early on.

Demyelinating Disease: An acute myelopathy can be the first presentation of multiple sclerosis (MS) or neuromyelitis optica spectrum disorder (NMOSD). These conditions involve autoimmune attacks on the myelin sheath of the central nervous system, and imaging is essential for diagnosis and prognosis.

Why Is MRI Without and With Contrast the Top Study for Acute Myelopathy?

For a patient with acute onset myelopathy, the ACR rates ‘MRI spine area of interest without and with IV contrast’ as Usually Appropriate. This comprehensive study is the cornerstone of the initial workup because of its unparalleled ability to visualize the spinal cord and differentiate between the critical diagnoses in this scenario.

The power of this protocol lies in its two components. The non-contrast sequences (T1- and T2-weighted images) are highly sensitive for detecting cord edema, which appears as high signal on T2 images, a common finding across inflammatory, ischemic, and compressive causes. These sequences also clearly delineate the anatomy, revealing any structural compression from a disc, hematoma, or tumor.

The addition of intravenous (IV) gadolinium-based contrast is what makes the study so specific. Contrast-enhanced T1-weighted images are essential for identifying processes that disrupt the blood-spinal cord barrier. Inflammatory conditions like transverse myelitis, demyelinating plaques from MS, infections like an epidural abscess, and most tumors will typically demonstrate enhancement. The absence of enhancement, in contrast, might point toward a spinal cord infarction.

While ‘MRI spine area of interest without IV contrast’ is also rated Usually Appropriate, proceeding directly to a study with and without contrast is often more efficient. Omitting contrast can miss or delay the diagnosis of inflammatory, infectious, or neoplastic causes, potentially requiring the patient to return for a second, contrast-enhanced scan.

Alternative studies are rated lower for good reason:

  • CT Myelography (‘May be appropriate’): This invasive test requires a lumbar puncture to inject contrast into the thecal sac. While excellent for defining structural compression, it provides limited information about intrinsic cord abnormalities and carries risks associated with the procedure. It is generally reserved for patients with contraindications to MRI.
  • Radiography (X-rays) (‘Usually not appropriate’): Plain films are insensitive to the soft tissues of the spinal cord and are not useful for evaluating the primary pathology in non-traumatic myelopathy.

A major advantage of MRI is the lack of ionizing radiation (adult_rrl=O 0 mSv), which is particularly important compared to CT-based methods (adult_rrl=Varies). Once you’ve decided on an MRI of the spine, our protocol guide covers the technique and reading principles for a common area of interest, though the specific sequences will need to be adapted for the cervical or thoracic spine based on clinical localization: MRI Lumbar Spine Without Contrast.

What’s Next After the MRI? Downstream Workflow

The results of the initial MRI will dictate the subsequent clinical pathway. The goal is to move quickly from diagnosis to treatment, as many causes of acute myelopathy are medical or surgical emergencies.

If the MRI shows cord compression: This is a neurosurgical emergency. An urgent consultation with neurosurgery or orthopedic spine surgery is required for consideration of surgical decompression. The specific cause (e.g., epidural abscess, hematoma, tumor) will guide further management, such as starting empiric antibiotics for an abscess or obtaining a tissue diagnosis for a suspected tumor.

If the MRI shows a non-compressive, enhancing lesion: This finding suggests an inflammatory or demyelinating process like transverse myelitis or MS. The next step is a neurology consultation. Further workup often includes a lumbar puncture for cerebrospinal fluid (CSF) analysis (e.g., for oligoclonal bands, cell count) and blood tests for specific antibodies (e.g., AQP4, MOG for NMOSD). Treatment typically involves high-dose corticosteroids.

If the MRI is negative or shows findings of infarction: A normal MRI in the face of clear myelopathic signs is a challenging scenario. Early spinal cord infarction can be MRI-negative. A repeat MRI with diffusion-weighted imaging (DWI) in 24-48 hours may be necessary. If the clinical suspicion remains high despite a negative scan, consultation with neurology and potentially vascular neurology is warranted to consider other etiologies or confirm a suspected infarct.

If the findings are indeterminate: In some cases, the MRI may be equivocal. At this point, a consultation with the reading radiologist can be invaluable to discuss the findings and consider additional imaging sequences or alternative modalities like CT myelography if appropriate.

Pitfalls to Avoid (and When to Get Help)

In the urgent setting of acute myelopathy, several common pitfalls can delay diagnosis and treatment. Be mindful of the following:

  • Imaging the wrong spinal segment: A careful neurologic exam to pinpoint the sensory level is critical. Imaging the lumbar spine when the lesion is in the thoracic cord will miss the diagnosis entirely. When in doubt, it is often prudent to image the entire spine.
  • Accepting a non-contrast MRI when contrast is needed: If the initial non-contrast study is unrevealing but clinical suspicion for an inflammatory or infectious process is high, do not delay ordering the contrast-enhanced portion of the exam.
  • Delaying the scan: For compressive lesions, “time is spine.” Delays in obtaining the definitive imaging study can lead to permanent neurologic deficits. This presentation should be treated with the same urgency as a potential stroke.

If the patient shows rapid neurologic deterioration or signs of respiratory compromise from a high cervical lesion, escalate immediately to a higher level of care and secure the airway while arranging the emergent imaging.

Related ACR Topics and Tools

Navigating the diagnostic pathway for myelopathy and other neurologic conditions requires access to reliable, evidence-based resources. The following tools can help you select the right test for the right patient and understand the technical details of each study.

Frequently Asked Questions

Why not start with a CT scan for acute myelopathy?

A non-contrast CT of the spine is very limited in this scenario because it cannot visualize the spinal cord itself. It is primarily useful for evaluating bone, such as in a trauma setting. While CT myelography is an option, it is invasive and provides less information about intrinsic cord pathology than an MRI. Therefore, MRI is the superior first-line test for non-traumatic acute myelopathy.

What if my patient has a pacemaker or other contraindication to MRI?

If a patient has an absolute contraindication to MRI (e.g., an incompatible implanted electronic device), the next best test is ‘CT myelography spine area of interest,’ which the ACR rates as ‘May be appropriate.’ This requires a consultation with radiology and often neurosurgery or neurology, as it involves a lumbar puncture to inject contrast. It is crucial to confirm that the patient’s device is truly MRI-incompatible, as many modern devices are now MRI-conditional.

Is an MRA or CTA ever appropriate for initial imaging of acute myelopathy?

No, for the initial workup, MRA and CTA are rated as ‘Usually not appropriate’ by the ACR. While a vascular cause like spinal cord infarction is on the differential, the primary goal of the first scan is to evaluate the cord parenchyma and rule out compression. Standard MRI sequences, including DWI, are the best way to detect infarction. A dedicated vascular study might be considered as a downstream test if a vascular malformation or dissection is suspected after the initial MRI.

Do I need to image the entire spine or just the area of the sensory level?

The neurologic exam is key. You should image the spinal segment that corresponds to the clinical signs and symptoms. However, the sensory level can sometimes be misleading, and some conditions (like multiple sclerosis) can have multiple, clinically silent lesions. If the initial targeted MRI is negative but clinical suspicion remains high, or if the localization is unclear, imaging the entire spine (cervical, thoracic, and lumbar) is often the most prudent next step.

How urgently do I need to get the MRI in a patient with acute myelopathy?

Extremely urgently. Acute myelopathy, particularly if it is compressive, is a neurologic emergency equivalent to a stroke or intracranial hemorrhage. The goal should be to obtain the MRI as soon as possible, ideally within hours of presentation. Any delay can result in permanent loss of function. This requires clear communication with the radiology department about the clinical urgency.

Reviewed by Pouyan Golshani, MD, Interventional Radiologist — May 29, 2026