Synopsis
Use MRI to localise spinal cord, conus and cauda equina compression, distinguish malignant, degenerative, infective and haemorrhagic causes, and preserve the cause-specific emergency timing that follows the clinical syndrome.
- MRI is the preferred examination for non-traumatic cord and cauda equina compression because it shows neural tissue, epidural space, marrow, discs and soft tissue across multiple levels.
- Localise clinically before scanning, but extend coverage when symptoms do not fit one level or when malignancy, infection or multifocal disease makes discontinuous lesions plausible. In suspected CES, a lumbosacral scan without cauda equina compression must be followed by a sagittal T2 screen of the cervical and thoracic spine.
- A normal radiograph or routine CT does not exclude epidural tumour, abscess, haematoma or disc compression; CT myelography is a specialist alternative when MRI is genuinely impossible.
Key red flags
Recent new urinary-flow sensation, saddle sensation, bowel awareness or sexual-function change with back or leg symptoms activates the suspected CES pathway; a low post-void residual does not exclude compression.
For suspected disc-related CES, the March 2026 GIRFT pathway requires emergency MRI as soon as possible and within four hours of the radiology request at the presenting hospital where possible.
Known cancer plus neurological symptoms or signs requires immediate MSCC-service contact and whole-spine MRI as soon as possible, always within 24 hours.
Fever, bacteraemia, immune compromise or recent spinal procedure with focal pain and deficit raises spinal infection; obtain urgent MRI without and with contrast while sepsis and surgical pathways proceed.
Abrupt severe axial pain followed by rapid neurological loss, especially with anticoagulation or neuraxial intervention, suggests epidural haematoma and needs immediate spinal, anaesthetic and haemostasis escalation.
Look for bilateral weakness, hyperreflexia, extensor plantars, a sensory level, gait change and sphincter symptoms. High cervical disease can threaten ventilation.
Ask directly about urinary filling, initiation and flow sensation, perianal sensation, bowel awareness and sexual function; retention is a late phenotype.
Cancer with progressive mechanical or night pain raises spinal metastasis; add any neurological symptom or sign and the case becomes an oncological emergency.
Fever may be absent. Focal pain, bacteraemia, immune compromise, injected-drug exposure or recent procedure plus neurological change justifies urgent infection imaging.
An abrupt pain-then-deficit sequence, anticoagulant exposure or recent neuraxial procedure should prompt immediate MRI and drug-specific haemostasis review.
Investigation priorities
Confirm or exclude cauda equina compression and identify disc, tumour, infection, blood or another cause within the national emergency pathway.
Management branches
An adult has new urinary-flow sensory change and saddle tingling but retains full leg power and a low residual.
- Treat the subjective sacral symptoms as positive and request emergency lumbosacral MRI; do not use the residual as a rule-out test.
- Record onset and progression, lower-limb findings and subjective perianal sensation, then aim to complete MRI within four hours of the radiology request. Use the sagittal T2 lumbosacral screening sequence; if compression is absent, obtain the cervical-and-thoracic sagittal T2 screen before concluding the imaging pathway.