Anterior Cord Syndrome

The spinal cord is not uniform: different nerve pathways run in different regions. Towards the front and sides of the cord run the pathways that carry movement signals (the corticospinal tracts) and those that carry pain and temperature (the spinothalamic tracts). Towards the back of the cord run the pathways that carry the sense of position, vibration and fine touch (the dorsal columns). The front two-thirds of the cord is supplied by a single blood vessel, the anterior spinal artery. This anatomy explains anterior cord syndrome precisely: when the front of the cord is damaged, movement and pain/temperature sensation are lost, while the back-of-cord functions — position sense and vibration — are preserved.

There are two broad mechanisms. The first is direct compression or injury to the front of the cord, most often from a flexion injury of the spine in which a vertebra is crushed and bone or disc is pushed backwards onto the cord (for example a burst fracture), or from a large disc herniation. The second is a loss of blood supply through the anterior spinal artery. This can happen during or after surgery on the aorta (the body's main artery), with a tear or blockage of the aorta, with a prolonged drop in blood pressure, or with a clot. Identifying which mechanism is responsible matters, because it shapes both the treatment and the outlook.

The hallmark of anterior cord syndrome is a "dissociated" pattern of loss. Below the level of injury there is weakness or paralysis, and a loss of the ability to feel pain and temperature, while the sense of joint position, vibration and light touch is preserved. In practice this can be confusing for patients: a limb may be unable to move and unable to feel a pinprick, yet the person can still tell whether it is being moved up or down. Bladder and bowel function are commonly affected as well.

Symptoms come on around the time of the injury or vascular event and include weakness or paralysis below the level involved, loss of pain and temperature sensation, and often loss of bladder and bowel control. When the cause is a sudden interruption of blood supply, there may be sudden back pain at the level involved. Because position sense is preserved, some people retain a degree of balance information even when movement is lost.

Sudden weakness or paralysis, a loss of feeling for pain or temperature, or loss of bladder or bowel control — whether after an injury or arising suddenly on their own — are medical emergencies and require immediate assessment. Sudden severe back pain accompanied by leg weakness, particularly in someone with heart or aortic disease or after aortic surgery, also needs urgent evaluation, because prompt treatment of the underlying cause can influence the outcome.

Diagnosis combines the clinical examination — which reveals the characteristic dissociated pattern — with imaging. An MRI scan is central, as it shows the spinal cord itself and can demonstrate both compression of the front of the cord and changes suggesting a loss of blood supply. A CT scan shows the bones and any fracture. Where a vascular cause is suspected, further tests of the heart and aorta may be arranged. Establishing the underlying cause is a key part of the assessment.

Treatment is directed at the underlying cause. Where the front of the cord is being compressed by bone or disc, surgery to relieve the pressure and stabilise the spine is often considered, following the same general principles as for other spinal cord injuries. Where the cause is a loss of blood supply, treatment focuses on the underlying vascular problem and on supporting the cord's blood flow, for example by maintaining an adequate blood pressure. Alongside this, rehabilitation — physiotherapy, occupational therapy and specialist spinal care — is central to maximising function and independence over the following months.

Among the incomplete spinal cord syndromes, anterior cord syndrome generally carries the least favourable outlook, with only a minority of people regaining substantial useful movement. Several factors are associated with a poorer outcome, including a vascular cause (particularly involving the aorta), a high (neck-level) injury, very severe symptoms at the outset, a lack of any improvement in the first day or so, older age, and female sex. That said, some recovery does occur in a proportion of people, and rehabilitation remains valuable regardless, both for the function that can be regained and for adapting to lasting changes.

As with other spinal cord injuries, care includes preventing and managing complications such as pressure sores, urinary infections, blood clots, breathing problems after higher injuries, spasticity and pain. Because pain and temperature sensation are lost, particular care is needed to protect insensate skin from burns and pressure damage. Good long-term, multidisciplinary care substantially reduces these risks.

Myth: "If you can't move a limb, you can't feel anything in it." Fact: In anterior cord syndrome, movement and pain/temperature are lost while position and vibration sense remain.

Myth: "All incomplete spinal cord injuries recover well." Fact: Anterior cord syndrome tends to have the least favourable outlook among them.

Myth: "Spinal cord injuries are always caused by trauma." Fact: Anterior cord syndrome can also result from a loss of the cord's blood supply, for example with aortic disease.

This page is for general education and does not replace an individual assessment. Treatment depends on a person's specific symptoms, examination findings, imaging findings and overall health, and should always be discussed with a suitably qualified healthcare professional.

Anterior cord syndrome (also called anterior spinal artery syndrome) is a pattern of incomplete spinal cord injury in which the front portion of the spinal cord is damaged while the back portion is relatively spared. Because different functions travel in different parts of the cord, this produces a very specific combination: loss of movement and of pain and temperature sensation below the level of injury, but preserved awareness of where the limbs are in space and of vibration. It can result either from direct injury — such as bone or disc pressing on the front of the cord — or from an interruption of the cord's front blood supply. It is important because, among the incomplete spinal cord syndromes, it tends to carry the least favourable outlook for recovery. This page explains, in plain language, why anterior cord syndrome produces its characteristic pattern, how it is assessed, and what current evidence says about treatment and recovery.

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• —Guideline note: NICE NG41 reviewed for initial assessment and immobilisation. No stand-alone AAOS clinical practice guideline specific to anterior cord syndrome was identified at the time of writing; AO Spine acute spinal cord injury guidance informed the surgical principles.

This information is for general patient education and is not a substitute for an individual consultation. Always seek personalised advice from a qualified spinal specialist.