Brown-Séquard Syndrome

The explanation lies in where the nerve pathways cross from one side of the body to the other. The pathways carrying movement and the sense of position and vibration travel down and up the same side of the spinal cord as the part of the body they serve, crossing over higher up, in the brainstem. The pathways carrying pain and temperature, by contrast, cross over within the spinal cord itself, just after they enter, and then travel up the opposite side. So when one half of the cord is injured, movement and position sense are lost on the same side as the injury, while pain and temperature sensation are lost on the opposite side — the crossed, or "dissociated", pattern that defines the syndrome.

Classically, Brown-Séquard syndrome results from a penetrating injury such as a stab or gunshot wound that damages one side of the cord. In practice, however, it more commonly arises from other causes that happen to affect one side more than the other: a fracture or dislocation of the spine, a disc herniation pressing on one side of the cord, or, outside of trauma, a tumour or other lesion. Recognising the underlying cause guides the treatment.

The defining feature is that the effects are split between the two sides of the body. On the same side as the injury, there is weakness or paralysis and a loss of the sense of position, vibration and fine touch. On the opposite side, there is a loss of pain and temperature sensation, usually beginning a few segments below the level of the injury. Many people are able to walk, because one leg is typically much stronger than the other.

Symptoms appear around the time of injury and reflect the crossed pattern: one-sided weakness with preserved pain and temperature sensation on that side, and, on the other side, an inability to feel pain or temperature despite reasonable strength. There may also be a narrow band of altered sensation at the level of the injury itself. Bladder and bowel function are affected less severely than in some other spinal cord syndromes, though they can be involved.

Any new weakness or numbness after an injury — and especially after a penetrating wound to the neck or back — requires urgent assessment. A one-sided weakness combined with a loss of pain or temperature sensation on the other side of the body is a pattern that should prompt immediate medical attention so that the spine can be protected and imaged.

The diagnosis is often suggested by the distinctive examination findings alone. Imaging confirms the cause and its extent: an MRI scan shows the spinal cord and any bruising, compression, disc or tumour, while a CT scan shows the bones and any fracture. In penetrating injuries, imaging also helps to define the track of the wound and any retained fragments.

Treatment depends on the cause. Where one side of the cord is being compressed by bone, disc or a fragment, surgery to relieve the pressure and stabilise the spine may be considered, following the same general principles as for other spinal cord injuries. Penetrating injuries are managed according to their specifics, including care of the wound. As with all spinal cord injuries, rehabilitation — physiotherapy, occupational therapy and specialist support — is central to recovery, and the relatively preserved strength on one side is often a useful foundation for regaining walking.

Brown-Séquard syndrome has the most favourable outlook of the incomplete spinal cord syndromes. A large majority of people regain the ability to walk independently, and many recover a useful degree of bladder and bowel control. Recovery tends to be greatest in the first one to two months, then continues more slowly over the following months, and improvement has been reported to continue for up to two years. As always, the exact outlook depends on the cause and severity of the individual injury.

The general complications of spinal cord injury still apply and are actively prevented and managed, including pressure sores, urinary infections, blood clots and pain. Because pain and temperature sensation are reduced on one side of the body, the skin on that side needs particular protection from burns and pressure. Good rehabilitation and long-term care reduce these risks.

Myth: "A spinal cord injury always affects both sides of the body equally." Fact: In Brown-Séquard syndrome the injury is mainly one-sided, producing a split pattern of effects.

Myth: "Incomplete cord injuries all have a poor outlook." Fact: Brown-Séquard syndrome has the most favourable outlook of the incomplete syndromes.

Myth: "If one leg is weak, walking is impossible." Fact: Because the other leg is often relatively strong, most people with this syndrome walk again.

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.

Brown-Séquard syndrome is an uncommon pattern of incomplete spinal cord injury in which one half of the spinal cord — the left or the right — is damaged more than the other. It is named after the nineteenth-century physiologist Charles-Édouard Brown-Séquard, who described the effects of injuring one side of the cord. The pattern it produces can seem puzzling at first because the effects are split between the two sides of the body: weakness and loss of the sense of position on the same side as the injury, and loss of pain and temperature sensation on the opposite side. A pure form is rare; more often people have a "Brown-Séquard-plus" pattern with a predominant one-sided injury. Importantly, of all the incomplete spinal cord syndromes, this one generally carries the best outlook for recovery. This page explains why the pattern occurs, how it is assessed, and what happens next.

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• —Guideline note: NICE NG41 reviewed for initial assessment. No stand-alone AAOS clinical practice guideline specific to Brown-Séquard 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.