Brown-Séquard syndrome is a pattern of neurological deficits that results from damage to one side of the spinal cord, producing a distinctive split: weakness and loss of position sense on the same side as the injury, with loss of pain and temperature sensation on the opposite side. It is classified as an incomplete spinal cord injury, meaning some function is preserved below the level of damage. Though the textbook version involves a clean hemisection of the cord, most real-world cases are messier, and the syndrome’s presentation and causes are more varied than many people expect.
What Happens Inside the Spinal Cord
The reason symptoms split between the two sides of the body comes down to how nerve pathways are arranged. Motor signals traveling from the brain to your muscles run down the same side of the spinal cord until they reach their destination. Sensory signals for fine touch and body position also stay on the same side as they travel upward. But the pathways carrying pain and temperature information cross to the opposite side of the cord shortly after entering it, then travel upward on that opposite side. When one half of the cord is damaged, the crossing arrangement produces the signature mismatch: motor loss and position-sense loss appear on the injured side, while pain and temperature loss show up on the other side, typically a couple of levels below the injury.
This pattern was first described in the mid-1800s by the Mauritian physiologist Charles-Édouard Brown-Séquard, based on animal experiments. In practice, a perfectly clean hemisection almost never happens in human injuries. Most patients present with a “Brown-Séquard-plus” pattern, meaning they have the core features but also additional neurological deficits that don’t fit the textbook picture neatly, such as bladder or bowel involvement or problems on both sides to varying degrees.1PubMed. Brown-Séquard-plus syndrome because of penetrating trauma in children One prospective study of traumatic cervical cases defined Brown-Séquard-plus syndrome simply as an incomplete injury with ipsilateral weakness and contralateral loss of pinprick sensation.2Spinal Cord. Relevance of the diagnosis traumatic cervical Brown-Séquard-plus syndrome: an analysis based on the neurological and functional recovery in a prospective cohort of 148 patients
Traumatic Causes
Penetrating injuries are the classic cause. Stab wounds and gunshot injuries that slice into one side of the spinal cord can produce the syndrome in near-textbook form. Case reports describe patients presenting with clear-cut motor loss on the side of the wound and pain-temperature loss on the opposite side after thoracic or cervical stab injuries.3PubMed Central. Brown-Séquard Syndrome Following a Thoracic Spine Stab Wound: A Case Report These penetrating cases tend to produce the most recognizable version of the syndrome because the damage is relatively focal and one-sided.
Blunt trauma, by contrast, is a less common trigger but does occur. Car accidents, falls, and sports injuries can cause cervical fractures or dislocations that compress one side of the cord. A retrospective review of blunt cervical spine trauma cases found the syndrome in patients with both upper and lower cervical fractures, though the presentation was often muddied by surrounding soft-tissue damage.4PubMed Central. Brown-Sequard syndrome after blunt cervical spine trauma: clinical and radiological correlations A case has even been documented after a hangman fracture at the C2 level following a motor vehicle accident, with MRI confirming one-sided cord damage.5PubMed Central. Brown-Sequard syndrome associated with hangman fracture after blunt trauma: A case report Prior spinal surgery can also make blunt trauma more dangerous: one report described a patient who had previously undergone cervical hemilaminectomies and developed Brown-Séquard syndrome after a relatively modest blunt injury, likely because the earlier surgery left the cord more vulnerable on one side.6Journal of Neurosurgery: Case Lessons. Brown-Séquard syndrome after blunt cervical spine trauma in a patient with preinjury multilevel hemilaminectomies and OPLL: illustrative case
Non-Traumatic Causes
Trauma gets most of the attention, but the syndrome can also develop without any injury at all. A number of medical conditions can compress or damage one side of the cord and produce the same clinical picture.
Disc herniations in the cervical spine are one such cause, though they rarely produce Brown-Séquard syndrome. When they do, it is typically a large disc fragment that pushes sharply to one side. Case series have documented patients with herniated discs at the C3-C4 or other cervical levels presenting with one-sided weakness and opposite-side sensory loss.7PubMed Central. Cervical disc herniation producing acute brown-sequard syndrome A review of five such patients confirmed that while disc herniations are a well-known cause of spinal cord compression in general, their association with the half-cord syndrome is rare.8PubMed Central. Cervical disc herniation as a cause of brown-séquard syndrome
Tumors within the spinal cord, known as intramedullary tumors, can also produce the syndrome. These are uncommon in themselves, and producing Brown-Séquard specifically is rarer still. Reports exist of lung cancer and colon cancer metastasizing to the spinal cord and presenting as the syndrome.9PubMed. Intramedullary spinal cord metastasis of lung adenocarcinoma presenting as Brown-Sequard syndrome 10PubMed Central. Intramedullary spinal cord metastasis from colonic carcinoma presenting as Brown-Séquard syndrome: a case report In these cases, the tumor grows asymmetrically within the cord, disrupting pathways on one side more than the other.
Ossification of spinal ligaments is another non-traumatic trigger. When the ligaments that run along the back of the vertebral bodies or inside the spinal canal gradually harden and thicken, they can compress the cord unevenly. One report documented a patient with thoracic ossification of the ligamentum flavum who developed incomplete Brown-Séquard syndrome from progressive compression.11PubMed Central. Thoracic ossification of the ligamentum flavum causing Brown-Séquard syndrome: a case report and literature review
Vascular and Inflammatory Triggers
Bleeding within the spinal canal, particularly epidural hematomas, can compress one side of the cord abruptly. One case involved a 55-year-old man who developed sudden one-sided weakness and opposite-side sensory loss after receiving a cervical epidural injection for shoulder pain; imaging revealed a hematoma spanning several vertebral levels.12PubMed Central. Cervical epidural hematoma with Brown-Sequard syndrome caused by an epidural injection: a case report Spontaneous epidural hematomas, occurring without any procedure or trauma, are an extremely rare but documented cause as well. Most spontaneous cases of Brown-Séquard syndrome have been traced to either spontaneous epidural bleeding or spinal cord ischemia.13American Journal of Neuroradiology. Brown-Séquard Syndrome Secondary to Spontaneous Bleed from Postradiation Cavernous Angiomas
Inflammatory conditions affecting the spinal cord can produce the pattern too. Transverse myelitis, an inflammatory attack on a segment of the cord, usually causes bilateral symptoms. But occasionally the inflammation is asymmetric enough to mimic a hemisection. Case reports have documented idiopathic transverse myelitis presenting as Brown-Séquard syndrome in the thoracic cord, emphasizing that myelitis belongs in the differential diagnosis when the syndrome appears without trauma.14Spinal Cord. Idiopathic transverse myelitis presenting as the Brown-Sequard syndrome 15PubMed Central. Idiopathic myelitis presenting as Brown-Séquard syndrome: two case reports and a review of the literature Multiple sclerosis, which also causes focal cord lesions, can occasionally do the same.
The Misdiagnosis Problem
When Brown-Séquard syndrome develops spontaneously rather than after an obvious injury, it is frequently mistaken for a stroke. The initial presentation of sudden one-sided weakness looks, at first glance, like a textbook stroke. In an emergency setting, clinicians naturally go to the most common diagnosis first. A retrospective review of eight non-traumatic patients who underwent surgical treatment for the syndrome found that all of them were initially misdiagnosed with stroke.16PubMed Central. Controversies in the differential diagnosis of Brown-Sequard syndrome due to cervical spinal disease from stroke: A case series
The distinguishing clue is the sensory pattern. In stroke, weakness and sensory loss usually affect the same side of the body. In Brown-Séquard syndrome, the sensory loss splits: reduced pain and temperature on the side opposite the weakness, with preserved or even intact fine touch on the weak side. This mismatch should prompt spinal imaging rather than a brain CT. But in the chaos of an emergency department, the split sensory pattern can be overlooked or attributed to an atypical stroke. The delay matters because the underlying cause, whether a hematoma, disc herniation, or tumor, may require urgent spinal surgery rather than stroke-oriented treatment.
How It Is Diagnosed
A thorough neurological exam is the first step. Clinicians test motor strength on both sides, then systematically check sensation by pricking the skin with a pin (for pain pathways) and using vibration or joint-position tests (for proprioceptive pathways). The signature finding is a clear asymmetry: motor loss and proprioceptive loss on one side, with pain and temperature loss on the other.
MRI is the gold-standard imaging tool. It can show the lesion responsible, whether that is a cord contusion, disc herniation, hematoma, tumor, or inflammatory plaque. In one documented case after blunt trauma, MRI showed a T2-signal abnormality at the level of injury, and diffusion tensor imaging was used to trace the damaged fiber tracts, showing disrupted pathways on one side and intact ones on the other.17PubMed. Diffusion tensor tractography demonstration of partially injured spinal cord tracts in a patient with posttraumatic Brown Sequard syndrome Diffusion tensor imaging remains mostly a research tool, but it illustrates how precisely modern imaging can map the damage. In routine clinical practice, a standard MRI is usually sufficient to confirm the location and cause.
Treatment
Treatment depends entirely on the underlying cause. When the syndrome results from something compressing the cord, such as a hematoma, disc fragment, tumor, or bone abnormality, surgical decompression is the standard approach. The goal is to relieve pressure on the cord as quickly as possible to give damaged nerve tissue the best chance of recovering. Emergency laminectomy, in which part of the vertebral bone is removed to open up space around the cord, is widely accepted for patients whose neurological deficits are worsening.18PubMed Central. Spontaneous epidural hematoma of thoracic spine presenting as Brown-Séquard syndrome: report of a case with review of the literature
There are exceptions. Some cases with incomplete deficits have been managed conservatively and done well. One report of thoracic ligament ossification causing incomplete Brown-Séquard syndrome documented a favorable response to conservative treatment alone. But the authors were careful to note that this does not make nonoperative management the standard; surgical decompression remains the default recommendation.19PubMed Central. Thoracic ossification of the ligamentum flavum causing Brown-Séquard syndrome: a case report and literature review Similarly, certain spontaneous epidural hematomas presenting with incomplete deficits have occasionally resolved without surgery, but this is the exception rather than the rule.20PubMed Central. Spontaneous epidural hematoma of thoracic spine presenting as Brown-Séquard syndrome: report of a case with review of the literature
Steroids have been used in the acute phase, particularly after traumatic injury. In one case of Brown-Séquard syndrome caused by isolated blunt cervical trauma, high-dose steroids were started after the injury was recognized, and the patient recovered much of his function within a month and was able to walk unassisted.21PubMed. Brown-Sequard syndrome due to isolated blunt trauma The broader use of high-dose steroids for spinal cord injury has become controversial in recent years, and practice varies between institutions.
Why Recovery Is Often Surprisingly Good
Among incomplete spinal cord injuries, Brown-Séquard syndrome carries one of the better prognoses. Because the damage is largely one-sided, the intact pathways on the opposite side of the cord can compensate over time. Roughly three-quarters of patients achieve independent walking ability by the time they are discharged from rehabilitation.22PubMed Central. Conservative Management of Traumatic Brown-Séquard Syndrome: A Case Report That figure is strikingly high for a spinal cord injury, and it reflects the fundamental advantage of having one side of the cord still functioning.
An important predictor of walking recovery is which limb is most affected. If the arm is weaker than the leg on the injured side, the chances of walking at discharge are better, because the intact cord pathways to the legs are relatively preserved.23PubMed Central. Conservative Management of Traumatic Brown-Séquard Syndrome: A Case Report Rehabilitation typically focuses on gait training, strength building, and relearning daily tasks with altered sensation.
The neurological basis for this recovery has been studied in both human patients and animal models. Research points to neuroplasticity in surviving nerve pathways as a key driver. One system that seems especially important is the reticulospinal pathway, which runs from the brainstem down the cord and plays a role in controlling proximal muscles like those around the shoulder and elbow. A case study using specialized brain-stimulation techniques found strong evidence of reticulospinal plasticity on the injured side, with the reticulospinal system essentially taking over some functions normally handled by the corticospinal tract (the main voluntary motor pathway). The corticospinal system, by contrast, appeared more important for recovery of fine hand and finger control.24PubMed Central. Evidence for reticulospinal plasticity underlying motor recovery in Brown-Séquard-plus Syndrome: a case report Earlier work had already proposed that neuroplasticity in spared descending pathways likely mediates much of the motor recovery seen after hemisection injuries.25PubMed. Temporal course of motor recovery after Brown-Sequard spinal cord injuries
What Chronic Life Looks Like
Recovery is typically good for motor function, but sensory problems can persist long-term and be a source of ongoing difficulty. Neuropathic pain, an abnormal chronic pain arising from nerve damage itself rather than from an injury to tissues, is a recognized long-term complication. Animal research modeling the hemisection injury has found that chronic neuropathic pain-like behaviors develop on the side opposite the injury, where pain pathways were disrupted. The same studies showed that the ipsilateral side lost innocuous sensation while the contralateral side actually became hypersensitive to certain stimuli.26PubMed Central. Sensory Deficits in Mice with Lateral Spinal Cord Hemisection Mimic the Brown-Séquard Syndrome In human patients, this can translate to a frustrating combination: numbness in some areas, heightened or distorted pain perception in others, and difficulty with tasks that require fine sensory feedback.
Bladder and bowel function can also be affected, particularly when the injury is higher in the cord or when the presentation fits the Brown-Séquard-plus pattern with involvement beyond the classic hemisection findings.27PubMed. Brown-Séquard-plus syndrome because of penetrating trauma in children Some patients regain full autonomic function; others manage ongoing issues with medication or catheterization.
Iatrogenic Cases and Surgical Complications
Brown-Séquard syndrome can also arise as a complication of spinal surgery itself, a sobering reminder of the risks involved in operating near the cord. Postoperative cases have been linked to spinal epidural hematomas that form after procedures like cervical laminoplasty. A literature review found only a handful of published case reports of Brown-Séquard syndrome caused by epidural hematoma after spine surgery, indicating that while the complication is rare, it is real.28Interdisciplinary Neurosurgery. Postoperative Brown–Séquard syndrome complicated by spinal epidural haematoma after cervical laminoplasty: A case report and literature review Epidural steroid injections, used commonly for pain management, have also been documented as a trigger when they cause bleeding that compresses one side of the cord.29PubMed Central. Cervical epidural hematoma with Brown-Sequard syndrome caused by an epidural injection: a case report In both scenarios, rapid recognition and repeat surgical decompression are critical to limiting permanent damage.
Brown-Séquard Syndrome in Children
The syndrome can occur in pediatric patients, though it is quite rare. In children, both traumatic and non-traumatic causes have been documented. Penetrating injuries in adolescents have produced the Brown-Séquard-plus pattern, with additional neurological deficits beyond the classic half-cord features.30PubMed. Brown-Séquard-plus syndrome because of penetrating trauma in children Non-traumatic spinal cord ischemia in childhood, while rare, has also presented as Brown-Séquard syndrome among other patterns of incomplete cord injury.31PubMed. Non-traumatic spinal cord ischaemia in childhood – clinical manifestation, neuroimaging and outcome Children generally have a greater capacity for neural recovery than adults, but the rarity of the condition means that large studies on pediatric outcomes are essentially nonexistent. Treatment principles follow the same logic as in adults: identify and address the underlying cause, protect the cord from further damage, and begin rehabilitation early.