What are the clinical features of Brown‑Sequard syndrome?

Brown-Séquard Syndrome: Clinical Features

Brown-Séquard syndrome presents with ipsilateral motor weakness, proprioception loss, and vibratory sensation loss, combined with contralateral pain and temperature sensation loss beginning two to three levels below the spinal cord lesion. 1, 2

Motor Deficits

• Ipsilateral motor weakness or paralysis occurs below the level of the cord lesion due to damage of the descending corticospinal tract, which crosses at the medullary level and therefore remains ipsilateral in the spinal cord. 1, 2
• Motor function loss manifests on the same side as the spinal cord injury and can range from weakness to complete paralysis depending on the severity of hemisection. 2

Sensory Deficits: The Hallmark Dissociated Pattern

• Ipsilateral loss of proprioception and vibratory sensation occurs below the lesion level because the dorsal columns (carrying these modalities) ascend ipsilaterally before crossing in the medulla. 1, 2
• Contralateral loss of pain and temperature sensation begins two to three levels below the injury because spinothalamic tract fibers cross within 1-2 segments after entering the spinal cord, then ascend contralaterally. 1, 2
• This dissociated sensory loss—where different sensory modalities are affected on opposite sides of the body—is the pathognomonic feature that distinguishes Brown-Séquard syndrome from other spinal cord syndromes. 2

Clinical Presentation Nuances

• Classic Brown-Séquard syndrome with pure hemisection is rare; most patients present with mixed or incomplete neurological deficits related to partial damage of the spinal cord and surrounding structures rather than perfect anatomical hemisection. 1
• A sensory level can be identified on examination, typically corresponding to the spinal level of injury, with ipsilateral findings for dorsal column modalities and contralateral findings for spinothalamic modalities. 2

Common Etiologies

• Penetrating trauma (stab wounds, gunshot injuries) is the most common cause in areas with high trauma burden where assaults with sharp weapons occur frequently. 1
• Cervical disc herniation can produce Brown-Séquard syndrome through unilateral spinal cord compression, though this etiology is often underdiagnosed and has been reported in only limited case series. 3, 4, 2
• Other causes include extramedullary spinal neoplasms, post-traumatic arachnoiditis, and various compressive lesions. 3, 5

Diagnostic Approach

• MRI with high-resolution sequences should be obtained early in patients presenting with the characteristic dissociated sensory and motor pattern, particularly when penetrating trauma or obvious external injury is absent. 2, 5
• Thin-slice high-resolution sequences (such as constructive interference in steady state) can be useful for identifying subtle causes including arachnoiditis or small compressive lesions. 5
• The presence of spinal cord hyperintensity on MRI indicates hemicord damage and helps confirm the diagnosis and guide prognosis. 4

Prognosis and Management

• Early surgical intervention is recommended when a compressive etiology (such as disc herniation) is identified, as prompt decompression is associated with better functional recovery. 4, 2
• Brown-Séquard syndrome has the best prognosis among incomplete spinal cord injury syndromes, with many patients achieving near-baseline functional recovery after appropriate treatment and rehabilitation. 1
• Complete motor deficit recovery and marked sensory improvement can be obtained following surgical decompression in cases caused by disc herniation. 3, 4

Key Pitfall to Avoid

• Do not dismiss Brown-Séquard syndrome in the absence of penetrating trauma—cervical disc herniation and other non-traumatic etiologies are frequently underdiagnosed because clinicians fail to consider them in the differential diagnosis of this classic neurological syndrome. 4, 2