Brown Sequard Syndrome: Symptoms, Types, Causes and Treatment

Brown Sequard Syndrome (BSS) is a rare but clinically significant neurological disorder that results from injury or dysfunction of one side (hemisection) of the spinal cord. Named after the French physiologist Charles-Édouard Brown-Séquard, this syndrome offers a fascinating insight into spinal cord anatomy and function, but also presents unique diagnostic and therapeutic challenges. This article explores BSS comprehensively—covering its symptoms, types, causes, and treatment options—synthesizing the latest research and clinical findings.

Symptoms of Brown Sequard Syndrome

Brown Sequard Syndrome is known for its distinctive pattern of neurological deficits, which can be both intriguing and perplexing for clinicians and patients alike. Understanding these symptoms is the first step toward recognizing and managing this condition effectively.

Symptom	Side (Relative to Lesion)	Description	Sources
Motor Weakness	Ipsilateral	Paralysis or weakness below the lesion	1 2 3 4
Proprioception Loss	Ipsilateral	Loss of position/vibration sense	2 3 4
Pain/Temperature ↓	Contralateral	Loss of sensation several segments below lesion	1 2 3 4
Segmental Findings	At lesion level	Flaccid paralysis, total sensory loss	1

Table 1: Key Symptoms

Classic Neurological Deficits

Brown Sequard Syndrome’s hallmark is the asymmetrical presentation of symptoms:

• Ipsilateral (same side as lesion):
  • Loss of motor function (weakness or paralysis) below the level of injury, due to disruption of the corticospinal tract.
  • Loss of proprioception and vibratory sense, as dorsal column tracts are affected.
• Contralateral (opposite side):
  • Diminished or absent pain and temperature sensation, typically starting a few segments below the lesion. This is because the spinothalamic tract fibers cross over within a few segments of spinal entry, so the deficit is not immediate at the injury level but slightly lower 1 2 3 4.

Segmental and Level-Dependent Findings

Direct damage at the level of injury may also cause:

• Flaccid paralysis
• Complete loss of all sensory modalities at the lesion segment 1.

Variability and Additional Features

While the classic presentation is well defined, real-world cases can vary. Some cases include incomplete patterns or additional findings, such as Horner's syndrome (ptosis, miosis, anhidrosis) if the sympathetic chain is involved at the cervical or upper thoracic level 3 7.

Types of Brown Sequard Syndrome

Although the term "Brown Sequard Syndrome" traditionally refers to the classic pattern, variations in presentation have led clinicians to recognize several types and subtypes.

Type	Key Features	Frequency/Outcome	Sources
Pure BSS	Classic complete hemisection signs	Rare	7
Incomplete BSS	Partial loss of classic deficits	More common	7
Brown-Sequard-Plus	Asymmetric paraplegia, more deficits	Worse prognosis	7
Atypical BSS	Additional symptoms (e.g., Horner's)	Variable	3 7

Table 2: Types of Brown Sequard Syndrome

Pure vs. Incomplete BSS

• Pure BSS is characterized by the full classic triad: ipsilateral motor and proprioception loss, contralateral pain/temperature loss. This pure form is surprisingly rare in clinical practice 7.
• Incomplete BSS is common, where symptoms may be less pronounced or not all classic features are present. This may reflect a partial injury or differing tract involvement 7.

Brown-Sequard-Plus Syndromes

• These variants include additional neurological deficits, often due to more extensive damage or involvement of other tracts—resulting in asymmetric paraplegia or other combinations of motor and sensory loss. Outcomes are often poorer compared to pure BSS 7.

Atypical Presentations

Cases may include:

• Horner's syndrome (if sympathetic fibers are involved)
• Segmental sensory or motor findings that do not fit the classic pattern 3.

Causes of Brown Sequard Syndrome

Understanding the causes of BSS is crucial for effective diagnosis and treatment, as the syndrome can arise from a diverse range of insults to the spinal cord.

Cause Category	Examples/Details	Notes	Sources
Traumatic	Stab wounds, gunshot wounds, blunt trauma	Most common historical cause	1 3 5 11
Degenerative	Cervical/thoracic disc herniation	Often underdiagnosed	2 9 12 13
Neoplastic	Tumors causing lateral cord compression	Both primary and metastatic	1 11
Vascular	Infarction, hematoma, embolization	Includes post-procedural cases	4 10 14
Infectious/Inflamm.	MS, herpes zoster, neurocysticercosis	Partial or complete BSS	1 4 8 11
Chemical	Heroin/quinine injection, vasculitis	Rare, with poor recovery	5
Miscellaneous	Idiopathic cord herniation, arachnoiditis	Treatable if identified early	6 11

Table 3: Causes of Brown Sequard Syndrome

Traumatic Causes

Historically, the majority of BSS cases have resulted from penetrating trauma (e.g., stab wounds, gunshot wounds) to the spinal cord, causing direct hemisection 1 3 5.

Degenerative and Disc-Related Causes

Non-traumatic etiologies are increasingly recognized, particularly:

• Cervical and thoracic disc herniation: These can compress one side of the spinal cord, producing the classic BSS picture. Disc herniation is often underdiagnosed as a cause, and early MRI is critical for identification 2 9 12 13.

Neoplastic and Vascular Causes

• Tumors (primary or metastatic) may cause lateral compression.
• Vascular causes include spinal cord infarction, extradural hematoma, or complications from procedures such as endovascular embolization 1 10 14.

Infectious, Inflammatory, and Other Causes

• Inflammatory diseases like multiple sclerosis can result in partial or complete BSS 1 4.
• Infections such as herpes zoster or neurocysticercosis are rare but documented triggers 4 8.
• Chemical injury from substances like heroin or its diluents has also been reported 5.

Idiopathic and Miscellaneous

• Idiopathic spinal cord herniation and post-traumatic arachnoiditis are rare but treatable causes that must be considered, especially in cases with progressive or unexplained symptoms 6 11.

Treatment of Brown Sequard Syndrome

Treatment of BSS is highly dependent on the underlying cause, the severity of neurological deficits, and the timing of intervention. Early recognition and targeted therapy can significantly improve outcomes for many patients.

Treatment Modality	Indication/Use	Outcome/Prognosis	Sources
Surgical Decompression	Disc herniation, tumors, herniation	Often good if early	2 9 12 13 6
Medical Management	Inflammation, infection, MS	Variable; cause-dependent	4 5 8 11
Rehabilitation	Post-acute phase	Essential for recovery	5 12 13
Supportive Care	All cases	Prevents complications	12

Table 4: Treatment Approaches

Surgical Intervention

Surgery is the mainstay for cases resulting from compressive lesions:

• Anterior cervical discectomy and fusion: Effective for cervical disc herniation causing BSS, with a majority of patients achieving significant or complete recovery, especially when performed early 2 9 12.
• Posterior laminectomy or transpedicular approaches: Used for thoracic disc herniation or idiopathic cord herniation. Intraoperative identification and careful closure of the dura are critical for good outcomes 6 13.

Medical Therapy

• High-dose corticosteroids: Used in cases of inflammatory or chemical injury (e.g., post-heroin injection, MS) 5 4.
• Antiviral or antibiotic therapy: Indicated in cases with infectious etiology, such as herpes zoster or neurocysticercosis 4 8.
• Management of underlying conditions: For example, treating vasculitis or MS as needed.

Rehabilitation and Supportive Care

• Physical and occupational therapy are vital for maximizing functional recovery and minimizing long-term disability. Early and intensive rehabilitation programs can lead to better outcomes 5 12 13.
• Supportive measures: These include preventing pressure sores, managing bladder and bowel function, and addressing spasticity or neuropathic pain 12.

Prognosis and Outcomes

• Early intervention—especially for compressive causes—substantially improves the chance for neurological recovery.
• Prognosis varies with etiology, completeness of deficits, and time to treatment. Pure BSS cases generally have a better outcome than Brown-Sequard-plus variants 7 12 13.
• Some cases (e.g., chemical injury, advanced neoplasm) may have poor recovery despite optimal therapy 5.

Conclusion

Brown Sequard Syndrome is a fascinating and complex neurological condition marked by a distinct pattern of motor and sensory deficits. While the classic form is well described, real-world presentations are often variable and may be caused by trauma, degenerative disease, tumors, vascular events, infection, or even chemical injury. Early diagnosis—often requiring MRI—and prompt, cause-specific treatment are crucial for the best possible outcomes.

Key Takeaways:

• BSS presents with ipsilateral weakness/proprioception loss and contralateral pain/temperature loss below the lesion.
• The pure "classic" syndrome is rare; incomplete and Brown-Sequard-plus forms are more common in clinical practice.
• Causes are diverse, with trauma, disc herniation, and neoplasm most common, but infections, vascular, and idiopathic cases also occur.
• Treatment should target the underlying cause, with surgery for compressive lesions and medical therapy for inflammation/infection.
• Early intervention and rehabilitation are essential for recovery.

Understanding Brown Sequard Syndrome’s nuances can make a significant difference in patient care—from rapid recognition to tailored intervention and support.