Brown-Séquard Syndrome (BSS) is a rare neurological condition that results from damage to one side of the spinal cord. This type of spinal cord injury leads to a very distinctive set of symptoms, including paralysis or weakness on one side of the body and loss of sensation (pain and temperature) on the opposite side. While BSS itself is a distinct medical condition, the causes of the syndrome can vary widely.
In this post, we'll explore the most common causes of Brown-Séquard Syndrome, how these causes lead to the characteristic spinal cord injury, and what makes some individuals more at risk for developing the condition.
One of the most common ways that Brown-Séquard Syndrome develops is through trauma. Injuries that lead to physical damage to the spinal cord often involve accidents, violence, or falls. Traumatic causes tend to result in an acute onset of symptoms.
Penetrating injuries are one of the leading causes of Brown-Séquard Syndrome. These types of injuries occur when an object pierces the body and damages the spinal cord, often affecting just one side of the cord. Some common examples of penetrating injuries include:
Because these types of injuries often affect only one side of the spinal cord, they create the distinct hemicord lesion that is associated with Brown-Séquard Syndrome.
In addition to penetrating injuries, blunt force trauma can also cause Brown-Séquard Syndrome. Blunt trauma may not penetrate the skin or bones, but it can cause enough force to compress or contuse (bruise) the spinal cord on one side. Some common causes of blunt trauma include:
While blunt trauma is more likely to cause other types of spinal cord injuries (such as complete or incomplete spinal cord transections), in some cases, the injury may be isolated to one side of the spinal cord, leading to BSS.
Spinal fractures or dislocations, especially of the cervical (neck) or thoracic (upper back) vertebrae, can result in Brown-Séquard Syndrome. These injuries typically occur as a result of significant trauma, such as in motor vehicle accidents, falls, or sporting accidents. If the vertebrae become displaced or fractured, they can compress or sever the spinal cord, damaging one side.
In cases where the injury results in a hemicord lesion, the individual may experience the classic symptoms of Brown-Séquard Syndrome, including weakness on one side of the body and sensory deficits on the opposite side.
While trauma is a common cause of Brown-Séquard Syndrome, non-traumatic conditions can also lead to the development of this syndrome. Non-traumatic causes tend to result in a more gradual onset of symptoms, though in some cases, symptoms may appear suddenly.
Tumors that grow within or near the spinal cord can lead to Brown-Séquard Syndrome by compressing one side of the cord. These tumors can be either benign or malignant (cancerous) and may arise from the spinal cord itself or from surrounding tissues. Types of tumors that can cause BSS include:
Tumor growth tends to cause a gradual compression of the spinal cord, so individuals may experience slowly progressing symptoms over time, rather than the sudden onset seen in trauma cases.
Certain infections can lead to the development of Brown-Séquard Syndrome by causing inflammation, abscesses, or other damage to the spinal cord. Some common infections that can result in BSS include:
Infectious causes of BSS often involve a combination of inflammation, abscess formation, and direct damage to the spinal cord, which can compress one side of the cord and produce the characteristic symptoms.
Certain degenerative diseases, such as multiple sclerosis (MS) or amyotrophic lateral sclerosis (ALS), can cause damage to the spinal cord that results in Brown-Séquard Syndrome. In these cases, the disease process leads to demyelination (loss of the protective covering around nerve fibers) or degeneration of the spinal cord tissue, which may affect one side more than the other.
While degenerative diseases usually progress over time, leading to gradually worsening symptoms, they can sometimes produce abrupt changes in function, particularly if new lesions or damage occurs.
A disruption in the blood supply to the spinal cord, known as spinal cord ischemia, can cause Brown-Séquard Syndrome. Ischemia occurs when the arteries that supply blood to the spinal cord become blocked or damaged, depriving the tissue of oxygen and nutrients. This can result from conditions such as:
The onset of symptoms from ischemia is often sudden and may mimic the symptoms of traumatic spinal cord injury.
In addition to the more common causes listed above, there are some rare conditions that can lead to the development of Brown-Séquard Syndrome. These include:
While Brown-Séquard Syndrome can affect anyone, certain risk factors may increase the likelihood of developing the condition. These include:
The causes of Brown-Séquard Syndrome are diverse, ranging from traumatic injuries to infections, tumors, and degenerative diseases. While the syndrome itself is rare, understanding the underlying causes can help in diagnosing and treating the condition early, potentially improving outcomes for those affected.
Each cause carries its own unique challenges and treatment options, making it crucial for healthcare providers to accurately diagnose the source of the spinal cord injury. Whether through physical trauma, disease, or infection, the damage to one side of the spinal cord ultimately leads to the distinctive symptoms of Brown-Séquard Syndrome.