Disease Overview

Brown-Séquard  syndrome is a rare disorder of the spinal cord.  The condition is named for Charles Brown-Séquard, a French physiologist of the 19th century.  It is a type of incomplete lesion resulting from impairment to one side only of the spinal cord; the other side of the spinal cord is left intact and functional.  Complete lesions, in contrast, disable the whole width of the cord.  The syndrome can develop from a variety of causes.

The spinal cord is part of the body’s central nervous system.  It contains neurons retrieving sensory information from the body to be transmitted to the brain.  For example, when you touch something hot, special sensory neurons detect this and send this information to the spinal cord.  Neurons in the spinal cord then convey the information to various regions of the brain.  The spinal cord also contains neurons that bring information from the brain to the rest of the body.  For example, when you want to move your arm, neurons in the brain send this signal via the spinal cord, communicating with other neurons in the spinal cord that stimulate the muscle cells that cause your arm to move.  The spinal cord is like a series of parallel highways that enable the body and brain to communicate with each other quickly.

Major problems occur when this highway gets blocked.  Most commonly this is due to traumatic injury to part or all of the spinal cord.  This creates a “hole” in the highway; the brain and body can no longer exchange information.

Classically, in Brown-Séquard syndrome, one lateral half of the spinal cord is unable to function (i.e., the left side or the right side).  An impairment involving some additional regions of the spinal cord or only part of the lateral half of the cord is sometimes termed “Brown-Séquard-plus.”  Patients with Brown-Séquard-plus might have some additional symptoms in addition to the classical impairment, or they might have only some of the classical symptoms.  Brown-Séquard-plus syndrome is much more common than pure Brown-Séquard.

Brown-Séquard or Brown-Séquard –plus syndromes usually result from transection or compression of the spinal cord.  It occurs most often in the neck region or in the upper back (in the cervical or thoracic regions), but can occur further down the cord.  Penetrating spinal trauma is the most common cause, e.g., from a gunshot wound or a knife injury.  More rarely, blunt trauma may cause the condition.

The nontraumatic causes of Brown-Séquard are numerous, though less common.  These include tumors originating from a part of the spinal cord, from the layers of tissue surrounding the spinal cord, or metastatic tumors originating from other sites.  Other mechanical causes are disc herniation, cervical spondylosis, cervical stenosis, or ossification of the ligamentum flavum.  Inflammatory causes include multiple sclerosis and transverse myelitis.   Infection related causes include tuberculosis, meningitis, syphilis, herpes zoster or herpes simplex, and empyema.  Causes due to blood flow issues include epidural hematoma, dissection of the vertebral artery, and hemorrhage or ischemia (lack of blood flow from various causes).  The condition also sometimes results from IV drug use or as a part of decompression sickness.

Depending on the origin and treatment of the syndrome, variable degrees of recovery occur.  Occasionally a Brown-Séquard pattern of symptoms may occur prior to symptoms which indicate a more complete lesion of the spinal cord.  If the symptoms are due to a mechanical problem which can be surgically altered, symptoms may diminish quite rapidly.  The syndrome carries a more favorable prognosis than do most other types of spinal cord injury.

The syndrome occurs in about 2% of traumatic injuries to the spinal cord.  These types of injuries occur in about 40 per million in the United States, resulting in about 12,000 new cases each year.  Thus doctors treat around 240 new individuals with Brown-Séquard syndrome in the US each year due to traumatic spinal cord injury.

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