Brown-Sequard syndrome
Synonyms and keywords: Brown-Sequard's hemiplegia; Brown-Sequard's paralysis

# Overview
Brown-Sequard syndrome is an uncommon spinal cord disorder in which the spinal cord is injured but is not severed completely. Brown sequard syndrome results from an injury to one side of the spinal cord typically to the spine in the region of the neck or back. In many cases, some type of puncture wound in the neck or in the back that injures the spine and causes symptoms to appear.
Typically, loss of touch, vibration and position below the level of injury is seen which is known as hemi paralysis or asymmetric paresis. However, the sensory loss is mostly ipsilateral to the spine injury. Loss of sensation for pain and temperature on the contralateral to the side were injury was sustained.

# Historical Perspective
The term was first described in 1850 by the historically famous British neurologist Charles Edouard Brown-Sequard (1817-1896), who was a student of the anatomy and physiology of the spinal cord.     Brown-Sequard was quite a controversial and eccentric figure, and is also known for self-reporting "rejuvenated sexual prowess after eating extracts of monkey testis".  The response is now thought to have been a placebo effect, but apparently this was "sufficient to set the field of endocrinology off and running."
Interestingly, many nations claim him as their own, he was the son of an American sea captain and a French woman, living in a British territory. He studied in the US, France, as well as the UK. He described this injury which resulted from caning knives trauma in Mauritius.

# Classification

# Pathophysiology
Additional sign and symptoms may also occur in hemi section of spinal cord. Interruption of the lateral corticospinal tracts, the lateral spinothalamic tract, and occasionally the posterior columns clinically causes a spastic weak leg with brisk reflexes and a strong leg with loss of pain and temperature sensation. Spasticity and hyperactive reflexes may not be present with an acute lesion.
As a result of the injury to these three main brain pathways the patient will present with three lesions.
- The corticospinal lesion produces spastic paralysis on the same side of the body (the loss of moderation by the UMN).
- The lesion to fasciculus gracilis or fasciculus cuneus results in ipsilateral loss of vibration and proprioception (position sense).
- The loss of the spinothalamic tract leads to pain and temperature sensation being lost from the contralateral side beginning one or two segments below the lesion.  At the lesion site all sensory modalities are lost on the same side, and also an ipsilateral flaccid paralysis.

# Causes
The most common causes of Brown- Sequard Syndrome can be divided into traumatic, non-traumatic injuries and infectious causes.
Traumatic injuries including stabbing, road traffic accidents fractured and miss alignment from a fall and gunshot wounds are most commonly seen as cause of brown Sequard syndrome.
Various non-traumatic injuries can also result in brown sequard syndrome comprising, cervical spondylosis, vertebral disk herniation multiple sclerosis, cystic disease and vertebral tumors.
Tuberculosis, transverse myelitis, herpes zoster and meningitis are some of the infectious causes linked to Brown Sequared syndrome.

# Differentiating Brown-Sequard syndrome from Other Diseases
Brown -Sequard syndrome must be differentiated from other diseases that cause poor muscle tone, muscle weakness, muscle spasticity and areflexia such as Motor neuron disease, Progressive spinal muscular atrophy, Primary lateral sclerosis and stroke..

# Epidemiology and Demographics
Brown sequard syndrome affects both male and female equally. Estimates indicate among all traumatic causes, 4% of spinal cord injuries are Brown-Sequard Syndrome. 
Approximately 11,000 new cases are reported each year in the United States alone, which include incomplete paraplegia and tetraplegia.
In 2007, the prevalence of brown- sequard syndrome was estimated to be 17.1% of patients diagnosed with spinal cord injuries admitted to Virginia commonwealth university,Virginia,USA..

# Risk Factors
Although risk factors for brown sequard syndrome is not well established yet, it has been observe that few pathological conditions can lead to the brown sequard syndrome. Among others spontaneous cervical epidural hematoma is a rare entity in clinical practice, which may results in brown sequard syndrome or more fatal progressive course.
Degenerative bone disease, bony spurs and diseases involving the spinal cord, such as multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Guillain-Barre syndrome, and transverse myelitis are considered as risk factors for brown sequard syndrome.

# Screening
There is insufficient evidence to recommend routine screening for .

# Natural History, Complications, and Prognosis
Symptoms of Brown sequard are frequently loss of sensation of pain and temperature, which usually appear after affected individual experiences a trauma to the neck or back. Weakness due to atrophy of muscles may occur. Further more loss of bowel and bladder control is commonly seen.
Overall prognosis of Brown sequard syndrome is good with almost complete recovery if timely management is provided. More than 90% of affected individuals recover bladder and bowel control, and the ability to walk.
Common complications of Brown -sequard syndrome include hypotension, spinal shock,UTI and pneumonia, hypercalcemia, osteoporosis, vertebral artery dissection, pressure ulcers and bowel impaction. These complications could be due to the trauma causing 'BSS or the overall problem in the body . Also patients with the pathology in their cervical or upper thorax spine need respiratory support.

# Diagnosis

## Diagnostic Criteria
There are no established criteria for the diagnosis of Brown-Sequard Syndrome.

## History and Symptoms
The majority of patients with Brown-Sequard Syndrome experience this syndrome following a trauma to their neck or back region. First symptoms are usually loss of pain and temperature sensation in dermatomes below the traumatized region ,which is due to the decussation of antero- lateral fibers within spinal tract through white commissure resulting in contralateral loss of pain and temperature sensation. Also ,decussation of corticospinal tract at medulla leads to ipsilateral spastic paresis and ipsilateral of vibration and proprioception sensation.

## Physical Examination
Although there are various cause for Brown-Sequard Syndrome, the main cause is due to traumatic injury.So initial examination for these patients should follow the ABCDE protocol suggested by advanced trauma life support.cervical spine should be immobilized. furthermore,Rectal exam should be done and ASIA score should be evaluated'Also other important causes of this syndrome such as infection,mass effect,stroke and multiple sclerosis should be ruled out.
The majority of patients with this syndrome ,usually experience classic hemi -cord syndrome,ipsilateral motor paralysis and loss of vibration and proprioception  sense .IN addition loss of pain and temperature sense on the other side.Loss of bowel and bladder control may be seen.

## Laboratory Findings
There are no diagnostic laboratory findings associated with Brown-Sequard Syndrome unless the disesase is due to spinal cord infections.

## Imaging Findings
MRI is the  imaging of choice in spinal cord lesions.The features of MRI in any case depends on the underlying cause. However, all of them may show unilateral pathology.

# Treatment
Like any other diseases, treatment of Brown-Sequard Syndrome is based upon the underlying cause. As the most common cause of this syndrome is due to spinal cord injuries,the first step in the management  would be dealing with injury then proceeding to BSS management . There are various options for treatment plan of BSS, such as medical,physical,occupational,recreational and surgical but there isn't any specific choice for it's treatment. Early intervention is usually associated with good prognosis. Although, in severe motor injury there is a low chance of improvement.

## Medical Therapy
corticosteroids are used in acute treatment of SCI through reducing the spinal cord inflammation .Also drugs that control muscle spasms may be prescribed to control muscle symptoms. Supportive treatments including braces, hand splits and wheelchairs may be essential to help the affected population to resume their daily activities.
However, there are some resources recommending not to use corticosteroids .

## Surgery
surgery  for those patients with BSS with specific underlying causes such as acute disc herniation or tumors is associated with good surgical outcome.
Also, surgery is recommended in patients with progressive neurologic deficits and unstable spine fracture.

## Prevention
There are no established measures for the primary prevention of Brown -Sequard Syndrome.