Brown-Sequard syndrome

Brown-Séquard syndrome, also known as Brown-Séquard's hemiplegia and Brown-Séquard's paralysis, is a loss of sensation and motor function (paralysis and ataxia) that is caused by the lateral hemisection (cutting) of the spinal cord. Other synonyms are crossed hemiplegia, hemiparaplegic syndrome, hemiplegia et hemiparaplegia spinalis and spinal hemiparaplegia.

Classification
Any presentation of spinal injury that is an incomplete lesion can be called a partial Brown-Séquard or incomplete Brown-Séquard syndrome, so long as it has characterized by features of a motor loss on the same side of the spinal injury and loss of pain and temperature sensation on the opposite side.

Diagnosis
Magnetic resonance imaging (MRI) is the imaging of choice in spinal cord lesions.

Causes
Brown-Séquard syndrome may be caused by a spinal cord tumor, trauma (such as a gunshot wound or puncture wound to the neck or back), ischemia (obstruction of a blood vessel), or infectious or inflammatory diseases such as tuberculosis, or multiple sclerosis.

Brown-Séquard syndrome is an incomplete spinal cord lesion characterized by clinical presentation reflecting hemisection of the spinal cord (cutting the spinal cord in half on one or the other side). It is diagnosed by finding motor (muscle) paralysis on the same side as the lesion and deficits in pain and temperature sensation on the opposite side on physical exam. This is called ipsilateral (on the same side as the spinal cord lesion) hemiplegia and contralateral (on the opposite side) pain and temperature sensation deficits. The loss of sensation on the opposite side of the lesion is because these nerve fibers of the spinothalamic tract cross the spinal cord. In its pure form, it is rarely seen. Incomplete forms are also observed. The most common cause is penetrating trauma such as a gunshot wound or stab wound to the spinal cord. This may be seen most often in the cervical (neck) or thoracic spine. Other causes are tumors, bleeding episodes, tuberculosis, and multiple sclerosis.

The presentation can be progressive and incomplete. It can advance from a typical Brown-Séquard syndrome to complete paralysis. It is not always permanent, and progression or resolution depends on the severity of the original spinal cord injury and the underlying pathology that caused it in the first place.

Pathophysiology
The hemisection of the cord results in a lesion of each of the three main neural systems:
 * the principal upper motor neuron pathway of the corticospinal tract
 * one or both dorsal columns
 * the spinothalamic tract

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 cuneatus 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.

Treatment
Treatment is directed at the pathology causing the paralysis. If it is because of trauma such as a gunshot or knife wound, there may be other life threatening conditions such as bleeding or major organ damage which should be dealt with on an emergent basis. If the syndrome is caused by a spinal fracture, this should be identified and treated appropriately. Although steroids may be used to decrease cord swelling and inflammation, the usual therapy for spinal cord injury is expectant.

Epidemiology
Brown-Séquard syndrome is rare.

History
The syndrome was first described in 1850 by the famed British / Mauritian neurologist Charles-Édouard Brown-Séquard (1817-1896), who studied the anatomy and physiology of the spinal cord. Brown-Séquard 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. He was born in Mauritius. He studied in the US and France and worked several years in the UK, US and France. He described this injury after observing spinal cord trauma happen to farmers while cutting sugar cane in Mauritius.

French physician Paul Loye attempted to confirm Brown-Séquard's observations on the nervous system by experimentation with decapitation of dogs and other animals and recording the extent of each animal's movement after decapitation.