Brown-Sequard syndrome

The Brown-Sequard syndrome is a cluster of signs and symptoms resulting from lateral hemisection of the spinal cord (severing the left or right side). Precise hemisection is clinically uncommon but is occasionally seen in the context of knife or gunshot injuries to the spine.

The syndrome was first described by the prominent 19^th Century Neurologist Charles-Édouard Brown-Séquard who observed it in  the accidental injury of a sugar-cane harvester in Mauritius. It commonly appears in written medical exams and vivas as predicting the pattern of deficit requires a basic understanding of spinal tract anatomy.

Though there are many spinal tracts, three are clinically fundamental: the spinothalamic, the corticospinal and the dorsal-column/medial lemniscus (DCML).

The corticospinal tract is a motor tract transmitting signals from the motor cortex through the cord, ultimately the signal reaches skeletal muscle.

The spinothalamic and DCML tracts are sensory, transmitting sensation from peripheral receptors up through the cord to the brain. The spinothalamic tract transmits pain and temperature sensations while the dorsal columns transmit fine touch, vibration and proprioception (joint-position sense).

These tracts decussate (cross the midline) at different points. The corticospinal and DCML tracts largely decussate in the region of the medulla, the lower part of the brainstem. The spinothalamic tract decussates in the spine itself.

Cord hemisection will terminate all signals below the lesion. There is therefore ipsilateral (same-sided) loss of corticospinal and DCML function below the lesion. The spinothalamic tracts interrupted have largely already crossed; there is therefore contralateral (opposite-sided) loss of spinothalamic function. The clinical presentation is an ipsilateral motor, fine touch, vibration and proprioception deficit and contralateral deficit in pain and temperature sensation.

Treatment for traumatic Brown-Sequard has changed little since Brown-Sequard’s day and is essentially supportive. Early high-dose steroids have been shown to improve outcome, probably by reducing secondary injury caused by inflammation. As our understanding of neurobiology improves, more effective treatments will become available. These may involve stimulating neural regeneration and providing microcellular scaffolding to direct it.

This simplified description would attract coughs and frowns from your local friendly Neurologist. For more detail and useful diagrams see here and here.