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 19th 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.