Taking Charge of Your Health

Brown-Sequard syndrome, first described by
the physiologist Charles-Edouard Brown-Sequard, is a condition associated with hemisection
or damage to one half of the spinal cord. The hemisection damages neural tracts in the
spinal cord that carry information to and from the brain. This results in a loss of sensations like
pain, temperature, touch, as well as paralysis or loss of muscle function in some parts of
the body. Now, if you look at the cross-section of the
spinal cord, the white matter is on the outside and the gray matter is on the inside, and
overall it looks like a butterfly. If we draw a horizontal line through the spinal
cord, the front half is the anterior or ventral half, and the back half is the posterior or
dorsal half. And the butterfly wings are sometimes referred
to as horns; so we have two dorsal horns that contain cell bodies of sensory neurons and
two ventral horns that contain cell bodies of motor neurons. The white matter consists of myelinated axons
which are separated into tracts that carry information to and from the brain. Think of them like highways for neural signals,
where some highways carry sensory information to the brain and some carry motor information
from the brain to the muscles. There are a few main tracts to remember. First, there’s the spinothalamic tract which
is an ascending pathway and it’s divided into two parts. The lateral tract carries sensory information
for pain and temperature, while the anterior tract carries information for crude touch–or
the sense one has been touched, without being able to localize where they were touched. Second, there are two ascending dorsal column
tracts- the fasciculus gracilis which carries sensory information from the lower trunk and
legs, and the fasciculus cuneatus which carries sensory information from the upper trunk and
arms. These tracts both carry sensations like pressure,
vibration, fine touch – which is where you can localize where you were touched, and proprioception
which is an awareness of your body position in space. Finally, there’s the corticospinal tract
which is a descending pathway that carries motor information from the brain to different
muscles in the body and it controls voluntary muscle movement. So, sensory information has to go through
three neurons to reach the brain; kind of like 3 people in a relay race. For example if you accidentally touch a hot
pan, the sensation of pain and temperature is carried from the nerves in the skin of
your fingers, through a 1st order neuron- which is a pseudounipolar neuron. A pseudounipolar neuron has a cell body from
which only one axon comes out- and then that axon splits into two branches- a lateral branch
that comes from the periphery and the a medial branch that runs towards the spinal cord. So, the nerve in the skin of your fingers
is served by the lateral branch of a 1st order neuron which carries the sensation to the
dorsal root ganglion. That’s where the cell body is located along
with the rest of the cell bodies of other pseudounipolar neurons. From there the signal continues through the
medial branch and into the spinal cord to reach the dorsal horn. Here, it passes off the sensory information
“baton” by synapsing with a 2nd order neuron which sends off its own axon which
ascends 1 or 2 spinal segments and crosses over to the opposite side to travel up the
spinal cord and eventually synapse with a 3rd order neuron located in the ventral posterior
nucleus of the thalamus. This 3rd order neuron then sends its axon
up to the sensory cortex of the brain, letting you know that there’s tissue damage. Similarly, if you suddenly grab a vibrating
cell phone, the sensation of vibration is carried from the nerves in the skin of your
palm, via the fasciculus cuneatus- which is a collection of nerves all composed of first
order neurons. The fasciculus cuneatus is contained within
the dorsal white column, located posteriorly in the white matter of spinal cord. The 1st order neuron then ascends up along
the same side of the whole length of the spinal cord to reach lower level of medulla oblongata
where it synapses with the cell body of a 2nd order neuron in the nucleus cuneatus. The 2nd order neuron then sends off an axon
that crosses over to the opposite side of the medulla, and travels up to the ventral
posterior nucleus of the thalamus to synapse with a 3rd order neuron. The 3rd order neuron then sends up an axon
that carries the sensory signals to the primary somatosensory cortex of brain, letting you
know that your phone is vibrating. Once your brain receives sensory information,
it sends a motor signal down the upper motor neurons through the corticospinal tract in
the midbrain and cross to the opposite side at the medulla before continuing down the
spinal cord. There, they synapses with lower motor neurons
in the ventral horn, and the lower motor neuron axons then leave the spinal cord to innervate
the muscles of your arm and forearm, which allows you to lift your fingers and hand from
the hot pan or pick your cell phone up. Hopefully this all happened quickly so you
haven’t sustained major tissue damage and the caller hasn’t hung up. In Brown-Sequard syndrome, a vertebral bone
fracture or any kind of penetrating trauma like a gunshot injury or stab wound in the
back can lead to the hemisection of the spinal cord; and this mostly happens in the neck
or cervical region. Besides trauma, non-traumatic conditions like
a spinal cord tumor may compress the spinal cord and lead to Brown-Sequard syndrome. Suppose a person was stabbed in the neck and
had a complete right hemisection of the spinal cord. This means all the principal neural tracts
in the right side of spinal cord are now damaged. Damage to the right sided corticospinal tract
means that, below the level of lesion, the lower motor neurons, like those going to the
right leg, are no longer receiving signals from the upper motor neuron, so the muscles
they control become paralyzed, this is called ipsilateral hemiplegia or paralysis on the
same side. Interestingly, these neurons become so starved
for stimulation, they become hypersensitive and start firing inappropriately, causing
increased muscle tone and muscle spasms so we call this spastic paralysis. Meanwhile, at the level of lesion, the lower
motor neuron of the right ventral horn will also be damaged. This means that the muscles innervated by
these lower motor neurons, like those in the arms, will not receive any neuro input at
all, so they go limp and decrease in tone, which is called flaccid paralysis. Similarly, there’s damage to the dorsal
column on the right side, which will lead to loss of fine touch, pressure, vibration,
and proprioception in the right side of the body at the level of the injury and below
it. Now the spinothalamic tract is a bit different
because it crosses over to the opposite side of the spinal cord 1 or 2 spinal segments
above where the 1st order neurons enter. So, damage to the right spinothalamic tracts
will cause loss of pain, temperature and crude touch sensation from the opposite or left
side beginning one or two segments below the lesion. But, at the level of the lesion, the spinothalamic
tract of the same right side will be damaged too. This will lead to complete loss of all cutaneous
sensation at the level of lesion. Besides those three tracts, very rarely, a
hemisection of the spinal cord above the T1 spinal level can also damage the sympathetic
chain that runs alongside the spinal cord and supplies the facial region. This leads to Horner’s syndrome on the same
side of the face as the lesion which include symptoms of miosis or constricted pupil, ptosis
or droopy eyelid, and anhidrosis or failure to sweat. Now, in clinical scenarios, a complete right
side or complete left side hemisection is pretty rare. That’s why, most of the time, individuals
with Brown-Sequard syndrome will only present with an incomplete hemisection and some sensory
or motor problems, depending on which tracts are damaged. For example, if an individual has been stabbed
in the back and has no pain and temperature sensation on the left side, but normal motor
function and normal fine touch and vibration, it means that there’s only damage to the
spinothalamic tract of the right side. Finally, magnetic resonance imaging or an
MRI, can be used to confirm any lesion or within the spinal cord. The treatment for Brown-Sequard syndrome is
mainly supportive and focused on rehabilitation with physical and occupational therapy. Typically, cord swelling and inflammation
can be managed with corticosteroids. All right, as a quick recap, Brown-Sequard
syndrome is a condition associated with hemisection of spinal cord which usually damages descending
corticospinal tracts, ascending dorsal column tracts and spinothalamic tracts. The result is paralysis and loss of proprioception
on the same side as the injury or lesion, and loss of pain and temperature sensation
on the opposite side of the lesion.

64 thoughts on “Brown-Séquard syndrome – causes, symptoms, diagnosis, treatment, pathology

  1. thank you i wish you were my teacher in medical college. I dont know why everything is so difficult in medical college and so easy on youtube.

  2. Congratulations for an excellent presentation.. grammar, assimilative graphics, subject knowledge, Thank you indeed.

  3. Very good video as always! However it'd be a lot more helpful if you orientated the spinal cord segment in the beginning 180° so the ventral aspect is actually anterior as it can get confusing esp as you rotated it later in the video the correct way round

  4. Osmosis , could please put videos on other neurological diseases like Lateral Medullary Syndrome , Medial Medullary Syndrome , etc.

  5. Hi im just confused as to why LMN lesion will cause spastic paralysis in lower limbs but flaccid paralysis on upper limbs?

  6. The flexor withdrawl reflex (instantly moving hand away from a hot pan) is a polysynatptic reflex mediated solely in the spinal cord. But eventually the dorsal column system does bring the injury to conscious awareness… but that's not necessary for your hand to jerk back.

  7. Perfect presentation.. if anybody could not get the video..go through dr.najeebs video and this will give you best revision of that long version where you can form your base …thank you osmosis.

  8. Great video, such an awesome resource for referencing. Only two things I would like to comment on:

    1. Lissaur's/Posterolateral Tract: I believe the primary sensory neuron of the spinothalamic tract travels up/down 1-2 spinal segments PRIOR to synapsing with the secondary sensory neuron in the substantia gelatinosa.

    2. Corticospinal decussation at medullary pyramids: This is a minor artistic issue, but I believe the pathway of the corticospinal upper motor neuron should be passing through the pyramids of the medulla (anterior brainstem) as opposed to the dorsal aspect of the brainstem.

  9. Crazy how this 10 min video summarised everything I was struggling to learn for months in a comprehensive and easy to understand manner…….phenomenal video

  10. Brilliant but too fast, you could have stretched it to 13 min. Also drawing lines to describe what it is and the tracts together was throwing me off a bit. Maybe do a short description at the beginning or leave them out.

  11. What is meant by "at the level of the lesion" vs. "below the level of the lesion"? Is level meant to indicate a certain dermatome or spinal column level?

  12. great video!! Thanks a lot, but I guess, you`ve got a little mistake there, [3:32] if this is the spinothalamic tract, the 2nd order axon should cross the spinal cord and join spinothalamic tract in the anterior portion of the spinal cord – you visualize that it goes in the posterior part of spinal cord 🙂 hope I'm right 🙂

  13. FYI any spinal cord injuries or diseases are completely covered under VA help, if you are a honorably discharged military service member

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  15. Hello, is it possible to have Brown Sequard Syndrome with no flexion of the leg (0/5) but with extension (2/5)? Thank you!

  16. Great video but I do have one question. Why if there was a lesion or injury to the right side of the spinal cord cause paralysis on the ipsilateral side. Wouldn't it be the contralateral side be affected because the right side of the brain controls the left side of the body? I know all the exam questions I've taken says ipsilateral motor loss and contralateral temperature/pain loss, but theoretically, it should be the opposite. Can anyone explain this to me?

  17. A correction required !
    Thank you for the video.
    In 3:20, you've described first order neutrons for pain & temperature relaying in dorsal horn. Should it not be on the Lateral horn ?

  18. Such a great video, guys! Thank you!
    There is one mistake I've noticed : 3:32 fibres of Spino-thalamic tract after they cross to controlateral side, in fact, they continue in a FRONT-LATERAL bandle of white matter in spinal cord (not at the back as it can appear from the video)
    That's important to mention
    All the rest is better than any tutorial I've seen
    Keep on doing medical studies more fun!

  19. Hi, am physiotherapists from Nigeria, I really find your video interesting. Keep the good job.
    But I will suggest if you can expand your scope of video to the field of physical therapy.
    Pls I just wanna you to start doing videos in physical therapy. Thanks

  20. hi osmosis, i think theres an illustration mistake at 5:00 the corticospinal tract should decussate at the medullary pyramids instead.

  21. at 6.10 , its upper motor neuron lesion causing spasticity.and at the level of lesion it has flaccid paralysis bcoz of lower motor neuron lesion

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