Know your spinal cord – Anterior spinal artery syndrome
Today we hit the three week mark in knowing your spinal cord! I’m hoping we can do a full four weeks, that would be quite the collection of knowledge. For those of you just joining in, you can find all of our posts in the neuroanatomy category ordered in reverse chronological order. As per the last few posts, we’ve covered the majority of the anatomy and now we are looking at different disorders of the spinal cord. Today we’re going to cover another type of injury, this one called anterior spinal artery syndrome, so let’s get started!
In our post yesterday we saw an image which sort of gave some spoilers to the more unique kinds of spinal cord injury. For those who haven’t read it, I suggest you do since it is very interesting, but if you’re only here for the anterior spinal artery syndrome, below is the image I’m referencing from yesterday. The middle image is what we will be covering today, tomorrow we will (probably) cover central cord syndrome.
Anterior spinal artery syndrome, labeled as anterior cord syndrome above, is somewhat similar to Brown-Sequard syndrome in that it almost a coronal version of a hemisection (Brown-Sequard). Like the name suggests, it is caused by a blood flow issue.
This type of lesion is caused by ischemia of the anterior spinal artery. Ischemia is a medical term meaning the flow of blood is restricted, this can happen anywhere on the body (one of the more common areas is the feet in fact). The anterior spinal artery is the artery that supplies blood to the anterior portion of the spinal cord. The anterior spinal artery follows the anterior median fissure and below we can see an actual cross section of cord showing the artery and because we tend to show the cord alone, we have included an image showing how blood is supplied to the cord.
Like Brown-Sequard, anterior cord syndrome can happen at any time and is not congenital (born with it). Because it disrupts the corticospinal tract, typically when it occurs you will have complete motor loss below the lesion. This will also disrupt the spinothalamic tract, you will also lose pain and temperature sensing below the lesion as well. What makes this type of injury interesting is that the medial lemniscus tract remains intact. Therefore, you still have proprioception (as well as vibration sensing). This means that you know where your extremities are in space, even below the injury; however, you have no real control over the affected extremities.
Causes of anterior cord syndrome are just as multifaceted as the causes of Brown-Sequard. These range from things like an aortic aneurysm, direct trauma to the aorta, surgery, disc herniation, damage to the spinal cord, sickle cell, decompression sickness, or even from infections like vasculitis. Like I said, it’s a long list and those are just a few of the things that comprise it.
Because this is caused by a blood flow issue, when it happens symptoms come on fast (10-15 minutes). Unfortunately, when diagnosed there isn’t much that can be done and the prognosis is not good. You can expect that while symptoms will (most likely) not get worse, they will not get better either. In fact, over 50% of people with anterior cord syndrome see little or no change to their condition and the mortality rate is approximately 20%.
Like with each of these I would like to remind you that treatment is in its infancy and unfortunately we haven’t seen much of an improvement for spinal cord injury outcomes since the 80’s really. However, that is slowly changing and with time (and a lot of luck) we will find ways to treat spinal cord injury. So while things are somewhat bleak now, they won’t always be. Who knows, maybe now that you’ve read this you will be inspired to find the fix.
Until next time, don’t stop learning!