The first lesion that we are going to take a look at is that of medial medullary syndrome. This occurs
within the medulla at the level of the olive and above the pyramidal decussation. This is a vascular lesion.
We can see that the basilar artery could be involved in causing this lesion. This lesion could also be due to
an issue with blood delivery through the vertebral artery. The anterior spinal artery could also be
involved in decreasing the blood flow to the medial region of the medulla. Here we see the involved
area of the medullary region. Here we have the medial aspect highlighted. Involved structures are going to
involve the corticospinal tract, the pyramid. You’re also going to damage the medial lemniscus.
The hypoglossal nucleus and its fibers are going to be lesioned. The pyramid is down here. Here, the medial
lemniscus is in this area. Then your hypoglossal nucleus is in the upper portion of this medial image.
Now, if you have damage to these three structures, then we have to think about what the symptoms
would be for each one that’s damaged. If we begin with the corticospinal tract and symptoms that attend here,
you’re going to be looking at contralateral hemiparesis in the upper and lower extremities. So again,
you’re looking at a tract and the findings will be contralateral and this is the case. That was one of the
pearls to keep in mind. Damage to the medial lemniscus component of this area is going to interfere
with the posterior columns. As a result, you’re going to have contralateral loss of vibration, conscious
proprioception as well as fine touch. Again, this is a spinal cord pathway, happens to be ascending but
findings of a pathway are going to be on the contralateral side of where the lesion is. Now lastly, we’re
going to involve a cranial nerve component. That is the hypoglossal nucleus and its fibers. When a
cranial nerve nucleus or the fibers are damaged, you’re looking at ipsilateral findings. So, since the
hypoglossal nerve innervates the tongue, you’ll have ipsilateral paralysis of the tongue. As a result,
when you ask a patient to stick out their tongue, the tongue will deviate to the same side of the lesion.