0:01

Well, I hope you're getting a sense that there are

0:03

so many reasons why a patient may have headaches.

0:08

The most common is going to be a migraine headache,

0:10

and that probably accounts for 90% of the patients

0:13

presenting to the emergency room with a severe headache.

0:17

However, we've looked at cases where there is

0:20

increased intracranial pressure in pseudotumor

0:25

cerebri or idiopathic intracranial hypertension.

0:28

I wanna show you this case.

0:30

This is a case of spontaneous intracranial hypotension.

0:38

In this situation, there actually is low

0:40

pressure intracranially, and the headache

0:44

that occurs with intracranial hypotension

0:48

is usually postural.

0:50

That is when the patient sits up or stands up,

0:53

they have a severe headache.

0:55

When they lie down, the headache goes away.

0:58

This is the etiology for the headache that occurs

1:01

after lumbar puncture or after, uh, spinal

1:07

anesthesia, where there is a CSF leakage at the

1:11

site of either the catheter that's put in for

1:14

spinal anesthesia or the needle tract

1:19

along which the spinal tap has been performed,

1:22

the lumbar puncture has been performed.

1:24

So you get leakage of CSF from that puncture area, and

1:28

that leads to low pressure in the brain, which leads to

1:33

a headache, which is postural intracranial hypotension.

1:38

The imaging findings of intracranial hypotension

1:40

are completely different from the imaging findings

1:43

of pseudotumor cerebri and pseudotumor cerebri.

1:47

You see, you have collapsed

1:48

venous sinuses, and you have the increased,

1:54

uh, you have an empty sella, and you

1:58

have the big optic nerve sheath complex.

2:00

Look at this case by contrast.

2:03

Here, what we see is a very large pituitary gland.

2:06

The pituitary gland actually is larger than normal

2:09

in appearance with intracranial hypotension.

2:12

What you see is the herniation

2:15

of the cerebellar tonsils

2:17

through the foramen

2:18

magnum, like a Chiari I malformation.

2:21

In fact, this is a curious case.

2:23

This patient had had a decompressive surgery

2:27

because it was thought that the patient had

2:29

idiopathic Chiari I malformation, when in point of

2:34

fact, this patient had intracranial hypotension

2:37

as the etiology for the patient's headaches.

2:40

On the parasagittal images,

2:43

what you see is enlargement—

2:46

not collapse, but enlargement—of the transverse sinus.

2:50

It's convex outward on both sides, so a big, fat, convex

2:57

outward venous sinus as opposed to sinus stenosis.

3:02

Look at this case. This case is really fascinating

3:04

because what you see on the axial scans is bilateral

3:12

herniation of the medial temporal lobe, the uncus,

3:16

across the tentorial edge and compressing the

3:20

brainstem. Everything is collapsing downward

3:24

and heading downward because of the low

3:26

pressure, which is occurring in the spinal canal.

3:32

On the coronal image, this is a

3:34

little bit better demonstrated.

3:35

You see the medial temporal lobes herniating

3:39

downward on either side of the midbrain.

3:41

This is all temporal lobe.

3:43

A tissue that should not be there, and it's all the

3:47

way down to the level of the internal auditory canal.

3:50

Here's the other uncus, medial temporal lobe

3:53

herniating downward. In this case, reduction

3:59

in the mammalopontine distance, so the

4:02

distance between the mammillary bodies and the pons.

4:06

That reduction in that distance

4:09

is another manifestation of

4:12

intracranial hypotension.

4:14

On post-gadolinium scan, you see that

4:18

the dura will show contrast enhancement.

4:21

This linear dural enhancement is also

4:26

very typical of intracranial hypotension.

4:30

Why does that occur? Effectively,

4:32

it's kind of venous congestion of the veins

4:34

of the dura, which leads it to have this

4:37

thickened appearance, and that also may lead

4:41

to prominent enhancement as well.

4:45

The epidural venous plexus in the spine will also be

4:50

prominent in a patient who has intracranial hypotension.

4:55

This is the epidural venous plexus down

4:57

here at C1-C2, and from right to

5:00

left, you see that this is very prominent.

5:02

Remember, in the midline, we don't

5:03

see it because there's some

5:05

dural duplication there. But off-midline, you have

5:09

the Batson plexus venous system, which is dilated

5:13

in patients who have intracranial hypotension.

5:19

I think that's, uh, all the findings

5:22

in this particular case.

5:25

However, this patient went on to get spinal imaging

5:30

in order to search for the source of the CSF leakage,

5:35

which was accounting for the intracranial hypotension.