0:00

With that, we're, we're gonna move to the what you came to see,

0:03

which is normal pressure hydrocephalus.

0:04

It usually affects older adults in the sixth and seventh decades of their life.

0:09

Um,

0:09

it results from an increased production of C ss f volume without obstruction or,

0:13

or, or elevated pressures,

0:15

presents with gait disturbances and cognitive decline and incontinence in some

0:19

cases. Um,

0:21

some of the etiologies are speculated to involve sort of changes in compliance

0:24

of the brain that result in kind of compression of the per ventricular white

0:27

matter and result in ischemia. Um,

0:29

imaging usually demonstrates enlargement of the lateral and third ventricles out

0:33

of proportion of the degree of volume loss with some resultant reduction in the,

0:37

um, uh, cosal angle.

0:39

So you get basically this acute colossal angle at the level,

0:41

the posterior Essure. One thing to keep in mind though,

0:44

is that this colossal angle is not specific to N P H. I've heard people say, oh,

0:49

it must be NPH H 'cause the collosal angle is narrow. That's not true. It just,

0:52

it, it's a way of determining whether you're dealing with hydrocephalus or just

0:57

plain old volume loss.

0:58

So if you measure the close angle and it's narrower than 80 degree, uh,

1:02

80 degrees, um, uh, and, uh, the patient essentially, uh,

1:07

has, you know,

1:07

findings that are concerning for N P H and they don't have aqueduct stenosis,

1:11

then probably is N P H. But at that point,

1:13

you're really just distinguishing N P a, or sorry,

1:16

you're just distinguishing hydrocephalus from volume loss. You're not dis,

1:19

you're not really making the diagnosis of M P H,

1:21

you're just suggesting that there's some form of communicating hydrocephalus at

1:24

that point. Um,

1:26

hyperdynamic flow through the cerebral aqueduct is often present in most of

1:29

these cases, but the diagnostic criteria for this is still pretty controversial.

1:33

Um, a lot of the, the work on, um, C S F flow dynamics was done here by,

1:38

um, a former chair. His name was Bill Bradley,

1:41

and I was actually here when we did the updated studies on our GE machine.

1:45

But originally all this was done on a Siemens, uh, m r I machine, uh, with 10,

1:50

20 and 30, uh, van, um, velocities or van um, settings.

1:55

Um, and essentially what they found was, uh,

1:57

stroke volume of greater than 42 microliters was, um,

2:01

correlated with a higher probability of shunt responsive N P H.

2:05

And then the same thing was found on the GE flow sequence, but,

2:08

but only for greater than a hundred microliters. Um, that being said,

2:12

these were small numbers of patients that we took and, um,

2:16

I think with that low of an end number, you have to be a little bit skeptical.

2:19

Same thing for the flow rate of 24 milliliters per minute. Um, that,

2:23

that also could indicate N P H.

2:25

The way I think about it though is that the gold standard is still temporary

2:28

diversion of C Ss f the actually, um, see if the patient's symptoms resolved.

2:32

So if you do a high volume LP or a three day lumbar drain trial and they,

2:35

they improve, then you know, they,

2:37

they probably do have N P H I look at the, um, the,

2:41

the flow study as sort of an adjunct to help me make a decision in those

2:45

patients where we have some equivocal issues. So things that can cause your,

2:50

your, um, uh,

2:51

gold standard temporary C S F diversion to be somewhat, um,

2:56

uh, more dodgy or difficult to trust

2:58

Is patients who've been immobilized for a long time and can't walk.

3:01

So you can't really do a get up and go test. You have to rely on their M M S E,

3:05

uh, or their MOCA test, um, after diversion. And honestly,

3:08

those things can be a little bit variable from day to day,

3:11

even with just normal dementia patients.

3:12

So they could just be having a good day.

3:14

And I think that the CSS F flow study can really help in those categories.

3:18

It can also, you know, help with screening too. If you,

3:21

if you're not really sure you're dealing with N P H and um,

3:24

you just wanna see if there's hyperdynamic flow and it kind of push you in that

3:27

direction, it can be helpful to do that. Um, but I, I think in the end,

3:31

you're still gonna have to, to,

3:32

to do it LP or a lumbar drain to be 100% certain that that's what you're dealing

3:36

with before you shunt the patient. And again,

3:38

it's treated by either a VP or LP shunt. I, I tend to like, um,

3:42

VP shunts for these patients because the LP shunts just not as easily controlled

3:45

and as, as older patients often do,

3:48

these patients usually have conant and volume loss. And if you do an LP shunt,

3:51

it's harder to control it.

3:53

And you can easily over drain these people with LP shunt and they can end up

3:57

with subdural collections and or, or subdural omas. You can end up with a,

4:00

a different problem going forward.