Hydrocephalus: Etiology and Examination

00:01 Thanks for joining me on this discussion of hydrocephalus in the section of neurosurgery.

00:07 Let’s start by asking you a question.

00:09 What are the causes of hydrocephalus? I’ll give you a second to think about this.

00:16 Hydrocephalus is caused by anything that increases the volume of the CSF.

00:21 You may recall from our discussion in the trauma series about the Monro-Kellie doctrine.

00:26 Remember, the skull is a fixed space containing CSF, brain and blood.

00:33 This is a little different than traumatic brain injury patients because CSF and hydrocephalus develops over time.

00:40 And as a result, there's some compensatory mechanisms in play, so that the patient does not herniate, like a traumatic brain patient.

00:49 Now, let's review the normal drainage of the CSF.

00:52 As you know, CSF is produced in the choroid plexus.

00:56 It then travels to the lateral ventricle, third ventricles, fourth ventricles and eventually dumps into the subarachnoid space.

01:06 Any obstruction along this pathway can cause CSF hydrocephalus.

01:14 What are some physical findings of hydrocephalus? Commonly, cognitive deterioration.

01:20 This may be subtle.

01:21 It may not be a comatose patient, somebody who's got increasing confusion.

01:26 It may, particularly in elderly patient, present as suspicion for dementia.

01:33 Maybe the patient has some vomiting.

01:36 And frequently patients discuss nuchal rigidity and neck pain.

01:40 Sometimes, patients are suspected of having meningitis in these situations.

01:47 Frequently, patients also present with imbalance and gait disturbances.

01:55 Let's discuss normal pressure hydrocephalus.

01:59 Normal pressure hydrocephalus is very high yield and it's got a classic association syndrome.

02:05 That includes gait disturbances, dementia, urinary incontinence.

02:12 In general, normal pressure hydrocephalus – in other words, it doesn't increase intracranial pressures – are communicating in nature.

02:20 It's usually due to a decreased absorption as opposed to an obstructing hydrocephalus.

02:26 And as we discussed previously, they tend to be chronic and slow.