Hydrocephalus

Question 1

Where is CSF made?

Answer 1

Choroid Plexus of Lateral ventricles

Question 2

Describe normal flow of CSF

Answer 2

Choroid plexi -> Lateral vent -> 3rd Vent -> Cerebral aqueduct ->4th vent - > basal cisterns, tentorium, subarachnoid space -> arachnoid villi -> venous channels of the sagittal sinus

Question 3

Why is it called Normal pressure hydrocephalus (NPH)?

Answer 3

• Pathologically enlarged ventricular size with normal opening pressures on lumbar puncture.
• Form of communicating hydrocephalus
• To distinguish from obstructive (noncommunicating) hydrocephalus, in which there is a structural blockage of the cerebrospinal fluid (CSF) circulation within the ventricular system

Question 4

Can be idiopathic or secondary. Causes of secondary is usually:

Answer 4

Impaired absorption of CSF

• Intraventricular or subarachnoid hemorrhage (either from aneurysm or trauma)
• Prior acute or ongoing chronic meningitis (from infection, cancer, or inflammatory disease).
• Paget disease at the skull base (rarely)

Question 5

Clinical Features

Answer 5

Usually - Gait dysfunction (Wobbly)

• Most responsive to shunting
• Magnetic or “glue-footed” gait, gait apraxia
• Move slowly and take small steps, often with a wide base
• Difficulty turning - Leads to falls

Cognitive impairment (Wacky) - Frontal + subcortical features

• Develops over months (after gait changes)
• Psychomotor slowing
• Decreased attention and concentration
• Impaired executive function
• Apathy

Urinary incontinence (Wet)

• Usually urinary urgency at early stages
• At later stages pt is apathetic re: incontinence

Notable negatives
- No HA/N+V/Visual loss/papilloedema

Question 6

Differential Dx of NPH:

Answer 6

Dementia with Lewy bodies

Parkinson disease dementia

Progressive supranuclear palsy

Multiple system atrophy

Corticobasal syndrome

Question 7

Investigations for suspected NPH

Answer 7

Cognitive testing - “frontal-subcortical” dysfunction, slow in tasks, poor in tesdts of divided attention/executive function/fluency/learning

MRI - Ventriculomegaly )without evidence of obstruction) out of proportion to sulcal enlargement (cortical atrophy), periventricular white matter high signal (correlates with cognitive impairment), aqueduct flow void (poor uptake in aqueduct due to high flow velocity)

If above then can perform the following to determine success of a ventriculoperitoneal shunt:

• High volume LP witth gait assessment
• Lumbar drain trial
• Cisternography

Question 8

Management of NPH

Answer 8

Ventricular shunting (usually VP)

• Most useful to improve gain, cognition not greatly altered
• Usually performed only if demonstrated improvement with trial test and minimal negative prognostic markers (dementia, alcohol, atrophy ++ on MRI)
• 50-60% response in gait