NPH Flashcards
What are the 4 types of NPH?
- Idiopathic (disease of older adults, >75)
a. DESH
b. Non DESH - Secondary (infection, hemorrhage, TBI, radiation - all affect CSF absorption)
- Familial
- Congenital/developmental
What are the etiologies of CSF in NPH?
- Overproduction in choroid plexus
- Blocked pathway at cerebral aqueduct
- Blocked pathway at all sites
- Impaired absorption in arachnoid granules
What is the triad of NPH presentation?
Complete triad in ~60% patients
No signs of inc ICP
1. Gait abnormalities
- Usually first, worsens over time
- Wide based, shuffling, magnetic, turn on
- Instability during walking, turning, standing
- Most responsive to shunting
2. Urinary urgency
- Urge and frequency then incontinence
3. Cognitive impairment
- Executive, psychomotor slowing, attention, apathy
- STM and poor verbal fluency in some
Other neurologic signs found in NPH outside of main triad
Snout reflex
Glabellar reflex
Palmar reflex
Bradykinesia
What is the grading scale for NPH?
iNPH Grading Scale
0-4 based on gait disturbance, dementia and UI
Imaging finds for NPH
MRI
- Ventriculomegaly out of proportion to sulcal enlargement (Evans ratio >0.3, width of frontal horns of lateral ventricle to internal width skull)
- DESH (disproportionately enlarged subarachnoid space with hydrocephalus)
- Periventricular white matter changes (due to transependymal egress of fluid)
- Loss of signal in aqueduct of Sylvius
Role of LP in NPH
Used for diagnostic
High frequency of false negatives
1. Check opening pressure, usually <200 mmH2O
2. Remove 30-50 cc
3. Monitor for improvement in 30-60 mins
- TUG, steps taken to turn 180 twice, 360 three times
Gait usually improves first, then cognition and incontinence
Japanese criteria for probable iNPH
- > 1 feature of triad and can’t be explained to another condition and no obvious preceding cause of ventriculomegaly
- CSF pressure <200 and normal content
- Either:
- Neuroimaging DESH
- Sx improved after CSF test
Management of NPH
Shunting - for primary and secondary
VP (ventriculo-peritoneal)
VA (atrial)
LP (lumbo-peritoneal)
Complications of shunting in NPH
Pooled rate ~38%
1. CSF over drainage = HA (33%), SDH
2. Blockage
3. Infection (12%)
4. Displacement
5. Seizures
6. Local damage - SDH, perforation
7. Abdo CSF collections (pseudocyst, CSFoma)
What is ex vacuo ventriculomegaly?
Ventriculomegaly due to age related atrophy of the brain
The ventriculomegaly is proportional to atrophy and sulcal size
What is the best time to assess for improvement to CSF study?
American/Canadian
30-60 mins after test done
(30-60 cc)
Japanese
2-4 hrs and again at 24 hours
(30-50 cc)
Mimickers of NPH
- Parkinson’s disease
- LBD
- MSA
- PSP
- CBD
- Vascular dementia
- Neurosyphilis
- Medications - anticholinergic
8 features of gait of normal pressure hydrocephalus
- Decreased step height
- Decreased step length
- Decreased speed
- Inc trunk sway
- Wide based
- Toes turn outward
- Retropulsion
- En bloc turning
4 features to suggest NPH would be responsive to shunting
- DESH on MRI
- Positive response to tap test
- Elevated Ro
- Impaired cerebral blood flow reactivity to acetazolamide
