Normal pressure hydrocephalus

Background

• May be idiopathic (mostly the focus here) or secondary (to prior infection, ICH, TBI, or radiation)
• Idiopathic is more common in older patients and is somewhat a disease of aging

Clinical Manifestations

• "Wobbly, wet, and wacky"
• Earliest symptoms is gait instability/apraxia ("magnetic gait") progressing over months to years
  • May be shuffling, magnetic, or wide-based
  • Increased mediolateral variability during quiet standing
  • Postural instability worsens with eye closure
• Next is dementia
  • Cognitive symptoms include psychomotor slowing, forgetfulness, decreased attention/concentration, impaired executive function
  • Apathy is a notable feature
• Usually last symptom is urinary incontinence, in about 50% of patients at diagnosis
  • First as urgency with an inability to reach the bathroom in time, then later progressing to incontinence with apathy
• There should be no headaches, nausea/vomiting, visual changes, or papilledema

Differential Diagnosis

• Dementia with Lewy bodies
• Parkinson disease dementia
• Progressive supranuclear palsy
• Multiple system atrophy
• Corticobasal syndrome
• Alzheimer disease
• Vascular dementia

Investigations

• Should have normal CBC, lytes, creatinine, vit B12, TSH, calcium
• CT head showing hydrocephalus
• Lumbar puncture confirming normal pressure
  • CSF glucose and protein are typically normal
• High-volume lumbar puncture (30 to 50 mL)
  • Observe for improvement, particularly in gait
  • Can use objective measures like a timed up and go test, where 5 seconds improvement is considered supportive

Grading

Grade	Gait	Cognition	Urinary Incontinence
0	Normal	Within normal range	Absent
1	Unsteadiness without objective abnormality	No clear dementia, but apathy present	Frequency and/or urgency without incontinence
2	Needs a cane	Needs support in social functioning, but remains independent at home	Occasional episodes at night
3	Needs a walker, or 2 canes	Requires partial assistance at home	Intermittent episodes during the daytime
4	Unable to ambulate	Fully dependent	Frequent urinary incontinence

Management

• If there is improvement in symptoms after large-volume lumbar puncture, consider implanting a ventriculoperitoneal shunt