Neurology · Year 3 · from Neurology

Case 3: Normal Pressure Hydrocephalus (NPH)

Patient Demographics

  • Age: 78 years
  • Sex: Male
  • Occupation: Retired postal worker

Chief Complaint

"He walks like his feet are glued to the floor, and he's been having accidents."

History of Present Illness

The patient's family has noticed progressive gait difficulty over the past 1 year. He takes small, shuffling steps and appears to have trouble lifting his feet, as if they are "magnetized to the floor." He has had multiple falls. Concurrently, he has developed urinary urgency progressing to urinary incontinence over the past 6 months. His memory has also declined, but the family emphasizes the gait and bladder problems came first and are more prominent. He previously walked 2 miles daily and was cognitively intact. No headaches or visual symptoms.

Neurological Examination Findings

Mental Status:

  • MMSE: 24/30
  • Impaired attention and concentration
  • Psychomotor slowing
  • Impaired recall (2/3) but improves with cueing (subcortical pattern)
  • No aphasia

Cranial Nerves:

  • Intact II-XII
  • No papilledema

Motor Examination:

  • 5/5 strength throughout
  • Normal tone (no rigidity)
  • No tremor

Sensory Examination:

  • Intact

Reflexes:

  • 2+ symmetric
  • Plantar responses flexor (or mildly extensor from frontal dysfunction)

Coordination:

  • Finger-to-nose: Normal
  • Heel-to-shin: Normal

Gait (hallmark finding):

  • Magnetic gait: Feet appear stuck to floor
  • Wide-based
  • Short steps, shuffling
  • Start hesitation (difficulty initiating)
  • Turn en bloc
  • Reduced foot clearance
  • Relatively preserved arm swing (unlike PD)
  • "Lower body parkinsonism"

Bladder:

  • Urgency, urge incontinence (detrusor overactivity)

Classic Triad of NPH (Hakim's Triad)

  1. Gait disturbance - usually first and most prominent
  2. Urinary incontinence - urge type, then incontinence
  3. Dementia - frontal-subcortical pattern, often least prominent

Mnemonic: "Wet, Wacky, and Wobbly"

Neuro Workup

  • MRI Brain:
  • Ventriculomegaly out of proportion to sulcal atrophy (Evans index >0.3)
  • Evans index: Maximal frontal horn width / biparietal diameter >0.3
  • Rounded frontal horns
  • Callosal angle <90 degrees (acute)
  • Periventricular T2 hyperintensity (transependymal CSF flow)
  • Aqueductal flow void present (patent aqueduct)
  • Lumbar Puncture with High-Volume Tap:
  • Opening pressure: 16 cm H2O (normal or mildly elevated - distinguishes from obstructive hydrocephalus)
  • Remove 30-50 mL CSF
  • CSF analysis: Normal
  • Clinical response to tap: Gait improved significantly 1-2 hours post-LP and over 24-48 hours
  • Pre- and Post-LP Gait Assessment:
  • 10-meter walk time: 28 seconds pre-LP → 18 seconds post-LP (>20% improvement = positive)
  • Timed Up and Go: Improved
  • Continuous Lumbar Drainage (if uncertain): 3-day trial with daily assessments

Diagnosis

Idiopathic Normal Pressure Hydrocephalus (iNPH) - probable (positive tap test)

Management

Surgical Treatment:

  1. Ventriculoperitoneal (VP) shunt placement - definitive treatment
  • Programmable valve preferred (allows pressure adjustments)
  • Response rate: 70-90% for gait, 50-70% for cognition, 50% for incontinence
  1. Endoscopic third ventriculostomy (ETV) - alternative in some cases

Predictors of Good Shunt Response:

  1. Gait predominant symptoms
  2. Shorter duration of symptoms
  3. Known etiology (SAH, meningitis) vs idiopathic
  4. Robust response to large-volume LP
  5. Less cognitive impairment

Post-Shunt Monitoring:

  1. Follow gait, cognition, and continence
  2. Adjust programmable valve if under- or over-drainage
  3. Watch for complications:
  • Subdural hematoma (from over-drainage)
  • Shunt infection
  • Shunt malfunction

Conservative Management (if not surgical candidate):

  1. Serial large-volume LPs (temporary improvement)
  2. Physical therapy for gait
  3. Bladder management (scheduled voiding, anticholinergics cautiously)
  4. Fall prevention

Differential Diagnosis Considered:

  1. Parkinson's disease (has tremor, rigidity, asymmetry)
  2. Vascular dementia/parkinsonism (significant white matter disease)
  3. Progressive supranuclear palsy (vertical gaze palsy, axial rigidity)
  4. Alzheimer's disease (memory predominant, no gait early)

Clinical Image

Image Description: Axial T2-weighted MRI showing ventriculomegaly with enlarged lateral ventricles out of proportion to sulcal atrophy, characteristic of normal pressure hydrocephalus.

Attribution: Image from Radiopaedia.org, Case courtesy of Dr. Ahmed Abd Rabou. Licensed under CC BY-NC-SA 3.0. Source: https://radiopaedia.org/cases/normal-pressure-hydrocephalus-11

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