What is the best management approach for normal pressure hydrocephalus (NPH)?

Management of Normal Pressure Hydrocephalus

Ventriculoperitoneal (VP) shunt placement is the definitive treatment for normal pressure hydrocephalus, with 70-90% of patients achieving clinical improvement and sustained benefit for 5-7 years in appropriately selected patients. 1, 2, 3

Diagnostic Confirmation Before Treatment

• Obtain MRI with contrast to confirm ventriculomegaly (Evans index >0.3), evaluate for transependymal edema, and exclude other causes such as cerebral atrophy, tumors, or vascular disease 1, 2
• Perform lumbar drain trial or high-volume lumbar puncture (30-50 mL CSF removal) to predict shunt responsiveness, as this semi-invasive testing is recommended when clinical and imaging findings alone are insufficient 3, 4
• Assess gait, cognition, and urinary function using validated measures (Timed Up & Go, Tinetti Balance, Mini-Mental Status Exam) before and after temporary CSF diversion to identify surgical candidates 4

Surgical Treatment Options

VP Shunt (First-Line Treatment)

• VP shunt with programmable valve remains the gold standard, providing sustained improvement in the classic triad (gait disturbance, urinary incontinence, cognitive decline) 1, 2, 3
• Optimal valve opening pressure is 120 mmH2O for women and 140 mmH2O for men, with adjustments based on clinical response rather than radiological changes 5
• Expected outcomes: 89.6% report symptomatic improvement at 6 weeks, though approximately 45% experience symptom recurrence at 1 year requiring valve adjustment 4, 2

Endoscopic Third Ventriculostomy (ETV)

• Consider ETV as an alternative when suitable anatomy exists (particularly aqueductal stenosis), as it demonstrates lower long-term complication rates than shunts 1, 2
• ETV has higher early failure rates (first 3 months) compared to shunts, but lower failure rates after 3 months 1, 2
• Both ETV and VP shunts show equivalent overall outcomes in many clinical scenarios when adjusted for patient age and etiology 1

Lumboperitoneal Shunt

• LP shunts are an alternative when intracranial surgery should be avoided, with 92% showing gait improvement at 2 weeks and 65% maintaining improvement at 6 months 6
• Revision rate is 24% due to catheter migration, CSF leak, or overdrainage symptoms 6

Critical Management Pitfalls

• Do not use serial lumbar punctures as definitive treatment - this is not recommended for managing NPH (Level I evidence) 1
• Recognize that 75% of NPH patients have coexisting neurodegenerative disease, complicating diagnosis and potentially limiting treatment response 3
• Monitor for shunt infection (11% risk within 24 months), which requires complete shunt removal and systemic antibiotics 2
• Watch for subdural fluid collections (18% incidence) and other complications including seizures, intracerebral hemorrhage, and stroke (6% combined rate) 4

Long-Term Follow-Up Strategy

• Reassess at 6 weeks, 6 months, and annually using the same validated gait, balance, and cognitive measures used preoperatively 4, 5
• Adjust programmable valve settings based on clinical symptoms rather than radiological findings, as Evans index and callosal angle changes do not correlate with clinical improvement 5
• Recognize that symptom recurrence at 1 year is common (45% of patients), requiring valve reprogramming or revision 4, 2
• Maintain treatment indefinitely once initiated, as untreated NPH progresses to nursing care dependence in the vast majority of patients 3

Special Considerations

• Diabetes mellitus and prior stroke significantly influence surgical outcomes, requiring more aggressive monitoring and potentially earlier intervention 5
• Early treatment is preferable to late intervention, as 80% of NPH cases remain unrecognized and progress to irreversible disability 3
• Clinical improvement is most pronounced in the first 6 months but can be maintained long-term with appropriate valve management 5