What is the preferred treatment for normal or low pressure hydrocephalus?

Treatment of Normal or Low Pressure Hydrocephalus

For normal or low pressure hydrocephalus, the preferred treatment is cerebrospinal fluid (CSF) shunting, with endoscopic third ventriculostomy (ETV) being an equally effective alternative in appropriate cases. Both surgical interventions have demonstrated equivalent outcomes in terms of morbidity, mortality, and quality of life 1.

Treatment Algorithm

First-Line Treatment Options:

1. Ventriculoperitoneal (VP) Shunting

   • Traditional approach with established efficacy
   • Involves placement of a catheter system to divert CSF from ventricles to peritoneal cavity
   • Particularly effective for idiopathic normal pressure hydrocephalus (iNPH)
   • Success rate of approximately 75% when properly selected 2

2. Endoscopic Third Ventriculostomy (ETV)

   • Increasingly preferred, especially for obstructive hydrocephalus
   • Creates an opening in the floor of the third ventricle to allow CSF flow
   • Avoids shunt-related complications
   • Higher success rates and fewer complications compared to VP shunts 1

Selection Criteria for Treatment Approach:

• ETV is preferred when:

  • Obstructive hydrocephalus is present
  • Patient has favorable anatomy for the procedure
  • Avoiding long-term shunt dependence is a priority
  • Patient is not an infant (better success rates in older children and adults)

• VP Shunt is preferred when:

  • ETV is technically challenging due to anatomical variations
  • Previous ETV has failed
  • Patient has communicating hydrocephalus
  • Narrow prepontine space or basilar artery anomalies are present 1

Special Considerations

For Low Pressure Hydrocephalic State:

Patients with low pressure hydrocephalus may require:

• Initial external ventricular drainage at subzero pressures (approximately -5.7 mm Hg)
• Extended drainage period (average 22 days) to restore brain viscoelasticity
• Subsequent placement of low or medium-pressure shunt systems 3

Timing of Intervention:

Early intervention is critical for better outcomes. Research indicates an optimal cut-off of 9.5 months from symptom onset for best clinical improvement 2.

Complications and Management

Common Complications:

• Shunt-related: Infection (5-10%), malfunction (10-20%), overdrainage (5-10%) 4
• ETV-related: Potential injury to basilar artery, CSF leak, treatment failure

Post-Operative Care:

• Close neurological monitoring
• Follow-up imaging to evaluate ventricular size
• Regular assessment of symptom improvement
• Shunt programming adjustments as needed

Pitfalls to Avoid

1. Delayed Diagnosis and Treatment

   • Symptoms may be mistaken for other neurodegenerative conditions
   • Early intervention significantly improves outcomes

2. Overreliance on CSF Pressure Measurements

   • Some patients may have hydrocephalic syndrome despite low-normal ICP readings
   • Ventricular size and clinical symptoms are often more reliable indicators than pressure alone 3

3. Placebo Effect in Assessment

   • Be aware that improvement after diagnostic CSF removal tests may represent placebo effect 5
   • Consider objective measures of improvement in addition to subjective reports

4. Multiple Shunt Revisions

   • Some low-pressure hydrocephalus patients may not respond to routine shunt revisions
   • Consider extended external ventricular drainage at negative pressures before additional revisions 3

The evidence supports that both CSF shunting and ETV are effective treatments for normal or low pressure hydrocephalus, with the choice between them depending on specific patient factors and the underlying etiology of the hydrocephalus 1, 4.