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

Management of Normal Pressure Hydrocephalus (NPH)

The optimal management approach for normal pressure hydrocephalus is surgical intervention with ventriculoperitoneal (VP) shunt placement, which leads to clinical improvement in 70-90% of treated patients. 1

Diagnosis and Clinical Presentation

• NPH is characterized by the clinical triad of gait disturbance (typically presenting first), cognitive impairment, and urinary incontinence, associated with ventriculomegaly on neuroimaging 1, 2
• Radiographic pattern of disproportionately enlarged subarachnoid space hydrocephalus (DESH) on MRI predicts a positive response to permanent CSF diversion 3
• Approximately 80% of NPH cases remain unrecognized and untreated, largely due to difficulty distinguishing it from other neurodegenerative disorders 1
• Three-quarters of patients with NPH severe enough to require treatment also suffer from another neurodegenerative disorder, complicating diagnosis 1

Diagnostic Evaluation

• Brain MRI or CT showing ventriculomegaly is essential for diagnosis 1, 2
• When clinical and imaging findings are insufficient to establish surgical indication, additional semi-invasive diagnostic procedures are recommended 1:
  • CSF tap test (CSF-TT): temporarily simulates the effect of shunting but has low sensitivity 2
  • Repeated CSF tap test (RTT) or continuous lumbar external drainage (LED) provides more reliable prediction of shunt response 2
  • Intracranial pressure monitoring showing B-waves during more than 50% of recording time suggests good surgical outcomes 2

Treatment Options

Surgical Management

• Ventriculoperitoneal shunt placement is the treatment of choice for NPH 1, 3
• Modern surgical techniques using stereotactic navigation for proximal catheter placement and laparoscopic assistance for distal catheter placement have demonstrated low complication rates 4
• Approximately 75% of patients with NPH improve after shunt surgery regardless of shunt type or location 3
• Clinical benefit and complication rates are similar for frontal and parietal ventricular catheter approaches 3
• MRI-safe programmable shunt valves allow for fluid drainage adjustment based on patients' symptoms and radiographic findings 3
• Endoscopic third ventriculostomy (ETV) is a viable alternative to shunting specifically for patients with NPH due to aqueductal stenosis 3

Medical Management

• Acetazolamide is not an effective treatment for NPH 3
• There are no effective medical therapies that can replace surgical intervention for NPH 1, 5

Complications and Postoperative Management

• Complication rates with modern surgical techniques are relatively low:
  • Zero patients required reoperation within 30 days in a recent study using stereotactic navigation and laparoscopy 4
  • Systemic complications occurred in 12% of patients within the first 30 days 4
• Patients with cardiac or other neurological comorbidities have higher rates of readmission and complications 4
• Potential complications include:
  • Intracranial hemorrhage (rare with modern techniques) 4
  • Catheter malposition requiring repositioning 4
  • Shunt infection requiring removal 4

Prognosis

• Without treatment, the natural course of NPH typically leads to dependence on nursing care 1
• Early diagnosis and treatment lead to better outcomes 1, 5
• Patients with the complete clinical triad and typical imaging findings have the best chance of improvement after shunting 2

Clinical Pearls and Pitfalls

• NPH should always be considered in the differential diagnosis of patients presenting with the characteristic triad of symptoms 1
• Early treatment is recommended when NPH is confirmed 1
• The presence of comorbidities, particularly cardiac or neurological conditions, increases the risk of complications 4
• Programmable shunt valves allow for post-surgical adjustments to optimize symptom control 3