Normal pressure hydrocephalus (NPH) causes symptoms and treatment

Normal Pressure Hydrocephalus (NPH) is a rare medical condition that occurs when cerebrospinal fluid (CSF) accumulates in the brain’s ventricles, but in a way that differs from traditional hydrocephalus. In NPH, the CSF pressure is usually normal or near normal. Despite this, the fluid buildup can cause noticeable symptoms affecting movement, thinking, and bladder control.The challenge is that these symptoms often resemble other conditions, such as dementia or movement disorders in older adults, making diagnosis sometimes difficult. With early detection and appropriate treatment, however, it is possible to significantly improve quality of life and reduce complications.

What is Normal Pressure Hydrocephalus (NPH)?

Normal Pressure Hydrocephalus (NPH) occurs when cerebrospinal fluid (CSF) accumulates in the brain’s ventricles. Unlike other types of hydrocephalus, the pressure inside the brain is usually normal. This fluid buildup causes the ventricles to enlarge and puts mild pressure on surrounding brain tissue, affecting movement, bladder control, and memory. The exact cause is often unknown, but the symptoms result from the subtle pressure on brain areas responsible for walking, urination, and cognition.

How is NPH Different from Other Types of Hydrocephalus?

In other forms of hydrocephalus, intracranial pressure is elevated. In NPH, the pressure is usually normal, making diagnosis more challenging, as symptoms develop gradually and can mimic normal aging or other neurological disorders.

When Does Improvement Occur After Surgery?

Walking and bladder control: Usually improve within days to weeks.
Memory and concentration: Improvement is gradual and may take several months.
Patients with shorter symptom duration before surgery often experience faster recovery.

Does NPH Develop Suddenly or Gradually?

Symptoms usually appear gradually over months or years, which can make diagnosis difficult, especially in older adults.

Can NPH Resolve Without Treatment?

No. NPH does not resolve on its own, and symptoms typically worsen over time, especially walking and bladder issues.

Is NPH Hereditary?

Most cases are not hereditary. Genetic factors are very rare. NPH usually develops due to aging or prior brain conditions.

Does Every Patient Require Surgery?

Most NPH patients require a shunt, as medications are generally not effective.
Some patients with very mild symptoms or high surgical risk may be managed with regular monitoring and temporary medications.

Can a Shunt Be Replaced if Blocked or Malfunctioning?

Yes. If a shunt becomes blocked or infected, it can be corrected or replaced. Regular follow-up is essential to ensure proper functioning.

Is Surgery Risky for Older Adults?

Any surgery carries risks, but shunt placement for NPH is relatively safe, even for older adults. Rare complications include infection, shunt blockage, or minor brain bleeding. Choosing an experienced surgeon and careful follow-up minimizes risks.

Can Patients Return to Normal Life After Treatment?

Yes. Most patients resume normal life after surgery, especially if diagnosed early.

Greatest improvement is usually seen in walking and bladder control.
Cognitive recovery may be partial, depending on the duration of symptoms before treatment.

Are Physical Therapy and Rehabilitation Helpful?

Yes. Rehabilitation after surgery is important to improve balance, muscle strength, and walking.

Daily walking exercises
Balance exercises
Leg-strengthening exercises
These measures help achieve faster and safer recovery.

How Often Should Patients Be Followed Up After Shunt Placement?

Initial follow-up: Usually within a few days after surgery.
Subsequent follow-ups: Every 3–6 months during the first year to check shunt function and adjust valves if needed.
Later: Follow-ups may be less frequent if the patient is stable.

Can NPH Symptoms Reappear After Treatment?

Rarely, symptoms may return if the shunt becomes blocked or malfunctions. Any recurrence of walking problems, urinary issues, or cognitive decline requires immediate medical review.

Types of Normal Pressure Hydrocephalus (NPH)

NPH primarily affects adults, especially the elderly, and is classified into two main types: Idiopathic NPH (iNPH) and Secondary NPH (sNPH).

1. Idiopathic NPH (Primary NPH)

Definition: Occurs without a clear cause or previous brain disease.
Most affected age: Usually over 60.
Possible causes:
- Age-related changes
- Impaired CSF absorption valves
- Gradual fluid accumulation over time
Characteristics:
- Symptoms develop gradually
- Most patients have no history of brain hemorrhage or prior infection
- Early diagnosis is crucial, as surgical outcomes are better when treatment begins before symptoms become long-standing

2. Secondary NPH

Definition: Results from a known cause or previous brain condition.
Common causes:
- Previous brain hemorrhage (subarachnoid or intraventricular)
- Brain or meningeal infections (encephalitis/meningitis)
- Severe head trauma
- Brain tumors that obstruct CSF flow
- Previous brain surgery
Characteristics:
- Can appear at any age depending on the cause
- Symptoms may appear more quickly than in idiopathic NPH
- Diagnosis is relatively easier because the patient’s medical history is clear

Causes of NPH

NPH occurs when CSF accumulates in the brain’s ventricles while intracranial pressure remains normal or near normal. This fluid buildup affects brain functions, especially walking, urination, and memory.

1. Idiopathic NPH

Most common in older adults over 60
Exact cause unknown, but contributing factors include:
- Age-related brain changes: Reduced CSF absorption with aging
- Valve dysfunction: Small brain valves regulating CSF may become less efficient
- Brain tissue changes: Loss of brain cells or fiber accumulation allows ventricles to enlarge easily

2. Secondary NPH

Has a known cause and can occur at any age
Common causes include:
- Previous brain hemorrhage
- Brain or meningeal infections
- Severe head injury
- Brain tumors obstructing CSF flow
- Previous brain surgery
Less common causes: small strokes, vascular disease, congenital malformations in adults

3. Contributing Factors

Age: NPH is more common after 60
Individual variations: Some people have predisposition to impaired CSF absorption
Other conditions: Chronic hypertension or diabetes may alter brain tissue

Symptoms of NPH

Symptoms usually appear gradually, making diagnosis challenging. The classic triad includes walking difficulties, cognitive decline, and urinary incontinence. Other related symptoms may also appear.

1. Gait Disturbance

Most common and earliest symptom
Walking is slow, with short steps, as if feet are glued to the floor (“magnetic gait”)
May include imbalance or fear of falling

2. Cognitive Impairment

Problems with memory, concentration, and decision-making
Forgetting appointments, places, or recent events
Cognitive changes are often less severe than Alzheimer’s and may improve after surgery

3. Urinary Incontinence

Sudden and frequent urge to urinate
Occasional urine leakage
Usually occurs after gait and memory issues

4. Additional Possible Symptoms

Mood changes: depression or irritability
Slowness in daily activities
Fatigue or quick exhaustion due to mild brain pressure

Note: Not all patients show the full triad, and symptoms can mimic other diseases such as Alzheimer’s or Parkinson’s, requiring careful evaluation.
Recovery after surgery is usually best for gait and bladder control, while cognitive improvement may be partial depending on symptom duration before treatment.

Diagnosis of NPH

Diagnosis is challenging because NPH symptoms resemble other neurological conditions. Physicians use clinical assessments and imaging to confirm the diagnosis.

1. Clinical and Neurological Evaluation

Assess walking and balance: speed, step length, stability
Evaluate cognitive functions: memory, concentration, decision-making
Assess bladder control: urgency or incontinence
Goal: Determine if symptoms match NPH’s classic triad

2. Neuroimaging

MRI: Best method; shows enlarged ventricles without significant pressure increase
CT scan: Alternative if MRI unavailable; shows ventricular enlargement but less precise

3. CSF Tests

Tap Test: Removal of 30–50 mL CSF via lumbar puncture; improvement in walking or bladder function within 24–48 hours indicates likely surgical benefit
Continuous Lumbar Drainage: CSF drainage over several days; improvement indicates high likelihood of shunt success

4. Additional Tests Sometimes Used

Electroencephalogram (EEG): To rule out seizures as the cause of symptoms.
Advanced CSF tests (CSF infusion test): Measures the brain’s ability to absorb cerebrospinal fluid.
Neurocognitive assessments: Detailed evaluation of memory, attention, and cognitive function before and after treatment.

5. Differential Diagnosis

Physicians need to distinguish NPH from other conditions with similar symptoms:

Alzheimer’s disease: Memory loss is more prominent than gait problems.
Parkinson’s disease: Tremors are evident, and movement issues differ from NPH’s “magnetic gait.”
Normal aging: Slow movement may occur but without ventricular enlargement on imaging.

Treatment of Normal Pressure Hydrocephalus (NPH) – Surgery

Surgery is the main treatment for NPH because medications are generally ineffective.
Goal: Reduce CSF accumulation in the ventricles and improve symptoms, particularly walking and bladder control.

1. CSF Shunt Surgery

The most common treatment involves surgically diverting CSF from the ventricles. Types include:

a. Ventriculoperitoneal Shunt (VP Shunt)

Procedure: A thin tube is placed from the ventricles to the abdominal cavity, where the excess fluid is absorbed naturally.
Advantages: Most commonly used, suitable for most NPH patients.
Potential complications: Shunt blockage, infection, rare brain hemorrhage.
Expected improvement: Walking and bladder control usually improve; memory may improve partially depending on symptom duration before surgery.

b. Ventriculoatrial Shunt (VA Shunt)

Procedure: CSF is diverted from the ventricles to the right atrium of the heart.
Advantages: Useful for patients with abdominal issues preventing VP shunt use.
Potential complications: Blood infection, heart valve problems, blood clots.
Use: Less common than VP shunt.

c. Ventriculopleural Shunt (VPL Shunt)

Procedure: CSF is drained from the ventricles to the pleural cavity around the lungs.
Advantages: Alternative if VP or VA shunts are unsuitable.
Potential complications: Pleural effusion (fluid around lungs), difficulty controlling fluid amount.

2. Adjustable and Anti-Blockage Shunts

Most modern shunts have adjustable valves to regulate CSF drainage, reducing low- or high-pressure complications after surgery. Follow-up is important to adjust the valve based on patient response.

3. Endoscopic Third Ventriculostomy (ETV)

Procedure: A small opening is made at the floor of the third ventricle to drain CSF directly into the subarachnoid space without using a shunt.
Advantages: No foreign body; lower risk of infection or blockage.
Disadvantages: Rarely used in NPH, more common in children or obstructed ventricles.

4. Preoperative Preparation and Postoperative Follow-up

Before surgery:

Comprehensive neurological evaluation.
MRI planning for shunt placement.
Tap test to confirm likely benefit from surgery.

After surgery:

Monitor walking, bladder control, and cognitive function.
Regular imaging to check shunt function.
Valve adjustments if needed for optimal pressure control.

5. Surgical Outcomes

Greatest improvement is seen in walking and bladder control.
Partial improvement may occur in memory and cognitive function, especially if symptoms existed for a long time before surgery.
Surgical success depends on early diagnosis, appropriate shunt choice, and careful postoperative follow-up.

Medical Treatment of NPH

Medications are not a primary effective treatment for NPH, as the main problem is CSF accumulation requiring surgical drainage.
However, medications may help temporarily or partially with:

Symptom control
Preventing complications before surgery

1. Diuretics

Examples: Furosemide, Acetazolamide
Function: Temporarily reduce CSF volume and intracranial pressure.
Notes:
- Very limited efficacy
- Mainly used for patients delaying surgery or before CSF responsiveness testing

2. Antidepressants or Anti-Anxiety Medications

Some NPH patients experience mood changes or depression.
SSRIs may improve mental well-being but do not affect walking or bladder control.

3. Cognitive Enhancers

Sometimes physicians try medications to improve memory or alertness (e.g., drugs used in Alzheimer’s disease).
Effect is limited and temporary, as the primary cause is brain pressure, not chemical deficiency.

4. General Role of Medications

Goal	Effectiveness in NPH	Notes
Reduce intracranial pressure (Diuretics)	Weak, temporary	Mainly before surgery or in non-surgical patients
Improve mood (Antidepressants)	Limited	Treats secondary depression
Enhance cognition (Cognitive enhancers)	Weak	Partial, temporary effect only

Recovery Time After NPH Treatment

Recovery depends on treatment type, with surgery (shunt placement) being the most effective. Improvement varies between patients.

1. Early Postoperative Improvement

Walking: Usually the first symptom to improve; noticeable improvement within days to weeks. Faster recovery if symptoms were recent.
Bladder control: Improvement may occur within weeks; in some cases, gradual improvement over several months.

2. Cognitive Recovery

Memory and concentration improve more slowly and less noticeably.
Noticeable improvement may appear 3–6 months after surgery.
If cognitive deficits were long-standing before surgery, recovery is often partial.

3. Factors Affecting Recovery Duration

Factor	Effect on Recovery
Symptom duration before surgery	Shorter duration → faster and better improvement
Age	Older patients may need longer to fully recover
Type of shunt	Adjustable shunts provide better pressure control and faster recovery
Comorbidities	Diabetes, hypertension, or other brain diseases may slow recovery

4. Follow-Up During Recovery

Regular visits with a neurologist to:
- Adjust shunt valves if needed
- Monitor walking, bladder control, and memory
- Check for shunt blockage or infection
Physical therapy: Essential to accelerate walking, balance, and overall recovery