Normal Pressure Hydrocephalus: Symptoms, Types, Causes and Treatment

Normal Pressure Hydrocephalus (NPH) is a fascinating and often misunderstood neurological condition that primarily affects older adults. While its hallmark symptoms can mimic other neurodegenerative diseases, NPH stands out because it is one of the few causes of dementia that is potentially reversible. This article explores the key aspects of NPH—from its symptoms and types to underlying causes and state-of-the-art treatments—using the latest research and clinical guidelines.

Symptoms of Normal Pressure Hydrocephalus

Recognizing the symptoms of NPH is crucial, as early diagnosis can lead to effective treatment and even reversal of debilitating symptoms. NPH is famous for its “classic triad” of symptoms, but the reality is more nuanced and variable.

Symptom	Description	Prevalence/Notes	Source(s)
Gait disturbance	Slow, broad-based, shuffling walk	Most common and earliest symptom	1 4 6 15 18
Cognitive decline	Memory, attention, and executive deficits	Often frontal-subcortical pattern	4 6 18 19
Urinary incontinence	Loss of bladder control/urge incontinence	Develops as disease progresses	6 15 18 19
Parkinsonism	Bradykinesia, rigidity, postural instability	Common, but tremor is rare	1
Depression	Depressive symptoms	Overrepresented compared to general elderly	2
Sleep disturbances	Sleep-disordered breathing, OSA	Particularly in idiopathic NPH	9 14

Table 1: Key Symptoms of Normal Pressure Hydrocephalus

The Classic Triad: Gait, Cognition, and Continence

• Gait disturbance is often the first and most noticeable symptom. Patients typically exhibit a slow, shuffling, broad-based walk, sometimes described as “magnetic” because it seems as though their feet are stuck to the floor. This symptom can easily be misattributed to age or orthopedic problems, leading to missed diagnoses 6 18.
• Cognitive impairment in NPH is distinct from Alzheimer’s disease. It frequently affects attention, processing speed, and executive functions (frontal-subcortical pattern), rather than just memory. Disorientation and apathy may also occur 4 18 19.
• Urinary incontinence usually appears later and may start as urgency or frequency. Eventually, loss of bladder control can lead to social withdrawal and increased risk of falls and infections 6 15 18.

Additional and Overlapping Symptoms

• Parkinsonian features, such as bradykinesia (slowness of movement), rigidity, and postural instability, are frequent, but classic resting tremor is rare. These symptoms are often symmetric and can be mistaken for Parkinson’s disease, making neuroimaging essential for differentiation 1.
• Depression is significantly more common in NPH patients than in the general population—even after shunt treatment—and can further complicate the clinical picture. Screening and addressing depression is recommended in all NPH patients 2.
• Sleep disturbances, particularly sleep-disordered breathing and obstructive sleep apnea (OSA), are highly prevalent in idiopathic NPH and may worsen cognitive symptoms. These are less common in other types of hydrocephalus 9 14.

Why Early Recognition Matters

NPH symptoms often overlap with those of other neurodegenerative and cerebrovascular disorders. However, unlike most other conditions causing dementia and gait disturbance, NPH is potentially reversible with timely intervention 6 15 18. This highlights the importance of careful clinical evaluation and the use of neuroimaging for accurate diagnosis.

Types of Normal Pressure Hydrocephalus

Not all cases of NPH are the same. Understanding the different types is key to guiding diagnosis and management.

Type	Description	Distinguishing Features	Source(s)
Idiopathic NPH	No identifiable cause, develops in elderly	Most common, classic triad, ventriculomegaly	4 6 13 18
Secondary NPH	Follows known insult (e.g., hemorrhage)	History of trauma, hemorrhage, infection, tumor	3 6 8 18
Congenital/delayed	Relates to congenital hydrocephalus	May surface in adulthood, often unrecognized	3 8 10
Acquired NPH	Due to later-life events (e.g., tumors)	History of acquired brain injury or disease	3 5 10

Table 2: Types of Normal Pressure Hydrocephalus

Idiopathic Normal Pressure Hydrocephalus (iNPH)

Idiopathic NPH refers to cases where no clear cause is found. It is the most common form among adults, especially those over age 60. Genetic factors may play a role: recent research has identified deletions in the CWH43 gene as a risk factor, supporting the concept that iNPH is a distinct disease entity 13. Classic imaging features include ventriculomegaly (enlarged ventricles) without significant cortical atrophy 8.

Secondary Normal Pressure Hydrocephalus

Secondary NPH develops after a known event or insult to the brain, such as:

• Subarachnoid hemorrhage
• Head trauma
• Meningitis or other infections
• Brain tumors or complications of neurosurgery 3 6 8

The symptoms and imaging findings mirror those of iNPH, but the history of an identifiable precipitating event helps distinguish this type.

Congenital and Delayed-Onset NPH

Some adults present with NPH symptoms later in life but have imaging or clinical evidence of longstanding, unrecognized congenital hydrocephalus. These cases may be related to subtle developmental abnormalities, such as aqueductal stenosis, that only become symptomatic with age 3 8 10.

Acquired NPH

Acquired NPH can result from later-life events like tumors (e.g., choroid plexus papilloma), which may cause CSF overproduction or impaired absorption, leading to a communicating hydrocephalus that mimics classic NPH 5 10.

Causes of Normal Pressure Hydrocephalus

NPH arises from an imbalance between CSF production and absorption, but the underlying mechanisms are complex and multifactorial.

Cause/Mechanism	Description	Notes/Examples	Source(s)
Impaired CSF absorption	Decreased resorptive capacity of arachnoid granulations	Most common mechanism in iNPH	11 12 7
Venous hypertension	Impaired cerebral venous drainage	Linked to sleep apnea, aging	14 11
Glymphatic dysfunction	Impaired brain waste clearance	Disrupted during sleep, aging	7 14
Genetic factors	CWH43 gene deletions	Identified in subset of iNPH patients	13
Secondary causes	Trauma, hemorrhage, infection, tumors	Typical in secondary NPH	3 5 6 8
Overproduction of CSF	Tumors (e.g., choroid plexus papilloma)	Rare mechanism, leads to communicating hydrocephalus	5
White matter ischemia	Chronic microvascular disease	“Two-hit” hypothesis in iNPH	11

Table 3: Causes and Mechanisms of NPH

CSF Dynamics: The Central Role

The most widely accepted mechanism is impaired absorption of cerebrospinal fluid (CSF) at the arachnoid granulations, despite normal CSF production. This leads to gradual accumulation of CSF in the ventricles, causing ventriculomegaly and stretching of surrounding brain tissue 11 12.

Vascular and Glymphatic Contributions

• Venous hypertension: Impaired drainage of venous blood from the brain, due to aging or comorbidities like sleep apnea, increases intracranial venous pressure. This can delay CSF absorption and promote ventricular enlargement 14 11.
• Glymphatic dysfunction: The glymphatic system clears waste from the brain during sleep. Disrupted sleep (e.g., from sleep-disordered breathing) impedes this clearance, possibly worsening CSF accumulation and contributing to cognitive symptoms 14 7.

Genetics and “Two-Hit” Model

Recent discoveries have linked deletions in the CWH43 gene to a subset of iNPH, supporting a genetic susceptibility 13. The “two-hit” model suggests that benign external hydrocephalus in infancy, followed by age-related white matter ischemia, precipitates iNPH in late adulthood 11.

Secondary and Rare Causes

• Secondary NPH can result from any event that disrupts CSF pathways or absorption, such as brain injury, infection, or tumor 3 6 8.
• CSF overproduction is rare but can occur in cases of choroid plexus tumors, leading to a communicating hydrocephalus with NPH symptoms 5.

Treatment of Normal Pressure Hydrocephalus

Timely and effective treatment of NPH can dramatically improve quality of life. Most importantly, NPH is one of the few causes of dementia and gait impairment that is potentially reversible.

Treatment Option	Description	Effectiveness/Notes	Source(s)
Ventriculoperitoneal shunt (VPS)	Surgical diversion of CSF from brain to abdomen	Gold standard; >75% improve; programmable valves reduce complications	15 16 17 18
Lumboperitoneal shunt (LPS)	CSF diverted from lumbar spine to abdomen	Comparable efficacy to VPS; less invasive	17
Endoscopic third ventriculostomy (ETV)	Creating a CSF bypass within the brain	Alternative in select cases (e.g., aqueductal stenosis)	16
Tap test / CSF drainage	Diagnostic and predictive procedure	Helps identify likely responders to shunting	18 19
Management of comorbidities	Treat depression, sleep apnea, infections	Improves overall outcomes	2 9 14 15
Long-term monitoring	Ongoing follow-up for shunt function and symptoms	Reduces complications and guides future care	10 18

Table 4: Treatment Options for NPH

Surgical Shunting: The Mainstay

• Ventriculoperitoneal shunt (VPS): The most commonly used procedure, where a catheter diverts CSF from the brain’s ventricles to the peritoneal cavity. VPS offers significant improvement in gait, cognition, and continence in more than 75% of well-selected patients 16 18. The use of programmable valves reduces the risk of complications such as subdural collections and the need for revision surgeries 16.
• Lumboperitoneal shunt (LPS): Diverts CSF from the lumbar spinal canal to the abdomen. LPS is less invasive and avoids brain surgery. Recent studies show comparable efficacy and safety to VPS, though shunt revisions may be more common 17.

Alternative and Adjunctive Treatments

• Endoscopic third ventriculostomy (ETV): An option in selected patients, especially those with obstruction of CSF pathways (e.g., aqueductal stenosis). However, shunting remains the standard of care for most NPH cases 16.
• Tap Test and Extended CSF Drainage: Removing a large volume of CSF via lumbar puncture can temporarily improve symptoms and help predict which patients will benefit from shunt surgery 18 19.

Managing Comorbidities and Long-Term Care

• Depression and sleep disorders: Screening and treatment of depression and sleep apnea are crucial, as they are common and can worsen cognitive impairment 2 9 14.
• Long-term monitoring: Regular follow-up is essential to monitor shunt function, manage complications, and address any recurrence or progression of symptoms 10 18.

Outcomes and Prognosis

• Improvement rates: Studies consistently report that 70–90% of patients improve following shunt surgery, particularly in gait and continence. Cognitive improvements are somewhat less robust but still significant 16 18.
• Complications: Include infection, shunt malfunction, subdural hematoma, and the need for revision surgery. The risk is reduced with modern programmable valves and careful patient selection 16 17.

Conclusion

Normal Pressure Hydrocephalus is a unique, often underdiagnosed cause of gait disturbance, cognitive decline, and urinary incontinence in older adults. With timely recognition and intervention, many patients experience dramatic improvements. Here’s a summary of the key points:

• Classic triad: Gait disturbance, cognitive impairment (especially frontal-subcortical), and urinary incontinence are hallmarks of NPH, but additional symptoms like depression, parkinsonism, and sleep disturbances are common.
• Types: NPH includes idiopathic, secondary, congenital/delayed, and acquired forms, each with different clinical implications.
• Causes: Impaired CSF absorption, often linked to aging, vascular factors, glymphatic dysfunction, and genetics, underlie NPH. Secondary causes include trauma, infection, and tumors.
• Treatment: CSF shunting (usually VPS) is highly effective in well-selected patients. Adjunctive management of depression, sleep disorders, and long-term follow-up are essential for optimal outcomes.

With increasing awareness, improved diagnostics, and advances in surgical techniques, NPH offers hope as a treatable cause of dementia and disability in the aging population. Early diagnosis and comprehensive management can make a life-changing difference for patients and families.