Normal Pressure Hydrocephalus (NPH) is a treatable condition that affects how cerebrospinal fluid (CSF) flows and is absorbed in the brain. People with NPH often develop a mix of problems with walking, thinking, and bladder control. Because these symptoms can look a lot like Parkinson’s disease or Alzheimer’s disease, NPH is frequently missed—especially in older adults. The good news: when NPH is identified early, many people improve with surgery that diverts excess fluid. This article explains what NPH is, how it’s diagnosed, and what treatment and recovery typically look like.

Normal Pressure Hydrocephalus (NPH) is a treatable condition that affects how cerebrospinal fluid (CSF) flows and is absorbed in the brain. People with NPH often develop a mix of problems with walking, thinking, and bladder control. Because these symptoms can look a lot like Parkinson’s disease or Alzheimer’s disease, NPH is frequently missed—especially in older adults. The good news: when NPH is identified early, many people improve with surgery that diverts excess fluid. This article explains what NPH is, how it’s diagnosed, and what treatment and recovery typically look like.

The exact cause isn’t fully understood. In many people, NPH seems to result from problems with how cerebrospinal fluid is absorbed and how pressure waves move through the brain. The most likely mechanisms are:

• Impaired CSF absorption: CSF is made normally but does not get absorbed efficiently at the arachnoid granulations, so the ventricles gradually expand.
• Altered CSF dynamics: Even when a single pressure reading looks normal, abnormal pressure pulsations can slowly stretch the ventricles.
• White matter changes: Enlarged ventricles can disrupt nearby nerve pathways that control gait and bladder function.
• Glymphatic dysfunction: Newer research suggests impaired clearance of waste products from the brain may contribute to cognitive symptoms.

NPH is categorized as:

• Secondary NPH: Occurs after events that affect CSF flow or absorption, such as subarachnoid hemorrhage, meningitis, traumatic brain injury, or previous brain surgery.
• Idiopathic NPH: The most common form; no clear trigger.

• Estimated prevalence is ~0.5% in adults over 65, but many cases go undiagnosed.
• Accounts for 5–10% of dementia cases, making it an important, potentially reversible cause of cognitive decline.
• Affects both men and women; some studies show a slight male predominance.

Symptoms of NPH can look different from person to person, but there are clear patterns doctors watch for. Many people first notice changes in walking, followed by slower thinking and issues with bladder control. These symptoms often develop gradually and can vary from day to day, which is why they’re sometimes mistaken for normal aging or other conditions. The signs below are among the most common clues that point toward NPH.

1) Gait disturbance (usually earliest and most prominent)

• Short, shuffling steps; feet seem to “stick” to the floor.
• Difficulty starting to walk or turning; wide-based stance.
• Imbalance and frequent falls.

2) Cognitive impairment

• Slowed thinking and mental processing.
• Trouble with attention, planning, and problem-solving (executive function).
• Apathy and reduced initiative are common; memory can be affected but is often less prominent than in Alzheimer’s disease.

3) Urinary symptoms

• Urgency and frequency early on.
• Progression to incontinence, sometimes with limited awareness of the need to void.

Other exam findings

• Typically no major weakness, numbness, or tremor—features that would suggest other diagnoses.
• Mild upper motor neuron signs (e.g., brisk reflexes).
• “Frontal release” reflexes (e.g., grasp or palmomental reflex).

Doctors start with your symptoms and exam, then use brain scans (CT or MRI) to confirm that the ventricles are enlarged. A lumbar puncture measures opening pressure and allows a high‑volume “tap test,” temporarily removing fluid to see whether walking or thinking improves. Taken together, these steps both support the diagnosis of NPH and help estimate how likely you are to benefit from shunt surgery.

A) Brain imaging (CT or MRI)

Key findings include:

• Ventriculomegaly (enlarged ventricles); an Evans Index > 0.3 supports the diagnosis (ratio of frontal horn width to inner skull width).
• Ventricles enlarged out of proportion to cortical atrophy.
• Periventricular T2/FLAIR changes (often due to fluid seepage) on MRI.
• DESH pattern (Disproportionately Enlarged Subarachnoid Space Hydrocephalus): tight high‑convexity sulci with enlarged Sylvian fissures.
• Narrow callosal angle on coronal MRI (often < 90°) favors NPH over atrophic dementias.

B) Lumbar puncture (spinal tap)

• Opening pressure is normal (typically 5–18 cm H₂O) in NPH.

C) High‑volume lumbar tap test

• Removal of 30–50 mL of CSF, followed by reassessment of walking and cognition over the next several hours to 24 hours.
• Improvement after the tap suggests a higher likelihood of benefit from shunt surgery.

D) External lumbar drainage (ELD)

• Continuous drainage over 2–3 days with repeated testing; can be more sensitive than a single tap in predicting shunt response.

E) Neuropsychological testing

• Baseline assessment helps document cognitive deficits and measure postoperative changes.

Conditions That Can Mimic NPH (Differential Diagnosis)

• Alzheimer’s disease: Memory loss is more prominent early; gait changes come later.
• Parkinson’s disease: Resting tremor, rigidity, and clear response to dopaminergic meds.
• Vascular dementia / small‑vessel disease: Stepwise decline; extensive white matter disease without marked ventriculomegaly.
• Progressive supranuclear palsy (PSP): Early falls, vertical gaze palsy, axial rigidity.
• Cervical myelopathy: Spinal cord compression causing gait and bladder issues; imaging shows cervical stenosis.

Careful history, exam, and targeted imaging help distinguish NPH from these conditions; some patients have overlapping disorders.

Treatment focuses on relieving excess fluid with a shunt, a small device that drains cerebrospinal fluid from the brain to another part of the body. Because not everyone with enlarged ventricles benefits the same way, clinicians pair your symptoms and MRI findings with bedside tests—such as a high‑volume tap or short‑term lumbar drainage—to predict your likelihood of improvement. People who show better walking or thinking after these tests are the most likely to benefit from surgery, with gait often improving first and bladder and cognitive changes following more gradually. Before proceeding, your care team will discuss the potential benefits, risks, alternatives, and the plan for valve settings and follow‑up adjustments. The sections below describe the main shunt types and what to expect before and after the procedure.

Surgical options

• Ventriculoperitoneal (VP) shunt (most common): A small catheter drains CSF from the lateral ventricle to the abdominal cavity, where it is absorbed.
  • Programmable valves allow noninvasive adjustments to fine‑tune CSF drainage.
• Ventriculoatrial shunt: CSF is diverted to the right atrium of the heart; used if the abdomen is not suitable.
• Lumboperitoneal shunt: Diverts CSF from the lumbar spine to the abdomen; avoids cranial surgery but may have higher complication or revision rates in some series.

Preoperative evaluation

• High‑volume tap or ELD to gauge potential benefit.
• Discuss realistic goals: gait often improves first; urinary and cognitive changes may lag or be incomplete.

Postoperative care

• Periodic imaging to assess ventricular size and detect complications.
• Early physical therapy to retrain gait and balance.
• Monitor for shunt function and fine‑tune valve settings as needed.

Shunt surgery can greatly improve walking, thinking, and bladder control, but it isn’t completely risk‑free. Knowing the most common complications—and the warning signs that mean you should contact your care team—helps you act quickly. Most issues are manageable when recognized early and monitored closely, so watch for the following:

• Shunt infection (meningitis or ventriculitis)
• Subdural hematoma (from over‑drainage and brain sagging)
• Shunt obstruction or malfunction
• Over‑drainage (low‑pressure headaches, slit ventricles)
• Seizures

Overall complication rates range from ~20–40%, underscoring the need for close follow‑up with a neurosurgical team.

While outcomes vary from person to person, many patients see meaningful gains when NPH is identified and treated early. Changes often appear at different speeds, with walking usually improving first and thinking and bladder control taking longer to catch up. Close follow‑up with the care team—including valve adjustments and rehabilitation—can maximize and sustain these benefits.

• Gait improvement is the most consistent and often appears within days to weeks of shunting.
• Cognition may improve, especially when surgery is performed earlier in the disease course.
• Urinary symptoms can improve but typically lag behind gait and may remain partially persistent.

Across studies, ~50–70% of well‑selected patients experience meaningful clinical improvement after shunt placement. Delayed diagnosis, advanced neurodegeneration, or significant coexisting disease may limit recovery.

Successful care extends beyond surgery:

• Caregiver support: Education on symptom monitoring and when to seek help (e.g., sudden gait decline or new confusion may indicate shunt issues).
• Rehabilitation: Ongoing physical and occupational therapy for gait, balance, and daily activities.
• Medication review: Minimize drugs that worsen cognition or balance when possible.
• Fall prevention: Home safety assessments, assistive devices, and exercise programs.

Normal Pressure Hydrocephalus is a potentially reversible cause of walking difficulty, cognitive slowing, and urinary problems in older adults. Because it can mimic other neurologic diseases, a high index of suspicion—paired with targeted imaging and tap testing—is essential. For many, shunt surgery provides substantial improvements in mobility and independence, with the greatest gains seen when diagnosis and treatment happen early.

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