Normal Pressure Hydrocephalus

Normal Pressure Hydrocephalus occurs when the natural balance between the production and absorption of cerebrospinal fluid (CSF) is disrupted. CSF is produced in the ventricles, circulates around the brain and spinal cord, and is eventually absorbed into the bloodstream. In NPH, the absorption mechanism becomes inefficient. Research published in Nature Reviews Neurology (2024) suggests that changes in the compliance of the brain's blood vessels and the 'glymphatic system' (the brain's waste clearance system) may play a role in this imbalance, causing the ventricles to slowly expand to accommodate the extra fluid.

Non-Modifiable Risk Factors

• Age: The risk increases exponentially after the age of 60.
• History of Brain Trauma: Previous head injuries can scar the areas where CSF is absorbed.
• Cerebrovascular Disease: Conditions affecting the blood vessels in the brain are strongly linked to iNPH.

Modifiable Risk Factors

• Hypertension (High Blood Pressure): Chronic high blood pressure can damage the small vessels in the brain, interfering with CSF flow.
• Diabetes Mellitus: Research suggests a higher prevalence of NPH in patients with poorly controlled blood sugar.
• Obesity: High BMI has been associated with increased intracranial pressure, which may exacerbate NPH symptoms.
• Sleep Apnea: Untreated sleep apnea can cause fluctuations in intracranial pressure during the night.

The primary at-risk population is adults over the age of 65. According to the National Institute of Neurological Disorders and Stroke (NINDS, 2024), individuals with a history of meningitis, subarachnoid hemorrhage, or brain surgery are at a significantly higher risk for developing secondary NPH. Interestingly, some studies suggest that patients with certain cardiovascular risk factors are more likely to develop the idiopathic form of the disease.

While there is no guaranteed way to prevent idiopathic NPH, managing cardiovascular health is the most effective evidence-based strategy. The American Heart Association (2023) emphasizes that controlling blood pressure, managing cholesterol, and maintaining a healthy weight may reduce the risk of the vascular changes that contribute to NPH. Early screening for gait changes in the elderly can lead to earlier diagnosis and better long-term outcomes.

Diagnosing NPH is a multi-step process that requires differentiating it from other forms of dementia and movement disorders. The diagnostic journey typically begins with a primary care physician and proceeds to a neurologist or neurosurgeon specializing in CSF disorders.

A thorough neurological exam is conducted, focusing on the patient's gait. Doctors often perform a 'timed up and go' (TUG) test, measuring how long it takes a patient to stand from a chair, walk 10 feet, turn around, and sit back down. They also assess cognitive function using tools like the Mini-Mental State Exam (MMSE).

• Brain Imaging (MRI or CT): MRI is the gold standard. It reveals enlarged ventricles (ventriculomegaly) that are out of proportion to any brain atrophy (shrinking). A specific sign called the 'Evans Index' is used to measure ventricle size.
• Lumbar Puncture (Spinal Tap): A large-volume lumbar puncture is performed to remove about 30-50 ml of CSF. If the patient's gait or cognition improves significantly within hours of the procedure, it is a strong predictor that surgical treatment will be successful.
• External Lumbar Drainage (ELD): In some cases, a catheter is placed to drain CSF continuously over 3-4 days in a hospital setting to provide a more definitive assessment of potential treatment response.

Clinical diagnosis is based on the presence of the classic triad (gait, cognition, bladder) combined with imaging evidence of enlarged ventricles (Evans Index > 0.3) and a CSF opening pressure within the normal range (usually 70–245 mm H2O).

NPH is often confused with:

• Alzheimer's Disease: Memory loss is more prominent and gait changes occur much later.
• Parkinson's Disease: Characterized by tremors and rigidity, whereas NPH gait is more 'magnetic.'
• Vascular Dementia: Resulting from multiple small strokes; imaging can usually distinguish this from NPH.

The primary goal of treating Normal Pressure Hydrocephalus is to improve the patient's mobility, cognitive function, and bladder control by diverting excess cerebrospinal fluid away from the brain. Successful treatment is measured by a reduction in fall risk, improved independence in daily activities, and stabilization or improvement of cognitive decline.

The gold standard treatment for NPH is the surgical implantation of a shunt system. According to clinical guidelines from the American Association of Neurological Surgeons (AANS, 2024), shunting is the only effective long-term treatment for most patients. The most common procedure is a Ventriculoperitoneal (VP) shunt, where a thin tube is placed in the brain's ventricle and routed under the skin to the abdomen, where the excess fluid is reabsorbed.

While surgery is the definitive treatment, certain medication classes may be used as adjuncts or in patients who are not surgical candidates:

• Carbonic Anhydrase Inhibitors (Diuretics): These medications work by decreasing the production of CSF in the choroid plexus of the brain. They are sometimes used to temporarily manage symptoms or in mild cases, though they are generally less effective than surgery. Common side effects include tingling in the extremities (paresthesia), fatigue, and taste changes.
• Loop Diuretics: These may be used to manage systemic fluid balance and associated cardiovascular risk factors, though their direct effect on NPH is limited.

• Programmable Shunt Valves: Modern shunts allow surgeons to adjust the drainage rate non-invasively using a magnetic tool in the office, allowing for 'fine-tuning' of the treatment.
• Endoscopic Third Ventriculostomy (ETV): In specific cases of NPH where there is a blockage, a surgeon may create a small hole in the floor of the third ventricle to allow fluid to bypass the obstruction.

• Physical Therapy: Essential for gait retraining and balance improvement both before and after surgery.
• Occupational Therapy: Helps patients adapt their home environment to prevent falls.
• Speech Therapy: May be used to address cognitive-linguistic deficits.

Shunt systems are intended to stay in place for the rest of the patient's life. Regular follow-up appointments (usually every 6-12 months) are required to ensure the shunt is functioning correctly and the valve setting is optimal.

In the elderly, the decision to undergo surgery must be balanced against the risks of anesthesia and potential complications like subdural hematomas (bleeding between the brain and its covering). Patients with multiple comorbidities (like heart disease or blood-clotting disorders) require a multidisciplinary approach involving cardiology and hematology.

> Important: Talk to your healthcare provider about which approach is right for you.

A heart-healthy diet is recommended to manage the vascular risk factors associated with NPH. Research in The Journal of Nutrition, Health & Aging (2023) suggests that the Mediterranean diet—rich in olive oil, fish, and antioxidants—may support brain health and vascular integrity. Reducing sodium intake is also crucial for patients taking diuretics to prevent electrolyte imbalances.

Physical activity should focus on balance and core strength. The National Institute on Aging (2024) recommends 'Tai Chi' or supervised balance exercises to reduce fall risk. Walking with assistive devices (walkers or canes) is encouraged to maintain muscle mass, but patients should avoid high-impact activities that could displace a shunt.

Proper sleep hygiene is vital, as the brain's CSF clearance system (the glymphatic system) is most active during deep sleep. Maintaining a consistent sleep schedule and treating underlying sleep apnea can improve the overall management of NPH symptoms.

Chronic stress can exacerbate cognitive 'fog.' Techniques such as mindfulness-based stress reduction (MBSR) and deep breathing exercises have been shown to improve quality of life in patients with chronic neurological conditions.

While acupuncture and yoga can help with general mobility and stress, there is no clinical evidence that they can replace the need for surgical intervention in NPH. Supplements like Omega-3 fatty acids may support general brain health, but should only be taken after consulting a doctor, as they can increase bleeding risks during surgery.

Caregivers should focus on fall prevention by removing rugs, improving lighting, and installing grab bars in bathrooms. It is also helpful to use a calendar or whiteboard to assist the patient with cognitive lapses and to monitor for any sudden changes in gait that might indicate a shunt complication.

The prognosis for NPH is generally positive if the condition is diagnosed and treated early. According to a 2023 study in JAMA Neurology, approximately 70% to 80% of patients experience significant improvement in their symptoms following shunt surgery. Gait usually improves first, followed by urinary control, while cognitive changes may take longer to resolve or may only stabilize rather than improve.

• Shunt Malfunction: The tube can become blocked or disconnected, requiring a revision surgery.
• Infection: A risk with any implanted device, usually occurring within the first few months.
• Over-drainage: If too much fluid is removed, it can lead to headaches or subdural hematomas.
• Under-drainage: Symptoms may return if the shunt is not removing enough fluid.

Management involves lifelong monitoring of the shunt system. Patients should be aware of the 'warning signs' of shunt failure and maintain regular contact with their neurosurgeon.

Many patients return to a high level of activity post-surgery. Joining support groups, such as those offered by the Hydrocephalus Association, can provide emotional support and practical advice for navigating life with a shunt.

Contact your healthcare provider immediately if you notice a return of shuffling gait, increased confusion, redness along the shunt track, or unexplained fever.