Normal pressure hydrocephalus (NPH) is a condition caused by abnormal cerebrospinal fluid (fluid typically found in the spinal cord and brain) building up primarily in the brain's ventricles. Hydrocephalus, in fact, means "water on the brain."
The fluid buildup occurs when there is a block in the flow or absorption of the cerebrospinal fluid. Often, despite the fluid buildup, there is little or no increase in the pressure inside the skull, thus the name "normal" pressure hydrocephalus. The term dates back to Dr. Salomon Hakim’s paper in 1964, where he first described the phenomenon of cerebrospinal fluid buildup.
NPH is often misdiagnosed as Alzheimer’s, Parkinson’s or Creutzfeldt-Jakob disease because the symptoms overlap. Some sources estimate that as many as 250,000 people with Alzheimer’s, another dementia or Parkinson’s may actually have NPH, while others place the number much lower.
CausesSometimes there are specific causes such as head injuries, bleeding brain aneurysms, meningitis, etc. Often, however, there is no distinguishable trigger.
SymptomsThere are three hallmark symptoms of NPH:
- Difficulty with walking: The earliest symptom is a change in walking and gait (leg movement and stride) or a feeling that one’s feet are stuck to the floor. Your balance may be poor, and you may walk with a wide, slow step.
- Urinary frequency or incontinence: You may have trouble with leaking urine or feeling like you have to go to the bathroom frequently. You may not be able to make it to the bathroom in time.
- Cognitive changes: People with NPH show some symptoms of dementia, such as confusion, short-term memory loss and behavioral changes.
How Is NPH Different from Alzheimer’s?The initial symptoms of NPH are usually the three outlined above. Alzheimer’s symptoms, on the other hand, start out primarily as cognitive issues, such as decreased short-term memory and difficulty learning new things. Incontinence and problems with the ability to move around often do develop as Alzheimer’s progresses, but they are not typical symptoms in the early stages of Alzheimer’s.
It is also possible to have both NPH and Alzheimer’s at the same time, which makes diagnosis and treatment challenging.
DiagnosisA diagnosis of NPH is considered when a person has impairment in walking and balance in addition to either incontinence or cognitive dysfunction. NPH is diagnosed usually by a neurologist or a neurosurgeon through several tests, which may include the following:
Some physicians also require a multiple-day hospital stay where they can continuously measure the cerebrospinal fluid levels by placing a small monitor in the brain. The doctor may also insert a small catheter drain, which looks like a tiny flexible tube, into the lower back, along the spine. This can allow additional spinal fluid to drain from the body. The medical team will then see if symptoms improve when there is less fluid building up. If functioning improves noticeably, the diagnosis is confirmed and the person would likely benefit from a shunt placed in his brain.
TreatmentTreatment usually consists of inserting a shunt into the brain ventricle to drain extra fluid through a small catheter. A shunt is a surgical drain. There are two types:
- Ventricoperitoneal shunt: This shunt is placed in the brain's ventricle and has a small catheter, or tube, that leads to the abdomen, where the extra fluid can be released and reabsorbed.
- Ventriculoatrial shunt: This shunt’s catheter is inserted into the ventricle and drains into the jugular vein, located just above the atrium of the heart.
In addition, medications such as acetazolamide are sometimes used to treat NPH.
PrognosisThe prognosis varies with NPH. Early diagnosis is imperative. While some individuals don’t improve much with shunt placement, others make almost a full recovery if NPH is diagnosed and treated early. Typically, the walking gait of the individual is the first to improve, and the cognitive functioning is the last to improve, if it does.
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Hydrocephalus Association. Normal Pressure Hydorcephalus. Accessed December 21, 2011. https://www.hydroassoc.org/hydrocephalus-education-and-support/normal-pressure-hydrocephalus/
Life NPH. Diagnosis of NPH. Accessed December 22, 2011. http://www.lifenph.com/diagnosis.asp
MedlinePlus.gov. Normal Pressure Hydrocephalus. Accessed November 18, 2011. http://www.nlm.nih.gov/medlineplus/ency/article/000752.htm
National Institute of Neurological Disorders and Stroke. National Institutes of Health. Normal Pressure Hydrocephalus Information Page. Accessed December 22, 2011. http://www.ninds.nih.gov/disorders/normal_pressure_hydrocephalus/normal_pressure_hydrocephalus.htm
Shprecher, David, Schwalb, Jason, and Kurlan, Roger. Current Neurology and Neuroscience Reports Normal Pressure Hydrocephalus: Diagnosis and Treatment. Accessed December 21, 2011. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2674287/
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