Normal pressure hydrocephalus
A form of hydrocephalus with normal CSF pressure.
Normal pressure hydrocephalus (NPH), also known as malresorptive hydrocephalus, is a type of communicating hydrocephalus where extra cerebrospinal fluid (CSF) accumulates in the brain’s ventricles, with CSF pressure remaining normal or only slightly raised. This buildup enlarges the ventricles and raises pressure inside the skull, squeezing nearby brain tissue and causing neurological issues. The condition was first identified by Salomón Hakim in his 1964 doctoral thesis.
The cause of idiopathic (or primary) NPH is unknown, but it has been linked to conditions like hypertension, diabetes, Alzheimer’s disease, and high cholesterol. Secondary NPH can result from trauma, bleeding, or infection. Symptoms typically appear as a classic triad—memory problems, frequent urination, and balance or gait issues—but relying on this triad for diagnosis is now outdated, as these signs emerge relatively late and can stem from many other disorders.
Treatment usually involves surgically placing a ventriculoperitoneal shunt to drain excess CSF into the abdominal lining, where it gets absorbed. Endoscopic third ventriculostomy is generally not effective for NPH, as it is primarily used for obstructive hydrocephalus. NPH is often mistaken for other conditions, such as Meniere’s disease (due to balance problems), Parkinson’s disease (due to gait changes), or Alzheimer’s disease (due to cognitive decline).
**Signs and symptoms** The classic triad—walking difficulty, reduced attention span, and urinary frequency or incontinence—appears gradually over three to six months. Gait problems are nearly universal and usually the first symptom, caused by enlarged lateral ventricles pressing on motor fibers in the corticospinal tract. The typical gait is broad-based, slow, with short steps, and feels “stuck to the floor” or “magnetic,” resembling Parkinson’s disease. It can be mild, marked (significant instability), or severe (requiring a cane or walker). Up to 40% of patients also have tremors in the hands, legs, or feet.
Dementia, seen in 60% of patients at treatment, involves progressive cognitive decline from frontal lobe and subcortex distortion. Early signs include trouble with planning, organization, attention, and concentration. Later, patients struggle with finances, medications, driving, appointments, daytime sleepiness, short-term memory, and slowed thinking. Late stages brin
- field
- Neurology
- known_for
- Classic triad of gait disturbance, urinary incontinence, and cognitive impairment; first described by Salomón Hakim in 1964
- symptoms
- Memory impairment, urinary frequency, balance problems/gait deviations
- treatment
- Surgical placement of a ventriculoperitoneal shunt; endoscopic third ventriculostomy is generally not effective for NPH
Lore & Background
Normal pressure hydrocephalus presents in a classic triad of symptoms: memory impairment, urinary frequency, and balance problems/gait deviations. The triad is considered obsolete for diagnostic purposes, and symptoms appear at a relatively late stage. Gait deviations are present in nearly all patients and are typically the first presenting symptom, caused by expansion of the lateral ventricles impinging on corticospinal tract motor fibers. Dementia presents as progressive cognitive impairment in 60% of patients at time of treatment, caused by distortions predominantly at the frontal lobe and the subcortex. Urinary incontinence appears late in the illness and is present in 50% of patients.
Reader's Guide
Normal pressure hydrocephalus is significant as a treatable cause of neurological decline in older adults, though it is often misdiagnosed as other conditions including Meniere's disease, Parkinson's disease, or Alzheimer's disease. The usual treatment is surgical placement of a ventriculoperitoneal shunt to drain excess CSF into the lining of the abdomen. An alternate, less invasive treatment is endoscopic third ventriculostomy. Up to 80% of cases are unrecognized and untreated due to difficulty of diagnosis. The exact pathogenesis is unknown, but consensus includes an imbalance between production and resorption of CSF and elevated resistance to CSF outflow. The disease is not caused by overproduction of CSF or obstruction of CSF flow at the ventricles. Primary NPH affects adults age 40 years or older, most commonly in adults over 60, while secondary NPH can affect persons of any age due to conditions such as subarachnoid hemorrhage, meningitis, brain surgery, brain radiation, or traumatic brain injury.
Did You Know?
- The classic triad of symptoms is considered obsolete for diagnostic purposes.
- Gait deviations are present in nearly all NPH patients and are typically the first presenting symptom.
- Up to 80% of cases are unrecognized and untreated due to difficulty of diagnosis.
- An associated tremor of the hands, legs, or feet can be seen in up to 40% of NPH patients.
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