NPH Misdiagnosed as Alzheimer's
Normal Pressure Hydrocephalus—NPH—Has Similar Symptoms As AD
Dec 7, 2007
NPH, Normal Pressure Hydrocephalus, is a non-genetic neurological disorder with three classic symptoms. It largely afflicts individuals 55 and older. It is often reversible, especially if diagnosed early. More cases of NPH are expected as the US population ages.
NPH Symptoms
Three symptoms, called the triad, characterize NPH:
- Walking difficulty (gait disturbance) evidenced by a wide-based, slow, shuffling gait; the feet may seem to be "stuck" to the floor. Patients have difficulty taking the first step (called start hesitation) or turning. Freezing episodes also can occur. Gait disturbance is often the earliest and most obvious symptom of NPH.
- Urinary incontinence distinguished both by inability to reach the toilet in time and by loss of bladder control.
- Reduced short-term memory, slow thought process and dementia, or memory difficulties, and problems performing normal daily activities.
Causes of NPH
NPH occurs when an excess accumulation of cerebrospinal fluid (CSF) in brain cavities (called ventricles) results in abnormal cranial pressure. Some people are born with NPH, or it has no obvious cause. It may be associated with:
- Brain injury from trauma
- Hemorrhage, blood clot and aneurysm
- Infections like meningitis
- Stroke, brain tumor or cyst
- Aging
NPH Diagnosis
Only neurologists guided by various tests can diagnose NPH and distinguish it from Alzheimer’s and Parkinson’s diseases. Specialists employ up to three different diagnostic strategies to assess NPH:
- Neuropsychological tests—evaluation of cognitive abilities, memory, mood, attention span, reasoning, problem solving and abstract thinking.
- Imaging studies—brain scans (CT and/or MRI).
- Spinal tap (lumbar puncture), which is the removal of some CSF from the area around the spinal cord in the lower back. If symptoms temporarily diminish when a large volume of CSF is taken out, it is another diagnostic indicator of NPH.
Remedy for NPH
There is no cure for NPH. The only treatment is surgical implantation of a flexible tube, called a shunt, to harmlessly drain excess cranial fluid away from the brain into the abdomen. This reduces intercranial pressure, and often relieves and reverses symptoms.
The shunt is hidden under the skin. A pressure valve controls the volume of fluid that exits the brain. According to the National Council on Aging there are two kinds of shunts, both the same size and implanted identically:
- Fixed Pressure—the valve chosen by the neurosurgeon has a fixed pressure setting. If the setting needs adjustment because cranial fluid drainage is excessive or insufficient, more surgery is needed. Fixed pressure valves have been in use since the 1960s.
- Programmable Pressure—The shunt valve pressure is quickly and easily adjusted in a doctor’s office, using an external magnetic device. No repeated surgery is needed.
Distinguishing NPH From Alzheimer’s and Parkinson’s
According to the Department of Neurological Surgery, University of California Irvine:
- In AD, cognitive changes predominate earlier and gait difficulties occur later compared to NPH.
- In Parkinson’s, symptoms of tremor and rigidity are usually more pronounced, the gait is often narrow-based, and cognitive decline appears late or not at all.
Incidence of NPH
Five to ten percent of all cases of dementia may be attributed to NPH. The National Council on Aging estimates that up to 750,000 Americans have NPH. Only 11,500 cases a year are correctly diagnosed and treated.
Further Resources
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