Neurology
Summary
Normal pressure hydrocephalus (NPH) is a subtype of communicating hydrocephalus characterized by the dilation of ventricles due to chronic insidious accumulation of cerebrospinal fluid (CSF), despite the presence of patent ventricular pathways and foramen. This accumulation leads to the stretching of neurons in the frontal lobe, corona radiata, and the periventricular white matter. The frontal lobe, in particular, plays a crucial role in personality, motor movements, and the micturition center. NPH can be categorized into two main types: idiopathic (primary) NPH, which predominantly affects the elderly (age 65 and above), and secondary NPH. Secondary NPH arises from decreased CSF absorption after a structural injury, such as subarachnoid hemorrhage (SAH), meningitis, or traumatic brain injury, and can manifest at any age.
Patients with primary NPH present over weeks to months with a triad of symptoms often dubbed the "wacky, wobbly, and wet" syndrome. This encompasses personality changes and progressive dementia ("wacky"), a distinctive gait that is described as magnetic, wide-based, and appearing as if "stuck to the floor" ("wobbly"), and incontinence, due to the affected micturition center ("wet"). Diagnostically, CT and MRI imaging will reveal enlarged ventricles with normal sulci. A large volume lumbar puncture may produce a temporary improvement in NPH symptoms; notably, both the opening pressure and CSF analysis will be within normal ranges. Laboratory testing is essential to exclude other causes, such as acute bacterial infections, thyroid disorders, or B12 deficiency. Additionally, comprehensive neurocognitive testing is necessary to check for neurodegenerative diseases. The definitive treatment for NPH in those who show improvement post-lumbar puncture is the placement of a ventricular shunt.
Lesson Outline
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FAQs
NPH is a type of communicating hydrocephalus, where dilation of ventricles, or brain cavities, happens due to increased cerebrospinal fluid (CSF) accumulation. This happens despite 'patent' or open ventricular pathways and foramina that normally allow CSF to flow freely.
The accumulation of CSF leads to stretching of frontal lobe neurons, the corona radiata, and the periventricular white matter. The frontal lobe, being crucial in personality, motor movements, and the micturition center, can cause personality changes, motor function issues, and incontinence when affected.
Idiopathic or primary NPH, occurs primarily in the elderly and results from a chronic insidious accumulation of CSF. Secondary NPH on the other hand, is due to reduced CSF absorption following a structural injury such as subarachnoid hemorrhage, meningitis or traumatic brain injury and can occur at any age.
Diagnosis of NPH involves enlarged ventricles with normal sulci visualized on CT and MRI scans. In addition, a large volume lumbar puncture can lead to symptom improvement, indicating NPH. Lab tests are also essential to rule out conditions such as an acute bacterial infection, thyroid disorder, and B12 deficiency.
Ventricular shunt placement is the definitive treatment for NPH. This procedure is chosen if improvement in symptoms occurs after a large volume lumbar puncture, which aids in relieving the built-up CSF pressure. Neurocognitive testing is also done to evaluate the presence of neurodegenerative disease.
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