(See also Overview of Delirium and Dementia Overview of Delirium and Dementia Delirium (sometimes called acute confusional state) and dementia are the most common causes of cognitive impairment, although affective disorders (eg, depression) can also disrupt cognition... read more and Dementia Dementia Dementia is chronic, global, usually irreversible deterioration of cognition. Diagnosis is clinical; laboratory and imaging tests are usually used to identify treatable causes. Treatment is... read more .)
Dementia is chronic, global, usually irreversible deterioration of cognition.
Normal-pressure hydrocephalus is thought to result from a defect in cerebrospinal fluid (CSF) resorption in arachnoid granulations. This disorder accounts for up to 6% of dementias.
Normal-pressure hydrocephalus is classified as
Secondary: When it develops as a complication of another disorder (eg, subarachnoid hemorrhage Subarachnoid Hemorrhage (SAH) Subarachnoid hemorrhage is sudden bleeding into the subarachnoid space. The most common cause of spontaneous bleeding is a ruptured aneurysm. Symptoms include sudden, severe headache, usually... read more , meningitis Overview of Meningitis Meningitis is inflammation of the meninges and subarachnoid space. It may result from infections, other disorders, or reactions to drugs. Severity and acuity vary. Findings typically include... read more , traumatic brain injury Traumatic Brain Injury (TBI) Traumatic brain injury (TBI) is physical injury to brain tissue that temporarily or permanently impairs brain function. Diagnosis is suspected clinically and confirmed by imaging (primarily... read more )
Idiopathic: When an underlying disorder cannot be determined
Dementia Dementia Dementia is chronic, global, usually irreversible deterioration of cognition. Diagnosis is clinical; laboratory and imaging tests are usually used to identify treatable causes. Treatment is... read more should not be confused with delirium Delirium Delirium is an acute, transient, usually reversible, fluctuating disturbance in attention, cognition, and consciousness level. Causes include almost any disorder or drug. Diagnosis is clinical... read more , although cognition is disordered in both. The following helps distinguish them:
Dementia affects mainly memory, is typically caused by anatomic changes in the brain, has slower onset, and is generally irreversible.
Delirium affects mainly attention, is typically caused by acute illness or drug toxicity (sometimes life threatening), and is often reversible.
Other specific characteristics also help distinguish dementia and delirium (see table ).
Symptoms and Signs of Normal–Pressure Hydrocephalus
The gait disturbance in normal-pressure hydrocephalus is usually nonspecific unsteadiness and impaired balance, although a magnetic gait (the feet appear to stick to the floor) is considered the characteristic gait disturbance.
Dementia Symptoms and Signs Dementia is chronic, global, usually irreversible deterioration of cognition. Diagnosis is clinical; laboratory and imaging tests are usually used to identify treatable causes. Treatment is... read more may not occur until late in the disorder. The most common early symptoms of dementia are disturbances of executive function and attention; memory tends to become impaired later.
Urinary incontinence is common.
Diagnosis of Normal–Pressure Hydrocephalus
Clinical evaluation
Neuroimaging
Sometimes removal of CSF
The classic symptoms (gait disturbance, urinary incontinence, and dementia), even combined, are nonspecific for normal-pressure hydrocephalus, particularly in older people. For example, some forms of vascular dementia Vascular Cognitive Impairment and Dementia Vascular cognitive impairment and dementia is acute or chronic cognitive deterioration due to diffuse or focal cerebral infarction that is most often related to cerebrovascular disease. (See... read more can cause dementia, gait disturbance, and, less commonly, urinary incontinence.
A general diagnosis of dementia Clinical criteria Dementia is chronic, global, usually irreversible deterioration of cognition. Diagnosis is clinical; laboratory and imaging tests are usually used to identify treatable causes. Treatment is... read more requires all of the following:
Cognitive or behavioral (neuropsychiatric) symptoms interfere with the ability to function at work or do usual daily activities.
These symptoms represent a decline from previous levels of functioning.
These symptoms are not explained by delirium or a major psychiatric disorder.
Evaluation of cognitive function involves taking a history from the patient and from someone who knows the patient plus doing a bedside mental status examination How to Assess Mental Status The mental status examination is used to evaluate the patient’s level of consciousness and the content of consciousness. Patients are considered alert if they are actively perceiving the world... read more or, if bedside testing is inconclusive, formal neuropsychologic testing Assessment of cognitive function Dementia is chronic, global, usually irreversible deterioration of cognition. Diagnosis is clinical; laboratory and imaging tests are usually used to identify treatable causes. Treatment is... read more .
Brain imaging may show ventricular enlargement disproportionate to cortical atrophy; this finding is nonspecific but may support the diagnosis of normal-pressure hydrocephalus. Sulci high on the cortical convexity are often compressed, and the Sylvian fissures are disproportionately atrophic.
Lumbar puncture Lumbar Puncture (Spinal Tap) Lumbar puncture is used to do the following: Evaluate intracranial pressure and cerebrospinal fluid (CSF) composition (see table ) Therapeutically reduce intracranial pressure (eg, idiopathic... read more is done. CSF opening pressure should be normal in patients with normal-pressure hydrocephalus. Removal of 30 to 50 mL of CSF can be done as a diagnostic trial. Improvement in gait, continence, and cognition after removal suggests that the patient can be a good candidate for ventriculoperitoneal shunting surgery, but improvement may not be evident until several hours after removal. Additional CSF may leak out after lumbar puncture, sometimes contributing to neurologic improvement.
Treatment of Normal–Pressure Hydrocephalus
Sometimes ventriculoperitoneal shunting
Ventriculoperitoneal shunting is useful for patients with acceptable surgical risks. Improvements after lumbar puncture to remove CSF, done during diagnosis, may predict the response to shunting. In several case series (but in no randomized trials), patients improved substantially, typically in gait, continence, and daily functioning, after shunting; improvement in cognition was less common.
Key Points
Suspect normal-pressure hydrocephalus based on classic symptoms (gait disturbance, urinary incontinence, dementia), but consider lumbar puncture to remove excess CSF as a diagnostic trial to help confirm the diagnosis.
If surgical risks are acceptable, insert a ventriculoperitoneal shunt, which may significantly improve gait, continence, and daily functioning; improvement in mental function is less.