What is the clinical presentation of Normal Pressure Hydrocephalus (NPH) manifesting as dementia?

From the Guidelines

Normal pressure hydrocephalus (NPH) presenting as dementia should be diagnosed using anatomical neuroimaging, specifically MRI, to assess ventricular enlargement and rule out other causes of dementia, as recommended by the 5th Canadian Consensus Conference on the diagnosis and treatment of dementia 1. When NPH presents primarily with dementia symptoms, patients typically show frontal-subcortical cognitive deficits including slowed thinking, apathy, impaired attention, and executive dysfunction, rather than the memory problems typical of Alzheimer's disease.

Key Diagnostic Considerations

• Diagnosis requires clinical evaluation combined with brain imaging showing ventricular enlargement without significant brain atrophy and normal or only slightly elevated cerebrospinal fluid pressure.
• Diagnostic workup should include MRI of the brain, neuropsychological testing, and often a high-volume lumbar puncture (30-50 mL) as a diagnostic trial, with improvement after CSF removal supporting the diagnosis.
• The use of semi-quantitative scales, such as the medial temporal lobe atrophy (MTA) scale, Fazekas scale, and global cortical atrophy (GCA), is recommended for routine interpretation of both MRI and CT scans 1.

Treatment and Management

• Treatment primarily involves surgical placement of a ventriculoperitoneal shunt, which diverts excess CSF from the ventricles to the peritoneal cavity.
• Patient selection for shunting is critical, with better outcomes typically seen in those with predominant gait disturbance, shorter symptom duration (less than 2 years), and positive response to diagnostic CSF removal.
• Without treatment, NPH typically progresses, but with appropriate shunting, 60-80% of well-selected patients show significant improvement in symptoms, particularly gait, though cognitive improvement may be less dramatic and depends on early intervention before permanent brain damage occurs.

Importance of Early Diagnosis and Treatment

• Early diagnosis and treatment of NPH are crucial to prevent permanent brain damage and improve symptoms, as highlighted in the management of dementia worldwide 1.
• The diagnosis of dementia should be based on medical history combined with neuropsychological and other clinical examinations to confirm mental decline, and NPH should be considered as a potentially reversible cause of dementia.

From the Research

Normal Pressure Hydrocephalus Presenting as Dementia

• Normal pressure hydrocephalus (NPH) is a reversible disorder characterized by gait impairment, subcortical dementia, and urinary urgency and incontinence associated with impaired cerebrospinal fluid circulation and ventriculomegaly 2.
• The typical clinical presentation of NPH includes gait disturbance and cognitive impairment, and a standard pre-/post-lumbar drain evaluation should include the Berg Balance Scale and trail making test to assess clinical change 3.
• Treatment with shunt surgery is most likely to increase mobility, and may also improve dementia and urinary symptoms 2.
• However, patients who present with dementia alone may not respond well to cerebrospinal fluid (CSF) shunting because of cerebral atrophy and the lack of tension within the cerebral ventricles 4.
• The evaluation of dementia usually includes a consideration of normal pressure hydrocephalus, which may be a treatable aspect of the patient's cognitive dysfunction 4.

Diagnosis and Management

• An international, independent study group recently published guidelines for the diagnosis and management of idiopathic NPH 2.
• The diagnosis of NPH can be supported by the presence of gait disturbance, cognitive impairment, and urinary urgency and incontinence, as well as impaired cerebrospinal fluid circulation and ventriculomegaly 2.
• A lumbar drain trial can be used to assess the potential benefit of ventriculoperitoneal shunting, and significant improvements in balance and neuropsychological measures can be seen in patients who undergo this procedure 3.

Pathophysiology

• NPH is considered to be an example of reversible dementia, although clinical improvement after shunting varies from subject to subject 5.
• The craniospinal compartment is a partially closed sphere with control device systems represented by the spinal axis and the sagittal sinus-arachnoid villi complex, which interact with each other in the clinical patient setting 5.
• Changing spinal compliance by altering the flow process and CSF dynamics can lead to hydrocephalus, and four NPH types have been distinguished according to the alterations in spinal compliance, decrease in CSF absorption at the sagittal sinus or both occurrences 5.