Normal Pressure Hydrocephalus Workup

  • Author: Arif I Dalvi, MD; Chief Editor: Selim R Benbadis, MD   more...
 
Updated: Oct 28, 2010
 

Laboratory Studies

After a detailed history and physical examination, further diagnostic testing is required to establish a diagnosis. In general, laboratory testing is unhelpful. However, imaging tests are invaluable in the diagnosis of this disease.

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Imaging Studies

In most cases of new onset neurologic symptoms, a CT scan of the brain is initially obtained. Although MRI is more specific than CT in NPH, a normal CT scan can exclude the diagnosis. CT and MRI findings in NPH include the following:

  • Ventricular enlargement out of proportion to sulcal atrophy, as shown in the image below
  • Prominent periventricular hyperintensity consistent with transependymal flow of CSF, also shown below T2-weighted MRI showing dilatation of ventricles oT2-weighted MRI showing dilatation of ventricles out of proportion to sulcal atrophy in a patient with normal pressure hydrocephalus. The arrow points to transependymal flow.
  • Prominent flow void in the aqueduct and third ventricle, the so-called jet sign, (presents as a dark aqueduct and third ventricle on a T2-weighted image where remainder of CSF is bright)
  • Thinning and elevation of corpus callosum on sagittal images
  • Rounding of frontal horns, shown below CT head scan of a patient with normal pressure hydCT head scan of a patient with normal pressure hydrocephalus showing dilated ventricles. The arrow points to a rounded frontal horn.
  • A narrow CSF space at the high convexity/midline areas relative to Sylvian fissure size was recently shown to correlate with a diagnosis of probable or definite iNPH.[10]

To establish a diagnosis of NPH (and exclude hydrocephalus ex vacuo), an MRI or CT must show an Evan’s index of at least 0.3.[11] In addition, one or more of the following must also be present:

  • Temporal horn enlargement
  • Periventricular signal changes
  • Periventricular edema
  • Aqueductal/fourth ventricular flow void

Prominent medial temporal cortical atrophy favors a diagnosis of hydrocephalus ex vacuo and is related to Alzheimer disease or vascular dementia. Patients may occasionally be referred for treatment of NPH based on an imaging diagnosis of hydrocephalus. However, with hydrocephalus ex vacuo, transependymal flow is uncommon. In contrast, sulcal atrophy and significant white matter ischemic disease are commonly seen.

This image shows ventriculomegaly, which is typicaThis image shows ventriculomegaly, which is typical in hydrocephalus ex vacuo. This image shows cortical atrophy, which is the deThis image shows cortical atrophy, which is the defining feature of hydrocephalus ex vacuo.

Additionally, the presence of abnormalities such as an Arnold Chiari malformation raise the possibility of a congenital hydrocephalus.

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Procedures

All patients with suspected NPH should undergo diagnostic CSF removal (either large volume lumbar puncture and/or external lumbar drainage), which has both diagnostic and prognostic value (see Surgical Care). When the CSF opening pressure is greatly elevated, other causes of hydrocephalus should be considered, although CSF pressures may be transiently elevated in NPH. Improvement in symptoms with large volume drainage is supportive of the diagnosis of NPH.

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Contributor Information and Disclosures
Author

Arif I Dalvi, MD  Director, Movement Disorders Center, NorthShore University HealthSystem, Clinical Associate Professor of Neurology, University of Chicago Pritzker Medical School

Arif I Dalvi, MD is a member of the following medical societies: European Neurological Society and Movement Disorders Society

Disclosure: Nothing to disclose.

Coauthor(s)

Ashvini P Premkumar, MD  Associate Director, Movement Disorders Center, NorthShore University HealthSystem, Clinical Instructor of Neurology, University of Chicago Pritzker Medical School

Ashvini P Premkumar, MD is a member of the following medical societies: American Academy of Neurology and Movement Disorders Society

Disclosure: Nothing to disclose.

Specialty Editor Board

Joseph F Hulihan, MD  Vice President, Medical Affairs, Ortho-McNeil Janssen Scientific Affairs, LLC

Joseph F Hulihan, MD is a member of the following medical societies: American Academy of Neurology, American Clinical Neurophysiology Society, American Epilepsy Society, American Headache Society, and American Medical Association

Disclosure: Johnson & Johnson Salary Employment; Johnson & Johnson Stock Employment

Francisco Talavera, PharmD, PhD  Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

Nestor Galvez-Jimenez, MD, MSc, MHA  Chairman, Department of Neurology, Program Director, Movement Disorders, Department of Neurology, Division of Medicine, Cleveland Clinic Florida

Nestor Galvez-Jimenez, MD, MSc, MHA is a member of the following medical societies: American Academy of Neurology, American College of Physicians, and Movement Disorders Society

Disclosure: Nothing to disclose.

Selim R Benbadis, MD  Professor, Director of Comprehensive Epilepsy Program, Departments of Neurology and Neurosurgery, Tampa General Hospital, University of South Florida College of Medicine

Selim R Benbadis, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Sleep Medicine, American Clinical Neurophysiology Society, American Epilepsy Society, and American Medical Association

Disclosure: UCB Pharma Honoraria Speaking, consulting; Lundbeck Honoraria Speaking, consulting; Cyberonics Honoraria Speaking, consulting; Glaxo Smith Kline Honoraria Speaking, consulting; Pfizer Honoraria Speaking, consulting; Sleepmed/DigiTrace Honoraria Speaking, consulting

Chief Editor

Selim R Benbadis, MD  Professor, Director of Comprehensive Epilepsy Program, Departments of Neurology and Neurosurgery, Tampa General Hospital, University of South Florida College of Medicine

Selim R Benbadis, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Sleep Medicine, American Clinical Neurophysiology Society, American Epilepsy Society, and American Medical Association

Disclosure: UCB Pharma Honoraria Speaking, consulting; Lundbeck Honoraria Speaking, consulting; Cyberonics Honoraria Speaking, consulting; Glaxo Smith Kline Honoraria Speaking, consulting; Pfizer Honoraria Speaking, consulting; Sleepmed/DigiTrace Honoraria Speaking, consulting

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T2-weighted MRI showing dilatation of ventricles out of proportion to sulcal atrophy in a patient with normal pressure hydrocephalus. The arrow points to transependymal flow.
CT head scan of a patient with normal pressure hydrocephalus showing dilated ventricles. The arrow points to a rounded frontal horn.
This image shows ventriculomegaly, which is typical in hydrocephalus ex vacuo.
This image shows cortical atrophy, which is the defining feature of hydrocephalus ex vacuo.
 
 
 
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