eMedicine Specialties > Neurology > Movement and Neurodegenerative Diseases
Normal Pressure Hydrocephalus: Differential Diagnoses & Workup
Updated: Feb 9, 2010
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
- Multimedia
Differential Diagnoses
Other Problems to Be Considered
Multiple other illnesses may present similarly to NPH that should be considered in the Differential diagnosis. In particular, Parkinson disease and NPH may present in a similar, but distinct manner. Start hesitation and freezing episodes can occur in NPH, often mimicking the gait in Parkinson disease. In contrast to Parkinson disease, rigidity and unilateral rest tremor are less commonly observed. Furthermore, a robust response to L-Dopa is not typically seen in NPH, in contrast to Parkinson disease.
Workup
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.
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 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 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 typical in hydrocephalus ex vacuo.
This 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.
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.
More on Normal Pressure Hydrocephalus |
| Overview: Normal Pressure Hydrocephalus |
 Differential Diagnoses & Workup: Normal Pressure Hydrocephalus |
| Treatment & Medication: Normal Pressure Hydrocephalus |
| Follow-up: Normal Pressure Hydrocephalus |
| Multimedia: Normal Pressure Hydrocephalus |
| References |
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References
Hakim S, Adams RD. The special clinical problem of symptomatic hydrocephalus with normal cerebrospinal fluid pressure. Observations on cerebrospinal fluid hydrodynamics. J Neurol Sci. Jul-Aug 1965;2(4):307-27. [Medline].
Brean A, Eide PK. Prevalence of probable idiopathic normal pressure hydrocephalus in a Norwegian population. Acta Neurol Scand. Jul 2008;118(1):48-53. [Medline].
Hiraoka K, Meguro K, Mori E. Prevalence of idiopathic normal-pressure hydrocephalus in the elderly population of a Japanese rural community. Neurol Med Chir (Tokyo). May 2008;48(5):197-99; discussion 199-200. [Medline].
Tanaka N, Yamaguchi S, Ishikawa H, Ishii H, Meguro K. Prevalence of possible idiopathic normal-pressure hydrocephalus in Japan: the Osaki-Tajiri project. Neuroepidemiology. 2009;32(3):171-5. [Medline].
Marmarou A, Young HF, Aygok GA. Estimated incidence of normal pressure hydrocephalus and shunt outcome in patients residing in assisted-living and extended-care facilities. Neurosurg Focus. Apr 15 2007;22(4):E1. [Medline].
Sakakibara R, Uchiyama T, Kanda T, Uchida Y, Kishi M, Hattori T. [Urinary dysfunction in idiopathic normal pressure hydrocephalus]. Brain Nerve. Mar 2008;60(3):233-9. [Medline].
Bech-Azeddine R, Hogh P, Juhler M, Gjerris F, Waldemar G. Idiopathic normal-pressure hydrocephalus: clinical comorbidity correlated with cerebral biopsy findings and outcome of cerebrospinal fluid shunting. J Neurol Neurosurg Psychiatry. Feb 2007;78(2):157-61. [Medline].
Golomb J, Wisoff J, Miller DC, et al. Alzheimer's disease comorbidity in normal pressure hydrocephalus: prevalence and shunt response. J Neurol Neurosurg Psychiatry. Jun 2000;68(6):778-81. [Medline].
Graff-Radford NR, Godersky JC. Symptomatic congenital hydrocephalus in the elderly simulating normal pressure hydrocephalus. Neurology. Dec 1989;39(12):1596-600. [Medline].
Sasaki M, Honda S, Yuasa T, Iwamura A, Shibata E, Ohba H. Narrow CSF space at high convexity and high midline areas in idiopathic normal pressure hydrocephalus detected by axial and coronal MRI. Neuroradiology. Feb 2008;50(2):117-22. [Medline].
Gyldensted C. Measurements of the normal ventricular system and hemispheric sulci of 100 adults with computed tomography. Neuroradiology. Dec 31 1977;14(4):183-92. [Medline].
Williams MA, Razumovsky AY, Hanley DF. Comparison of Pcsf monitoring and controlled CSF drainage diagnose normal pressure hydrocephalus. Acta Neurochir Suppl. 1998;71:328-30. [Medline].
Governale LS, Fein N, Logsdon J, Black PM. Techniques and complications of external lumbar drainage for normal pressure hydrocephalus. Neurosurgery. Oct 2008;63(4 Suppl 2):379-84; discussion 384. [Medline].
Marmarou A, Young HF, Aygok GA, et al. Diagnosis and management of idiopathic normal-pressure hydrocephalus: a prospective study in 151 patients. J Neurosurg. Jun 2005;102(6):987-97. [Medline].
Murai R, Hashiguchi F, Kusuyama A, et al. Percutaneous stenting for malignant biliary stenosis. Surg Endosc. 1991;5(3):140-2. [Medline].
Walchenbach R, Geiger E, Thomeer RT, Vanneste JA. The value of temporary external lumbar CSF drainage in predicting the outcome of shunting on normal pressure hydrocephalus. J Neurol Neurosurg Psychiatry. Apr 2002;72(4):503-6. [Medline].
Burnett MG, Sonnad SS, Stein SC. Screening tests for normal-pressure hydrocephalus: sensitivity, specificity, and cost. J Neurosurg. Dec 2006;105(6):823-9. [Medline].
Stein SC, Burnett MG, Sonnad SS. Shunts in normal-pressure hydrocephalus: do we place too many or too few?. J Neurosurg. Dec 2006;105(6):815-22. [Medline].
Hebb AO, Cusimano MD. Idiopathic normal pressure hydrocephalus: a systematic review of diagnosis and outcome. Neurosurgery. Nov 2001;49(5):1166-84; discussion 1184-6. [Medline].
Vanneste J, Augustijn P, Davies GA, Dirven C, Tan WF. Normal-pressure hydrocephalus. Is cisternography still useful in selecting patients for a shunt?. Arch Neurol. Apr 1992;49(4):366-70. [Medline].
Aimard G, Vighetto A, Gabet JY, Bret P, Henry E. [Acetazolamide: an alternative to shunting in normal pressure hydrocephalus? Preliminary results]. Rev Neurol (Paris). 1990;146(6-7):437-9. [Medline].
Vanneste J, Augustijn P, Dirven C, Tan WF, Goedhart ZD. Shunting normal-pressure hydrocephalus: do the benefits outweigh the risks? A multicenter study and literature review. Neurology. Jan 1992;42(1):54-9. [Medline].
Boon AJ, Tans JT, Delwel EJ, et al. Dutch Normal-Pressure Hydrocephalus Study: the role of cerebrovascular disease. J Neurosurg. Feb 1999;90(2):221-6. [Medline].
Pujari S, Kharkar S, Metellus P, Shuck J, Williams MA, Rigamonti D. Normal pressure hydrocephalus: long-term outcome after shunt surgery. J Neurol Neurosurg Psychiatry. Nov 2008;79(11):1282-6. [Medline].
Hertel F, Zuchner M, Decker C, Schill S, Bosniak I, Bettag M. The Miethke dual switch valve: experience in 169 adult patients with different kinds of hydrocephalus: an open field study. Minim Invasive Neurosurg. Jun 2008;51(3):147-53. [Medline].
Wikkelso C, Andersson H, Blomstrand C, Lindqvist G, Svendsen P. Normal pressure hydrocephalus. Predictive value of the cerebrospinal fluid tap-test. Acta Neurol Scand. Jun 1986;73(6):566-73. [Medline].
Walter C, Hertel F, Naumann E, Morsdorf M. Alteration of cerebral perfusion in patients with idiopathic normal pressure hydrocephalus measured by 3D perfusion weighted magnetic resonance imaging. J Neurol. Dec 2005;252(12):1465-71. [Medline].
Tsakanikas D, Relkin N. Normal pressure hydrocephalus. Semin Neurol. Feb 2007;27(1):58-65. [Medline].
Tisell M, Hellstrom P, Ahl-Borjesson G, Barrows G, Blomsterwall E, Tullberg M. Long-term outcome in 109 adult patients operated on for hydrocephalus. Br J Neurosurg. Aug 2006;20(4):214-21. [Medline].
Further Reading
Keywords
normal pressure hydrocephalus, NPH, occult hydrocephalus, extraventricular obstructive hydrocephalus, abnormal gait, urinary incontinence, dementia, intracranial pressure, ICP, CSF pressure, cerebrospinal fluid pressure, extraventricular obstructive hydrocephalus, gait apraxia, gait disorder, parkinsonism
