Nor­mal Pres­sure Hydro­cephalus (NPH)

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The term Hydro­cephalus refers to a con­di­tion where the fluid filled spaces (ven­tri­cles) in the brain become enlarged due to an abnor­mal build up of cere­brospinal fluid (CSF). This can be caused by either abnor­mal­i­ties in how the CSF is pro­duced, cir­cu­lated, or reab­sorbed. In Nor­mal Pres­sure Hydro­cephalus (NPH) there is lit­tle or no increase in the pres­sure of the fluid in the brain, even though the ven­tri­cles may become enlarged.

Cere­brospinal fluid (CSF) is a clear, water-​like fluid, which bathes the brain. The fluid cir­cu­lates into the space around the brain and spinal cord, where it func­tions as shock absorber, or as a pro­tec­tive cush­ion. Under nor­mal con­di­tions, you have about 125ml (a half cup) of CSF. CSF con­tains dis­solved sugar (glu­cose), pro­teins, salts, and some white blood cells.


NPH devel­ops slowly, often over weeks to months. There­fore NPH can be dif­fi­cult to diag­nose. Symp­toms are some­times over­looked or attrib­uted to the age­ing process (most peo­ple with NPH are over the age of 60). Symp­toms of NPH include:

  • Gait dis­tur­bances (dif­fi­culty walking)
  • Mild demen­tia (for­get­ful­ness, short term mem­ory loss)
  • Uri­nary incon­ti­nence (mild or com­plete loss of blad­der control)


In most cases the cause of NPH is unknown. In some cases, NPH may be the result of head injury, menin­gi­tis, encephali­tis, hem­or­rhage, tumor, or cysts.


CT Scan, Lum­bar Punc­ture (LP), and Mag­netic Res­o­nance Imag­ing (MRI) are the main diag­nos­tic tests used to find out whether or not you have NPH.



The place­ment of a Ven­tricu­loperi­toneal (VP) or Lum­boperi­toneal (LP) shunt is the most com­mon treat­ment. In a shunt sys­tem, a flex­i­ble sil­i­con tube is used to drain the excess fluid (CSF) from the brain or the space around the spinal cord to another part of the body (usu­ally the abdom­i­nal cav­ity). The surgery for the place­ment of a VP shunt is explained in more detail in the patient guide, VP Shunt for Hydrocephalus.

After shunt place­ment, a grad­ual improve­ment in symp­toms is expected to occur over a period of months.


The ven­tri­cles con­tain a spe­cial­ized tis­sue called choroid plexus, which pro­duces cere­brospinal fluid (CSF). The ven­tri­cles are inter­con­nected by nar­row passageways.

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Infor­ma­tion about InfoNEURO
Neuro-​Patient Resource Cen­tre
Mon­treal Neu­ro­log­i­cal Hosp­tial Room 354
Tel: (514) 3985358
E-​mail: infoneuro@​muhc.​mcgill.​ca
Web site: http://​infoneuro​.mcgill​.ca/

This infor­ma­tion is for edu­ca­tional pur­poses only, and is not intended to replace the advice of a pro­fes­sional health­care prac­ti­tioner, or to sub­sti­tute for med­ical care.

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Con­trib­u­tors: Carole-​Ann Miller MSc(A), Nurse Man­ager and Andrew Stein­metz (Med­ical Librar­ian).
Series Edi­tor: Dr. David Sin­clair (Neu­ro­surgery).
Orig­i­nal Illus­tra­tion: Neu­ropho­tog­ra­phy.
Pro­duced by the Neuro-​Patient Resource Cen­tre and Mon­treal Neu­ro­log­i­cal Hos­pi­tal staff.

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