What is the role of intracranial pressure (ICP) in the pathophysiology of hydrocephalus?

Updated: Jun 04, 2018
  • Author: Stephen L Nelson, Jr, MD, PhD, FAACPDM, FAAN, FAAP; Chief Editor: Jasvinder Chawla, MD, MBA  more...
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ICP rises if production of CSF exceeds absorption. This occurs if CSF is overproduced, resistance to CSF flow is increased, CSF resorption is decreased, or venous sinus pressure is increased. CSF production falls as ICP rises. Compensation may occur through transventricular absorption (subependymal flow) of CSF and also by absorption along nerve root sleeves (which may result in enlarged optic nerve sheaths). The temporal and frontal horns dilate first, often asymmetrically. This may result in elevation of the corpus callosum, stretching or perforation of the septum pellucidum, thinning of the cerebral mantle, or enlargement of the third ventricle downward into the pituitary fossa (which may cause pituitary dysfunction) as well as dorsal midbrain compression resulting in Parinaud's syndrome (aralysis of upgaze, Pseudo-Argyll Roberson pupils, convergence-retraction nystagmus, eyelide retraction, and setting sun sign).

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