Understanding Hydrocephalus and Normal Pressure Hydrocephalus

Hydrocephalus is a condition where there is an abnormal accumulation of cerebrospinal fluid (CSF).  This fluid is produced within chambers of the brain called ventricles.  The fluid circulates around the brain and spinal cord to cushion and support the central nervous system.  CSF is constantly produced and reabsorbed at a rate of approximately one pint per day.  Spinal fluid can build up in certain circumstances, and the ventricles, or chambers, become larger than normal.  This excessive fluid is called hydrocephalus, and can increase pressure inside the brain.  Hydrocephalus can occur from a blockage of the normal circulation of fluid, an interruption in the reabsorbing process, or an over production of CSF.

Normal Pressure Hydrocephalus (NPH) is a syndrome where spinal fluid builds up in the brain, enlarging the ventricles.  But, it is not necessarily associated with increased pressure, thus the term, Normal Pressure Hydrocephalus.  Most commonly seen in older adults, the syndrome has three main symptoms: gait/walking disturbance, mild dementia and impaired bladder control.    Although NPH can occur after brain trauma or infection, most cases have no known cause.

Diagnosing NPH

Diagnoses of NPH can be difficult based on a clinical exam and brain imaging alone.  The USC Neurosurgery team may perform other tests such as a CSF flow study or an evaluation of the CSF external drainage. 

While mild dementia may be a symptom, patients and their family should know that NPH is not Alzheimer’s disease. It also differs from hydrocephalus seen in children.  These diseases are vastly different and should not be confused with one another.

Treatment Options

Draining the excess spinal fluid from the brain can be achieved through insertion of a shunt tube, but not all patients benefit from the shunt procedure.  Ultimately, the best predictor of success is the external lumbar drain test.  This involves inserting a very small tube in the lower back near the spinal canal in order to drain CSF fluid into a collection receptacle.  A physical therapist and a neurologist specializing in NPH then evaluate the patient for improvements with walking, bladder control and memory function during a three to four day hospital stay.  Then the drain is removed and the patient goes home.  Close observation at home by family members is valuable input during this time.  Patients that achieve a measurable improvement from the CSF drainage are considered good potential candidates for the CSF shunt surgery.

If shunt surgery is indicated, a tube that redirects the CSF from the brain to another part of the body to be reabsorbed is placed in a brain ventricle.  A neurologist can then make adjustments to the shunt valve based on a patient’s progress.

Fight On!
Contact Us

Learn more about our neurosurgery physicians at Faculty.

Keck Hospital of USC
Department of Neurosurgery
(323) 442-7542
nsmessage@med.usc.edu

J. Peter Gruen, MD
Associate Professor
USC Department of Neurological Surgery
(323) 442-7542

Learn more at Hydrocephalus Association.