Normal Pressure Hydrocephalus

Normal Pressure Hydrocephalus

Ashley Davidoff MD

The Common Vein Copyright 2010


 Normal pressure hydrocephalus (NPH) is a mechanical abnormality of CSF fluid dynamics thought to be caused by a impaired absorption of CSF in the face of normal production resulting in a dilated ventricular system but with normal or near normal pressure.

Structurally it is characterized by a patent but dilated ventricular system most easily recognized by an increase in size of the lateral ventricles.

Functionally it impairs mental faculties, gait, and urinary continence.

Clinically it has an insidious onsetand manifests in the triad noted above of mental deterioration, gait disurbance and urinary incontinence. (Adams triad)

Imaging shows by CT or MRI shows enlarged lateral ventricles and patent ventricular system.  Transependymal flow of CSF may be seen on the T2 weighted or FLAIR sequences.

Lumbar puncture shows normal or near normal CSF pressures (high normal = 150-200mms water.)  If a hifh volume of CSF is removed at the time of the LP (25-30ccs) and the patients gait improves this is diagnostic of the condition.

The diagnosis is made on the basis of clinical, imaging and LP results.

Treatment is by placement of a ventriculo-peritoneal shunt.

70 year Brain in Two Different Patients

“Normal” Involution (a) Normal Pressure Hydrocephalus (b)

The 2 CT scans show 70 year old brains in two different patients. The patient on the left (a), reveals normal involution of the brain characterized by deepening of the sulci and prominence of the gyri together with a prominent ventricular system. Contrast this brain with the CT scan of the 22 year old above where the sulci and gyri are barely distinguished and the ventricles are slit like. The second patient (b) has a condition called normal pressure hydrocephalus (NPH). In addition to having “normal” involution, the patient also has dilated ventricles more than one would expect for the degree of involution. This is an abnormal finding.

CTscan Courtesy Ashley Davidoff MD copyright 2010 72179c01

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