Neurosurgery for Hydrocephalus

Updated: Sep 27, 2017
  • Author: Herbert H Engelhard, III, MD, PhD, FACS; Chief Editor: Brian H Kopell, MD  more...
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Overview

Background

Hydrocephalus, a condition first described by Hippocrates, is the abnormal rise in cerebrospinal fluid (CSF) volume and, usually, pressure, that results from an imbalance of CSF production and absorption.

Hydrocephalus was not treated effectively until the mid-20th century, when the development of appropriate shunting materials and techniques occurred. At the beginning of the 20th century, doctors (including urologists) attempted to introduce scopes into the ventricular system. Attempts were also made to remove the choroid plexus, which generates much of the CSF, in an attempt to treat hydrocephalus. 

Hydrocephalus research and treatment have advanced tremendously in the last 20 years. Today, the focus of hydrocephalus research is on pathophysiology, shunting (eg, new shunt materials and programmable valve design), and minimally invasive techniques of treatment. Areas of research include the following:

  • Transplantation of tissue, such as vascularized omentum, to reestablish normal CSF could be the best method for treating communicating hydrocephalus
  • Third ventriculostomies and aqueductoplasty eliminate the need for shunting in noncommunicating cases of hydrocephalus; new optics and smaller scopes are expanding this field
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Pathophysiology

Hydrocephalus can be subdivided into the following three forms:

  • Disorders of CSF production - This is the rarest form; choroid plexus papillomas and choroid plexus carcinomas can secrete CSF in excess of its absorption
  • Disorders of CSF circulation - This form results from obstruction of the pathways of CSF circulation, which can occur at the ventricles or arachnoid villi; tumors, hemorrhages, congenital malformations (such as aqueductal stenosis), and infections can cause obstruction at either point in the pathways
  • Disorders of CSF absorption - Conditions such as the superior vena cava syndrome and sinus thrombosis can interfere with CSF absorption.

Some forms of hydrocephalus cannot be classified clearly. This group includes normal-pressure hydrocephalus and pseudotumor cerebri.

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Etiology

The etiology of hydrocephalus in congenital cases is unknown. Very few cases (<2%) are inherited (X-linked hydrocephalus). The most common causes of hydrocephalus in acquired cases are tumor obstruction, [1] trauma, intracranial hemorrhage, and infection.

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Epidemiology

The overall incidence of hydrocephalus is unknown. When cases of spina bifida are included, congenital hydrocephalus occurs in 2-5 births per 1000. The incidence of acquired types of hydrocephalus is unknown.

Tanaka et al concluded that the incidence of idiopathic normal-pressure hydrocephalus was 1.4% in their study of an elderly Japanese population. [2]

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Prognosis

In general, outcome is good. A typical patient should return to baseline after shunting, unless prolonged elevated intracranial pressure (ICP) or brain herniation has occurred. The neurologic function of children is optimized with shunting. Infection, especially if repeated, may affect cognitive status.

The best long-term results in the most carefully selected patients are no better than 60% in normal-pressure hydrocephalus. Few complete recoveries occur. Often, gait and incontinence respond to shunting, but dementia responds less frequently.

Often, various other neurologic abnormalities associated with hydrocephalus are the limiting factor in patient recovery. Examples are migrational abnormalities and postinfectious hydrocephalus.

In a study of responders and nonresponders to shunt surgery for idiopathic normal-pressure hydrocephalus, responders were found to have much higher preoperative pulsatile ICP than nonresponders did. [3]

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