What is hydrocephalus?

The term hydrocephalus comes from the Greek: hydro (water) + kefale (skull). We commonly diagnose hydrocephalus in patients with ventricular dilation, which results in an increase in the volume of cerebrospinal fluid (CSF). However, this definition does not include brain atrophy caused by neurodegenerative diseases, the so-called "ex vacuo" hydrocephalus.
Preferably, the term hydrocephalus should be used to cover all mechanisms that cause an over accumulation of intraventricular CSF, either due to an increase in CSF production, or change in circulation or absorption.

Hydrocephalus is a direct consequence of active CSF secretion through the choroid plexuses of the lateral, third and fourth ventricles (70-80%) and, to a lesser extent, the formation of extra-arachnoidal CSF that comes from the wall of the capillaries. This increase in CSF can be correlated with an increase in intracranial pressure (ICP), but we can also find ourselves with a normal ICP, the so-called "normotensive hydrocephalus of the adult". It is frequently, but not always, associated with ventriculomegaly. Similarly, excess cerebrospinal fluid in the subdural or subarachnoid space in the cranial convexity may also cause hydrocephalus.

The symptoms seen in these patients are usually related to how fast the rate of increase in ventricular size and intracranial pressure is.


The causes are different for different types of hydrochephalus. Below is a list of some of the main causes.


The symptoms vary according to the kind of hydrocephalus the patient has. With acute hydrocephalus, the symptoms are as follows: 

  • Severe headache 
  • Nausea
  • Vomiting
  • Sleepiness 
  • Lowered level of consciousness including coma.

Sub-acute or chronic hydrocephalus

The most common symptoms are as follows: 

  • Gradual increase in intracranial pressure, manifested as headache that occurs mostly in the mornings, or that worsens with deep breathing, upon lying down, or changing position.
  • Progressive cognitive decline, that is, short-term memory loss; altered gait or slowness in performing fine movements or requiring coordination of movements; change in the control of the sphincters, both urinary and fecal. 

Normal Pressure Hydrocephalus (NPH)

Finally, in the particular case of Normal Pressure Hydrocephalus (NPH), the symptoms usually appear within the so-called "Hakim Triad"; Although not all symptoms are always presented together, it is common to find them in adults over the age of 60 with symptoms similar to dementia.

  • Progressive cognitive degeneration
  • Difficulty walking (Apraxia)
  • Loss of sphincter control


Diagnosis of hydrocephalus in adult patients continues to be a challenge due to the great variety of etiology and symptoms that we see in daily clinical practice. If a patient has ventriculomegaly, it is common to associate it with a ventriculoperitoneal shunt. However, sometimes it is difficult to find the pathophysiological mechanism that causes ventriculomegaly and whether or not this increase in ventricular size is accompanied by an increase in intracranial pressure. There are numerous diagnostic techniques currently used:

Neuroimaging techniques

Cranial CT, different brain and spinal MRI sequences, brain SPECT…

Neuropsychological tests

To evaluate possible cognitive deterioration.

More or less invasive measurements of physiological parameters

Related to circulation of cerebrospinal fluid by using continuous recording of intracranial pressure waves with direct implantation of an intraventricular/intraparenchymal ICP sensor or by lumbar puncture.

Since there is no gold-standard test (of high sensitivity and specificity) for the diagnosis of hydrocephalus, we use a combination of several diagnostic techniques to prepare a clinical evaluation when treating hydrocephalus. Among those techniques, the most widely used are magnetic resonance imaging (MRI) of the brain, neuropsychological tests, and ICP measurement by lumbar or intracerebral puncture.


In patients with acute hydrocephalus, caused by an obstructive tumor or by intracranial bleeding, symptoms have usually started very recently, within hours or days.

Emergency neurosurgeries

These cases are emergency neurosurgeries, which is why they require monitoring in the Intensive Care Unit (ICU) and, frequently, respiratory support. The placement of an external ventricular drain or ventriculoperitoneal shunt relieves intracranial pressure and is usually the first step in treating a tumor process or intracranial hemorrhage.

Subacute or chronic hydrocephalus

Patients with by subacute or chronic hydrocephalus may show a gradual increase in ICP and milder symptoms, due to the action of intracranial pressure compensatory mechanisms. They are usually scheduled for ventriculoperitoneal shunt (VPS) implant surgery, if an obstructive cause is ruled out.

Obstructive hydrocephalus

In cases when obstructive hydrocephalus (arachnoid cysts or membranes, slow growing tumors ...) is strongly suspected, primary treatment of the obstructive cause is possible through tumor resection, or open or endoscopic fenestration of the arachnoid cyst or membrane.

Normal pressure hydrocephalus

Patients suffering from normal pressure hydrocephalus, more often exhibit symptoms related to cognitive deterioration, difficulty walking, and/or changes in control of sphincters.  In these patients, the etiological diagnosis is essential when choosing the most appropriate treatment. Placement of an external ventricular drain or ventriculoperitoneal shunt is usually the most common treatment. Different types of ventriculoperitoneal shunt valves can be used, with fixed flow pressure opening, or programmable.

Recovery and rehabilitation

Because there is such a broad clinical spectrum in patients with hydrocephalus, recovery can vary greatly. In general terms, patients with acute hydrocephalus require prolonged hospital stay due to their underlying pathology (tumor or bleeding). On the other hand, patients with subacute or chronic hydrocephalus tend to have a more rapid and favorable evolution. In the latter case, the patients operated on by scheduled surgery that requires approximately 3-7 days of hospital stay.  

It is advisable for these patients to undergo post-surgical rehabilitation in specific centers that have neuro-rehabilitators and a team of specialized physiotherapists. Re-education of gait is important, and also support destined to teach memory stimulation mechanisms both to the patient and to their relatives and people they live with.

Who are the doctors at Instituto Clavel who treat hydrocephalus?


  • Martín-Láez R, Caballero-Arzapalo H, López-Menéndez LA, Arango-Lasprilla JC, Vázquez-Barquero A: Epidemiology of idiopathic normal pressure hydrocephalus: asystematic review of the literature. World Neurosurg 84:2002–2009, 2015.
  • Wikkelsø C, Hellström P, Klinge PM, Tans JT: The European iNPH Multicentre Study on the predictive values of resistance to CSF outflow and the CSF Tap Test in patients with idiopathic normal pressure hydrocephalus. J Neurol Neurosurg Psychiatry 84:562–568, 2013 24.
  • Williams MA, Relkin NR: Diagnosis and management of idiopathic normal-pressure hydrocephalus. Neurol Clin Pract 3:375–385, 2013.
  • Eide PK, Sorteberg W: Diagnostic intracranial pressure monitoring and surgical management in idiopathic normal pressure hydrocephalus: a 6- year review of 214 patients. Neurosurgery 2010, 66:80-91.
  • Hashimoto et al. Diagnosis of idiopathic normal pressure hydrocephalus is supported by MRI-based scheme: a prospective cohort study. 2010, 7:18.
  • Marmarou A, Bergsneider M, Relkin N, Klinge P, Black PM: Development of guidelines for idiopathic normal-pressure hydrocephalus: introduction. Neurosurgery 2005, 57(Suppl):S1-3.
  • McGirt MJ, Woodworth G, Coon AL, Thomas G, Williams MA, Rigamonti D: Diagnosis, treatment, and analysis of long-term outcomes in idiopathic normal-pressure hydrocephalus. Neurosurgery 2005, 57:699-705. 27.
  • Marmarou A, Young HF, Aygok GA, Sawauchi S, Tsuji O, Yamamoto T, Dunbar J: Diagnosis and management of idiopathic normal-pressure hydrocephalus: a prospective study in 151 patients. J Neurosurg 2005, 102:987-97.

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