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(''water-head'', term derived from
Greek ) is an abnormal accumulation of
Cerebrospinal Fluid in the
Ventricle s of the
Brain . This increase in intracranial volume results in elevated
Intracranial Pressure and compression of the brain.
Like various other neurologic conditions (s,
Vomiting (in some cases not accompanied by
Nausea ),
Papilledema ,
Somnolence ,
Coma . Elevated
Intracranial Pressure may result in
Uncal and/or
Cerebellar Tonsill herniation, with resulting life threatening
Brain Stem Compression .
and
Dementia . Focal neurologic deficits may also occur, such as
Abducens Nerve palsy and vertical
Gaze Palsy (
Parrinaud Syndrome , due to compression of the
Quadrigeminal Plate , where the neural centers coordinating the conjugated vertical eye movement are located).
Hydrocephalus is caused by impaired
Cerebrospinal Fluid (CSF) production, flow or reabsorption.
The most common cause of hydrocephalus is a flow
Obstruction , hindering the free passage of
Cerebrospinal Fluid through the ventricular system and
Subarachnoid Space (e.g.
Stenosis of the
Cerebral Aqueduct , obstruction of the
Interventricular Foraminae - ). This can be secondary to
Tumor s,
Hemorrhage s,
Infection s or
Congenital Malfomation s. It can also be caused by overproduction of
Cerebrospinal Fluid (relative obstruction).
Based on its underlying mechanisms, hydrocephalus can be classified into , and '''non-communicating''' (obstructive). Both communicating and non-communicating forms can be either '''congenital''', or '''acquired'''.
, a.k.a. '''non-obstructive''' or '''communicating hydrocephalus''' is caused by impaired
Cerebrospinal Fluid resorption, in the absence of any CSF-flow obstruction. It has been theorized that this is due to functional impairment the arachnoid granulations (located along the
Superior Sagittal Sinus ) - they represent the site of
Cerebrospinal Fluid resorption back into the venous system). Various neurologic conditions may result in communicating hydrocephalus. These include subarachnoid/intraventricular
Hemorrhage ,
Meningitis ,
Chiari Malformation , and congenital absence of
Arachnoidal Granulations , a.k.a. '''Pacchioni's granulations'''.
(NPH) is a particular form of '''communicating hydrocephalus''', characterized by enlarged
Cerebral Ventricle s, with only intermittently elevated
Cerebrospinal Fluid pressure. The diagnosis of NPH can be established only with the help of continuous intraventricular pressure recordings (over 24 hours or even longer), since more often than not, instant measurements yield normal pressure values. Dynamic compliance studies may be also helpful. Altered compliance (elasticity) of the ventricular walls, as well as increased
Viscosity of the
Cerebrospinal Fluid may play a role in the genesis of '''
Normal Pressure Hydrocephalus '''.
, as it occurs in
Dementia s, after
Traumatic Brain Injuries and even in some psychiatric disorders, such as
Schizophrenia , may also result in an enlargement of
Cerebral Ventricles and
Subarachnoid Space s. This is often referred to as ''hydrocephalus ex vacuo''. As opposed to hydrocephalus, this is a '''compensatory enlargement''' of the CSF-spaces in response to '''
Brain Parenchyma loss''' - it '''is not''' the result of increased CSF pressure.
Non-communicating hydrocephalus, or , is caused by a CSF-flow obstruction (either due to external compression or intraventricular mass lesions). In many cases, the flow obstruction is located at the level of the
Cerebral Aqueduct (
Aqueduct Stenosis ), which connects the third and fourth ventricle.
Third Ventriculostomy (i.e. a surgical connection between the
Third Ventricle and the
Subarachnoid Space ) should be considered as an alternative therapeutic option to traditional CSF-shunting procedures (
Ventriculo-peritoneal Shunt ,
Ventriculo-atrial Shunt ).
In newborns and toddlers with hydrocephalus, the head circumference is enlarged, since the skull bones are not yet firmly joined together. A bulging, firm fontanelle (soft spot) may be an early sign of hydrocephalus in this age group.
About 80-90% of fetuses or newborn infants with
Spina Bifida - often associated with
Meningocele or
Myelomeningocele - develop hydrocephalus.
This condition is acquired as a consequence of CNS-
Infections ,
Brain Tumors ,
Head Trauma ,
Intracranial Hemorrhage (subarachnoid or intraparenchymal).
State-of-the-art treatment is surgical. It involves the placement of a
Ventricular Catheter (a tube made of
Silastic ), into the
Cerebral Ventricles to bypass the flow obstruction/malfunctioning
Arachnoidal Granulations and drain the excess fluid into other body cavities, from where it can be resorbed. Most shunts drain the fluid into the
Peritoneal Cavity (
Ventriculo-peritoneal Shunt ), but alternative sites include the
Right Atrium (
Ventriculo-atrial Shunt ),
Pleural Cavity (
Ventriculo-pleural Shunt ), and
Gallbladder . An alternative treatment is the
Endoscopic Third Venstriculostomy (ETV), whereby a surgically created opening in the floor of the third ventricle allows the CSF to flow directly to the basal cisterns, thereby shortcutting any obstruction, as in
Aqueductal Stenosis .
Hydrocephalus was first described by
Hippocrates , but it remained an intractable condition until the 20th century, when
Shunts and other
Neurosurgical treatment modalities were developed.
It is often informally referred to as 'water on the brain'.
Water baby, Waterhead, Waterface
- http://www.ifglobal.org, the International Federation for Spina Bifida and Hydrocephalus (IF), the umbrella organisation for national spina bifida and hydrocephalus organisations
- http://www.fetalcarecenter.org/medicine/fetal-surgery/hydrocephalus-surgery.htm, Fetal Care Center of Cincinnati: Fetal Surgery: Ventriculo-Peritoneal Shunting for Hydrocephalus
