History
Hydrocephalus was foremost described by Hippocrates, but it remained an intractable affliction until a 20th century, whenever shunts and other neurosurgical treatment modalities were developed.

Causes
Hydrocephalus is from either afflicted cerebrospinal fluid (CSF) production, flow or reabsorption.

A usual are causal agents for of hydrocephaly occurs as flow obstruction, hindering the loose passage of cerebrospinal fluid through the ventricular system & subarachnoid space (e.g. stenosis of the cerebral aqueduct, obstruction of the interventricular foraminae - foramen of Monro). This may be secondary to tumors, hemorrhages, infections or congenital malfomations. It can likewise become from either overrun of cerebrospinal fluid (relative obstruction).

According to its underlying mechanisms, hydrocephaly may be classified into communicating, & non-communicating (hindering).

Each communicating & non-communicating forms may be either inborn, or even acquired.

Normal pressure hydrocephalus (NPH) is a particular form of communicating hydrocephaly, characterized by hypertrophied cerebral ventricles, with just intermittently elevated cerebrospinal fluid pressure. A diagnosing of NPH may be established sole by using a support of continuous intraventricular pressure recordings (complete Two dozen hours or yearn), since additional typically than does'nt, instant measuring yield rule pressure values. Dynamic compliance studies can be too helpful. Altered compliance (snap) of the ventricular bulwarks, also when increased viscosity of the cerebrospinal fluid may play a role in the genesis of normal pressure hydrocephalus. Brain atrophy, as it occurs within dementias, after traumatic brain injuries and even within a bit of psychiatrical disorders, like schizophrenia, may besides effect around an enlargement of cerebral ventricles and subarachnoid spaces. When opposed to hydrocephaly, this occurs as compensatory enlargement of the CSF-spaces within response to brain parenchyma loss - it isNon a effect of increased CSF pressure.

Communicating hydrocephalus
Communicating hydrocephaly, the.k.the. non-obstructive or even communicating hydrocephaly is from either afflicted cerebrospinal fluid resorption, in the absence of any CSF-flow obstruction. It has been theorized that this is due to functional impairment a spiderly granulations (placed along a superior sagittal sinus) - they represent a places of cerebrospinal fluid resorption back into the venous rules). Various neurological conditions can effect around communicating hydrocephaly. These include subarachnoid/intraventricular hemorrhage, meningitis, [Chiari malformation]], and congenital absence of arachnoidal granulations, a.k.a. '''Pacchioni's granulations.

Non-communicating hydrocephalus
Non-communicating hydrocephalus, or obstructive hydrocephalus, 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).

Congenital hydrocephalus
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.

Acquired hydrocephalus
This condition is acquired as a consequence of CNS-infections, brain tumors, head trauma, intracranial hemorrhage (subarachnoid or intraparenchymal).

Clinical presentation

Like various other neurologic conditions (brain tumors, strokes, traumatic brain injury, etc.), hydrocephalus results in elevated intracranial pressure. Possible clinical manifestations include: headaches, 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. Normal pressure hydrocephalus (NPH) is distinguished by a relatively typical clinical triad: gait instability, urinary incontinence 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).

Treatment
State-of-the-art hydrocephalus''' 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.

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