Hydrocephalus

Mr. Mallappa ShalavadiHSK College of Pharmacy, Bagalkot

Water on the brain

Formation and circulation of cerebrospinal fluidCerebrospinal fluid (CSF) is a clear, colorless

liquid that protects the brain and spinal cord from chemical and physical injuries.

It also carries oxygen, glucose, and other needed chemicals from the blood to neurons and neuroglia.

CSF continuously circulates through cavities in the brain and spinal cord and around the brain and spinal cord in the subarachnoid space (between the arachnoid mater and pia mater).

Below fig., shows the four CSF-filled cavities within the brain, which are called ventricles (VEN-tri-kuls little cavities). A lateral ventricle is located in each hemisphere of the cerebrum. Anteriorly, the lateral ventricles are separated by a thin membrane, the septum pellucidum (SEP-tum pe-LOO-sidum; pellucid transparent). The third ventricle is a narrow cavity along the midline superior to the hypothalamus and between the right and left halves of the thalamus. The fourth ventricle lies between the brain stem and the cerebellum.

The CSF contributes to homeostasis in three main ways:

1. Mechanical protection. CSF serves as a shock-absorbing medium that protects the delicate tissues of the brain and spinal cord. The fluid also buoys the brain so that it “floats” in the cranial cavity.

2. Chemical protection. CSF provides an optimal chemical environment for accurate neuronal signaling. Even slight changes in the ionic composition of CSF within the brain can seriously disrupt production of action potentials and postsynaptic potentials.

3. Circulation. CSF allows exchange of nutrients and waste products between the blood and nervous tissue.

Formation of CSFThe sites of CSF production are the choroid plexuses (KO¯ -

royd membrane like), networks of blood capillaries (microscopic blood vessels) in the walls of the ventricles.

The capillaries are covered by ependymal cells that form cerebrospinal fluid from blood plasma by filtration and secretion.

Because the ependymal cells are joined by tight junctions, materials entering CSF from choroid capillaries cannot leak between these cells; instead, they must pass through the ependymal cells.

This blood–cerebrospinal fluid barrier permits certain substances to enter the CSF but excludes others, protecting the brain and spinal cord from potentially harmful blood borne substances.

Circulation of CSFThe CSF formed in the choroid plexuses of each lateral ventricle

flows into the third ventricle through two narrow, oval openings, the interventricular foramina.

More CSF is added by the choroid plexus in the roof of the third ventricle.

The fluid then flows through the aqueduct of the midbrain (cerebral aqueduct), which passes through the midbrain, into the fourth ventricle.

The choroid plexus of the fourth ventricle contributes more fluid. CSF enters the subarachnoid space through three openings in the roof of the fourth ventricle: a median aperture and the paired lateral apertures, one on each side.

CSF then circulates in the central canal of the spinal cord and in the subarachnoid space around the surface of the brain and spinal cord.

CSF is gradually reabsorbed into the blood through arachnoid villi, fingerlike extensions of the arachnoid that project into the dural venous sinuses, especially the superior sagittal sinus (A cluster of arachnoid villi is called an arachnoid granulation.) Normally, CSF is reabsorbed as rapidly as it is formed by the choroid plexuses, at a rate of about 20 mL/hr (480 mL/day). Because the rates of formation and reabsorption are the same, the pressure of CSF normally is constant.

In adults, children, and infants the volume of CSF is approximately 150 mL, 60 to 100 mL, and 40 to 60 mL, respectively.

Normal values (CSF):

CSF opening pressure: 50–180 mmH2O

Glucose: 40–85 mg/dL.Protein (total): 15–45 mg/dL.Lactate dehyrogenase: 1/10 of serum level.Lactate: less than 35 mg/dL.Leukocytes (WBC): 0–5/µL (adults / children); up to 30/µL (newborns). Specific gravity: 1.006–1.009.Syphilis serology: negative.Gross appearance: Normal CSF is clear and colorless.Differential: 60–70% lymphocytes; up to 30% monocytes and macrophages; other cells 2% or less.

also known as "water on the brain," is a medical condition in which there is an abnormal accumulation of cerebrospinal fluid (CSF) in the ventricles, or cavities, of the brain.

Hydrocephalus

Types of Hydrocephalus

Based on its underlying mechanisms, hydrocephalus can be classified into communicating and non-communicating (obstructive). Both forms can be either congenital or acquired.

Communicating hydrocephalus, also known as non-obstructive hydrocephalus, is caused by impaired cerebrospinal fluid reabsorption in the absence of any CSF-flow obstruction between the ventricles and subarachnoid space.

this is due to functional impairment of the arachnoidal granulations (also called arachnoid granulations or Pacchioni's granulations), which are located along the superior sagittal sinus and is the site of cerebrospinal fluid reabsorption back into the venous system.

Various neurologic conditions may result in communicating hydrocephalus, including subarachnoid/intraventricular hemorrhage, meningitis and congenital absence of arachnoid villi.

Scarring and fibrosis of the subarachnoid space following infectious, inflammatory, or hemorrhagic events can also prevent resorption of CSF, causing diffuse ventricular dilatation.

Normal pressure hydrocephalus (NPH) is a particular form of communicating hydrocephalus, characterized by enlarged cerebral ventricles, with only intermittently elevated cerebrospinal fluid pressure.

Hydrocephalus ex vacuo also refers to an enlargement of cerebral ventricles and subarachnoid spaces, and is usually due to brain atrophy (as it occurs in dementias), post-traumatic brain injuries and even in some psychiatric disorders, such as schizophrenia.

Non-communicating hydrocephalus, or obstructive hydrocephalus, is caused by a CSF-flow obstruction ultimately preventing CSF from flowing into the subarachnoid space (either due to external compression or intraventricular mass lesions).

Foramen of Monro obstruction may lead to dilation of one or, if large enough (e.g., in Colloid cyst), both lateral ventricles.

The aqueduct of Sylvius, normally narrow to begin with, may be obstructed by a number of genetically or acquired lesions (e.g., atresia, ependymitis, hemorrhage, tumor) and lead to dilation of both lateral ventricles as well as the third ventricle.

Fourth ventricle obstruction will lead to dilatation of the aqueduct as well as the lateral and third ventricles (e.g., Chiari malformation).

The foramina of Luschka and foramen of Magendie may be obstructed due to congenital failure of opening (e.g., Dandy-Walker malformation).

CongenitalThe cranial bones fuse by the end of the third year of life. For head enlargement to occur, hydrocephalus mustoccur before then. The causes are usually genetic but can also be acquired and usually occur within the first few months of life, which include 1) intraventricular matrix hemorrhages in premature

infants, 2) infections3) type II Arnold-Chiari malformation 4) aqueduct atresia and stenosis 5) Dandy-Walker malformation.

AcquiredThis condition is acquired as a consequence of

CNS infections, Meningitisbrain tumorshead traumaintracranial hemorrhage (subarachnoid or

intraparenchymal) is usually extremely painful.

Symptoms

In infants with hydrocephalusEyes that appear to gaze downwardIrritabilitySeizuresSeparated suturesSleepinessVomiting.

Symptoms that may occur in older children can include:Brief, shrill, high-pitched cryChanges in personality, memory, or

the ability to reason or thinkChanges in facial appearance and

eye spacingCrossed eyes or uncontrolled eye

movementsDifficulty feedingExcessive sleepinessHeadacheIrritability, poor temper controlLoss of bladder control (urinary

incontinence)Loss of coordination and trouble

walkingMuscle spasticity (spasm)Slow growth (child 0–5 years)Slow or restricted movements

Exams and Diagnostic TestsThe doctor will examine the baby. This may show:Stretched or swollen veins on the baby's scalpAbnormal sounds when the health care provider taps lightly on the skull, suggesting a problem with the skullbonesAll or part of the head may be larger than normal, usually in the front partEyes that look "sunken in"White part of the eye appears over the colored area, making it look like a "setting sun"Reflexes may be normalHead circumference measurements, repeated over time, may show that the head is getting bigger.

A head CT scan is one of the best tests for identifying hydrocephalus. Other tests that may be done include:Brain scan using radioisotopesCranial ultrasound (an ultrasound of the brain)Lumbar puncture and examination of the cerebrospinal fluid (rarely done)Skull x-raysMagnetic resonance imaging.

Normal Head CT

Hydrocephalus

Post-Infectious Hydrocephalus

TreatmentThe goal of treatment is to reduce or prevent brain

damage by improving the flow of CSF.Surgery may be done to remove a blockage, if possible.If not, a flexible tube called a shunt may be placed in the

brain to re-route the flow of CSF. The shunt sends CSF to another part of the body, such as

the belly area, where it can be absorbed.Other treatments may include:Antibiotics are given if there are signs of infection.

Severe infections may require the shunt to be removed.A procedure called endoscopic third ventriculostomy

(ETV), which relieves pressure without replacing the shunt.

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Hydrocephalus

Treatment alternatives

Shunting Immediate effect ~ 100% reliability (although

50% of current shunts are replaced within 5 years)

~75% of patients are treated by this methodology3. Ventriculostomy

(intracranial procedure) Immediate effect When first developed the

procedure had high mortality and morbidity rates. Today it is a very safe procedure

~25% of patients are treated by this methodology

Drug treatment Initially, it was shown that

Acetazolamide reduced CSF production by the choroid plexus

In a series of Hydrocephalus in immature infants the drug was used and success was claimed as shunts was avoided in 50% of the cases

0% of patients are treated by this methodology

Shunting is the preferred treatment

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. A shunt system can also be placed in the lumbar space of the spine and have the CSF redirected to the peritoneal cavity (Lumbar-peritoneal shunt).An alternative treatment for obstructive hydrocephalus in selected patients is the endoscopic third ventriculostomy (ETV), whereby a surgically created opening in the floor of the third ventricle allows the CSF to flow.

CSF shunt

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The SinuShunt vs. traditional shuntsSinuShunt Traditional shunts

Complications of ventriculoperitoneal shunt

The major possible complications are:• infection of the shunt• obstruction of the shunt• intracranial haemorrhage.

Shunt LeftFront Vent 03-13-12.mp4.mp4

hydrocephalus v p shunt+ s.mp4

Endoscopic Third Ventriculostomy_ Technique (Cirurgia cerebral Endoscopia ) Neurosurgery.mp4