Hydrocephalus

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Hydrocephalus

• Definition-Hydrocephalus is a disorder in which
  the cerebral ventricular system contains an
  excessive amount of cerebrospinal fluid (CSF) and
  is dilated because of increased pressure
• PHYSIOLOGY
• CSF is produced - choroid plexus.
• circulates through the ventricular system
  absorbed into the systemic circulation

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Hydro Fig. CSF circulation drainage
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• CSF production
• Choroid plexus - located in the cerebral
  ventricles.
• - consists of villous folds lined by
  epithelium with a central core of highly
  vascularized connective tissue.
• - produces CSF by active secretion and
  diffusion.
• The production rate of adults is approximately 20
  mL/hour, turnover 3 4x/ d, less in newborns-
  children
• The volume - infants is 50 mL 150 mL adults
  in adults, 25 percent is within the ventricular
  system.
• CSF formation continues in raised intracranial
  pressure unless extremely high

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• Ventricular system
• comprised of lateral ventricles connected via
  foramen of Monro to the midline third ventricle.
• third ventricle is connected to fourth
  ventricle aqueduct of Sylvius.
• Three exits from the fourth ventricle, the paired
  lateral foramina of Luschka and a midline foramen
  of Magendie, lead to a system of interconnecting
  and focally enlarged areas of subarachnoid spaces
  known as cisterns. The cisterns in the posterior
  fossa connect to the subarachnoid spaces over the
  cerebral convexities through pathways that cross
  the tentorium. The basal cisterns connect the
  spinal and intracranial subarachnoid spaces.
• CSF absorption CSF flows from the lateral
  ventricles to the third and fourth ventricles and
  then through the basal cisterns, tentorium, and
  subarachnoid space over the cerebral convexities
  to the area of the sagittal sinus. The net flow
  of CSF in the spinal subarachnoid space is
  cephalad.
• CSF is absorbed via arachnoid villi into the
  venous channels of the sagittal sinus. Some CSF
  absorption also occurs across the ependymal
  lining of the ventricles and from the spinal
  subarachnoid space.

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• PATHOGENESIS
• imbalance - the production and absorption of CSF.
  
• principal mechanism is deficient absorption from
  a mechanical or functional obstruction to the
  flow of CSF excessive volume of CSF increased
  ventricular pressure dilatation.
• CSF production continues resulting in extreme
  elevations of intracranial pressure that preclude
  neurologic function and survival.
• Three mechanisms of imbalance of CSF formation
  and absorption 1.obstruction of CSF pathways
• 2. impaired venous absorption
• 3. oversecretion of CSF.
• The disorder that results from obstruction of
  the ventricular system is known as obstructive,
  or noncommunicating, hydrocephalus Communicating
  hydrocephalus occurs when the subarachnoid
  pathways are blocked. CSF production is nearly
  always normal.

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• Obstruction
• Anatomic or functional obstruction - most common
  mechanism
• The obstruction occurs at the foramen of Monro,
  the aqueduct of Sylvius, or the fourth ventricle
  and its outlets
• Dilatation of the ventricular system occurs
  proximal to the block. Obstruction of one foramen
  of Monro results in dilatation of the lateral
  ventricle on that side
• If the aqueduct of Sylvius is blocked- lateral
  and third ventricles dilate, while fourth
  ventricle remains relatively normal.
• Impaired absorption A less common mechanism due
  to inflammation of the subarachnoid villi. This
  results in communicating hydrocephalus, in which
  the entire ventricular system is dilated.
• Excessive production of CSF is a rare cause of
  hydrocephalus, may occur with a functional
  choroid plexus papilloma and leads to enlargement
  of the entire ventricular system.

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• PATHOPHYSIOLOGY Acute obstruction increased
  pressure and rapid enlargement of the ventricular
  system.
• The frontal and occipital horns of the lateral
  ventricles enlarge first.
• flattening of gyri compression of the sulci,
  obliteration of the subarachnoid
• The vascular system is compressed, the venous
  pressure in the dural sinuses increases
• Ventricular enlargement thinning of the cerebral
  mantle disrupts the ependymal lining CSF move
  directly into brain tissue alternate route of
  CSF absorption that may limit further dilatation
  contributes to the development of interstitial
  edema of the periventricular white matter.
• compensatory mechanism is spreading of the
  cranial sutures
• Intracranial pressure is less in chronic
  hydrocephalus the force of is distributed over
  the greater surface area

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• PATHOLOGY ventricular dilatation before
  fusion of the cranial sutures enormous
  enlargement of the head
• The intracranial pressure increases more slowly
• Marked head enlargement not occur if
  hydrocephalus occurs acutely or after fusion of
  sutures significantly ICP
• ventricular dilatation results in atrophy of the
  white matter caused by tissue ischemia from the
  edema and increased intraventricular pressure.
• The width of the cerebral mantle may be reduced,
  gray matter is better preserved than white
  matter, even in advanced stages.
• congenital CNS abnormalities like cortical
  dysplasias, pachygyria, and polymicrogyria, are
  associated with X-linked hydrocephalus

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• A.Congenital hydrocephalus can result from
  CNS malformations (which include nonsyndromic and
  syndromic disorders), infection, trauma, and
  teratogens- rare cause is obstruction by a
  congenital CNS tumor, located near the midline.
• Neural tube defects majority with
  myelomeningocele have hydrocephalus.
  obstruction of fourth ventricular outflow or
  flow of CSF through the posterior fossa due to
  the Chiari malformation or an associated
  aqueductal stenosis.
• Isolated hydrocephalus by aqueductal stenosis
  due to congenital narrowing of the aqueduct, or
  intrauterine infection.
• X-linked hydrocephalus most common genetic
  form of congenital hydrocephalus with stenosis of
  the aqueduct of Sylvius (HSAS). Approximately
  50 affected boys have adducted thumbs. Some
  have other CNS abnormalities such as agenesis or
  dysgenesis of the corpus callosum, small
  brainstem, or absence of the pyramidal tract.
• is due to mutations in the gene encoding L1, a
  neuronal cell adhesion molecule that belongs to
  the immunoglobulin superfamily and is essential
  in neurodevelopmen. The gene for L1 has been
  mapped to Xq28. Mutations in L1 also result in
  other conditions, known as the L1 spectrum, that
  are characterized by neurologic abnormalities and
  mental retardation. These include MASA spectrum
  (Mental retardation, Aphasia, Shuffling gait,
  Adducted thumbs), X-linked spastic paraplegia
  type 1, and X-linked agenesis of the corpus
  callosum.

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• CNS malformations frequently associated with
  hydrocephalus.
• Chiari malformation, accompanies a neural tube
  defect, the brain stem and cerebellum- displaced
  caudally obstructing the flow of CSF in the
  posterior fossa
• The Dandy-Walker malformation consists of a large
  posterior fossa cyst continuous with the fourth
  ventricle and defective development of the
  cerebellum, including partial or complete absence
  of the vermis secondary obstruction of the
  foramina of Luschka and Magendie.
• Vein of Galen malformation is a rare cause
  compression of the aqueduct of Sylvius by the
  markedly dilated and distorted vein .
• Syndromic forms - The most frequent are trisomies
  13, 18, 9 and 9p, and triploidy
• Intrauterine infection -rubella,
  cytomegalovirus, toxoplasmosis, and syphilis
  inflammation of the ependymal lining of the
  ventricular system and the meninges in the
  subarachnoid space obstruction of CSF flow
  through the aqueduct or basal cisterns.
• Acquired hydrocephalus Common are CNS
  infections - bacterial meningitis or viral
  infections including mumps, and tumors,
  especially posterior fossa medulloblastomas,
  astrocytomas, and ependymomas.
• Another cause is hemorrhage into the subarachnoid
  space or, less commonly, into the ventricular
  system, by ruptured aneurysms, arteriovenous
  malformations, trauma, or systemic bleeding
  disorders induces an inflammatory response
  followed by fibrosis, obstructing the flow and/or
  absorption of CSF.
• Posthemorrhagic hydrocephalus occurs in
  approximately 35 percent of preterm infants with
  intraventricular hemorrhage (IVH). It can be
  obstructive, communicating, or both, and can be
  transient or sustained, with slow or rapid
  progression.

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Hydro Fig.Third ventricular tumor

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Hydro-Fif choroid plexus papilloma
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• CLINICAL FEATURES signs and symptoms result
  from
• - increased ICP and dilatation of the
  ventricles
• -time of presentation depends upon the
  acuity of the process.
• Symptoms are nonspecific and independent of the
  etiology
• Headache is a prominent symptom. It is caused by
  distortion of the meninges and blood vessels. The
  pain often varies in intensity and location and
  may be intermittent or persistent. Headaches due
  to increased ICP often occur in the early morning
  and are associated with nausea and vomiting
• often have changes in their personality and
  behavior (irritability, obstreperousness,
  indifference, and loss of interest), mechanism is
  uncertain, but related in part to increased ICP.
  As the hydrocephalus worsens, midbrain and brain
  stem dysfunction may result in lethargy and
  drowsiness.
• Increased ICP in the posterior fossa often leads
  to nausea, vomiting, and decreased appetite.

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• In infants, common signs and symptoms of
  hydrocephalus include
• An unusually large head
• A rapid increase in the size of the head
• A bulging "soft spot" on the top of the head
  (anterior fontanel)
• Vomiting
• Sleepiness
• Irritability
• Seizures
• Eyes fixed downward (sunsetting of the eyes)
• Developmental delay

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• In older children and adults, common signs and
  symptoms of hydrocephalus include
• Headache followed by vomiting
• Nausea
• Blurred or double vision
• Eyes fixed downward (sunsetting of the eyes)
• Problems with balance, coordination or gait
• Sluggishness or lack of energy
• Slowed development or loss of development
• Memory loss
• Urinary incontinence
• Irritability
• Change in personality

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• Physical examination Physical findings are due
  to the effects ICP.
• Distortions of the brainstem may result in
  changes in vital signs such as bradycardia,
  systemic hypertension, and altered respiratory
  rate.
• Excessive head growth ventricular dilatation
  occur before head growth becomes abnormal.
• The anterior fontanelle may become full or
  distended.
• Young infants may develop frontal bossing, an
  abnormal skull contour in which the forehead
  becomes prominent.
• The scalp veins may appear dilated and prominent.
  
• Compression of the third or sixth cranial nerve
  may result in extraocular muscle pareses leading
  to diplopia. Pressure on the midbrain may result
  in impairment of upward gaze. This is known as
  the setting-sun sign because of the appearance of
  the sclera visible above the iris.
• Fundoscopic examination may reveal papilledema.
• Stretching of the fibers from the motor cortex
  around the dilated ventricles may result in
  spasticity of the extremities, especially the
  legs.
• Accelerated pubertal development, as well as
  disturbed growth and fluid and electrolyte
  homeostasis, may result from pressure of the
  dilated third ventricle on the hypothalamus

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• DIAGNOSIS suspect in an infant whose head
  circumference is enlarged at birth, or when
  serial measurements cross growth curves,
• In some cases, the diagnosis is made by antenatal
  ultrasonography. Hydrocephalus should be
  considered in children with severe headache and
  other features suggesting increased ICP
• The diagnosis is confirmed by neuroimaging.
• In older infants and children, CT or MRI should
  be performed. Neuroimaging studies will also
  detect associated CNS malformations or tumors.
• The site of obstructed CSF flow may be suggested
  by the pattern of ventricular dilatation.
  Stenosis of the aqueduct typically results in
  dilated lateral and third ventricles and a fourth
  ventricle of normal size. In contrast, an
  extraventricular obstruction usually results in
  symmetric dilatation of all ventricles.
• A lumbar puncture (LP) should be performed and
  the CSF should be examined if an infection
  causing adhesive arachnoiditis or ependymitis is
  suspected. However, LP is contraindicated if the
  patient has evidence of a space-occupying lesion
  such as an intracranial tumor or a brain abscess,
  because of the risk of cerebral herniation.

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• MANAGEMENT The most effective is surgical
  drainage- does not cure but treat the symptoms
  and stops progression.
• Shunt A mechanical shunt system involves
  placement of a catheter into one of the lateral
  ventricles, usually the right
• The catheter is connected to a one-way valve
  system (usually placed beneath the scalp of the
  postauricular area) that opens when the pressure
  in the ventricle exceeds a certain value
• ventriculoatrial, VA or ventriculoperitoneal, VP

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Hydro -Fig .VP VA shunts
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• Complications
• The severity of hydrocephalus depends on the time
  of onset and whether the disease is progressive.
  If the condition is well advanced at birth, major
  brain damage and physical disabilities are
  likely. In less severe cases, with proper
  treatment, it's possible to have a nearly normal
  life span and intelligence.
• Other complications of hydrocephalus include
• Intellectual impairment
• Neurological damage, such as decreased function,
  movement or sensation
• Problems with the artificial CSF drainage channel
  (surgical shunt), such as a blockage or kinking
  of the shunt tubing
• Infection at the site of the shunt

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• Complications In general, complications of
  treated hydrocephalus are due to malfunction of
  the shunt. If the hydrocephalus is still active,
  symptoms recur and another drainage procedure is
  required. Shunt revision is unnecessary in rare
  cases when alternate pathways of absorption
  develop or normal mechanisms for handling CSF
  become reestablished, resulting in compensation
  or spontaneous arrest of the hydrocephalus.
• Malfunction is due to infection or mechanical
  failure Approximately 40 percent of standard
  shunts fail within the first year after placement
  .

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• Infection Shunt infection is common 5 to 10
  percent of procedures . may be higher in
  newborns . Most occur in the first six monthst.
  Ventriculitis may develop.
• organisms are own skin flora, such as
  Staphylococcus epidermidis, less frequently S.
  aureus, enteric bacteria, diphtheroids, and
  Streptococcus species .
• Infection must be considered with a shunt
  persistent fever. Antibiotics should be started,
  but alone is usually not effective. In most
  cases, an infected shunt must be removed and an
  external ventricular drain temporarily placed.
• Shunt infections may promote the development of
  loculated compartments of CSF and contribute to
  impaired cognitive outcome and death .
  Perioperative antibiotic prophylaxis in a
  meta-analysis of 12 trials in 1359 patients,
  reduced the risk of subsequent shunt infection by
  50 percent.
• Mechanical failure The failure rate
  (including infection) is approximately 40 percent
  in the first year, and 5 percent in subsequent
  years .
• The majority of first shunt failures result from
  obstruction at the ventricular catheter. This is
  because shunts typically overdrain, greatly
  reducing the size of the ventriclescatheter to
  lie against the ependyma and choroid plexus which
  block the holes at the end of the catheter.
• Fractured tubing is the cause in 15 percent of
  cases . Other causes include migration of part or
  all of the shunt (7.5 percent) and problems with
  overdrainage (7 percent).

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• Third ventriculostomy Endoscopic third
  ventriculostomy (ETV), perforation is made to
  connect the third ventricle to the subarachnoid
  space, in the initial treatment of selected
  cases of obstructive hydrocephalus and as an
  alternative to shunt revision. The success
  depends upon the cause and previous
  complications
• Medical therapy diuretics, fibrinolysis, and
  serial lumbar punctures- have significant
  complications and are less effective than
  surgical treatment.
• Diuretics The diuretics furosemide and
  acetazolamide decrease CSF production. They have
  been used for short periods in slowly progressive
  hydrocephalus in patients too unstable for
  surgery. Diuretics are also used in newborns with
  posthemorrhagic hydrocephalus, although their use
  is controversial .
• A systematic review by the Cochrane database
  examined two eligible trials of diuretic therapy
  in newborns . These trials included 177 and 16
  infants with posthemorrhagic ventricular
  dilation. The administration of acetazolamide and
  furosemide did not decrease the risk for VP shunt
  or the combined outcome of shunt or death. In the
  larger trial, the administration of acetazolamide
  and furosemide was associated with a borderline
  increase in the risk for motor impairment at one
  year (relative risk 1.27) . However, the combined
  outcome of delay, disability or motor impairment
  among survivors, or the risk of the combined
  outcome of death, delay, disability or impairment
  at one year were not affected. Diuretic treatment
  significantly increased the risk of
  nephrocalcinosis.

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• Fibrinolytic therapy Intraventricular
  administration of fibrinolytic agents has been
  used in newborns with posthemorrhagic
  hydrocephalus in an attempt to prevent permanent
  obstruction to CSF flow. This treatment does not
  appear to reduce the need for shunt placement and
  may increase the risk of hemorrhage, but adequate
  trials are lacking
• Serial lumbar punctures Repeated lumbar
  punctures - as a temporizing measure in preterm
  infants with posthemorrhagic hydrocephalus
• In cases of rapidly progressive hydrocephalus, a
  temporary ventricular drainage device may be
  needed until a permanent shunt can be placed or
  the hydrocephalus resolves spontaneously

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• OUTCOME depends upon the etiology, associated
  abnormalities, and complications such as
  infection.
• Survival untreated -50 percent die before
  three years and 77 to 80 percent die before
  reaching adulthood Treatment( if no tumor) with
  89 and 95 percent survival
• Epilepsy occur frequently in children with
  shunted hydrocephalus.
• Seizures are associated with poor cognitive
  outcome
• Functional outcome depends upon prematurity,
  CNS malformations, other congenital
  abnormalities, epilepsy, and sensory and motor
  impairments
• In a report from France, outcome at 10 years was
  evaluated in 129 consecutive children with
  hydrocephalus without tumor who had shunt
  placement before two years of age . Motor
  deficits, visual or auditory deficits, and
  epilepsy occurred in 60, 25, and 30 percent of
  patients, respectively. IQ was gt90 in 32 percent
  and lt50 in 21 percent. Attendance at a normal
  school was possible for 60 percent, although
  one-half were one to two years behind for their
  age or having difficulties. Of the remainder, 31
  percent were in special classes or
  institutionalized and 9 percent were not
  considered educable.
• In a series from the United Kingdom, 155 children
  with shunted hydrocephalus were followed for 10
  years or until death (which occurred in 11
  percent) . For survivors until school age, 59
  percent attended a normal school. Children with
  hydrocephalus caused by infection or IVH were
  more likely to need special school than those
  with congenital hydrocephalus (52 and 60 versus
  29 percent).

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Case history

• Age 15yr/M sudent, Mersa
• C/C behavioral change/11/2 years
• Irritable, over talkative, aggression asaultive,
  grandiose, crying
• Headache, vomiting, weakness, sweating
• Repeated attacks of ear discharge
• Failure to thrive
• Got worse 8-months back-scaly lesions over
  skin-Desse H/L-ART
• Gait change imbalance-6 months-visual complaint
• Recent enuresis but no incontinence
• Negative symptoms

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History contd

• Development non remarkable
• He used to be calm good student
• Family-father died cough empyemia-9mon
• Mother on ART, 4-other siblings-one younger
  sister healthy

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Physical finding

• GA- Chronically sick
• V/S-B/P __ P/R78, T36.7
• scaly multiple lesions over scalp, LAP
• Labile mood, appropriate affect, has insight
• RT-6th N- palsy

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Lab -

• WBC3,600, 3,100/ml
• HCT34.1, 32.4
• Platelet214,000, 122,000/ml
• ESR102mm/hr, 120mm/hr
• U/S-abdomen-Normal
• RFT LFT-normal
• CT-scan