Hydrocephalus

• obstructive
• communicating

block proximal to arachnoid granulations

ex: block at aqueduct of sylvius causing proximal ventricular enlargement- triventricular hydrocephalus

CSF circulation blocked at level of arachnoid granulation

• hydrocephalus ex vacuo
• otic hydrocephalus
• external hydrocephalus
• hydranencephaly

enlargement of ventricles due to loss of cerebral tissue (cerebral atrophy)

may be a product of normal aging or disease

obsolete term now refered to idiopathic intracranial hypertension

increased ICP in pts with otitis media

• seen in infancy
• enlarged subarachnoid space with increasing OFCs
• normal to dialated ventricle

• post neurulation defect
• total or near to total absence of cerebrum most often due to b/l infarcts of ICA

• severe maximal hydrocephalus
• shunting for true HCP may produce some reexpansion

• normal pressure hydrocephalus
• entrapped fourth ventricle
• arrested hydrocephalus

benign external hydrocephalus

• enlarged subarachnoid sspaces over frontal poles in first year of life
• ventricles normal or minimally enlarged
• abn increase in head circumference
• no developmental delays

subdural hematoma by cortical vein sign

spontaneously by 2yrs

MRI or CT demonstrates cortical veins extending from surface of the brain to inner table of skull coursing throug fluid collection

EH and SDH in which there is compression of the subarachnoid space apposing veins on surface of brain

• resolves by 12 to18 mo without shunting
• follow with serial US or CT to r/o abn ventricular enlargment

• Inherited hydrocephalus with phenotypically normal mother and hyrocephalus inflicted son.
• Skips everother generation.

• size of temporal horns >= 2mm width
• sylvian and interhemispheric fissures and cerebral sulci not visible
• OR
• both TH >= 2mm and ratio of frontal horns/internal diameter>0.5

• subnormal CSF reabsorption
• CSF over production (rare choroid plexus paillomas)

• chiari type 2 malformaion or myelomeningocele
• Chiari type I malformation - 4th vent outlet obstruction
• Primary aqueductal stenosis
• Secondary aqeuductal gliosis
• Dandy Walker malformation
• X-linked inherited disorder (rare)

• atresia of foramina of luschka and magendi
• 2.4% of pt with HCP

• infectious - most common cause of communicating hydrocephalus
• post hemorrhagic 2nd most common
• secondary to masses
• post op
• neurosarcoidosis
• constitutional ventrculomegaly
• association with spinal tumors

• post-meningitis
• cystercercosis

• post SAH
• post intraventricular hemorrhage
• (many transient - 20 to 50% permanent)

• non neoplastic masses - vascular malformations
• neoplastic

p-fossa tumor removal

• asymptomatic
• needs no treatment

• hydrocephalus ex vacuo
• hydranencephaly
• developmental anomalies with ventricular enlargment

• papilledema
• HA
• N/V
• gate changes
• upgaze and or abducens palsy
• if enlargment occurs slowly may be asymptomatic

• beaten copper cranium
• 3rd ventricle herniation into sella
• erosion of sella turcica (leads to empty sella)
• temporal horns (less prominant then with acute)
• macrocrania - greater then 98th percentile
• atrophy of corpus callosum
• infants - sutural diastasis, delayed closure of fontanells, failure to thrive, developmental delay

• acetazolamide
• spinal tap
• surgery

acetazolamide may be tried with infants

• ONLY indicated in communicating HCP
• indicated post intraventricular hemorrhage
• seriel taps until resorption resumes
• if resorption does not resume and protein < 100 mg/dl then shunt

• choroid plexoctomy
• elimination of obstruction
• third ventriculostomy
• shunting

• removal of choroid plexus which generates CSF
• reduces rate of CSF production

• higher morbidity and lower success rate that CSF diversion
• eg: opening stenosed sylvian aqueduct

• obstructive HCP
• shunt infx
• SDH after shunting
• Slit ventricle syndrome

• absolute: communicating hydrocephalus
• relative: comorbidity associated with low success rate

• hypothalamic injury
• transient 3rd and 6th nerve palsies
• uncontrollable bleeding
• cardiac arrest
• traumatic basilar artery aneurysm

thermal injury from laster in ETV

• aprox: 56%
• 60 to 94% in nontumoral aqueductal stenosis

• tumor
• previous shunt
• previous SAH
• previous whole brain radiation
• adhesions at floor of third ventricle

• ventriculoperitoneal (VP) shunt ventriculoatrial (VA) shunt
• Torkilden shunt
• Miscellaneous non-traditional shunts
• lumboperitoneal (LP) shunt
• cyst or subdural shunt

• most commonly used shunt
• proximal location: lateral ventricle
• intraperitoneal pressure: near atm

• aka vascular shunt
• shunt runs from ventricle through jugular through SVC to right cardiac atrium

abdominal abnormalities are present

• short tubing results in lower distal pressure and less siphon effect
• pulsatile pressures may alter CSF hydrodynamics

• shunts ventricle to cisternal space
• effective only in aquired HCP
• rarely used

• have problems with traditional shunt placement locations
• such as pleural space, gall bladder, ureter or bladder

• indicated ONLY for communicating HCP
• used for
• pseudotumor cerebri
• CSF fistula
• Small ventricles

from arachnoid cyst or subdural hygroma cavity to peritoneum

• obstruction
• disconection or break
• infection
• hardware erosion through the skin
• seizure
• drop mets
• silicone allergy
• hemorrhage at time of insertion
• undershunting and overshunting

obstruction

• proximal: ventricular catheter (most common)
• valve mechanism
• distal: 12-34%

• 17% ingunial hernia
• outgrowth of catheter
• obstruction at peritoneal end
• peritonitis from shunt infx
• hydrocele
• CSF ascities
• tip migration
• intestinal obstruction
• volvulus
• intestinal strangulation
• overshunting

• outgrowth of catheter
• high risk of infx/septicemia
• retrograde flow of blood to ventricles
• shunt embolus
• vascular complications

• dangerous in children ~scoliosis, herniation
• difficult to control overshunting
• difficult to access patency in proximal end
• lumbar nerve root irritation/radiculopathy
• CSF leak at catheter
• pressure regulation difficulty
• 6th, 7th CN dysfunction from overshunting
• arachnoiditis and adhesions

prevents drop mets

prevents siphoning effect when pt is erect

used with LP shunts to increase resistance when pt is vertical and prevents overshunting

externially programable pressure valve

opens and occludes shunt system by external shunt manipulation

ex: portnoy device

• Strata by Medtronic
• Polaris by Sophysa
• Codman Hakim

magnet

• always after MRI (big magnet)
• Strata and Polaris may be checked with hand held device
• xray may also be used to check valve pressure

the less CSF drainage

ventricular catheter - inlet - inlet ocluder - reservoir - one-way valve - outlet

x-ray

• intraparenchymal or intraventricular hemorrhage 4%
• seizures
• malposition of either catheter
• infection

• CSF collection: infx, cytology, blood
• evaluate shunt function
• tempory measure to allow function of occluded shunt
• injection of medication
• to withdraw fluid or inject radioactive fluid into tumor cyst