Hydrocephalus

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Author:
mbrieger
ID:
95189
Filename:
Hydrocephalus
Updated:
2011-07-26 15:08:33
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Hydrocephalus Neurosurgery
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Description:
Greenberg on Hydrocephalus
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  1. 2 main functional subdivisions of hydrocephalus
    • obstructive
    • communicating
  2. obstructive hydrocephalus
    block proximal to arachnoid granulations

    ex: block at aqueduct of sylvius causing proximal ventricular enlargement- triventricular hydrocephalus
  3. communicating hydrocephalus
    CSF circulation blocked at level of arachnoid granulation
  4. forms of pseudohydrocephalus
    • hydrocephalus ex vacuo
    • otic hydrocephalus
    • external hydrocephalus
    • hydranencephaly
  5. hydrocephalus ex vacuo
    enlargement of ventricles due to loss of cerebral tissue (cerebral atrophy)

    may be a product of normal aging or disease
  6. otitic hydrocephalus
    obsolete term now refered to idiopathic intracranial hypertension

    increased ICP in pts with otitis media
  7. external hydrocephalus
    • seen in infancy
    • enlarged subarachnoid space with increasing OFCs
    • normal to dialated ventricle
  8. hydranencephaly
    • post neurulation defect
    • total or near to total absence of cerebrum most often due to b/l infarcts of ICA
  9. it is important to decern hydranencephaly from
    • severe maximal hydrocephalus
    • shunting for true HCP may produce some reexpansion
  10. special forms of hydrocephalus
    • normal pressure hydrocephalus
    • entrapped fourth ventricle
    • arrested hydrocephalus
  11. External hydrocephalus aka
    benign external hydrocephalus
  12. external hydrocephalus on CT
    • enlarged subarachnoid sspaces over frontal poles in first year of life
    • ventricles normal or minimally enlarged
    • abn increase in head circumference
    • no developmental delays
  13. external hydrocephalus must be distinguished from
    subdural hematoma by cortical vein sign
  14. external hydrocephalus usually resolves
    spontaneously by 2yrs
  15. cortical vein sign
    MRI or CT demonstrates cortical veins extending from surface of the brain to inner table of skull coursing throug fluid collection
  16. cortical veins sign deliniates between
    EH and SDH in which there is compression of the subarachnoid space apposing veins on surface of brain
  17. tx of EH
    • resolves by 12 to18 mo without shunting
    • follow with serial US or CT to r/o abn ventricular enlargment
  18. X-linked hydrocephalus
    • Inherited hydrocephalus with phenotypically normal mother and hyrocephalus inflicted son.
    • Skips everother generation.
  19. Main imaging signs of Hydrocephalus
    • 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
  20. etiology of hydrocephalus
    • subnormal CSF reabsorption
    • CSF over production (rare choroid plexus paillomas)
  21. Congenital etilology of hydrocephalus
    • 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)
  22. Dandy Walker malformation
    • atresia of foramina of luschka and magendi
    • 2.4% of pt with HCP
  23. acquired etioligies of hydrocephalus
    • infectious - most common cause of communicating hydrocephalus
    • post hemorrhagic 2nd most common
    • secondary to masses
    • post op
    • neurosarcoidosis
    • constitutional ventrculomegaly
    • association with spinal tumors
  24. infectious etiology of HCP
    • post-meningitis
    • cystercercosis
  25. post-hemorrhagic causes of HCP
    • post SAH
    • post intraventricular hemorrhage
    • (many transient - 20 to 50% permanent)
  26. HCP secondary to masses causes
    • non neoplastic masses - vascular malformations
    • neoplastic
  27. 20% of pediatric pts develop permanenet hydrocephalus following
    p-fossa tumor removal
  28. constitutional ventriculomegaly
    symptoms and tx
    • asymptomatic
    • needs no treatment
  29. differential diagnosis for HCP
    • hydrocephalus ex vacuo
    • hydranencephaly
    • developmental anomalies with ventricular enlargment
  30. symptoms of HCP or ICP in older children and adults
    • papilledema
    • HA
    • N/V
    • gate changes
    • upgaze and or abducens palsy
    • if enlargment occurs slowly may be asymptomatic
  31. features of chronic HCP
    • 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
  32. main general hydrocephalus treatments
    • acetazolamide
    • spinal tap
    • surgery
  33. diuretic therapy for HCP
    acetazolamide may be tried with infants
  34. spinal tap as treatment of HCP
    • 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
  35. surgical procedures that tx HCP
    • choroid plexoctomy
    • elimination of obstruction
    • third ventriculostomy
    • shunting
  36. choroid plexectomy for tx of HCP
    • removal of choroid plexus which generates CSF
    • reduces rate of CSF production
  37. elimination of obstruction as tx of HCP
    • higher morbidity and lower success rate that CSF diversion
    • eg: opening stenosed sylvian aqueduct
  38. third ventriculostomy indications
    • obstructive HCP
    • shunt infx
    • SDH after shunting
    • Slit ventricle syndrome
  39. third ventriculostomy contraindications
    • absolute: communicating hydrocephalus
    • relative: comorbidity associated with low success rate
  40. third ventriculostomy complications
    • hypothalamic injury
    • transient 3rd and 6th nerve palsies
    • uncontrollable bleeding
    • cardiac arrest
    • traumatic basilar artery aneurysm
  41. traumatic basilar artery aneurysm may be caused from
    thermal injury from laster in ETV
  42. Third ventriculostomy success rate
    • aprox: 56%
    • 60 to 94% in nontumoral aqueductal stenosis
  43. low success rates are produced in third ventriculostomy if the following are present or have occured:
    • tumor
    • previous shunt
    • previous SAH
    • previous whole brain radiation
    • adhesions at floor of third ventricle
  44. types of shunts
    • ventriculoperitoneal (VP) shunt ventriculoatrial (VA) shunt
    • Torkilden shunt
    • Miscellaneous non-traditional shunts
    • lumboperitoneal (LP) shunt
    • cyst or subdural shunt
  45. VP shunt
    • most commonly used shunt
    • proximal location: lateral ventricle
    • intraperitoneal pressure: near atm
  46. ventriculo atrial shunt
    • aka vascular shunt
    • shunt runs from ventricle through jugular through SVC to right cardiac atrium
  47. ventriculoatrial shunt is the treatment of choice when
    abdominal abnormalities are present
  48. ventriculo atrial shunt qualities effecting use
    • short tubing results in lower distal pressure and less siphon effect
    • pulsatile pressures may alter CSF hydrodynamics
  49. torkildsen shunt
    • shunts ventricle to cisternal space
    • effective only in aquired HCP
    • rarely used
  50. miscellaneous shunts: various distal projections are used in pts who
    • have problems with traditional shunt placement locations
    • such as pleural space, gall bladder, ureter or bladder
  51. lumboperitoneal (LP) shunt
    • indicated ONLY for communicating HCP
    • used for
    • pseudotumor cerebri
    • CSF fistula
    • Small ventricles
  52. cyst or subdural shunt
    from arachnoid cyst or subdural hygroma cavity to peritoneum
  53. complications that occur with all shunts
    • obstruction
    • disconection or break
    • infection
    • hardware erosion through the skin
    • seizure
    • drop mets
    • silicone allergy
    • hemorrhage at time of insertion
    • undershunting and overshunting
  54. the most common cause complication of shunts
    obstruction
  55. location of obstruction of shunt
    • proximal: ventricular catheter (most common)
    • valve mechanism
    • distal: 12-34%
  56. VP shunt complications
    • 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
  57. VA shunt complications
    • outgrowth of catheter
    • high risk of infx/septicemia
    • retrograde flow of blood to ventricles
    • shunt embolus
    • vascular complications
  58. LP shunt 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
  59. tumor filter
    prevents drop mets
  60. antisiphon device
    prevents siphoning effect when pt is erect
  61. horizontal vertical (H-V) valve
    used with LP shunts to increase resistance when pt is vertical and prevents overshunting
  62. variable pressure valves
    externially programable pressure valve
  63. on-off device
    opens and occludes shunt system by external shunt manipulation

    ex: portnoy device
  64. 3 externally programable stents available in the US
    • Strata by Medtronic
    • Polaris by Sophysa
    • Codman Hakim
  65. programmable shunts are programed by
    magnet
  66. checking valve settings
    • always after MRI (big magnet)
    • Strata and Polaris may be checked with hand held device
    • xray may also be used to check valve pressure
  67. the higher the valve pressure
    the less CSF drainage
  68. order of valve parts
    ventricular catheter - inlet - inlet ocluder - reservoir - one-way valve - outlet
  69. how to check valve pressure without a hand held device
    x-ray
  70. complications of shunt insertion
    • intraparenchymal or intraventricular hemorrhage 4%
    • seizures
    • malposition of either catheter
    • infection
  71. indications to tap a shunt
    • 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

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