Dandy-Walker Hydrocephalus

Discussion in 'Step I' started by seminoma, 09.26.14.

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  1. seminoma

    seminoma 2+ Year Member

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    Why does dandy-walker cause obstructive/non-communicating hydrocephalus (versus communicating)?
     
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  3. Halothane27

    Halothane27 2+ Year Member

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    In Dandy Walker, the absence of the cerebellar vermis causes the fourth ventricle to dilate and obstruct the flow through Foramen of Megendie and Luschka into the subarchnoid space. = Hydrocephalus
    Ill expand on that and add even Arnold Chiari or even a tumor like a astrocytoma can cause noncommunicating hydrocephalus.

    Communicating (Non- obstructive)= Is more of a problem in the arachnoid villi not reabsorbing that CSF. = Hydrocephalus

    Think of it in context of the Ventricles.
    When we OBSTRUCT the flow through the ventricle we block the communication of each ventricle to one another, there is a noncommunication (totally poor english lol)
    With communicating hydrocephalus, the ventricles are connected with each other just fine.
     
  4. seminoma

    seminoma 2+ Year Member

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    I'm pretty sure I read somewhere that obstructive only referred to between ventricles. So basically an obstruction anywhere after the aqueduct is considered communicating. Is that just completely wrong?
     
  5. Transposony

    Transposony Do or do not, There is no try 5+ Year Member

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    Arnold Chiari:
    A congenital anomaly resulting from a normal-sized cerebellum developing in an abnormally small posterior fossa with a low tentorial attachment. There is a narrow craniospinal junction and malformation of the posterior fossa leading to downward displacement of the medulla, fourth ventricle, and cerebellum into the cervical spinal canal, as well as elongation of the pons and fourth ventricle. This results in impaction of the foramen magnum, compression of the cervicomedullary junction by the ectopic tonsils, and interruption of normal flow of cerebrospinal fluid (CSF). Two types, type I is asymptomatic (till adulthood) and type II is symptomatic and commonly associated with syringomyelia and meningomyelocele respectively. Symptoms arise from dysfunction of brainstem and lower cranial nerves.

    Dandy Walker:
    Also congenital but this time there is agenesis or hypoplasia of the cerebellar vermis, cystic dilatation of the fourth ventricle, and enlargement of the posterior fossa with aqueductal obstruction leading to hydrocephalus or it may be associated with atresia of the foramen of Magendie and foramen of Luschka.
    The enlarged fourth ventricle balloons out backward as a membrane-wrapped cyst and lifts and displaces the posterior portion of the brain, as well as cause an internal obstruction of normal CSF flow, with resultant supratentorial hydrocephalus.
    Unlike Arnold Chiari, the posterior fossa is large ( there's a lot of space in the post fossa for the 4th ventricle to WALK around and expand).
     
    Last edited: 04.23.15
    DeeJay2728 and usmleswot like this.

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