Galassi classification of middle cranial fossa arachnoid cyst [Neurosurgery Wiki]

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====== Galassi classification of middle cranial fossa arachnoid cyst ======

The Galassi classification of [[middle cranial fossa]] [[arachnoid cyst]]s is used to classify arachnoid cysts in the middle cranial fossa, which account for 50-60% of all arachnoid cysts. 

Galassi et al published this classification in [[1982]], and remains the most widely used system for these lesions. 

It is a simple system, using the size and degree of displacement of adjacent brain to divide cysts three types. The size also correlates with the ease with which the cyst communicates with the subarachnoid space as discerned on [[CT cisternography]] or phase contrast MRI.

{{::galassi_.jpg|}}

[[Galassi type 1 middle cranial fossa arachnoid cyst]]

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type II
superior extent along sylvian fissure
displacement of the temporal lobe
slow communication with subarachnoid space

type III
large, fills the whole middle cranial fossa
displacement of not only the temporal lobe but also the frontal and parietal lobes
often results in midline shift
little communication with subarachnoid space

((Galassi E, Tognetti F, Gaist G, Fagioli L, Frank F, Frank G. CT scan and
metrizamide CT cisternography in arachnoid cysts of the middle cranial fossa:
classification and pathophysiological aspects. Surg Neurol. 1982 May;17(5):363-9.
PubMed PMID: 7089853.
)).