Galassi Classification

Last edit by Alaric Steinmetz on

The Galassi classification is used in neuroradiology to categorize arachnoid cysts in the middle cranial fossa into three distinct types and was first described in 1982 by Galassi et al.[^1].

Classification

Galassi Type

Criteria

Galassi Type I

Small, spindle-shaped. The cyst is located in the anterior part of the temporal fossa. The temporal pole is compressed posteriorly but does not have a significant space-occupying effect. There is no displacement of the ventricular system or midline.

Galassi Type II

The lesion is medium-sized and in a triangular or quadrangular shape. The lesion occupies the anterior and middle part of the temporal fossa and extends superiorly along the Sylvian fissure. The temporal lobe appears shortened.

Galassi Type III

The lesion is large and appears oval or round. It almost completely fills the space in the temporal fossa, extending into the respective hemisphere and separating the operculum from the Sylvian fissure. The temporal lobe appears atrophic, and the frontal and parietal lobes are largely compressed. There is a clear mass effect with a shift of the ventricular system and the midline.

Figure

Galassi classification
Illustration of the arachnoid cyst classification from the original publication by Galassi et al. The left column shows the preoperative images and the right column shows a follow-up CT after one year. -A- Type I arachnoid cyst -B- Type II arachnoid cyst -C- Type III arachnoid cyst.