GALASSI CLASSIFICATION OF MIDDLE TEMPORAL FOSSA IACS

MTF ACs account for more than half of all ACs . The widely used Galassi Classification (1982) provides a schematic radiological classification of these lesions. There are three types of MTF IACs based on size and degree of mass effect.

Type I cysts are characterized by the following: lens-shaped, anterior tip of the MTF, freely communicate with CSF/surrounding subarachnoid space on MR-cine/CT-ventriculography, they rarely require surgery.

Type II cysts are characterized by intermediate size, more rectangular morphology, extend into the Sylvian fissure, have variable communication with CSF pathways, and exert local mass effect on the temporal lobe; they occasionally and sometimes require surgery.

Type III cysts constitute the largest group, extend the full length of the Sylvian fissure, exert significant mass effect (often with midline shift), and do not communicate with the subarachnoid space; these usually require surgery.

There is no Class I evidence regarding the optimal treatment of ACs. We must, therefore, weigh the risks versus benefits of conservative versus surgical treatment of these lesions in symptomatic patients on an individual patient basis.