How to understand an enlarged Meckel's cave? An anatomical study

Area of Science:

• Neurosurgery
• Radiology

Background:

• Dilatation of the trigeminal cavum (Meckel's cave) is often linked to idiopathic intracranial hypertension.
• The normal anatomical dimensions of the trigeminal cavum are not well-defined.

Purpose of the Study:

• To anatomically characterize the normal dimensions and arachnoid extension within the trigeminal cavum.
• To reassess the trigeminal cavum's utility as a radiological marker for idiopathic intracranial hypertension.

Main Methods:

• Dissection of 18 trigeminal cavum specimens.
• Measurement of arachnoid web length and width, and its extension along trigeminal nerve branches (V1, V2, V3).

Main Results:

• Arachnoid cysts attached to V1 and V2 without skull base extension.
• Arachnoid extension to V3 measured 2.5mm anteromedially, 4.5mm laterally, and 4.0mm posteriorly.
• Trigeminal cavum arachnoid dimensions: 20.0mm width and 24.5mm length.

Conclusions:

• Variable arachnoid extension within the trigeminal cavum may explain imaging size variations.
• The arachnoid web extends significantly beyond previous descriptions, particularly near V3.
• The findings question the diagnostic value of trigeminal cavum size in idiopathic intracranial hypertension.