Transitional cavernous aneurysms of the internal carotid artery

Area of Science:

• Neurosurgery
• Vascular Neurology
• Neuroradiology

Background:

• Cavernous sinus aneurysms (CSAs) are rare cerebrovascular lesions.
• Transitional cavernous aneurysms (TCAs) are a subgroup of CSAs originating within the cavernous sinus but projecting into the extracavernous intradural subarachnoid space.
• This projection increases their risk of rupture, similar to other intracranial aneurysms.

Purpose of the Study:

• To present a series of transitional cavernous aneurysms.
• To analyze their clinical presentation, treatment, and outcomes.
• To propose a classification system for clinoidal-region aneurysms.

Main Methods:

• Retrospective review of 23 cases of transitional cavernous aneurysms.
• Analysis of aneurysm size, clinical presentation (subarachnoid hemorrhage, compressive symptoms), and treatment modalities (direct surgical clipping, indirect bypass).
• Evaluation of surgical outcomes and complications.

Main Results:

• Of 23 TCAs, 13 (57%) presented with subarachnoid hemorrhage and 9 (39%) with compressive symptoms.
• Aneurysm sizes varied: 6 small (<15 mm), 6 large (15-25 mm), and 11 giant (>25 mm).
• Direct surgical clipping was successful in 18 cases (78%), with an overall excellent outcome in 87% of patients, despite 3 complications (13%) including one fatality.

Conclusions:

• Transitional cavernous aneurysms represent a distinct entity with a high risk of subarachnoid hemorrhage.
• Aggressive management with direct clipping is advocated whenever feasible.
• A simplified classification for clinoidal-region aneurysms, including TCAs, is proposed.