Ruptured Mycotic ICA Aneurysm with Invasive Sphenoid Sinusitis
- Background
- Extremely rare but potentially fatal cause of epistaxis.
- ICA mycotic aneurysm secondary to fungal sphenoid sinusitis has been rarely reported.
- High rate of mortality because of arterial wall instability and high rate of recurrence, before advances in endovascular techniques for parent vessel sacrifice.
- Key Diagnostic Features
- Sphenoid sinus opacification on CT with bone destruction and without hyperostosis indicating acute/aggressive sinusitis.
- Fungal infection should be suspected in immunocompromised patients with rapid clinical progression and cranial neuropathy. This may be confirmed by non enhancing mucosa (mucosal necrosis) and intracranial extension on post contrast MRI.
- In suspected mycotic aneurysm, DSA can show features of arteritis with irregularity of arterial wall adjacent to aneurysm.
- Differential Diagnosis
- Ruptured (non mycotic) saccular aneurysm - Would not invade the sinus and adjacent the vessel adjacent to the aneurysm sac should be normal on DSA. Very unlikely to present with epistaxis.
- Previous surgery/iatrogenic injury causing bone dehiscence and dissecting aneurysm – History of recent procedure or trauma together with possible high attenuation +/- fluid level indicating haemorrhage within the sinus, gas adjacent to the aneurysm and a more irregular aneurysm wall.
- Incidental aneurysm with chronic sinusitis – Smooth aneurysm, normal adjacent vessel on DSA, rupture is unlikely. Hyperostosis of sinus wall bone as well as features of inspissated mucus with internal high attenuation on CT.
- Mucosal sinus disease – Usually exophytic and often multifocal polypoid mucosal swelling within sinus with submucosal edema, fluid density on CT and hyperintense on T2WI, can peripherally enhance. Bone erosion is not usually seen.
- Treatment
- Sinus drainage is imperative if invasive fungal infection is suspected but cannot be performed until the aneurysm is protected. Endovascular treatment such as coil embolization can acutely prevent bleeding but has high recurrence rates (image D). Parent vessel sacrifice rather than localised embolization prior to sinus surgery should be preferred over coiling.
- Empirical antimicrobial treatment including antifungal therapy should be commenced and tailored after sinus drainage and culture. Long term antifungal treatment is required.
- Timing of definitive treatment needs to be weighed against risk of colonisation of foreign body versus aneurysm stability and potential for re-rupture.
