Turbulent Flow in a Cavernous Sinus Lesion: Does It Suggest Something?

ABSTRACT

A 14-year-old boy who had been complaining of double vision for the previous month was referred for neuro-ophthalmological evaluation. He was carrying a diagnosis of a cavernous sinus haemangioma causing a right VIth nerve palsy, based on imaging elsewhere. He reported having a boil at the angle of his mouth, which was associated with left-sided facial cellulitis, two weeks before the onset of the diplopia. His blood investigations showed a leukocytosis with elevated inflammatory markers. Re-evaluation of the magnetic resonance imaging suggested a sac-like out-pouching in the intracavernous part of the right internal carotid artery with differential intensity suggestive of turbulent flow. On the basis of the clinico-radiological findings, a diagnosis of mycotic aneurysm of the cavernous sinus part of internal carotid artery was made. A high index of suspicion is required to detect this rare clinical entity, which is associated with a potentially catastrophic clinical course.

Introduction

A mycotic aneurysm of the intracavernous part of the internal carotid artery is a rare clinical entity with less than 50 published cases according to a clinical review.¹ Mycotic aneurysm is synonymous with an infective aetiology and the diagnosis of it can be challenging. Herein, we present a rare case of a mycotic aneurysm that posed a significant diagnostic dilemma and was managed based on careful evaluation of the clinico-radiological findings.

Report of case

A 14-year-old boy was referred for neuro-ophthalmological evaluation due to a one month history of double vision. He reported having a boil at the angle of his mouth with cellulitis on the left side of the face two weeks before the onset of the diplopia, which had resolved on systemic antibiotics. On examination at his initial presentation elsewhere, he had visual acuity of 20/20 in each eye. A −3 restriction of abduction of the right eye was noted on ocular motility examination.² The rest of the ophthalmological examination including the pupillary reactions and fundi was within normal limits. His systemic evaluation did not reveal any abnormalities. A clinical diagnosis of an isolated VIth nerve palsy was made and a post-infectious cause, intracavernous sinus lesion, or clival chordoma were suspected. Magnetic resonance imaging (MRI) with contrast demonstrated a sellar mass with contrast enhancement and extension into the right cavernous sinus with the internal carotid artery being pushed peripherally, suggestive of a cavernous sinus haemangioma.

The initial blood investigations showed a leukocytosis with a raised erythrocyte sedimentation rate (70 mm/hr) and C-reactive protein (101 mg/L). There was no growth in blood cultures. Other investigations (2D-Echocardiography, chest radiograph, computed tomography of the paranasal sinuses) were performed to rule out any possible source of infection but they did not reveal any abnormality.

The MRI was re-evaluated at our institution. We felt that there was a sac-like out-pouching of the cavernous part of the right internal carotid artery with turbulent flow on T2-weighted imaging (Figure 1a). Also, differential enhancement was seen on post-contrast imaging (Figure 1b). The appearances suggested the diagnosis of a mycotic aneurysm of the right cavernous sinus internal carotid artery. Digital subtraction angiography confirmed the diagnosis (Figure 2a).

Figure 1.

(a) Axial T2-weighted MRI showing a sac-like outpouching of the cavernous part of the internal carotid artery with peripheral hyper and hypo-intensity and central hyperintensity in the cavernous sinus lesion suggesting turbulent flow within the lesion characteristic of a mycotic aneurysm (white arrow). (b) Post-contrast coronal T1-weighted MRI showing intense enhancement suggestive of a mycotic aneurysm of the right cavernous sinus internal carotid artery (white arrow)

Figure 2.

Digital subtraction angiogram of the same patient. (a) A large aneurysm is present arising from the cavernous part of the right internal carotid artery (ICA) with pre-aneurysmal vascular narrowing (black arrow). (b) An Amplatzer vascular plug has been used to occlude the feeding artery (black arrow). (c) Post-embolisation angiogram taken from right common carotid artery (black arrow at the lowest end pointing towards common carotid artery and black arrow with dashed line showing the carotid bulb) shows no filling of the right internal carotid artery (thick black arrow pointing towards the blocked right internal carotid artery and multiple white arrows showing the course of the blocked right internal carotid artery) with all the flow going towards the external carotid artery and no filling of the aneurysm is seen

A course of systemic antibiotics (intravenous amoxicillin-clavulanate 1.2 g eight hourly and metronidazole 500 mg six hourly) was given for six weeks for broad-spectrum antimicrobial cover. After being treated with the antibiotics, he underwent parent vessel occlusion of the right internal carotid artery with a vascular plug of the petrous and upper cervical part of the artery as there was good cross-flow from the left internal carotid artery and vertebral artery (Figure 2b). Post occlusion, there was no flow in the right internal carotid artery (Figure 2c). His visual acuity was maintained after the procedure and the abduction deficit had recovered completely after four months.

Discussion

A mycotic aneurysm of the cavernous part of the internal carotid artery is an unusual clinical entity as its course and management differ significantly from other intracranial aneurysms. Due to its strategical location, it is often missed clinically as it may present with ophthalmoparesis, a cavernous sinus syndrome, or sinusitis. The clinical course of this entity is more catastrophic compared with non-mycotic aneurysms and also there is a potential risk of aneurysm rupture with associated morbidity and mortality.

A possible mechanism of mycotic aneurysm formation of the intracavernous part of the internal carotid artery after facial infection could be retrograde spread and extension into the cavernous sinus through the facial vein which communicates with the pterygoid plexus through the deep facial vein. The pterygoid plexus of veins is connected to the cavernous sinus through emissary veins and both cavernous sinuses communicate with each other through the anterior and posterior intercavernous sinuses and basilar plexus of veins.³ All of these communications are valveless and blood can flow through them in either direction. In our case, the cellulitis was in a dangerous area of face which led to the cavernous sinus thrombophlebitis via above mentioned pathway leading to the focal angiitis of the intracavernous part of internal carotid artery that could have caused vessel wall weakness with subsequent aneurysm formation.⁴ Similar to our case, other cases of mycotic intracavernous internal carotid artery aneurysm following facial infection have been reported.^5–7

Intracavernous internal carotid mycotic aneurysms have been reported sparsely. The previous cases with ophthalmological manifestations have been tabulated in Table 1. The clinical manifestations arise from compression of neurovascular structures passing through the cavernous sinus with consequent IIIrd, IVth, and/or VIth nerve palsies and hypoaesthesia in the V1 and/or V2 divisions of the trigeminal nerve. Devadiga et al. reported a similar case of intracavernous internal carotid aneurysm in a 14-month-old boy who presented with orbital cellulitis, which was confirmed on carotid angiography.⁸ It resolved with conservative treatment. A series of six cases of similar diagnosis with cavernous thrombosis, blepharitis, and conjunctivitis have been reported by Suwanwela.⁹ There has been an unusual report of an enlarging mycotic internal carotid artery aneurysm after cavernous sinus thrombosis presenting with blindness due to optic chiasm and optic tract involvement.¹⁴ The patient recovered clinically, including his visual acuity, after endovascular occlusion of the internal carotid artery. Visual loss, proptosis with complete IIIrd, IVth, and VIth nerve palsies were reported in a case of cavernous sinus thrombosis due to a mycotic aneurysm, which resolved with amphotericin B treatment and coil embolisation.¹⁷ Another report of mycotic aneurysm with endogenous endophthalmitis due to possible infective endocarditis has been described in the literature.²⁰

Table 1.

Cases of mycotic aneurysm of the intra-cavernous part of the internal carotid artery with ophthalmological manifestations

Authors	Age (Years)	Presentation/clinical manifestations	Management	Clinical outcome
Devadiga et al.8	1	Orbital cellulitis	Conservative	Resolution
Suwanwela et al.9	6, 6,10, 33	Cavernous sinus thrombosis, blepharitis, conjunctivitis	Conservative except for ligation in one case	Resolution except for one case
Tomita et al.10	2	Meningitis, systematic abscess, total ophthalmoplegia	Carotid ligation	Resolution
Rout et al.11	3, 6, 18, 59	Orbital cellulitis, periorbital abscess, cavernous sinus thrombosis	Conservative except for ligation in one case	Resolution
Abbassioun et al.12	6	Meningitis, ophthalmitis	Ligation of right side; conservative left side	Resolution
Michelli et al.5	19	Furuncle on cheek with cellulitis	Balloon occlusion	Resolution
Hurst et al.4	73	Headache, decreased vision, epistaxis, sphenoid sinusitis	Coil occlusion	Death
Ueki et al.13	79	Progressive visual disturbance, diplopia, ptosis	Conservative	Death
Quisling et al.14	19	VIth nerve palsy with decreased vision, pansinusitis	Coil occlusion	Resolution
Philippeau et al.15	61	Ophthalmoplegia after tooth extraction, sphenoid and ethmoid sinusitis	Conservative	Resolution
Yen et al.16	46	Cavernous sinus thrombosis	Endovascular stent and coil occlusion	Resolution
Kim et al.17	62	Headache, fever, decreased vision, restricted abduction	Coil occlusion	Resolution
Pant et al.18	32	Fever, neck pain, dysphagia, diplopia, ophthalmoplegia	Conservative	Resolution except for ophthalmoplegia
Gupta et al.6	11	Pustule over left ala of nose with high fever, frontal headache then chemosis, ophthalmoplegia, ptosis, diplopia	Endovascular stent graft	Resolution
Shi et al.19	63	Acute blepharoptosis with imaging feature of pituitary infection	Endovascular stenting with detachable coils	Resolution
Carmelli et al.20	69	Blurring of vision with discharge, fever, vomiting	Conservative	Resolution
Sharma et al.7	3,10	Boil at the tip of nose, orbital cellulitis, esotropia, restriction of abduction	Endovascular embolisation in the first case; flow diverter planned in the second case	Resolution in case 1
Imamura et al.21	35	Eye pain, ptosis, fever	Endovascular pipeline embolisation device	Resolution

An absence of specific treatment algorithms for mycotic intracavernous internal carotid aneurysm makes the management of this entity relatively complex and challenging. Due to the rarity of the disease, the management is individualised based on the previous cases and clinical experience. Management comprises initial broad-spectrum antibiotics then guided by culture and sensitivity, serial angiography to monitor the aneurysm, and surgical carotid ligation or endovascular intervention (coiling, stent graft or flow diverter). Medical therapy controls the microbial load and halts the progression of the aneurysm in many cases.^8,9,11,18,20 The duration of antibiotic treatment is typically 4–6 weeks, monitored by resolution of clinical symptoms like ophthalmoplegia and angiographic halt or resolution of aneurysm progression.¹ While carotid ligation carries a high risk of ischaemic complications if done without evaluating cross flow and collaterals, endovascular approaches offer a promising alternative as cross-flow and collaterals can be assessed before any permanent occlusion of the internal carotid artery is performed for the definitive treatment of the aneurysm.²² When the circle of Willis is complete and good collaterals are present then there should be no neurological deficit after parent vessel occlusion but if the circle of Willis is incomplete and collaterals are not good then there is a high risk of post-procedure neurological deficit. During endovascular treatment, if there is any doubt about the collateral circulation then a balloon occlusion test should be performed before therapeutic occlusion. In a clinical review of intracavernous carotid mycotic aneurysm cases, 76.9% of patients treated by an endovascular approach experienced resolution of disease.¹ However, the definitive treatment should be performed after antibiotic treatment to decrease the risk of colonisation of the stent or aneurysm rupture due to the friable vessel wall in the acute setting. Enlargement or persistence of the aneurysm, worsening or non-resolution of symptoms including ophthalmoplegia are the possible indications for definitive therapy.

The diagnosis of this entity is relatively difficult due to the lack of defined diagnostic criteria. It is based on the clinical history of infective lesion and its temporal relationship to the underlying illness, the localising clinical signs, laboratory findings, and most importantly the imaging appearances. Our case presented with a VIth nerve palsy due to a cavernous sinus lesion. The temporal relationship of the symptoms with the facial cellulitis led us to think about the possibility of a mycotic aneurysm. Neuro-radiological review of the imaging led to the discovery that there was peripheral hyper- and hypo-intensity with central hyperintensity in the cavernous sinus lesion, which suggested turbulent flow within the lesion, confirming our suspicion of a mycotic aneurysm of the intracavernous internal carotid artery. We emphasise the importance of this radiological clinical sign suggesting the presence of turbulent flow in diagnosing this clinical entity. Prompt diagnosis carries a successful key in managing this disorder as it is associated with significant morbidity and mortality. Endovascular intervention appears to be safe and effective for the definitive treatment of this condition after prolonged antibiotic coverage.