The treatment of pseudoaneurysms with flow diverters after malignant otitis externa

Abstract

Background

We report a case of bilateral malignant otitis externa complicated with bilateral petrous internal carotid artery pseudoaneurysms and their successful treatment with a flow diverter.

Case report

A 68-year-old woman with serious complications of type II diabetes mellitus had malignant otitis externa on the right side. She was treated with combined antibiotic therapy and underwent mastoidectomy for mastoiditis. She presented at our hospital with acute hemorrhage from the right external auditory canal. The emergency computed tomography (CT) angiography revealed a multiobulated pseudoaneurysm at the petrous segment of the right internal carotid artery. The pseudoaneurysm was treated with a 5 × 40-mm Surpass flow diverter. Three months later, she developed a malignant external otitis on the left side. As the infection progressed, a left-sided mastoiditis, a brain abscess, and a pseudoaneurysm at the petrous segment of the left internal carotid artery developed. The pseudoaneurysm caused bleeding from the left ear, and was treated with a 5 × 50-mm Surpass flow diverter. No recurrent bleeding was observed. Four months later, a follow-up angiography showed complete occlusion of the pseudoaneurysm on the left side, but a residual aneurysm could be detected on the right side. One year after the first intervention, the follow-up CT and magnetic resonance angiography revealed the complete occlusion of the aneurysms bilaterally.

Conclusion

The use of a flow diverter appears to be an efficient and safe method to occlude carotid pseudoaneurysms even in an inflammatory milieu.

Background

A pseudoaneurysm in the petrous segment of the internal carotid artery is very rare. The possible underlying causes include arterial dissection, surgical injury, fibromuscular dysplasia, tumor infiltration, radiation therapy, trauma (including gunshot injury), and inflammation (i.e. chronic otitis media and malignant otitis externa).^1–6 The main risks of pseudoaneurysms include the high propensity to cause massive (sometimes life-threatening) bleeding from the ear and nose, and, less frequently, thromboembolic complications.

We report a case of a patient who developed internal carotid artery pseudoaneurysms as a result of malignant otitis externa bilaterally. The pseudoaneurysms ruptured on both sides resulting in severe bleeding, which required relatively urgent therapeutic interventions. A successful therapy with a flow diverter was applied bilaterally.

Case report

A 68-year-old female patient who suffered from severe symptoms and complications of type II diabetes mellitus developed right-sided otitis externa with otalgia and otorrhea. In spite of the targeted local, subsequently oral plus local antibiotic treatment she received, the inflammation spread to the mastoid cells, necessitating mastoidectomy. Several months later, the local inflammation still persisted despite multiple regimens of targeted oral antibiotics based on the bacteriological analyses of the intraoperative specimen and the discharge from the ear, and profuse bleeding occurred from her right ear multiple times. An urgent cranial computed tomography (CT) and a CT and a magnetic resonance (MR) angiography were performed, which revealed a multilobulated pseudoaneurysm of the petrous internal carotid artery on the right side as the source of the bleeding (Figure 1).

Figure 1.

(a) Pseudoaneurysms on the right internal carotid artery (three-dimensional magnetic resonance angiography images). (b) Spatial relationship of the pseudoaneurysms with the surrounding structures, with an arrow pointing to one of the pseudoaneurysms, which reaches the external auditory canal and the resected space of the mastoid bone (computed tomography angiography, semi-sagittal reconstruction).

We assumed that the pseudoaneurysms had resulted from the weakening of the vessel wall exposed to inflammatory changes; therefore, we performed an urgent digital subtraction angiography (DSA), which showed a rather tortuous right common and internal carotid artery with pseudoaneurysms (Figure 2).

Figure 2.

(a) Multilobulated pseudoaneurysm on the right internal carotid artery before treatment and kinking of the artery (subtraction image). (b) Three-dimensional digital subtraction angiography image of the pseudoaneurysms. (c) Follow-up angiography of the right internal carotid artery, immediately after the deployment of the flow diverter. (d) Six-month follow-up angiography of the right internal carotid artery.

Our first treatment plan included the endovascular occlusion or surgical ligation of the affected right internal carotid artery. However, the circle of Willis did not prove to be functionally sufficient to provide adequate cross-perfusion on the basis of the carotid occlusion tests; therefore, the plan of the occlusion/ligation of the carotid artery had to be rejected. As an alternative treatment, we decided to use a flow diverter stent to reduce the flow and support the thrombotic process within the pseudoaneurysms, in hope that these changes would stop the recurrence of bleedings. A Surpass flow diverter (5 × 40-mm, Surpass™; Streamline™; Stryker Neurovascular, Fremont, CA, USA) was selected and used for the treatment. The intervention was under mono antiplatelet therapy (acetylsalicylic acid) and a total of 5000 U of intravenous heparin was administered on inserting the flow diverter. At the end of the intervention, the stagnation of the contrast agent within the aneurysms could be detected, as an encouraging predictor of future thrombosis. The follow-up magnetic resonance imaging (MRI) demonstrated inflammation around the affected mastoid, with no signs indicative of further local extension of the infection. In the next few days following the intervention, no profuse bleeding could be observed; however, the patient was temporarily confused as a result of anemia. Because of the considerable amount of blood loss, the patient received four units (∼2000 ml) of blood transfusion. Targeted systemic and local antibiotic treatments were administered based on the bacteriological analysis of the discharge from the right ear. The patient did not develop fever throughout the course, and inflammatory alterations in the serum laboratory examination were only mild (with serial normal serum procalcitonin (PCT) and only slightly elevated C-reactive protein (CRP, between 30 and 75 mg/l) levels, and normal leukocyte counts). Two weeks later, the patient could be discharged with the regular follow-ups scheduled.

Nonetheless, one month after the first intervention, she presented with signs of severe otitis externa (otalgia and otorrhea) on the contralateral (left) ear, and in spite of the local and systemic antibiotic treatment administered, her condition did not improve and she had to undergo a left-sided mastoidectomy as the inflammation affected the mastoid cells as well. Soon after, the patient presented with bleeding from her left ear. The MR angiography revealed a very severe inflammation in the left ear consistent with malignant otitis externa. The inflammation extended along the skull base, and was accompanied by a brain abscess in the right hemisphere and a pseudoaneurysm located at the petrous segment of the left internal carotid artery, as source of the bleeding (Figure 3). Serum laboratory alterations were, of note, still unremarkable. Although there is a possibility that the abscess was caused by bacillemia in spite of an almost continuous targeted antibiotic therapy, a local spread of the infection along the meninx can also be presumed as the underlying etiology, on the basis of its close vicinity to the skull base, its direct contact with the meninx, its unilateral localization with respect to the first-affected internal carotid artery, its solitary presentation, and the lack of laboratory and clinical signs indicative of a systemic inflammatory response throughout the course. A preceding blood culture, which was not taken because of the absence of signs indicative of a systemic inflammatory response, could have resolved this issue. Nevertheless, the brain abscess was small in size hence not requiring surgical therapy, and was successfully treated conservatively with combined targeted antibiotic therapy according to the recommendation of an infectious disease specialist, who based the decision on prior and most recent findings of bacteriological analyses. Bleeding from the left ear recurred on several occasions; therefore, we performed a DSA, confirming the pseudoaneurysm on the left internal carotid artery (Figure 4). This pseudoaneurysm was also treated with a Surpass flow diverter (5 × 50-mm, Surpass™; Streamline™; Stryker Neurovascular) by using similar antithrombotic conditions as before. At the end of the intervention, stagnation of the contrast agent within the aneurysm could be observed, and there was no recurrent bleeding subsequently. We continued the antibiotic therapy with an orally available regimen for nearly a month and followed-up the brain abscess with MRI. The size of the abscess did not increase, the skull base inflammation showed a decrease, and the condition of the patient gradually improved; therefore, we changed to local treatment.

Figure 3.

(a) Extended inflammation affecting the skull base. (b) Brain abscess. (c) Arrow points to the pseudoaneurysm of the petrous part of the left internal carotid artery.

Figure 4.

(a) Pseudoaneurysm on the left internal carotid artery before treatment (subtraction image). (b) Three-dimensional digital subtraction angiography image of the pseudoaneurysm. (c) Follow-up angiography of the left internal carotid artery, immediately after deployment of the flow diverter (venous phase, demonstrating the stagnation of the contrast agent). (d) Six-month follow-up angiography of the left internal carotid artery.

Six months after the treatment of the right-sided pseudoaneurysms (four months after that of the left-sided pseudoaneurysm), a follow-up DSA was performed that showed complete occlusion of the pseudoaneurysms on the left side and an almost complete occlusion of that on the right side. Twelve months after the first procedure, a follow-up CT angiography revealed the complete occlusion of the pseudoaneurysms on both sides (Figure 5).

Figure 5.

Reconstruction based on follow-up computed tomography angiography one year after the first intervention reveals the occlusion of the pseudoaneurysms on both the left ((a) and (b)) and the right side ((c) and (d)).

Discussion

There are two main options for the treatment of pseudoaneurysms of the petrous segment of the internal carotid artery.¹ The first option means sacrificing the internal carotid artery by means of endovascular occlusion or surgical ligation, whereas the other one aims at excluding the pseudoaneurysms from the circulation. In an emergency setting, performing the Matas and Allcock maneuvers are imperative before the definitive occlusion of the internal carotid artery; the tests inform us if the circulation in the circle of Willis is adequate or inadequate to provide sufficient cross-perfusion after unilateral occlusion.⁷ If the tests reveal inappropriate collateral circulation, the occlusion of the internal carotid artery is hazardous, and associated ischemic complications are very likely.⁸ If the pseudoaneurysm is not excluded from the circulation (also known as trapping), it might grow and can eventually rupture. Surgical treatment of these aneurysms may be rather complicated, and in case the test reveals insufficient collateral circulation, a bypass surgery has to be performed before ligation of the internal carotid artery. The time-consuming nature of this procedure, however, makes the endovascular intervention more suitable as a treatment of choice in such an urgent situation as during bleeding. All these considerations made us opt for an endovascular treatment of the pseudoaneurysms. The aim of endovascular treatment is to exclude the pseudoaneurysm from the circulation, thereby preventing further bleeding and growth of the pseudoaneurysm.⁹ A limited number of case reports are available in the literature in which detachable coils (with or without a stent) were used for such a purpose.¹⁰ The weakened vessel wall, however, represents a serious hazard in case the intervention is based on the use of coils, with which the wall of the pseudoaneurysms can easily be injured. If a pseudoaneurysm is wide necked, a self-expanding stent (e.g. a Neuroform stent (Boston Scientific, Stryker Neurovascular) or an Enterprise Stent (Codman Neurovascular, Raynham, MA, USA)) with detachable coils could as well be applicable; however, the original problem would still remain unsolved as the use of detachable coils is still part of the procedure.

Recognizing the problem detailed above, some case reports gave an account of the use of a covered stent to avoid inserting detachable coils. Alexander et al. was the first to successfully apply the Symbiot-covered stent (Boston Scientific) for the treatment of petrous internal carotid artery pseudoaneurysms, which was followed by similar reports of others.^1,2,11 The Symbiot-covered stent is, however, not available any longer as its production has been stopped.

On devising the treatment plans for our patient, we kept in mind that the carotid artery should be preserved and surgical treatment (i.e. bypass surgery) was not feasible in such acute settings; therefore, we opted for the deployment of flow diverter stents, despite the fact that their exogenous nature makes them a possible novel source of further infections. Furthermore, because of the tortuosity of the internal carotid artery, a flexible stent was needed. A disadvantage of the use of a flow diverter is the absolute requirement of antiplatelet therapy. In both procedures (particularly in the case of the right-sided multiple pseudoaneurysms), considering the possible consequences of recurrent profuse bleeding, we decided to continue with mono antiplatelet therapy with acetylsalicylic acid 100 mg once daily, a therapy the patient had already been on, with its effectivity being thoroughly checked and confirmed by the Multiplate ASPItest (Roche Diagnostics Limited, Rotkreuz, Switzerland) on admission, instead of applying dual antiplatelet therapy, as is conventional. On the basis of similar considerations, the total amount of intravenous heparin given was not more than 5000 U in both cases. Fortunately, the bleeding did not recur after the interventions and thromboembolic complications did not develop. Combined targeted antibiotic therapy was administered for the infection, which gradually subsided after the second procedure. One and a half years after the interventions, the patient developed chronic external and middle ear inflammation, which could be managed by local antibiotic treatment. One year after the first procedure, the follow-up CT angiography revealed the complete occlusion of the pseudoaneurysms on both sides. We can conclude that the patient is in a stable condition.

Conclusion

The use of flow diverters seems to be an effective method for the treatment of bleeding pseudoaneurysms and for those with high risk of bleeding, even in an inflammatory environment.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.