Abstract

Background:The appearance of edematous lesions in the subacute phase is a rare complication following neuroendovascular therapy. Effective management of these lesions remains unclear. In this report, a case with progressive edematous lesions in the subacute phase after neuroendovascular therapy was described, and the clinical features and therapeutic strategies were discussed.

Case Description:A 54-year-old female with a large, right cavernous internal carotid artery aneurysm was treated with a flow diverter. Left hemiparesis developed 15 days after the procedure, and multiple edematous lesions in areas of prior catheter procedures were revealed on radiological findings. Steroid pulse therapy was employed, and the lesions were gradually reduced without any additional neurological deficits. No recurrence was recognized in the follow-up study.

Conclusion:In some reports, pathological findings indicate that these lesions result from the presence of foreign bodies, and emboli could be caused by cotton fibers or hydrophilic polymers used as surface coatings on endovascular catheters. In this case, the edematous lesions were most likely caused by hydrophilic polymer emboli. Steroid pulse therapy had a beneficial effect on the lesions. It is important to effectively manage prescribed periods after the procedure to avoid such a rare complication.

Keywords: Flow diverter, foreign body emboli, hydrophilic polymer, neuroendovascular therapy

INTRODUCTION

Neuroendovascular therapy is commonly used for intracranial aneurysms. Recently, the complication rate of this procedure is relatively low and mostly includes thromboembolic events and intraprocedure aneurysm rupture. Foreign body emboli in the distal cerebral arteries during neuroendovascular therapy are occasionally encountered, and are a potential cause of ischemic stroke and parenchymal hemorrhage. Of these cases, there have been only a few reports concerning focal edematous lesions.[ 1 2 3 4 5 6 7 8 9 ] Although the pathological basis of these lesions is postulated from the surgical specimens,[ 2 ] effective therapeutic strategies remain unclear. In this report, we present a case of multiple edematous lesions in the subacute phase following neuroendovascular therapy, and we review their clinical features and therapeutic management.

CASE REPORT

A 54-year-old female with a history of nephrotic syndrome and hypertension presented with a persistent headache at her local clinic. A right thrombosed cavernous internal carotid artery aneurysm measuring 22.5 × 19.7 × 19.2 mm was detected on computed tomography angiography (CTA). She was introduced to our hospital and underwent flow diverter deployment for the aneurysm with a pipeline embolization device (PED) (Covidien, Irvine, California, USA). Under general anesthesia, a 5 Fr Navien 058 Intracranial Support Catheter (Covidien, Irvine, California, USA) and a Marksman Catheter (Covidien, Irvine, California, USA) were advanced over the neck of the aneurysm using a 0.014 inch Asahi Chikai microguidewire (Asahi Intecc, Aichi, Japan) through the shuttle sheath. A 4.75/20 mm PED was deployed to cover the neck of the aneurysm through the triaxial system, and the stent was re-sheathed twice. The procedure was performed in 61 min without any complications [Figure 1a and b ], though diffusion-weighted imaging (DWI) after the procedure revealed a few scattered hyperintensities in the right hemisphere [Figure 2a and b ]. Fifteen days after the procedure, left hemiparesis developed and multiple edematous lesions were revealed in the right hemisphere on magnetic resonance imaging (MRI) 28 days after the procedure [Figure 2c and d ]. The hemiparesis gradually progressed, and the edematous lesions were enlarged on MRI [Figure 2e and f ]. At this time, white blood cell count was 149 × 102 cells/mm³, C-reactive protein was 2.37 mg/dl, and creatinine was 1.28 mg/dl. Three courses of steroid pulse therapy (intravenous administration of methylprednisolone 1000 mg daily × 3 days and oral prednisolone 50 mg daily × 4 days) were then performed. Subsequently, hemiparesis was improved in association with the improvement of edemas [ Figure 2g ]. Eighty-one days after the procedure, the edemas were diminished, though nodular enhancing lesions were persistent on contrast-enhanced MRI [ Figure 2h ]. During the 6-month follow-up periods, there has been no recurrence and no neurological deficits.

Figure 1

Preprocedural angiography showed a right large cavernous internal carotid artery aneurysm (a). Postprocedural angiography showed a remarkable reduction of the blood flow to the aneurysm (b)

Figure 2

T2-weighted magnetic resonance imaging after the procedure showed no edema (a) and diffusion-weighted imaging showed a few hyperintensities in the right hemisphere (b). Magnetic resonance imaging 28 days after the procedure showed multiple edematous lesions in the right hemisphere (c), although there were no remarkable changes in diffusion-weighted imaging (d). Magnetic resonance imaging 42 days after the procedure showed a progression of edemas (e), though there were no remarkable changes on diffusion-weighted imaging (f). Magnetic resonance imaging after three courses of steroid pulse therapy (81 days after the procedure) showed a regression of edemas (g), and Gd-enhanced T1-weighted magnetic resonance imaging showed residual multiple enhancing lesions (h)

DISCUSSION

Clinical features of edematous lesions following neuroendovascular therapy are summarized in Table 1 . The time from the procedure to the appearance of the clinical presentation varied from 1 day to 9 months,[ 2 3 4 5 6 7 8 10 11 12 13 ] indicating that the complications might possibly occur over relatively long periods. Delayed allergic reactions might be associated to the complications, although there is no finding to support this. In terms of embolic sources, cotton fibers have been reported in previous studies,[ 10 ] though hydrophilic polymers applied as a surface coating on endovascular catheters are the most common cause in recent years.[ 1 9 ] From DWI findings, the scattered hyperintensities after the procedure are thought to be foreign body emboli and inflammatory cells surrounding them rather than acute cerebral infarctions, because their locations seem to be atypical for ischemic lesions and are at center of each edematous lesion. Moreover, the edematous lesions surrounding them are considered to be vasogenic edemas, and steroid therapy should be theoretically appropriate for such lesions. Steroid therapy is reported to result in relatively good prognoses.[ 4 7 11 ] Cruz et al. reported seven cases of foreign body emboli, and one of the patients treated with steroids improved and showed no neurological deficit at their last follow up.[ 2 ] Shapiro et al. reported five cases of similar legions treated by steroids, and their MRI findings at the last follow up showed resolution of the edemas.[ 11 ] Lorentzen et al. reported similar lesions after neuroendovascular therapy with a flow diverter. The patient was also treated with steroids and immunosuppressants, and showed substantial regression of the edemas.[ 7 ] Overall, there are few cases of recurrences and progression, and the symptoms are relatively mild in comparison with their initial imaging findings. From a pathological point of view, cerebral inflammation caused by foreign body emboli could be related to these edematous lesions. Mehta et al. reviewed several biopsy-proved cases of foreign body emboli with parenchymal inflammation. In all of these cases, foreign polymer materials and the surrounding inflammatory responses were identified pathologically.[ 8 ] If necessary, immunosuppressants might also be considered for such lesions to suppress the reactions due to their anti-inflammatory effects.

Table 1

Summary of 20 patients with multiple edematous lesions after neuroendovascular therapy

Cerebral foreign body emboli could be related to intercatheter friction, made increasingly common by the adoption of the triaxial catheter technique for deployment of a flow diverter. For that reason, the incidence of this complication is expected to increase in the near future. Treatment with a flow diverter is currently on the rise for both large and giant unruptured aneurysms. Advanced catheter stability is necessary to obtain a precise and secure delivery of the device. To achieve this stability, it is customary to use the triaxial catheter technique, which can lead to increased friction between catheters and may create a predisposition for small emboli from the coating of the catheters. Our case might also be associated with the use of tight-fitting catheter combinations to deploy the device. The accumulation of similar cases is necessary to more fully understand the technical factors involved.

CONCLUSION

A case with progressive edematous lesions in the subacute phase after neuroendovascular therapy was described. In this case, the edematous lesions were most likely caused by hydrophilic polymer emboli. Steroid pulse therapy had beneficial effect on the lesions. It is important to effectively manage prescribed periods after the procedure to avoid such a rare complication.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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