Polymer-induced central nervous system complications following vascular procedures: spectrum of iatrogenic injuries and review of outcomes

Abstract

Polymer substances are commonly applied as surface coatings on endovascular catheters and vascular devices. Adverse effects related to their use have been reported, although the overall clinical significance and appropriate methods of detection of these complications have been unclear. In this analysis, we systematically reviewed clinical and diagnostic features in 32 patients (age, 36-87years; mean, 59years) in whom intracranial polymer reactions were documented following vascular interventions. Associated neuroradiologic and neuropathologic findings were variable and included cerebral vasculitis or vasculopathy (63%), abscess or granuloma formation (38%), ischemic infarcts (28%), parenchymal hematomas (28%), white matter change (25%), and/or chemical meningitis (22%). Location(s) of polymer reactions varied and included sites adjacent to and/or downstream from instrument insertion or implantation. Presenting clinical signs included focal neurologic deficits (41%), headache (22%), constitutional symptoms (19%), meningitis (16%), seizure and/or involuntary movements (9%), coma (6%), and syncope (3%). Adverse outcomes included stroke (31%), death (28%), delayed communicating hydrocephalus (9%), steroid dependency (9%), steroid complications (6%), and cerebral volume loss (3%). In some cases, these complications necessitated increased cost and length of medical care. In this review, we highlight the diverse features of polymer-induced reactions involving the central nervous system and summarize distinct diagnostic patterns that may enable earlier premortem detection of these lesions in the postprocedural clinical setting. Further work in this area is necessary to identify additional etiologic, preventative and therapeutic strategies. These data have potentially broad implications pertaining to the safety, efficacy, standards of use, storage, manufacturing, and regulation of new and emerging vascular devices and polymer nanotechnologies.

Keywords: Embolism; Endovascular procedure; HPE; Hydrophilic polymer; Iatrogenic complication; Inflammation; Vascular device.

Fig. 1

Arteritis, with aseptic meningitis and communicating hydrocephalus. A 46-year-old woman (case 6) underwent endovascular coil embolization of an unruptured PCA aneurysm and subsequently developed thickening and enhancement of the aneurysm wall, perianeurysmal edema, and aseptic meningitis due to presumed polymer reaction (A and B, FLAIR; C, postcontrast T1-weighted MRI images; reprinted with permission from Wolters Kluwer Health, Inc. [9]). Postmortem histology (case 11) revealed marked meningeal vascular inflammation downstream from polymer emboli (D, H&E).

Fig. 2

Sterile microabscess and granuloma formation, with foreign body inflammation. A 58-year-old woman (case 10) was treated via endovascular coil embolization for a supraclinoid right ICA aneurysm and subsequently developed parietal lobe ring-enhancing lesions with surrounding vasogenic edema. Biopsy confirmed necrotizing granulomatous inflammation and abscess, with foreign polymer material. (A and B, postcontrast T1-weighted MRI images; C–F, H&E; reprinted with permission from Wolters Kluwer Health, Inc. [11]). Another 46-year-old woman (case 14) developed symptomatic nodular enhancing lesions with associated vasogenic edema in the parietal and occipital lobes following basilar artery aneurysm coiling (G, T2-weighted and H, postcontrast T1-weighted MRI images; reprinted with permission from Elsevier [12]).

Fig. 3

Parenchymal hematoma. A 63-year-old woman (case 17) underwent endovascular aneurysm flow diversion for a left paraophthalmic ICA aneurysm and developed a large ipsilateral parenchymal hematoma with associated brain herniation that led to her demise; autopsy revealed hemorrhagic cerebral infarcts due to occlusive polymer emboli (A, selective ICA catheter angiogram; B, noncontrast CT image; C–F, H&E; reprinted with permission from Rockwater, Inc. [13]).

Fig. 4

Multifocal embolic infarcts. An 87-year-old woman (case 11) with a left ICA aneurysm was treated with coil embolization and subsequently died from multiple ischemic infarcts, which were most extensive within the left MCA/PCA territories. At autopsy, polymer emboli were present throughout the brain and were associated with intravascular inflammation, granulomas, fibrosis, and areas of infarcts, which led to her demise (A, CT angiogram image; B, selective ICA catheter angiogram; C and D, DWI MRI images; reprinted with permission from Elsevier [6]) (E–H, H&E; I, H&E; reprinted with permission from Nature Publishing Group [7]).

Fig. 5

Intravascular biodegradation of polymer emboli. Polymer emboli undergo biodegradative changes with marked variation in histologic appearances. Note progressive alteration in coloration, size, and shape; concomitant inflammation (predominantly intravascular histiocytic, giant cell, and neutrophilic response); microthrombus formation and/or fibrous response (images from cases 11 and 19) (H&E).