Reactive Expansive Intracerebral Process as a Complication of Endovascular Coil Treatment of an Unruptured Intracranial Aneurysm: Case Report

BACKGROUND AND IMPORTANCE: As a consequence of the increased use of endovascular coiling of intracranial aneurysms, a growing number of case reports on complications are being reported. This article presents a case with a previously undescribed complication of coil treatment: a reactive, noninfectious process after coiling of an unruptured intracranial aneurysm CLINICAL PRESENTATION: A 60-year-old hypertensive woman with hypoxic encephalopathy after respiratory arrest following a total thyroidectomy had extensive intentional myoclonus and reduced quality of life as sequelae. An asymptomatic 15-mm internal carotid artery bifurcation aneurysm was discovered on magnetic resonance imaging (MRI) 6 months after the thyroidectomy. After documented growth, the aneurysm was treated endovascularly with bare platinum Guglielmi detachable coils. Three months later, an expansion in the right frontal lobe cranially to the coiled aneurysm was observed. The lesion had grown at the 12-month postcoil MRI and, because of its increasing mass effect, was resected through a craniotomy 2 years after the coiling. As a result of lesion regrowth and cyst formation, she underwent a new craniotomy 5 years later with excision of the now 21-mm large coiled aneurysm, internal carotid artery clip reconstruction, and lesionectomy. Five months postoperatively, the process had not recurred. No signs of malignancy or infection were observed during the histological evaluation of the resected tissue. The tissue is described as a reactive, noninfectious process, most likely resulting from the coils acting as a foreign body. CONCLUSION: This article presents a case with a reactive expansive intracerebral process as a complication to endovascular coil treatment of an unruptured intracranial aneurysm.