Reactive Expansive Intracerebral Process as a Complication to Endovascular Coil Treatment of an Unruptured ICA Aneurysm

Objective: Following the increased use of endovascular coiling of intracranial aneurysms, a growing number of case reports on complications are being reported.

Design: We present a case with a previously undescribed complication to coil treatment—a reactive, noninfectious process after coiling of an unruptured ICA aneurysm.

Patient: 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 ICA bifurcation aneurysm was discovered on MRI 6 months after the thyroidectomy.

Results: After documented aneurysm growth, the ICA 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 12 months post-coil MRI and, due to its increasing mass effect, was resected through a craniotomy 2 years after the coiling. Due to lesion regrowth and cyst formation, she underwent a new craniotomy 5 years later with excision of the now 21-mm large coiled aneurysm, ICA clip reconstruction, and lesionectomy. Five months postoperatively, the process has 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 due to the coils acting as a foreign body.

Conclusion: We present a case with a reactive expansive intracerebral process as a complication to endovascular coil treatment of an unruptured intracranial aneurysm.