Largest documented cerebral aneurysm mimicking a giant brain tumor and treated by highly selective occlusion of inflow: illustrative case

Journal of Neurosurgery Case Lessons, vol. 10

Abstract

BACKGROUND: Giant intracranial aneurysms (GIAs) are rare vascular lesions associated with significant morbidity and mortality. Their management is particularly challenging due to the absence of universal treatment guidelines, necessitating individualized strategies tailored to each case's unique morphology and hemodynamics. OBSERVATIONS: The authors report the case of a 66-year-old woman who presented with progressive aphasia, gait disturbance, and hemiparesis over several months. Initial CT imaging revealed a large, left-sided, partially calcified mass measuring 11 cm in diameter with significant perilesional edema, initially suspected to be a brain tumor. Further evaluation with angiography confirmed a giant, partially thrombosed aneurysm, the largest cerebral aneurysm documented to date, to the authors' knowledge. Hemodynamic analysis demonstrated a delayed intra-aneurysmal "washout" phenomenon and an anteroposterior pressure gradient, with adequate collateralization. A targeted approach using highly selective anterograde and retrograde coil embolization only of the aneurysm's inflow and outflow points achieved complete parent artery occlusion. This resulted in full aneurysm thrombosis, resolution of perilesional edema, significant reduction in mass effect, and complete neurological recovery. LESSONS: Despite their size, GIAs may still allow for a straightforward, safe, and effective treatment strategy. This case underscores the critical importance of thoroughly assessing the morphology and hemodynamics of GIAs to guide treatment decisions. https://thejns.org/doi/10.3171/CASE2539.

Authors 11

1. Lukas Andereggen

   University of Bern · Kantonsspital Aarau

   Affiliation as printed

   Department of Neurosurgery, Kantonsspital Aarau, Switzerland

   Medical Faculty, University of Bern, Switzerland

2. Javier Añon

   Kantonsspital Aarau

   Affiliation as printed

   Department of Neuroradiology, Kantonsspital Aarau, Switzerland

3. Angelo Tortora

   Kantonsspital Aarau

   Affiliation as printed

   Department of Neurosurgery, Kantonsspital Aarau, Switzerland

4. Serge Marbacher

   University of Bern · Kantonsspital Aarau

   Affiliation as printed

   Department of Neurosurgery, Kantonsspital Aarau, Switzerland

   Medical Faculty, University of Bern, Switzerland

5. Christian Musahl

   Kantonsspital Aarau

   Affiliation as printed

   Department of Neurosurgery, Kantonsspital Aarau, Switzerland

6. Philipp Gruber

   Kantonsspital Aarau

   Affiliation as printed

   Department of Neuroradiology, Kantonsspital Aarau, Switzerland

7. Michael Diepers

   Kantonsspital Aarau

   Affiliation as printed

   Department of Neuroradiology, Kantonsspital Aarau, Switzerland

8. Soojin Park

   Columbia University

   Affiliation as printed

   Department of Neurology, Columbia University, New York, New York

9. Hans‐Jakob Steiger

   Kantonsspital Aarau

   Affiliation as printed

   Department of Neurosurgery, Kantonsspital Aarau, Switzerland

10. Luca Remonda

    University of Bern · Kantonsspital Aarau

    Affiliation as printed

    Department of Neuroradiology, Kantonsspital Aarau, Switzerland

    Medical Faculty, University of Bern, Switzerland

11. Gerrit Alexander Schubert Aachen Department of Neurosurgery

    RWTH Aachen University · Kantonsspital Aarau

    Affiliation as printed

    Department of Neurosurgery, Kantonsspital Aarau, Switzerland

    Department of Neurosurgery, RWTH Aachen University, Aachen, Germany