"Microbleeding" from intracranial aneurysms: Local hemosiderin deposition identified during microsurgical treatment of unruptured intracranial aneurysms.
BACKGROUND
During elective surgery for unruptured aneurysms, we have identified a group of patients with hemosiderin staining of the pial surface immediately adjacent to the aneurysm dome suggesting a remote and unrecognized history of microbleeding from the aneurysm. These cases form the basis for this report.


METHODS
Medical records of 421 unruptured cerebral aneurysm patients treated surgically between January 2003 and September 2010 were retrospectively reviewed. Patients with a history of prior subarachnoid hemorrhage, craniotomy, or significant closed head injury were excluded from review. Records were reviewed for intraoperative descriptions of hemosiderin deposition in the vicinity of the aneurysm as well as history of headaches, time to presentation, comorbidities, aneurysm characteristics, procedures, and radiologic imaging.


RESULTS
Local hemosiderin staining immediately adjacent to the aneurysm was identified intraoperatively in 13 cases. Each of these patients had a history of remote atypical headache prior to presentation. Eight of these patients (62%) had aneurysms described as particularly "thin-walled" at the time of surgery. Aneurysm locations included the internal carotid artery (ICA) (54%), middle cerebral artery (MCA) (23%), anterior communicating artery (ACOMMA) (15%), and the anterior cerebral artery (ACA) (8%). More than half (54%) of these patients had a history of smoking, while 31% had hypertension, and 23% had a history of alcohol abuse. Dyslipidemia and family history of aneurysms were present in 15% and hypercholesterolemia was noted in one patient (8%).


CONCLUSIONS
We suggest this group of patients had suffered a "microbleed" resulting in local hemosiderin deposition next to the aneurysm. The origins and clinical implications of such microbleeds are unknown and warrant further investigation.
National Brain Aneurysm Center at the John Nasseff Neuroscience Institute, United Hospital, Allina Health System, St. Paul, MN, USA ; Minnesota Neurovascular and Skull Base Surgery, Minneapolis, MN, USA.
Eric S
ES
Nussbaum
Centra Care, St. Cloud Hospital, MN, USA.
Archie
A
Defillo
Health East Care System, St. Paul, MN, USA.
Andrea
A
Zelensky
Health East Care System, St. Paul, MN, USA.
Swaroopa
S
Pulivarthi
Minnesota Neurovascular and Skull Base Surgery, Minneapolis, MN, USA.
Leslie
L
Nussbaum
Hemosiderin; microbleed; unruptured aneurysms