Keyword
pericallosal artery aneurysms
Palavra-chave
aneurisma de arteria pericalosa
Introduction
Distal anterior cerebral artery aneurysms, also known as pericallosal artery (PA)
aneurysms, are located on the anterior cerebral artery distal to the anterior communicating
artery.[1] These aneurysms represent ∼ 6% of all intracranial aneurysms and 4% of those that
rupture.[2]
[3]
[4]
[5]
[6] Mirror aneurysms are paired aneurysms found with similar distributions on bilateral
intracranial arteries. The frequency of mirror aneurysms is unknown. Estimates range
from less than 5% of all patients with unruptured intracranial aneurysms to as many
as 40% of patients with multiple unruptured intracranial aneurysms.[7]
[8] The most common distribution for mirror aneurysms is the middle cerebral artery
(34%) followed by the non-cavernous internal carotid artery (32%), the posterior communicating
artery (16%), the cavernous internal carotid artery (13%), the anterior cerebral artery/anterior
communicating artery (3%), and the vertebrobasilar circulation (2%).[9] Bilateral PA aneurysm in mirror position is an extremely rare condition.
The aim of the present study is to describe the case of an adult woman with subarachnoid
hemorrhage and bilateral PA aneurysm in mirror position.
Discussion
Pericallosal artery aneurysms represent ∼ 6% of all intracranial aneurysms and 4%
of those that rupture.[2]
[3]
[4]
[5]
[6] When associated with subarachnoid hemorrhage, PA aneurysms may be technically difficult
to clip because of the narrow exposure afforded by an interhemispheric approach, and
because of the difficulty to control the parent artery, as well as the fact that a
bridging vein must be sacrificed in order for the adequate surgical exposure to be
achieved. Furthermore, many patients suffer intraoperative hemorrhage. As a consequence,
the surgical morbidity has been reported to be relatively high, with incidences ranging
from 0 to 25%.[10]
[11]
[12]
[13]
According to Lee and colleagues,[14] the successful surgical treatment of PA aneurysms depends on the precise understanding
of their unique microsurgical anatomy, on the avoidance of pitfalls, and on the surgeon's
experience. The performance of an atraumatic opening of the interhemispheric fissure,
the preservation of major draining veins, the accurate localization of the aneurysm,
and the early exposure of the proximal segment A2 of the anterior cerebral artery
are all unavoidable and necessary steps for a safe and adequate clip placement. Additionally,
Lehecka and colleagues[6] discussed the importance of meticulous dissection toward the aneurysm and of projecting
the dome as relevant points for a successful operation.
Bilateral PA aneurysm in mirror position is an extremely uncommon situation. Niijima
and colleagues,[15] in 1989, described the case of a 47-year-old woman who presented a ruptured bilateral
PA aneurysm in mirror position that was successfully treated using the interhemispheric
approach. The authors discussed that cigarette smoking and chronic uncontrolled arterial
hypertension may be possible predisposing factors for bilateral intracranial aneurysm
and rupture.
In the present investigation, we described the case of a 46-year-old woman who presented
acute severe headache associated with subarachnoid hemorrhage and bilateral PA aneurysm
in mirror position. She mentioned she was a heavy smoker (around 20 cigarettes/day)
and treated her arterial hypertension irregularly. The patient was surgically treated
via a right interhemispheric approach, and was discharged without any additional neurological
deficits.
In conclusion, the authors highlight that ruptured bilateral PA aneurysm in mirror
position is an extremely rare condition, and the success of the treatment depends
on a meticulous microsurgical technique, on the surgeon's experience, and on the avoidance
of unnecessary maneuvers.
