- Distal anterior cerebral artery (DACA) aneurysms arise on the ACA or its branches distal to the anterior communicating artery. They are uncommon and most commonly occur at the bifurcation of the pericallosal and callosomarginal arteries. - DACA aneurysms are typically small, less than 5mm, and giant aneurysms are rare. They are often associated with additional intracerebral aneurysms. Surgical clipping via a microsurgical approach is generally the preferred treatment due to their peripheral location and size. - Clinical presentation of a ruptured DACA aneurysm commonly includes subarachnoid hemorrhage, often prominent in the interhemispheric fiss

1. Microsurgery of Distal Anterior
Cerebral Artery Aneurysms
Youmans,Neurological surgery 6th chapter 369
Andrew F. Ducruet, E. Sander Connolly Jr
12/01/59

2. Distal anterior cerebral artery
(DACA) aneurysms
• aneurysms arise on the ACA or its branches
distal to the ACoA
• uncommon
• most commonly at the bifurcation of the
pericallosal and callosomarginal arteries
• less than 5 mm,giant is rare
• common association with additional
intracerebral aneurysms : MCA bifurcation or
ICA bifurcation

3. Etiology
• Spontaneous
• Mycotic or infectious
– septic emboli from vegetative heart
– inflammatory reaction leads to a loss of intima and elastic tissue
– often involves much of the circumference of the vessel
• Traumatic
– shearing forces exerted on the distal pericallosal artery at the
lower level of the falx
• Tumor emboli
– most commonly observed in patients with atrial myxomas

4. Relevant Anatomy

5. Perlmutter and Rhoton
• A1 : ACA proximal to ACoA
• A2 : ACoA to the junction of the rostrum and genu of corpus callosum
– Orbitofrontal a.
– Frontopolar a..
• A3 : extends from the genu to a point where the artery makes a posterior
turn above the genu
– anterior middle, posterior internal frontal a.
– callosomarginal a
• A4 : posterior extension of the artery from A3 and extends to a point
bisected by the coronal suture
– paracentral a.
• A5 : extends distally to include the anastomoses with the splenial arteries
– superior and inferior parietal a.

6. variants in distal ACA anatomy

7. Clinical Presentation
• 50 years
• Female
• 4 vessel angiogram : undiscover aneurysm
• SAH
– often prominent in the interhemispheric fissure
across the top of the corpus callosum
– frontal hematoma : Mutism,memory loss
– IVH : frontal horn of lateral ventricle
– Intracallosal hemorrhage

8. Surgical Considerations
• Microsurgically first line
– peripheral location
– small size
– unfavorable neck-to-parent artery ratio
– tendency to “blow out” the bifurcation at
which they occur
– amount of brain retraction and muscle
dissection needed to clip these lesions is
comparatively minimal relative to other
aneurysms

9. Surgical Considerations
• Endovascular treatment
– extreme age
– significant medical comorbidities
– poor neurological condition
– irreversible coagulopathy

10. Surgical Considerations
• unruptured DACA aneurysm and a ruptured
aneurysm at another location
– repairing all aneurysms during one procedure to
facilitate treatment of vasospasm with hemodynamic
therapy
– repair only the ruptured aneurysm and leave the
unruptured DACA aneurysm because it requires both
extending the craniotomy and further brain
manipulation and operative time

11. Preoperative Preparation
• Normovolemia
• Normotension
• Hydrocephalus  EVD
• PPI
• ATB
• Anti-seizure drug

12. Positioning
• Just at or distal to the genu of the corpus
callosum
– supine with head in neutral position
• lies below or proximal to the genu of the corpus
callosum
– supine with head extened
• Just above the ACoA
– supine head rotated 15 to 30 degrees away and
maximally extended

13. Skin Incision and Craniotomy
• Proxinal A2 lesion
– bicoronal, modified bicoronal, or pterional incision
– with or without orbital or orbitozygomatic extension
• Callosomarginal artery, origin in the region of
the genu
– modified bicoronal scalp incision
– parasaggital craniotomy

14. Skin Incision and Craniotomy

15. Microsurgical Dissection
• Dura
– cruciate fashion with a medial triangular dural flap
based on the superior sagittal sinus
– not to thrombose the sinus nor to interrupt any of the
bridging veins large vein
– anterior to the coronal suture may be taken
without risking venous infarction
• Microscope, brain retractor and cortical surface
of the frontal lobe is covered with Telfa

16. Microsurgical Dissection
• Frontal lobe is gently dissected from the falx
– A 2- to 3-cm working corridor is developed
– exposure of the cingulate gyri bilaterally
– identification of the callosomarginal a.
• Base of the cingulate gyri lies the cistern of the
corpus callosum
– pericallosal arteries
– both arteries must be identified and followed
proximally
– if a frontal lobe hematoma limits the exposure, a
small cortical incision may be made to partially
decompress the brain

17. Microsurgical Dissection
• Aneurysm usually points superiorly and
forward along with the callosomarginal artery
– dissect forward on the inferior surface of the
pericallosal vessels to where they begin to dive
around the genu of the corpus callosum
– resecting a small portion of corpus callosum often
brings the proximal trunks into view for temporary
control
• Dissection of aneurysm
• Clip placement
– perpendicular or parallel to the pericallosal artery

18. Complication
• Embolization from the aneurysm dome and
tearing of the thin-walled aneurysm
• Intraoperative rupture with prolonged trapping
has also been seen and can lead to ischemia in
the ACA territory
• Frontal bridging brain tear
– venous infarction
• Vasospasm
– focal distal spasm involving the DACA segments may
be difficult to treat with angioplasty and hemodynamic
therapy

19. Clinical Series

20. Clinical Series