Ch77 Aneurysm Type By Location Flashcards
(28 cards)
Which aneurysm may present with DI or hypothalamic dysfunction?
ACom
What are the angiographic considerations with suspected ACom aneurysms?
If the ACom is not visualised on the DSA then cross compression is needed to visualise contrast flowing through the communicating segment.
How do you approach ACom aneurysms?
Frontally biased pterional craniotomy
How do you position for ACom aneurysms?
Shoulder roll Head turned 60 degrees
What are the surgical steps in clipping an ACom aneurysm?
Subfrontal dissection > Olfactory > Optic > ICA > ACA. Drain CSF from optic and carotid cisterns and prox sylvian fissure split. Following A1>A2 ipsi. Identify contra A2 and A1. Proximal control Gyrus rectus resection may be needed. Circumferential neck dissection. **Watch out for Heubner!
Where does Heubner arise?
A2 and runs backwards to the anterior perforated substance
What approach is needed for distal ACA approaches?
Interhemispheric. Note prolonged retraction on the anterior cingulate may cause mutism or incontinence (persistent dribbling)
Label the common carotid DSA
- Common carotid
- ICA
- Ascending pharyngeal
- Occipital
- Superficial temporal
- MCA
- ACA
- Middle meningeal
- Maxillary artery
- Facial artery
- Lingual
- ECA
- Superior thyroid
(Note: Posterior auricular artery not shown)
What segment of the ICA is this?
Petrous segment
What segment of the ICA is this?
Petrous segment
Label the branches of the ICA
Petrous = Vidian / caroticotympanic / persistent stapedial
Cavernour = Inferior lateral trunk, Meningohypophysial trunk and McConnell’s capsular artery
Clinoidal = Opthalmic / PCom / Ant Choroidal
Where is the A2 ACA?
From ACom to pericallosal / callosomarginal bifurcation
What are the branches of the A2?
Orbitofrontal and Fronto-polar arteries (may arise from a common stem)
What are the vascular territories of the ACA branches?
What is a fetal PCom?
Where the PCA fills from the anterior circulation. The P1 is usually the same size as the PCom.
What is the head position for PCom clipping?
Head turned 30 degrees to contralateral side
How do you perform a PComm aneurysm clipping?
Pterional approach - head turned 30 deg
Subfrontal identification of olfactory nerve
Follow back to find Optic nerve
Look laterally to find ICA
Open arachnoid around optic and ICA to relax brain and gain prox. control
Proximal sylvian fissure split
PComs usually point lateral, posterior and inferion under the free edge of the tentorium
How do you position the head for MCA clipping?
45 degree head turn to contralateral side
What direction do opthalmic artery aneurysms project?
Medially and dorsally towards the optic nerve. 50% present with visual field defects (uniocular superior nasal quadrantiopia)
What are the anatomical considerations for clipping of opthalmic artery aneurysms?
Opening of the falciform ligament to decompress the optic nerve. Removal of the anterior clinoid. Drilling down of the optic strut. Opening the distal dural ring to allow low exposure to the neck. Proximal control needed from the cervical cartoid.
What is Allcock’s test?
Vertebral DSA injection with carotid compression to allow patency of the flow from the posterior circulation to the anterior circulation through the PCom to be assessed.
What is the dentate ligament?
Pial extensions from the spinal cord to the dura composed of 21 pairs of fibrous structures. These connect to the spinal cord between the ventral and dorsal roots.
What is the cause of a fusiform aneurysm of the vertebral artery?
Dissection
What approach is used to clip PICA aneurysms?
Far lateral. Clip placed below the CN9/10 complex but above the CN11.
Temporary lower CN palsies are common so may need to keep patient intubated after. Consent for the need for tracheostomy!
