Supraclinoid Segment Mirror Aneurysms

ICA -  Supraclinoid Segment Mirror Aneurysms: Case report and Review of the Literature

D.Gunia                   E.Ekvtimishvili                     Harshavardhan.B

Abstract :

We report a case of 65 year old female who presented with right sided ptosis, anisocoria & right sided subarachnoid hemorrhage visualized in MRI for whom DSA revealed a Bilateral symmetrical Aneurysm at the C7 part of Internal Carotid Artery in which the right side was ruptured , which was treated with endovascular coiling on the 5th day.

Introduction :

Bilateral Symmetrical aneurysms are called mirror aneurysms, and they most often involve the internal carotid arteries or the middle cerebral artery bifurcations. These are usually diagnosed when one of the aneurysm is ruptured & hence being symptomatic, while the other unruptured aneurysm will be an incidental finding as it tends to be asymptomatic.

Case Report :

A 65 year old female presented with right sided occulomotor nerve paresis, anisocoria & subarachnoid hemorrhage of Hunt & Hess scale Grade 2, visualized in MRI .

Diagnostic four vessel DSA revealed two symmetric saccular Aneurysm at the C7 part of Internal Carotid Artery (at the location of origin of atresic posterior communicating artery), the right one was 4mm/10mm  (medium sized) ruptured & left one 1mm (small) unruptured.

The right sided aneurysm showed diverticles (daughter sacs) which are characteristic of rupture & so coiling of the right-ruptured aneurysm was decided.

On Right Femoral arterial approach, coiling of the Right sided aneurysm was done using GDC 360 SR 4mm x 8cm, GDC soft 4mm x 10 cm, Matrix ultrasoft 3mm x 20 cm & GDC soft SR  2mm x 8cm. The aneurysm was totally occluded.



Fig 1.

  1. Lateral Projection of Right ICA DSA with 4mm/10mm aneurysm in the Right ICA supraclinoid segment in the position of the origin of atresic Right Posterior communicating Artery (C7)
  2. Right ICA angiography showing the same right aneurysm on anterior projection.
  3. Right ICA angiography showing dome of the aneurysm (white arrow) and the diverticular projection (black arrow)
  4. (e) & (f) The aneurysm after endovascular coiling.

(g) & (h) Left ICA angiography with Left ICA supraclinoid segment 1mm aneurysm in the position of the origin of the atresic Left Posterior communicating artery which is symmetrical in location with the Right ICA aneurysm

The Left sided aneursym was unruptured & hence coiling was not performed. Patient was discharged with GOS grade 5.

Follow up with DSA should be done in six months.

Discussion :

Multiple bilateral aneurysms account for 12.9% in angiographic series and 22.7% in autoptic series, as shown by a large review of 27 series of brain aneurysms.[1] About 25% of them occur in symmetrical localizations of the same right and left artery (mirror aneurysms), with an incidence ranging from 2.7% to 7.1% (average 4.2%).

Bilateral mirror-image aneurysms mainly affect female patients in the sixth decade.[2] They occur with a high frequency at the internal carotid (intracavernous and bifurcation) artery as well as at the middle cerebral artery (bifurcation) (up to 98% of the cases).[3]

Although various nomenclature classification systems defining the segments of the ICA exist in the literature, we will refer to the one proposed by Bouthillier, et al.,[5] because it uses a numerical scale in the direction of blood flow and takes into account anatomical information and clinical considerations for neurosurgical practice. In this system, the ICA is divided into seven segments according to their adjacent anatomical structures and the compartments they traverse: C1, cervical; C2, petrous; C3, lacerum; C4, cavernous; C5, clinoidal; C6, ophthalmic; and C7, communicating

Classification of cerebral aneurysm based on size

Small:             1mm – 4 mm

Medium:       4mm  to 10 mm in diameter

Large:            10 to 25 mm in diameter

Giant:             >25 mm in diameter.

Of all aneurysms, 95% are less than 25 mm in diameter; i.e., only 5% are "giant".


Hunt and Hess scale[4] of subarachnoid hemorrhage severity:

Grade 1:          Asymptomatic; or minimal headache and slight nuchal rigidity.

Grade 2:          Moderate to severe headache; nuchal rigidity; no neurologic deficit except cranial nerve palsy.

Grade 3:          Drowsy; minimal neurologic deficit.

Grade 4:          Stuporous; moderate to severe hemiparesis; possibly early decerebrate rigidity and vegetative disturbances.

Grade 5:          Deep coma; decerebrate rigidity; moribund.

Grade 6:          Death. By definition, someone who presents brain dead following SAH is grade 6.

Although the incidence of ruptured cerebral aneurysms is relatively small, when rupture occurs, morbidity and mortality are exceptionally high. The understanding of the pathological and physiological forces driving aneurysmal pathogenesis and progression is crucial. When there is a ruptured aneurysm, endovascular coiling should be done as early as possible because, re-bleed rate within 1st day (2-4%),2 weeks (about 25%) & 1st year (95%).[10],[11].

A recent large scale study suggests that the annual risk of hemorrhage from small incidental aneurysms is substantially lower than previously thought and the risk of elective intervention higher. [6],[7]. So for small incidental aneurysms it is better to avoid elective intervention.

The following figure is another case of Mirror aneurysms at the location of bifurcation of Middle Cerebral Artery in which the patient presented with Acute SAH & intraventricular hemorrhage (Hunt & Hess Grade 3 & Fischer grade 4),9th day after SAH both the aneurysms were occluded using endovascular coiling& patient was discharged with GOS grade 5.


In summary, by mirror cerebral aneurysms we indicate two aneurysms in the same patient and at the same location in the cerebral vasculature but symmetrically with respect to a sagittal plane. Treatment with endovascular coiling should be done for ruptured aneurysm which is symptomatic due to Sub arachnoid hemorrhage.

References :

  1. Yasargil MG. Microneurosurgery. Vol 1. Stuttgart: Georg Thieme Verlag, 1984
  2. Suzuki J Suzuki J, Sakurai Y. The treatment of intracranial multiple aneurysms. In: Suzuki J, ed. Cerebral aneurysms. Tokyo: Neuron, 1979 pp. 293–307.
  3. Kassel NF, Torner JC. The international cooperative study on timing of aneurysm surgery: an update. Stroke 1984;15:566
  4. Hunt, WE; Hess RM (1968). "Surgical Risk as Related to Time of Intervention in the Repair of Intracranial Aneurysms". J Neurosurg 28 (1): 14–20. doi:10.3171/jns.1968.28.1.0014. PMID 5635959
  5. Bouthillier A, van Loveren HR, Keller JT: Segments of the internal carotid artery: a new classification. Neurosurgery 38: 425–433, 1996
  6. Weibers D O, Whinant J P, Huston J 3rd et al 2003 International Study of unruptured Intracranial Aneurysms Investigators. Unruptured Intracranial aneurysm : natural history , clinical outcome & risks of surgical and endovascular treatment. Lancet 362: 103-110
  7. Vindlacheruvu R R, Mendelow A D, Mitchell P 2005 Risk – benefit analysis of the treatment of unruptured Intracranial aneurysms. J Neurol Neurosurgery Psychiatry 76:234-239
  8. Armando Manduca, Xiaoping P. Hu, Combined clinical and computational information in complex cerebral aneurysms: application to mirror cerebral aneurysms Proc. SPIE 6511, 65111F (2007)
  9. Pravin Salunke, Vinod Malik, Nitin Yogesh, N K Khandelwal, S N Mathuriya Mirror-like aneurysms of proximal anterior cerebral artery: report of a case and review of literature. British journal of neurosurgery (2010) Volume: 24, Issue: 6, Pages: 686-687

(10)Jonathan L Brisman, MD; Chief Editor: Allen R Wyler, MD, Neurosurgery for               Cerebral Aneurysm

(11) Wiebers DO, Whisnant JP, Huston J 3rd, et al. Unruptured intracranial aneurysms: natural history, clinical outcome, and risks of surgical and endovascular treatment. Lancet. Jul 12 2003;362(9378):103-10.

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