Incidental Postmortem Diagnosis of Anterior Communicating Artery Aneurysm After Successful Treatment of Double Aneurysms of the Superior Cerebellar and Paraclinoid Internal Carotid Arteries

of


Introduction
Acute subarachnoid hemorrhage (SAH) is still associated with a high mortality rate, reaching 25%, and morbidity, with at least one-third of patients losing autonomy.Aneurysmal SAH is the most common non-traumatic form We present this case for two purposes: reporting an exceptional association of a paraclinoid aneurysm and a PCA-SCA aneurysm, and highlighting the usefulness of 3D slicer modeling in the diagnosis and assessment of intracranial aneurysms.

Case report
A 43-year-old hypertensive woman visited the emergency department of her local community for a sudden onset of headaches.On the physical exam, she was hemodynamically stable with a blood pressure of 150/90 mm Hg.Her Glasgow Coma Scale (GCS) score was 15/15, and her pupils were isochoric and reactive to light and accommodation.No seizures, visual disturbance, sensorimotor deficit, or fever were noticed.A brain CT showed diffuse SAH with blood in basal cisterns, cerebellar tentorium, and temporal sulci associated with discreet brain edema (Figure 1).The SAH was graded as Hunt and Hess grade 1 and Fisher CT grade 3.
Given brain CT results and hypertensive peak, aneurysmal SAH was suspected.Thus, the patient was referred to the neurosurgery department.On admission, her GCS score was 14/15, and she had neck stiffness, photophobia, and phonophobia.In addition, left-sided ptosis and mydriasis were elicited, suggesting left oculomotor nerve palsy.The DSA was unavailable at our institution (a public hospital), and the cost was prohibitive at private facilities.So, a brain CTA with 3D reconstruction was performed, which revealed a 10 mm left paraclinoid aneurysm and a 9 mm left PCA aneurysm (Figure 2, Figure 3, Figure 4).The initial therapeutic strategy was maintaining systolic pressure between 120 and 140 mm Hg using an antihypertensive drug and preventing vasospasm using nimodipine.Since Thus, an external ventricular drain was urgently placed.
Unfortunately, the patient succumbed to this event.As a part of our research routine, we realized a retrospective CTA-based 3D modeling using the « 3D slicer » software.
The 3D model's results met the surgical findings concerning the paraclinoid and posterior aneurysm (Figure 5).In addition, it incidentally revealed a 5.2mm ACOA aneurysm (Figure 6).After discussion with neurosurgeons, the rebleeding was attributed to the rupture of the ACOA aneurysm. 5

The incidental diagnosis of the ACOA aneurysm
The 3D slicer modeling incidentally revealed an ACOA aneurysm.When we revised the CTA and 3D CTA images, a little outpouching from the ACOA drew our attention (Figure 4, Figure 7, Figure 8).Regarding the anatomical layout of the ACOA complex, it was difficult to determine whether the lesion was an aneurysm or to decide on its origin.Given the urgency and within the limits of the CTA images, we believe that the radiologist and neurosurgeons did not analyze the ACOA complex properly.It is probably why they missed the diagnosis.In the 3D slicer modeling, we used an uncommon view angle to see the aneurysm.In addition, with the automatic segmentation, we got a good-quality 3D model in a few minutes.Thus, 3D slicer modeling is adaptable to urgency.Neurosurgeons were surprised by the quality of the 7 3D model since it met the surgical findings and added new features about the ACOA aneurysm.They believed that, with this method, they would have optimized the therapeutic choice and avoided the tragedy.Indeed, if 3D modeling had been done before surgery, the ACOA aneurysm would have been diagnosed and treated.The patient would have less risk of rebleeding.

Comparison between imaging modalities
The DSA could help to diagnose the aneurysm.However, it was unavailable in our community.In addition, DSA has   Probably, the hemorrhage originated from the ACOA and paraclinoid aneurysms.

Conclusion
Aneurysmal subarachnoid hemorrhage is still a world health problem, with high mortality and morbidity stats.Reducing its impact relies on accurate diagnosis and evaluation of the etiology, which determines an optimal management strategy.
Despite the radiological exploration progress, there are still cases of misdiagnosis.This paper presents a rare association between a paraclinoid and SCA-PCA aneurysms.It also illustrates a fatal cerebral hemorrhage complicating the rupture of an undiagnosed ACOA aneurysm.This tragic event was related to a lack of diagnosis accuracy related to the radiological tool and the human factor.Although the 3D slicer modeling was retrospective, it highlights the usefulness of this tool.We recommend approving this tool worldwide and using it for aneurysm diagnosis.

2 2
[1].It represents a critical health problem since it results in 3-5% of strokes [2].Anterior circulation aneurysms account for 80www.acquirepublications.org/JCRMH potentially bleeding, have complex anatomical relationships, and are consequently difficult to manage [3].Posterior circulation aneurysms, especially those of the posterior cerebral artery (PCA) and superior cerebellar artery (SCA), are uncommon and account for 10-20% of intracranial aneurysms [4,5,1].They represent a surgical challenge with serious complications [4,5].An unruptured aneurysm may still be asymptomatic, provoke compression symptoms, or lead to fatal and insidious SAH if ruptured.Anterior communicating artery (ACOA) aneurysms are the most common and often present complex morphology and blood flow conditions.Improving the management of aneurysmal SAH requires accurate diagnosis and perfect assessment of the aneurysm and its anatomical environment to enable adequate therapeutic planning.Brain aneurysm diagnosis is possible with conventional radiological exams such as computed tomography angiography (CTA), magnetic resonance angiography, and digital subtraction angiography (DSA) [3].Even if DSA is the gold standard [1,3], CTA is widely used for aneurysm assessment thanks to its high sensitivity and specificity [2].DSA is reserved for cases where the CTA does not give relevant information [6].In addition, CTA is more adaptable to situations when surgery is urgently required, such as massive bleeding or cerebral herniation [1].However, all these modalities provide 2D images.3D models generated on 2D radiological images facilitate the diagnosis and improve radiological evaluation.It allows neurosurgeons to adapt their treatment strategy.The 3D slicer provides high-quality 3D modeling images.However, it is still used only for research and is not approved for clinical applications [3].A 43-year-old woman underwent successful surgery for ruptured paraclinoid and superior cerebellar artery (SCA) aneurysms.However, she succumbed to an unexplained postoperative rebleeding.CTA-based 3D slicer modeling incidentally detected an ACOA aneurysm.
endovascular therapy was unavailable, surgeons chose surgical clipping.Therefore, the patient was transferred to the operating room, placed in the dorsal decubitus position, and the head right turned 60 degrees.Then, a left fronto-temporopterional craniotomy was performed.The paraclinoid aneurysm was oriented behind and was wide-necked.Its sac was bilobed and close to the pituitary fossa, the posterior communicating artery (PCOA), the superior wall of the cavernous sinus, and the left clinoid processes.Thus, the operating field was too narrow, and clipping might injure surrounding structures.Therefore, surgeons preferred muscle wrapping instead of clipping.The posterior aneurysm had a wide neck involving the left SCA and PCA origins and was close to the P1 and P2 segments.However, there was a good safety margin to clip the neck without interrupting the blood flow in the SCA and the PCA, which has been done.Despite revealed a ventricular hemorrhage with diffuse cerebral edema, graded as Hunt and Hess 5 and Fisher CT grade 4.

Figure 1 :
Figure 1: Brain CT scan slices: white arrows indicate the subarachnoid hemorrhage in basal cisterns, cerebellar tentorium, and temporal sulci.

Figure 2 : 4 Figure 3 :
Figure 2: Sagittal, axial, and coronal slices of the brain CTA: the paraclinoid aneurysm (1) is close to the left clinoid processes and the left posterior communicating artery (2).The CTA shows a left posterior cerebral artery aneurysm (3).The origin of the left superior cerebellar artery (4) is not visible.

Figure 4 :
Figure 4: 3D CTA volume rendering: the posterior aneurysm (1) involves the left posterior cerebral artery origin.The origin of the superior cerebellar artery (2) is still not clear.A little suspicious outpouching from the anterior communicating artery complex (3) is observed.The paraclinoid aneurysm is indicated in (4).

Figure 5 :
Figure 5: 3D slicer modeling images: (A) the arterial model shows that the paraclinoid aneurysm (1) is of the inferior type according to Krisht and Hsu classification.The aneurysm is close to the posterior communicating artery (2).(B) Complete 3D representation of the paraclinoid region shows the relationship of the aneurysm with cavernous sinus (3) roof and left clinoid processes (4,5).(C) The arterial model shows an SCA aneurysm (6) involving the origin of the left posterior cerebral artery and the left superior cerebellar artery (7) and related to the P1 (7) and P2 (8) segments.

Figure 7 :
Figure 7: Sagittal, axial, and coronal brain CTA images: the white arrow indicates a suspicious lesion of the anterior communicating artery.

Figure 8 :
Figure 8: 3D brain CTA images: the white arrow indicates a suspicious outpouching from the anterior communicating artery.

3 ]
some limits.With unilateral contrast injection, only one-sided A1 and A2 segments are visualized, and the skull is not represented [3].In addition, DSA remains expansive and invasive [and provokes procedure-related complications.It includes ischemia, bleeding, radiation side effects, contrastinduced allergy, and neurological complications [3,6].3D-CTA simplifies the vascular representation but sometimes with insufficient size and quality.However, 3D slicer modeling offers a 3D model as the 3D DSA with additional options, such as viewing angle control, image contrast, magnification, and measurement.Especially with the virtual 8 reality option, 3D slicer modeling combines the 3D-DSA precision level to an exact spatial representation of aneurysm relationships with the parent artery and the skull.With such options, the surgeon can optimize the choice of head position, surgical approach, and craniotomy extent.As a result, the neurosurgeon can adapt the exposure of the lesion and surrounding structures and reduce cerebral retraction [3].3D Slicer facilitates the manipulation of medical images and enhances the quality of analysis reported a 20% postoperative rebleeding rate in 15 patients who underwent wrapping and 12% in a systematic review of 197 wrapped aneurysms [17].No post-wrapping rebleeding occurred in the Safavi-Abbasi et al. series [18,19].In our case, the rebleeding occurred early.A priori, the time between the surgery and rebleeding was too short to consider a re-rupture of treated aneurysms.Regarding what the literature reports about clipping, we believe the SCA aneurysm was sufficiently secured.However, since the paraclinoid aneurysm was wrapped, a re-rupture was still possible.