1.1. Background: Distal Posterior Inferior Cerebellar (PICA) aneurysms are quite rare. The infrequency of distal PICA aneurysms has limited our understanding of their underlying pathology, natural history, and clinical management. Moreover, vascular anomalies are frequently noted in association with distal PICA aneurysms.
1.2. Case Description: We present a very unique case of a ruptured distal PICA aneurysm associated with an Arteriovenous Malformation (AVM) which was successfully identified by Intraoperative Indocyanin Green (ICG) video angiography. In the current era, we tend to perform Computed Tomographic Angiography (CTA) studies as the initial imaging for vascular lesions. CTA revealed the distal PICA aneurysm but failed to reveal the associated AVM. However, intraoperative ICG video angiography strongly suspected the existence of an AVM.
1.3. Conclusion: Intraoperative ICG video angiography is very useful in detecting small vessel anomalies. DSA should be considered for all distal PICA aneurysms even in the era of advanced CTA.
Keywords: Arteriovenous Malformation; Cerebral Aneurysm; Distal
Posterior Inferior Cerebellar Artery; Indocyanin Green Video angiography; Intraventricular
Figure 1: (A): Axial view, CT shows IVH of fourth ventricle. (B): Preoperative CTA demonstrates left distal PICA aneurysm without any other vascular anomalies.
Figure 2: (A-B): Intraoperative view of mid-line suboccipital craniotomy shows normal cerebellum surface without SAH and red veins, and the view via the tonsilomedullary and cerebellomedullary fissure (A: arrow line) shows the ruptured distal PICA aneurysm (B: arrow) which appeared to be connected via an abnormal vessel (B: arrow head). (C-D): ICG video angiography (C: early phase, D: delayed phase) demonstrate delayed flow on the abnormal vessel (arrow head). The aneurysm (arrow) appeared to be located at the branching point.
Figure 3: (A): Intraoperative view shows clip applied to the aneurysm and abnormal vessel suspected as feeding artery to AVM, with temporary clip (lower clip). (B): The next view shows final clip preserving branches of PICA. (C): ICG video angiography after clipping demonstrates disappearance of the aneurysm and abnormal vessel. Arrow: aneurysm, arrow head: abnormal vessel
Figure 4: (A-B): Postoperative conventional DSA shows a superior vermian AVM (arrow head, A: frontal view, B: lateral view). (C-D): Three dimensional DSA demonstrates AVM fed by PICA (C: arrow head), and complete clipping of the aneurysm (D: arrow) and abnormal vessel.
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