J Korean Neurosurg Soc.  2024 Jan;67(1):22-30. 10.3340/jkns.2023.0059.

Frequency and Characteristics of Paraclinoid Aneurysm in Ruptured Cerebral Aneurysms

• Shigematsu H
• Yokota K
• Hirayama A
• Sorimachi T

• KMID: 2550456
• DOI: http://doi.org/10.3340/jkns.2023.0059

Abstract

Objective
: This study aimed to determine the frequency of paraclinoid aneurysms among ruptured cerebral aneurysms and compare paraclinoid aneurysms with other aneurysms to clarify the characteristics of ruptured paraclinoid aneurysms.
Methods
: This study included 970 ruptured cerebral aneurysms treated at our hospital between 2003 and 2020.
Results
: There were 15 cases (1.3%) of paraclinoid aneurysms with maximum diameters of 5–22 mm (mean±standard deviation [SD], 11.6±5.4 mm). Treatment consisted of clipping in four patients and endovascular treatment in 11. Factors significantly different in multivariate analysis for paraclinoid aneurysms compared with those for other aneurysms were a history of hypertension (odds ratio [OR], 1.2–9.8; p=0.021) and aneurysm ≥10 mm (OR, 7.5–390.3; p<0.001). The sites of paraclinoid aneurysm were ophthalmic artery type in nine patients, anterior wall type in five, medial wall type in one, and ventral wall type in zero. The medial wall type (22 mm) was significantly larger than the ophthalmic artery type (mean±SD, 7.2±2.0 mm) (p=0.003), and the anterior wall type (mean±SD, 12.2±4.8 mm) was significantly larger than the ophthalmic artery type (p=0.024).
Conclusion
: This study showed a low frequency of paraclinoid aneurysms among ruptured cerebral aneurysms. Most were upward-facing with relatively large aneurysms, and no aneurysms were smaller than 5 mm. With recent advances in endovascular treatment devices, paraclinoid aneurysms are easily treatable. However, the treatment indication of each paraclinoid aneurysm should be carefully considered.

Keyword

Endovascular procedures; Intracranial aneurysm, paraclinoid; Subarachnoid hemorrhage

Figure

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  Fig. 1. A schema of Barami’s paraclinoid aneurysm classification. Type I : ophthalmic artery type; type II : anterior wall type; type III : medial wall type; and type IV : ventral wall type. Oph.a : ophthalmic artery, Pcom.a : posterior communicating artery, Ant.Chor.a : anterior choroidal artery.

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  Fig. 2. Comparisons of paraclinoid aneurysm types. The maximum diameters of the ophthalmic artery type, the medial wall type, and the anterior wall type, were 7.2±2.0 mm (mean±standard deviation), 22 mm, and 12.2±4.8 mm. The medial wall type was significantly larger than the ophthalmic artery type (p=0.003), and the anterior wall type was significantly larger than the ophthalmic artery type (p=0.024). *Indicates a significant difference of p<0.05.

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  Fig. 3. A didactic case of enlargement of a ruptured internal carotid artery (ICA)-posterior communicating artery (Pcom) aneurysm was revealed after embolization of a paraclinoid aneurysm following subarachnoid hemorrhage (SAH). A : A head computed tomogram showing thick SAH in the basal cistern. B and C : Lateral image of the preoperative left ICA angiogram (C : 3-dimensional digital subtraction angiogram, 3-DDSA). The medial wall type paraclinoid aneurysm is 3.6×3.0 mm (thick white arrow), and the left ICA cavernous aneurysm is 2.9×2.3 mm (thin white arrow). ICA-Pcom aneurysm (white arrowhead) with a size of 1.1×0.9 mm is observed. D : Left ICA 3-DDSA 10 days after 1st embolization. The embolized medial wall type paraclinoid aneurysm (thick white arrow) and ICA cavernous aneurysm (thin white arrow) are unchanged, but the ICA-Pcom aneurysm (white arrowhead) enlarges to 3.1×3.6 mm. E : Lateral image of the left ICA angiogram after 2nd embolization. The white arrowhead indicates coils inserted into the ICA-Pcom aneurysm, and the white arrows indicate the preserved posterior communicating artery. The thick white arrow indicates embolized medial wall-type paraclinoid aneurysm, and the thin white arrow indicates ICA cavernous aneurysm.

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  Fig. 4. A typical ruptured paraclinoid aneurysm case with a size more than 10 mm. A : A head computed tomogram showing thin subarachnoid hemorrhage in the left Sylvian fissure (white arrow). B : A left internal carotid artery (ICA) angiogram (lateral view) showing an ophthalmic artery type paraclinoid aneurysm with a diameter of 17 mm (white arrowhead). A white arrow indicates the ophthalmic artery. C : A left ICA 3-dimensional angiogram revealing a relationship between an aneurysm (white arrowhead) and the ophthalmic artery (white arrow). D : A left ICA angiogram after embolization showing the disappearance of the aneurysm filled with coils (white arrowhead). The ophthalmic artery is preserved (white arrow).

Reference

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