case_images: PMC11225396_01
case_images: At the presentation. Axial views of cranial computed tomography scan (a) without and (b) with contrast show an enhancing hyperdense round mass, approximately 15 mm in size, with surrounding edema at the medial aspect of the left superior frontal gyrus. There was a small hyperdense lesion (black arrowheads) located at the left side of the anterior interhemispheric fissure adjacent to the medial part of the mass, extending posteriorly along the interhemispheric fissure, representing acute interhemispheric subdural hemorrhage.
case_images: SNI-15-206-g001.jpg
case_images: PMC11225396_01_SNI-15-206-g001.jpg
case_images: F1
case_images: Initial diagnostic imaging through a computed tomography scan revealed a hyperdense, approximately 15 mm mass with surrounding edema in the left superior frontal gyrus and an adjacent acute thin subdural hematoma (SDH) [Figure 1].
case_images: Magnetic resonance imaging (MRI) of the brain obtained 1 week after symptom onset. (a) Axial, (b) coronal, and (c) sagittal T1-weighted contrast-enhanced MRI show peripheral rim enhancing round mass with an eccentrically located signal void (white arrows), probably indicating a large partially thrombosed aneurysm. (d and e) Axial T2-weighted MRI reveals a tangle of abnormal flow voids (black arrowhead), probably representing pial arteriovenous malformations associated with a large aneurysm with the progression of perianeurysmal edema at the medial side of the left superior frontal region. (f) Sagittal maximum intensity projection image from 3D time-of-flight magnetic resonance angiography confirms the pial arteriovenous malformation with a large intranidal aneurysm (white arrowhead).
case_images: SNI-15-206-g002.jpg
case_images: PMC11225396_01_SNI-15-206-g002.jpg
case_images: F2
case_images: MRI highlighted the progression of perianeurysmal edema in the same region. Magnetic resonance angiography (MRA) confirmed the pial AVM with a large intranidal aneurysm [Figure 2].
case_images: Magnetic resonance imaging (MRI) of the brain obtained 1 month after symptom onset. Sagittal T1-weighted MRI (a) with and (b) without contrast show heterogeneous signal intensity with eccentrically rim enhancing lesion, probably representing a laminated appearance of partially thrombosed aneurysm. (c) Axial and (d) coronal T2-weighted MRI reveals heterogeneous signal intensity in a large aneurysm surrounded by edema of the left superior frontal gyrus.
case_images: SNI-15-206-g003.jpg
case_images: PMC11225396_01_SNI-15-206-g003.jpg
case_images: F3
case_images: One month after symptom onset, a follow-up MRI indicated complete resolution of the SDH and a laminated appearance in the partially thrombosed aneurysm, with persistent perianeurysmal edema [Figure 3].
case_images: (a) Anteroposterior (AP) and (b) lateral views of the left internal carotid artery injection show a small pial arteriovenous malformation supplied by the left middle internal frontal branches of the left anterior cerebral artery (ACA) with early venous drainage into medial frontal veins and forward to superior sagittal sinus. A large aneurysm was located within the small nidus. (c) AP and (d) lateral views of the left ACA injection with microcatheter clearly demonstrate a small nidus, multiple indirect small feeders, large intranidal aneurysm, and early draining veins.
case_images: SNI-15-206-g004.jpg
case_images: PMC11225396_01_SNI-15-206-g004.jpg
case_images: F4
case_images: The super selective injection with the microcatheter of the left ACA visualized a small nidus with multiple indirect small feeders, a large intranidal aneurysm, and early draining veins [Figure 4].
case_images: Magnetic resonance imaging (MRI) of the brain obtained 7 months after symptom onset. Sagittal T1-weighted MRI (a) with and (b) without contrast demonstrate a significant reduction in the size of a large partially thrombosed aneurysm. (c) Axial and (d) coronal T2-weighted MRI revealed a reduction in aneurysm size and complete resolution of perianeurysmal edema at the left superior frontal gyrus.
case_images: SNI-15-206-g005.jpg
case_images: PMC11225396_01_SNI-15-206-g005.jpg
case_images: F5
case_images: A follow-up MRI 5 months later showed a significant reduction in the aneurysm size and complete resolution of the edema [Figure 5].
case_images: At age 7. (a) Axial T2-weighted magnetic resonance imaging (MRI) reveals a decrease in the size of the aneurysm (arrow) at the medial part of the left superior frontal gyrus. (b) sagittal T1-weighted contrast-enhanced MRI demonstrates complete thrombosis of the large aneurysm (arrowhead). (c) Sagittal maximum intensity projection image from 3D time-of-flight magnetic resonance angiography confirms complete obliteration of the pial arteriovenous malformation and large intranidal aneurysm.
case_images: SNI-15-206-g006.jpg
case_images: PMC11225396_01_SNI-15-206-g006.jpg
case_images: F6
case_images: Six years after symptom onset, at age 7, a follow-up MRI and contrasted MRA confirmed the complete obliteration of the pial AVM and the intranidal aneurysm [Figure 6].
case_images: At age 10. (a) Axial, (b) coronal, and (c) sagittal views of maximum intensity projection reformatted image of angiographic computerized tomography, and (d) anteroposterior and (e) lateral views of the left internal carotid artery demonstrate a group of loosely packed tiny vessels (arrowheads) surrounding previous area of large thrombosed intranidal aneurysm without early draining vein, probably focal hyperemia. Arrowheads represent a group of loosely packed tiny vessels in all Figures 7a-7e.
case_images: SNI-15-206-g007.jpg
case_images: PMC11225396_01_SNI-15-206-g007.jpg
case_images: F7
case_images: This area, devoid of early draining veins, was suggestive of focal hyperemia [Figure 7].
case_images: At age 12. (a) Axial T2-weighted magnetic resonance imaging (MRI) shows a further reduction in the size of the aneurysm (arrow) at the medial part of the left superior frontal gyrus. (b) Coronal view of contrast-enhanced magnetic resonance angiographic source image, and (c) axial and (d) coronal views of T1-weighted contrast-enhanced MRI reveal enhancing area (arrowheads) surrounding previous area of large thrombosed intranidal aneurysm, probably focal hyperemia, corresponding with prior cerebral angiography.
case_images: SNI-15-206-g008.jpg
case_images: PMC11225396_01_SNI-15-206-g008.jpg
case_images: F8
case_images: In addition, an enhancing area was observed, corresponding to the prior angiographic findings of probable focal hyperemia [Figure 8].
case_images: Imaging findings at 16 years of age. (a) Three-dimensional raw time-of-flight magnetic resonance angiography (MRA) source image demonstrates a cluster of diminutive vessels featuring an early draining vein (indicated by an arrow) located in the left superior frontal region. (b) Anteroposterior (AP) projection and (c) lateral projection of maximum-intensity 4D contrast-enhanced MRA reveal a recurrent pial arteriovenous malformation (AVM) characterized by an early draining vein (marked by white arrowheads). (d) AP and (e) lateral views of the left internal carotid artery injection confirm the presence of a recurrent pial AVM with an early draining vein (denoted by black arrowheads).
case_images: SNI-15-206-g009.jpg
case_images: PMC11225396_01_SNI-15-206-g009.jpg
case_images: F9
case_images: At age 16, further imaging was undertaken, including a 3 Tesla cranial MRI and 4D dynamic contrast-enhanced MRA, which identified a recurrent pial AVM located in the left superior frontal region [Figure 9a-c]. Subsequent cerebral angiography performed 1 week later corroborated the findings of a recurrent pial AVM [Figure 9d and e].