PMC8769413_01
Preoperative 3D-DSA showing a lt. IC-Pcom aneurysm with a maximum diameter of 15.8 mm. 3D-DSA: three-dimensional digital subtraction angiography, IC-Pcom: internal carotid-posterior communicating artery.
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F1
IC-PC aneurysm with a maximum diameter of 15.8 mm (Fig. 1). Intracranial blood flow distal to the aneurysm did not delay.
Post-surgical MRI showing no new infarction on DWI (A) or hemorrhage on T2* (B). And post-surgical DSA showed no spasm (C, D). DSA: digital subtraction angiography, DWI: diffusion-weighed imaging.
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F2
Magnetic resonance (MR) images showed neither infarction nor hemorrhage (Figs. 2A and 2B) and DSA showed no spasm (Figs. 2C and 2D) on postoperative day (POD) 2.
15O-gas PET performed on POD 5 shows elevated CBF (A) and CBV (D) in the area supplied by the lt. superior trunk of the MCA. CMRO2 (B) was slightly decreased (arrowhead) while OEF (C) was decreased in the same area. CBF (E) and CMRO2 (F) were decreased in the contralateral cerebellar hemisphere (arrow). CBF: cerebral blood flow, CBV: cerebral blood volume, CMRO2: cerebral metabolic rate for oxygen, MCA: middle cerebral artery, OEF: oxygen extraction fraction, PET: positron emission tomography, POD: postoperative day.
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F3
Electroencephalography showed no abnormalities. 15O-gas PET performed on POD 5 showed remarkably increased rCBF in the territory of the superior trunk of the middle cerebral artery (MCA) (Fig. 3A), and the regional cerebral metabolic rate for oxygen (rCMRO2) was slightly decreased in this territory (Fig. 3B). Consequently, the regional oxygen extraction fraction (rOEF) was extremely decreased (Fig. 3C). Regional cerebral blood volume (rCBV) was slightly elevated (Fig. 3D). Moreover, crossed cerebellar diaschisis was recognized, along with decreased blood flow and metabolism, in the contralateral cerebellar hemisphere (Figs. 3E and 3F).
CBF on 15O-gas PET revealed the CHS involvement to extend to the area of the lt. inferior trunk of the MCA on POD 13 (A) and to have normalized by POD 27 (B). CBF: cerebral blood flow, POD: postoperative day, PET: positron emission tomography.
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F4
Her symptoms showed amelioration starting on POD 9 and the follow-up 15O-gas PET on POD 13 revealed moderate improvement of hyperperfusion in the MCA superior trunk area, whereas the MCA inferior trunk area had newly become hyperemic (Fig. 4A). Her symptoms showed full resolution by POD 18, and rCBF normalization was confirmed on POD 27 (Fig. 4B).