PMC4533418_01
A: Preoperative computed tomography (CT) scan showing a 60-mm diameter mass in the right frontal lobe connected to the cerebral falx with partial calcification, evident cerebral edema at the periphery, and median deviation from the cerebral ventricle. B: CT scan at 1 month after surgery showing the clip artifact, disappearance of the mass and edema, and preservation of the structure of the ventricle.
nmc-54-205-g1.jpg
PMC4533418_01_nmc-54-205-g1.jpg
F1
Computed tomography (CT) demonstrated a 60-mm diameter mass in the right frontal lobe contiguous to the falx, associated with partial calcification and peripheral edema, leading to a diagnosis of meningioma or oligodendroglioma (Fig. 1A). Just after surgery, no additional symptom was observed, and 1 month later, CT confirmed disappearance of the mass effect and edema (Fig. 1B), and motor weakness improved entirely with MMSE score of 29 points.
Preoperative T1-weighted (A), T1-weighted with contrast medium (B), and T2-weighted magnetic resonance images (C). Intraaneurysmal thrombus was primarily present as hyperintensity on the T1-weighted image and hypointensity on the T2-weighted image. Heterochronous thrombi in the hyperintensity were confirmed on both T1- and T2-weighted images in part of the aneurysm wall (arrows).
nmc-54-205-g2.jpg
PMC4533418_01_nmc-54-205-g2.jpg
F2
T1-weighted magnetic resonance (MR) imaging showed the component continuing to the falx as isointense, and the surrounding crescent-shaped component as hyperintense (Fig. 2A). T1-weighted MR imaging with gadolinium showed the medial part of the isointense region as uniformly enhanced and apparently continued further to the ACA (Fig. 2B). T2-weighted MR imaging showed the crescent-shaped part as hypointense, suggesting a thrombus (Fig. 2C). T1- and T2-weighted imaging showed a hyperintense portion on the walls of the mass, suggesting heterochronous thrombus (arrows in Fig. 2). The diagnosis was partially thrombosed giant aneurysm of the ACA.
Preoperative right (A) and left (B) internal carotid angiograms. Right internal carotid angiograms at one month postoperatively (C). The bilateral peripheral parts of the anterior cerebral arteries (ACAs) were perfused by one azygos ACA. Thick arrow indicates right ACA; thin arrow, left ACA.
nmc-54-205-g3.jpg
PMC4533418_01_nmc-54-205-g3.jpg
F3
Angiography disclosed that the aneurysm was located at the distal bifurcation of the azygos ACA (A2-A3 bifurcation) (Fig. 3A). Left internal carotid angiography delineated a very small part of the left frontal lobe (Fig. 3B), and right internal carotid angiography through the azygos ACA perfused the bilateral frontal lobes including motor areas responding to the bilateral lower extremities (Fig. 3A). Angiography performed intraoperatively and 1 month later revealed adequate obliteration of the aneurysm and good patency of the surrounding vessels (Fig. 3C).
Intraoperative photographs. A: Exposure of the 60-mm-diameter aneurysm. B: Cut surface of the aneurysm and thrombus. C: Aneurysm neck was reconstructed with 8 clips.
nmc-54-205-g4.jpg
PMC4533418_01_nmc-54-205-g4.jpg
F4
The aneurysm was dissected and then the distal parts of the azygos ACA were confirmed (Fig. 4A). The aneurysm wall was excised and the thrombus removed with an ultrasonic aspirator (Fig. 4B), and when hemorrhage occurred, the azygos ACA was temporarily occluded (Fig. 5, at time 20:53). Aspiration and removal of the thrombus was conducted quickly, the lumen was rinsed thoroughly with heparinized saline, and then neck plasty was performed with 8 clips to preserve the parent artery (Fig. 4C).
Motor evoked potentials of the bilateral lower extremities during surgery.
nmc-54-205-g5.jpg
PMC4533418_01_nmc-54-205-g5.jpg
F5
The amplitude of the bilateral L-MEPs first increased and then decreased to under 50% at the bilateral soleus muscles at 21:58 (5 min after occlusion), before disappearing at the rt. soleus muscles at 21:01 (9 min after occlusion) and nearly disappearing at the lt. soleus muscles at 21:09 (16 min after occlusion) (Fig. 5). L-MEPs reappeared after 22 minutes at 21:35 and the bilateral L-MEPs were normalized after 78 minutes at 22:37 (Fig. 5).