Neurol Med Chir (Tokyo) 50, 1012¿1014, 2010 Intracerebral Hemorrhage From a Ruptured Aneurysm at the Site of Anastomosis 27 Years After Superficial Temporal Artery-Middle Cerebral Artery Bypass —Case Report— Masaaki HOKARI, Hiroshi YASUDA, Motoyuki IWASAKI, Masahito KAWABORI, Satoshi KURODA*, Satoru ABE, and Hisatoshi SAITOH Sapporo Azabu Neurosurgical Hospital, Sapporo, Hokkaido; *Department of Neurosurgery, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido Abstract A 77-year-old female presented with a very rare case of intracerebral hemorrhage (ICH) from a ruptured aneurysm at the site of the anastomosis 27 years after superficial temporal artery-middle cerebral artery (STA-MCA) bypass manifesting as sudden onset of unconsciousness and right hemiparesis. Computed tomography (CT) on admission demonstrated massive ICH in the left frontoparietal region. Magnetic resonance angiography showed good patency of the anastomosis and no obvious aneurysm, but threedimensional CT (3D-CT) angiography revealed a small aneurysm at the site of the left STA-MCA anastomosis. Emergency evacuation of the hematoma was performed, and the aneurysm was trapped and resected after ligation. After the operation, she continued to exhibit deep consciousness disturbance. Unfortunately, her general condition grew steadily worse and she died 3 months later. Patients who undergo STA-MCA anastomosis should be carefully followed up by periodical imaging examinations. 3DCT angiography is very useful to detect aneurysm formation at the anastomosis site. Key words: superficial temporal artery-middle cerebral artery anastomosis, aneurysm, intracerebral hemorrhage, surgery, three-dimensional computed tomography angiography Introduction Direct cerebral revascularization through a superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis has been performed to prevent ischemic attack in patients with occlusive carotid artery diseases.1,2,5,6,13,16,17) Postoperative aneurysm formation at the anastomosis site is a relatively rare complication of this procedure. Moreover, formation of aneurysm more than several years after STA-MCA anastomosis is quite rare, with only 3 reported cases.11,12,18) We describe a very rare case of intracerebral hemorrhage (ICH) from a ruptured aneurysm at the site of anastomosis 27 years after STA-MCA bypass. Case Report A 50-year-old female was first admitted to the Department of Neurosurgery of Hokkaido University because of periodic transient right hemiparesis in March 1981. Cerebral angiography showed occlusion of the left MCA at the M1 segment. The patient underwent a left STA-MCA double anastomosis without complication on April 15, Received January 12, 2010; Accepted March 11, 2010 1012 1981. After her operation, she had worked as a nurse. Since her retirement in 1985, she had attended our hospital and had been managed with ticlopidine hydrochloride. Moderate hypertension was identified, but was not controlled adequately. She had undergone magnetic resonance (MR) imaging and three-dimensional time-of flight (3D-TOF) MR angiography every year in our hospital to confirm the patency of the anastomosis (Fig. 1A). She had not suffered a transient ischemic attack for 27 years. However, she was admitted to our hospital after sudden onset of unconsciousness and right hemiparesis on February 24, 2008, when she was 77 years. MR imaging and MR angiography showed massive ICH and good patency of the anastomosis (Fig. 1B). Computed tomography (CT) demonstrated massive ICH in the left frontoparietal region, which is an unusual location for a hypertensive ICH (Fig. 1C). Although MR angiography had shown no obvious aneurysm (Fig. 1B), 3D-CT angiography revealed a 3.5-mm aneurysm at the site of the left STA-MCA anastomosis in the direction of the STA flow (Fig. 1D). The proximal limb of the recipient cortical artery was dilated, whereas the distal limb of the cortical artery was very narrow and almost occluded (Fig. 1D). Emergency evacuation of the hematoma was performed Aneurysm Rupture 27 Years After STA-MCA Bypass 1013 Fig. 1 A: Magnetic resonance (MR) angiogram in 2007 showing patency of the left superficial temporal artery-middle cerebral artery (STA-MCA) double anastomosis (white arrows). B: MR angiogram on February 24, 2008, showing patency of the left STA-MCA double anastomosis as before (white arrows). C: Computed tomography (CT) scan on February 24, 2008, showing massive intracerebral hemorrhage in the left frontoparietal region. D: Three-dimensional CT angiogram demonstrating patency of the left STA-MCA double anastomosis (white arrows) and a small aneurysm at the site of anastomosis in the direction of STA flow (white arrowhead). Note that the proximal limb of the recipient cortical artery was dilated (black arrowhead), whereas the distal limb of the cortical artery was very narrow (black arrow). E, F: Photograph (E) and schematic drawing (F) showing the STA (white arrow), small aneurysm at the site of the anastomosis in the direction of STA flow (white arrowhead), proximal limb of the recipient cortical artery (black arrowhead), and distal limb of the cortical artery (black arrow). through a large craniotomy. The anastomosis site was dissected with preservation of the STA-MCA anastomosis, and the aneurysm was found at the site of the anastomosis in the direction of the STA flow, with the dome projecting into the hematoma cavity (Fig. 1E, F). The aneurysm was trapped and resected after ligation, considering the extensive frontoparietal irreversible damage. Histological examination showed that the surgical specimen consisted of connective tissue without muscle or elastic lamina component. Therefore, the final diagnosis was pseudoaneurysm at the site of the STA-MCA anastomosis. After the operation, she continued to exhibit deep consciousness disturbance. Unfortunately, her general condition grew steadily worse and she died 3 months later. Discussion Complications of aneurysm formation at an anastomosis site after STA-MCA bypass are uncommon, with only 12 previously reported cases (Table 1).3,4,7–9,11,12,15,18) Such complications usually occur within a few years after bypass surgery. Only 3 of the 12 previous aneurysms at the anastomosis site, as well as the aneurysm in our patient, ruptured more than 2 years after STA-MCA bypass surgery. Moreover, only one previous case developed complication more than 20 years after the bypass for moyamoya disease. The present case of ICH from the ruptured aneurysm at the site of anastomosis occurred 27 years after bypass surgery for occlusive carotid artery disease caused by arteriosclerosis. Various factors are plausible for aneurysm formation at the anastomosis site. One possible mechanism of aneurysm formation after bypass surgery is intraoperative manipulation, including vascular injury by temporary clipping, resulting in excessive adventitial stripping.9) Neurol Med Chir (Tokyo) 50, November, 2010 Such technical failures might be the main cause of rapid aneurysm formation at the anastomosis site. However, aneurysm formation long after the bypass surgery could not be primarily caused by such technical failures. The experience of such complications several years after bypass surgery has suggested that hypertension and hemodynamic stress might be a factor in the development of aneurysm at the anastomosis site.11,12,18) Therefore, long-term careful and constant control of blood pressure has been recommended.12) In addition, repeated long-term follow-up MR angiography should be performed to confirm the patency of the anastomosis and to identify aneurysm formations after STA-MCA anastomosis.11) However, turbulent flow and overlap of the artery and aneurysm are likely to make detection of aneurysms by 3D-TOF MR angiography very difficult.14) Turbulent flow often occurs at the anastomosis site, and the donor or recipient arteries commonly overlap with the aneurysm. MR angiography with contrast medium is better than 3D-TOF MR angiography for the detection of aneurysms with slow flow because less signal reduction occurs due to turbulence or flow saturation effect.10) Although we failed to detect the aneurysm in our case by repeated 3D-TOF MR angiography, MR angiography with contrast medium possibly could have done so. The present case suggests that patients who undergo STA-MCA anastomosis should be carefully followed up by periodical imaging examinations. 3D-CT angiography is very useful to detect aneurysm formation at the anastomosis site. References 1) Baron JC, Bousser MG, Rey A, Guillard A, Comar D, Castaigne P: Reversal of focal ``misery-perfusion syndrome'' M. Hokari et al. NS yes (not controlled) yes (controlled) yes (not controlled) NS yes (not controlled) F M 57 65 M M M F 49 43 52 77 Kohno et al. (1996)7) Sasaki et al. (1996)18) Nishizawa et al. (2000)12) Nishimoto et al. (2005)11) Present case 8 9 10 11 12 13 2) 3) D: dead, GR: good recovery, ICA: internal carotid artery, MD: moderate disability, NS: not specified, OA: occipital artery, TIA: transient ischemic attack. SD D true pseudo 20 yrs 27 yrs no NS NS NS M M F M 70 70 48 58 moyamoya disease lt MCA (M1 portion) occlusion ruptured ruptured 8 3.5 clipping trapping MD pseudo 5 yrs ruptured small clipping MD true clipping 4 yrs rt ICA occlusion yes (controlled) M 60 4 5 6 7 3 1 2 Fleischer et al. (1979)4) Leclercq and Ambler (1980)9) Parent and Smith (1981)15) Lantos et al. (1984)8) Fein (1985)3) lt ICA occlusion bil ICA stenosis rt ICA occlusion lt ICA occlusion, rt ICA stenosis lt ICA occlusion rt ICA occlusion lt ICA occlusion bil ICA occlusion no NS M M 60 61 bil MCA (M1 portion) occlusion lt ICA occlusion ruptured NS 5 2 wks 2 mos incidental ruptured 8 GR GR true true GR coating coating clipping suture ligation coagulation OA-MCA GR GR GR GR true true true true true clipping 9 13 6 NS NS 2 wks 13 mos 1 yr 2 wks 2 wks incidental headache headache headache incidental GR D pseudo pseudo 2 mos 25 days TIA ruptured 4 NS OA-MCA none Outcome Histology Treatment Size (mm) Interval Presentation Associated vascular anomalies Hypertension Sex Age (yrs) Author (Year) Case No. Table 1 Reported patients with aneurysm formation at the anastomosis site after superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery 1014 4) 5) 6) 7) 8) 9) 10) 11) 12) 13) 14) 15) 16) 17) 18) by extra-intracranial arterial bypass in hemodynamic cerebral ischemia. 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