In major cerebral arterial occlusive diseases, patients with increased oxygen extraction fraction (OEF), which is measured with positron emission tomography (PET), may be at increased risk for cerebral ischemia. The purpose of the first study was to determine whether increased OEF is a predictor of long-term risk of subsequent stroke. We prospectively evaluated the relationship between the regional hemodynamic status of cerebral circulation and the subsequent risk of stroke in 40 patients with symptomatic internal carotid artery (ICA) or middle cerebral artery occlusive diseases who underwent PET. Patients were divided into 2 hemodynamic categories according to the mean hemispheric value of OEF in the hemisphere supplied by the artery with symptomatic disease: patients with increased OEF and those with normal OEF. All patients were followed for 5 years with medical treatment until death or the recurrence of stroke. During 5 years, 11 strokes, 9 of which were ipsilateral ischemic, occurred. Five of 7 patients with increased OEF had ischemic strokes, and 6 of 33 patients with normal OEF had ischemic strokes. There were 4 ipsilateral ischemic strokes in patients with increased OEF and 5 in those with normal OEF. Kaplan-Meier analysis revealed that the risks of all stroke and ipsilateral ischemic stroke in patients with increased OEF were significantly higher than in those with normal OEF (log-rank test; p<0.0002 and p<0.0018, respectively). Multivariate analysis with the Cox proportional hazards model demonstrated that increased OEF significantly increased stroke recurrence: the relative risk was 7.2 (95% confidence interval [CI], 2.0-25.5; p<0.005) for all stroke and 6.4 (95% CI, 1.6-26.1; p<0.01) for ipsilateral stroke. These findings suggest that an increased OEF is an independent predictor of 5-year risk of subsequent stroke. The purpose of the second study was to determine whether in patients with ICA occlusion and initially normal OEF, subsequent deterioration of cerebral hemodynamics occurs during long-term follow-up and, if so, whether the increase of the OEF is associated with subsequent ischemic stroke. We used PET to serially evaluate 7 medically treated patients with unilateral ICA occlusion and initially normal OEF at intervals ranging from 24 to 64 months. No intervening ischemic attacks occurred between the 2 examinations. In the hemisphere with ICA occlusion, the OEF increased and the blood flow decreased during follow-up. At the follow-up evaluation, 3 patients showed an abnormally increased OEF value. In all patients with increased OEF, subsequent ipsilateral ischemic strokes occurred, whereas none of those who still showed normal OEF had a subsequent stroke. In patients with ICA occlusion and initially normal OEF, subsequent deterioration of cerebral hemodynamics occurred. The increase of the OEF was associated with subsequent ischemic stroke. Evaluation of the changes in cerebral hemodynamics may be useful for identifying patients in whom the risk for ischemic stroke increases during long-term follow-up. Identification of patients with increased OEF may have clinical significance in preventing recurrent stroke.
Hemodynamic cerebral ischemia can be stratified into Stage I and Stage II (Misery perfusion). According to vasodilatory and metabolic compensation toward reduction of CPP, Stage I ischemia is defined as both preservation of resting CBF and reduction of vascular reserve. Stage II ischemia is defined as reduction of resting CBF, loss of vascular reserve and elevation of oxygen extraction fraction (OEF). The vasodilatory response to acetazolamide, a carbonic anhydrase inhibitor, provides an effective parameter of cerebrovascular reserve. Recently, quantitative measurement of CBF and cerebrovascular reserve (VR): (acetazolamide-activated CBF / resting CBF — 1)× 100% was introduced in clinical practice and hemodynamic cerebral ischemia can be quantitatively stratified into Stage I and Stage II. Both 123I-IMP-microsphere method and 123I-IMP-ARG method indicate acceptable accuracy, and can be commonly used as quantitative brain perfusion SPECT imaging. In 123I-IMP-ARG methods, Stage I ischemia is defined as follows: resting CBF more than 34 ml/100 g/min (this value corresponds to 80% of mean CBF of normal subjects) or VR from 10% to 30%, Stage II ischemia is defined as follows: rCBF less than 34 ml/100 g/min and VR less than 10%. Hemodynamically normal subjects are involved in VR more than 30% (Stage 0). Twenty-four patients with hemodynamic stroke were selected for a recent EC-IC bypass study. In this study, EC-IC Bypass surgery was performed in patients with Stage II and I (nearly II) ischemia using 123I-IMP-ARG methods. In the affected areas, the mean values of resting CBF and VR after surgery (35.0+/−7.2 ml/100 g/min, 32.9+/−15.2%) were significantly improved compared with the values before surgery (29.6+/−5.3 ml, −4.5+/−12.4%). In the unaffected areas, the mean values of resting CBF and VR after surgery (38.8+/−7.9 ml/100 g/min, 40.8+/−15.8%) were not significantly different than those values before surgery. The stage after surgery (Stage 0 in 16, Stage I in 8, Stage II in 0) was statistically improved in comparison with the stage before surgery (Stage 0 in 0, Stage I in 7, Stage II in 17). Stage II hemodynamic cerebral ischemia defined by quantitative brain perfusion SPECT imaging was successfully reversed to Stage I or 0 by EC-IC Bypass surgery. A Japanese EC-IC Bypass trial (JET Study) is being carried out to clarify the surgical benefits for Stage II ischemia, and quantitative measurement of CBF and VR has been recognized to be essential for the inclusion criteria for this trial. 99mTc-HMPAO or 99mTc-ECD-Patlak plot method could be another option for quantitative brain perfusion SPECT imaging. However, these methods can indicate acceptable values of resting CBF but could not demonstrate accurate values of VR activated by acetazolamide challenge. First-pass extraction of these radiotracers is generally lower in the relative high-flow range. Therefore the quantitative CBF value tends to be underestimated in the area with normally vasodilatory response under acetazolamide-activated condition. Linearization corrections should be modified in these methods, especially using acetazolamide activation. Hemodynamic cerebral ischemia can be stratified into Stage I and Stage II (Misery perfusion) and the stratification may be important to determine future risk of stroke. The characteristics and kinetics of brain perfusion radiotracers should be considered in quantitative stratification of hemodynamic cerebral ischemia using brain perfusion SPECT.
Visual disturbance is not necessarily included in the common symptoms of internal carotid artery occlusive disease although it is occasionally the only clinical sign of this disease. We analyze the clinical features of the internal carotid artery occlusion and stenosis presenting visual acuity disturbance and the role of superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis for ameliorating visual problems. We summarize 10 cases of internal carotid occlusive disease that presented visual disturbance as their first symptom retrospectively. Seven patients were seen by ophthalmologists initially and consulted a neurosurgeon for a second evaluation. On average, 56 weeks were required for the patients whose only symptom was visual disturbance to be diagnosed as internal carotid artery occlusive disease. All patients suffered retinal ischemia on the affected side, and secondary neovascular glaucoma was seen in most cases. All cases showed decreased cerebral blood flow on SPECT. Retrograde blood flow of the ophthalmic artery was recognized in 9 cases. STA-MCA anastomosis was performed for the patients who showed decreased cerebral blood flow and cerebral circulation reserve capacity on single photon emission computed tomography. STA-MCA anastomosis was performed in 5 patients. Improvement of visual acuity was not apparently recognized in any patients after the surgery although decrease of iridic neovasculization and improved retinal circulation was confirmed. Visual disturbance of internal carotid occlusive disease might be caused by retinal blood steal by chronic ischemic brain. STA-MCA anastomosis might be effective for such a condition because of reduction of steal flow to the brain. Early diagnosis and treatment are essential to obtain recovery of visual acuity. More coordination with ophthalmologists is essential to raise the quality of treatment.
Intraoperative angiography has been performed to confirm the complete clipping of intracranial aneurysm at the time of the surgery. However, this procedure, which has some risks, requires complex techniques and expensive devices. Therefore we have tried Three Dimensional Color Power Angio (hereinafter referred to 3D CPA) with power Doppler method using ultrasound instrument instead of angiography. Nineteen patients with intracranial aneurysms were studied. Conventional angiography was performed before and after surgery. 3D CPA was also performed before and after the clipping of the aneurysms. In the operation, after craniectomy and dural flapping, the linear probe was carefully swept on the brain surface in parallel to the target vessels. 3D CPA calculated power Doppler data and reconstructed the 3D image by using the full-volume rendering method. 3D CPA findings were found to clearly correspond to the findings of conventional angiography. 3D CPA is a new, noninvasive and repeatable tool that could replace conventional angiography. This is the first report of 3D CPA studies of intracranial aneurysms during surgery.
The prospective effect of bypass surgery against recurrent bleedings should be statistically evaluated to establish treatment guidelines for moyamoya disease with hemorrhagic onset. Twelve Japanese centers have combined to evaluate the benefits of direct anastomotic bypass surgery in randomized patients who have experienced hemorrhagic episodes related to moyamoya disease and who have received either best medical treatment alone or best medical treatment plus extracranial-intracranial bypass surgery. This prospective study (Japan Adult moyamoya ‹JAM› Trial) was initiated in January 2001.
Endovascular treatment of intracranial aneurysms using Guglielmi detachable coils (GDCs) was performed on 10 patients aged 80-89. Preoperative Hunt and Kosnik grading revealed that 4 patients were in Grade II, 4 in Grade III, and 2 in Grade IV. The aneurysms were located in the internal carotid artery in 5 patients, in the anterior communicating aneurysm in 2, in the posterior inferior cerebellar artery in 2, and in the basilar artery in 1. The approach was transfemoral in 8 patients and transcarotid in 2. Intra-aneurysmal occlusion was performed in 10 patients with total occlusion in 4, subtotal occlusion in 5 and partial occlusion in 1. Procedure-related morbidity or mortality was not observed. All patients who were successfully treated, 4 patients in Grade II and 1 in Grade III had a good outcome (GR, MD), but the other 3 patients in Grade III and 2 patients in Grade IV had a poor outcome (SD, Dead). The follow-up period ranged from 6 to 22 months. No evidence of recurrent hemorrhage was noted during follow-up. Endovascular coil embolization, done without craniotomy, may offer particular advantages in managing ruptured intracranial aneurysms in patients over 80 years of age, especially those in Hunt and Kosnik Grade II.
Twelve high flow bypass (HFB) surgeries with 6 saphenous vein grafts and 6 radial artery grafts were performed in 12 patients with cerebrovascular disease: 5 with giant internal carotid artery (ICA) aneurysms, 2 with ICA dorsal aneurysms, 1 with cervical ICA dissecting giant aneurysm, and 4 with occlusive vascular lesions. In 2 patients with ICA dorsal aneurysm, constructed HFB was removed after the successful clipping. In 10 other patients, patency of the graft was good in 90% with a mean follow-up period of 3.2 years and did not show any difference between the 2 grafts. The perioperative complications included 1 with intracerebral hemorrhage, 1 with hearing disturbance, and 1 with lethal lung thrombosis that unexpectedly occurred 2 weeks after surgery. Reconstruction of ICA with HFB is an effective and reliable option for the surgical treatment of some cerebrovascular disease, particularly for those that require parent artery occlusion during surgery. In contrast, indication of HFB for occlusive vascular lesions remains controversial. Adequate selection of patients, sophisticated surgical techniques, and careful perioperative management are essential for success in HFB surgery.
We retrospectively analyzed the results of our aneurysm cases treated with Guglielmi detachable coils (GDCs), and evaluated the efficacy and safety of this technique. Between March 1997 and December 2000, 281 aneurysms in 258 patients were treated with GDCs. Of the 258 patients 128 aneurysms in 121 patients were ruptured, and 153 aneurysms in 137 patients were unruptured. The mortality and morbidity rate of ruptured aneurysms were 1.7% and 6.6%, respectively. The mortality and morbidity rate of unruptured ones were 0% and 3.6%, respectively. Aneurysm perforation was found in 6.3% of ruptured aneurysms and 6.5% of unruptured ones. Ischemic complications were found in 10.9% of ruptured aneurysms and 17.0% of unruptured ones. However, these complications have been decreasing year by year. Rebleeding occurred in 7 aneurysms (5.4%) (6 large and 1 small aneurysms) after embolization of ruptured aneurysms. No bleeding was found in unruptured aneurysms. Long-term stability of embolized aneurysm was significantly correlated with the size of aneurysm and volume embolization rate. Small aneurysms had a higher volume embolization rate and higher stability after embolization. In conclusion, GDC embolization was a safe and effective method for the treatment of small aneurysms, but the indication of this technique should be considered carefully for the treatment of large aneurysms.
The carotid PTA and/or STENT placement for the carotid stenosis is an alternative treatment especially in patients with high-position stenosis, associated coronary artery disease and special condition of stenosis such as post irradiation stenosis or post carotid endoarterectomy (CEA) stenosis. Bilateral carotid disease is also a high-risk condition of CEA stenosis. The North American Symptomatic Carotid Endarterectomy Trial (NASCET) demonstrated that the perioperative rate of stroke and death is 14.3% if the contralateral artery is occluded. We treated with PTA and/or STENT placement 10 patients with bilateral carotid artery occlusive disease. In 3 cases, the contralateral carotid arteries were occluded, and in the other 7 cases, the bilateral carotid arteries had severe stenosis. All patients were symptomatic, and the angiographical percentages of the stenosis ranged from 70% to 99%. We performed 18 procedures of PTA and/or STENT placement and 6 procedures of CEA for 17 carotid stenotic lesions. In every case PTA and/or STENT placement was performed as a prior treatment for the symptomatic lesion. One minor stroke occurred during the PTA caused by a procedure-related complication (7.1%) but no major strokes occurred in this series. In surgical high-risk groups such as bilateral carotid artery occlusive disease, the combination of PTA/STENT and CEA is useful to prevent and reduce perioperative ischemic complications.
We experienced 2 cases of small ophthalmic segment aneurysm arising from the posteromedial wall of the internal carotid artery. Based on the angiographic and operative findings, we examined the characteristics of the aneurysms in this location with reference to the origin of the superior hypophyseal artery. They were unruptured aneurysms, and were clipped successfully through the contralateral pterional approach with sacrifice of the superior hypophyseal artery because of its adhesion with the aneurysm. The postoperative course was uneventful. In this approach, we emphasize less invasiveness for clipping of the aneurysm with neither damage to the optic nerve nor the necessity of resection of the skull base such as the anterior clinoid process. We report 2 cases and review some literature that discusses the merits and demerits of the contralateral pterional approach for superior hypophyseal artery aneurysm.