Taketomo Ohmomo

Preoperative superselective embolization of skull-base meningiomas: Indications and limitations

We evaluated the clinical significance of preoperative superselective embolization for skull-base meningiomas. The subjects consisted of 20 patients with skull-base meningiomas, and were classified into a preoperative embolized group and a non-embolized group. The volume of blood transfused during the operation, the length of the operative procedure and the neurological outcome were compared between the two groups. The results showed that, in tumors smaller than 6 cm, the blood lost during the operation was significantly less in the embolized group. In tumors larger than 6 cm, there was not difference in blood lost, perhaps because larger meningiomas tend to have tiny blood vessels that are unsuitable for preoperative embolization. There was no difference in the length of the operation between the two groups. The embolized group tended to show a better clinical outcome than the non-embolized group.

The value of long-term clinical follow-up for cases of spontaneous carotid cavernous fistula.

Summary To clarify the value of clinical long-term follow-up with radiological examination, ranging from 12 to 63 months (average: 35 months), 18 consecutive patients suffering from spontaneous carotid cavernous fistula (CCF), were studied prospectively.Five aged patients without aggressive symptoms were treated conservatively, and the other 13 underwent transarterial embolization. The radiological follow-up was primarily by magnetic resonance angiography (MRA), performed from 2 to 6 times (average: 4.1 times) during the follow-up period.In three cases, CCFs persisted, but the other fifteen (83%) demonstrated complete cure as defined by long-term follow-up MRA. The three patients with persistent CCFs were comparatively young, less than 60 years old, had no atherosclerotic factors and demonstrated multiple venous drainage routes with cortical venous drainage on angiography. In two of them, the symptoms completely disappeared, and the other had only mild chemosis. However, surprisingly, in two, MRA revealed residual CCF with drainage into only cortical veins through the sphenoparietal sinus, this radiological finding being well known to signify danger. During the follow-up period, central retinal vein thrombosis occurred in two cases. The common point in these cases was that the superior ophthalmic vein was the only venous drainage route. This is also a point requiring care. We therefore emphasize the importance of careful long-term radiological follow-up for spontaneous CCF patients even when their symptoms improve or disappear. MRA is particularly suitable for this purpose and applicable in the out-patient clinic because of its non-invasive nature.

Spontaneous carotid cavernous fistulas with special reference to the influence of estradiol decrease

The etiology of the dural arteriovenous fistula (AVF) involving the cavernous sinus is still unknown. However, it is of interest that this condition usually occurs in post-menopausal women. The purpose of the present study was therefore to clarify the relationship between sex hormone blood levels and the occurrence of dural AVFs in the cavernous sinus. Serum sex hormone levels and factors associated with atherosclerosis were examined in 26 consecutive patients with dural AVF involving the cavernous sinus presenting at our institute during the last eight years and compared with those of a post-menopause control group. Of the present patient series, 21 (81%) were women. All except five had passed menopause. Five (24%) of the women patients presented with symptoms consistent with cessation of menstruation, namely, a blood level of estradiol significantly lower than the control value. Hypertension was recognized in 10 (71%) of 14 females who had experienced menopause 10 or more years previously and in all male patients. A sudden abnormal decrease of blood estradiol levels in female patients demonstrating symptoms consistent with menopause may thus be an important precipitating factor in the occurrence of dural AVFs involving the cavernous sinus. Hypertension, in older female and male patients, with or without longstanding low blood estradiol levels, may cause atherosclerosis of the feeding vessels in the dura mater, resulting in the opening of a normal AV shunt to provide collateral circulation.

Effects of Grapefruit Juice Consumption on Pharmacokinetics of Low Dose Simvastatin: Cross-over Study with a Review of the Literature

The effects of consumption of grapefruit juice on the pharmacokinetics of conventional low-dose simvastatin in Japan were investigated. In a randomized cross-over study with two phases, 10 healthy volunteers ingested grapefruit juice 400ml or water for 2 days. On day 3, a single 5mg dose of simvastatin was administered with grapefruit juice 200ml or water. Plasma concentrations of HMG-CoA reductase inhibitor were determined up to 8 h thereafter. Grapefruit juice increased the area under the plasma concentration-time curves from 0 to 8 h of total HMG-CoA reductase inhibitor 1.7- fold (p=0.002) and that of active HMG-CoA reductase inhibitor 1.7-fold (p=0.024). However, the peak concentrations (Cmax) and Tmax of total and active HMG-CoA reductase inhibitors were not significant influenced.Consumption of grapefruit juice with low-dose simvastatin thus resulted in mild increase of the plasma HMG-CoA reductase inhibitor, so that the pharmacokinetic interaction can be labeled as of weak CYP3A type.

The Efficacy of Coil Embolization at the Dissection Site of Ruptured Dissecting Vertebral Aneurysms

Proximal occlusion of the parent artery has been widely used for treatment of vertebral dissecting ruptured aneurysms, but this does not always completely prevent re-rupture. In this series, the efficacy of occlusion at the dissection site using detachable coils was compared with proximal balloon occlusion. Over a five year period, 25 patients suffering from subarachnoid hemorrhage with dissecting vertebral aneurysms were treated by endovascular surgery. The first three of these 25 patients were treated with proximal balloon occlusion of the parent artery. The remainder underwent platinum coil occlusion at the affected site as early as possible after the diagnosis. In two of the three cases treated with proximal balloon occlusion, clipping or coating surgery were added because of progressive dissection. In all 22 cases of coil embolization, the intervention was successfully performed without complication. In one case with a dissection involving bilateral vertebral arteries, minor rebleeding from a contralateral dissection occurred after embolization. In the other 21 cases, rebleeding was not apparent (clinical follow-up: mean 24 months). Radiological findings showed complete occlusion of the dissection site and patency of the non affected artery (follow-up: mean ten months). We conclude that detachable platinum coil embolization at the dissection site is more effective than proximal occlusion for treatment of ruptured vertebral dissecting aneurysms because of immediate cessation of blood flow to the dissection site. However, in cases with bilateral dissections or hypoplastic contralateral vertebral arteries, preceding bypass surgery or stent treatment to preserve the affected vertebral artery may be needed.

Endovascular Surgery for Ruptured Aneurysms with Vasospasm

With the existence of vasospasm, it is recommended that direct clipping surgery for a ruptured aneurysm be delayed until its disappearance, but this may be associated with aneurysmal re-rupture resulting in a poor outcome for the patients. Indications for endovascular coil embolization in such cases are discussed. Since November in 2003, we have applied endovascular coil embolization in 11 consecutive patients with ruptured aneurysms and apparent vasospasm of the parent artery from two to 17 days (average: eight days) after initial subarachnoid hemorrhage. Three patients had aneurysmal re-rupture before treatment, but the other eight had only experienced the one episode of subarachnoid hemorrhage. With one exception, all endovascular procedures could be successfully performed, resulting in complete occlusion of aneurysms and remarkable dilatation of inserted spastic vessels without technical complications or aneurysmal re-rupture. For the one case of failure because of a tortuous artery, direct clipping surgery was performed after disappearance of vasospasm. Cerebral infarction occurred in four, but only one correlated with the distribution of catheterization, and neurological deficits had completely disappeared three months after the onset. This preliminary report concerning a small number of patients suggests that endovascular coil embolization is not contra-indicated for aneurysms with vasospasm requiring catheterization. A large study for confirmation is now warranted.

The efficacy of endovascular surgery for treatment of giant aneurysms with special reference to coil embolization for endosaccular occlusion.

We assessed the long-term follow-up results of platinum coil embolization and aneurysmography (ARG) with endovascular surgery for giant aneurysms. 24 cases of giant aneurysms were treated over a period of seven years. In the present study, the 16 of these for which surgical dipping was impossible so that only endovascular surgery was employed were investigated in detail. In 10 cases the cavernous sinus area was involved, in two each the tip of the basilar artery, and the bifurcation of the ophthalmic artery, and in one each the extracranial internal carotid and the vertebral artery. Since conventional angiography did not allow the position and size of the neck of 10 cavernous sinus aneurysms to be identified, making treatment decisions difficult, we applied the ARG developed by the senior author. Prior to treatment, balloon test occlusion of the parent arteries was performed. In all 10 cavernous sinus cases, ARG successfully revealed the morphology of the aneurysm. A small neck was diagnosed for seven of the aneurysms of the cavernous sinus and all those located at the basilar and ophthalmic arteries, making a total of 11, and for these endosaccular embolization was carried out. In the other 5 cases, proximal occlusion using Gold valve balloons was performed. Under ARG, embolization of the aneurysms could be safely accomplished with platinum coils, without dislocation of the coils into the parent arteries in all cases. In four out of 10 cases, re-opening of the aneurysms occurred after 2 months or longer, so that re-embolization was required. Regarding complications, transient monoparesis of the upper extremity was encountered in one case. After angiographic and MRA follow-up of 1–36 months (average, 13.8 months), 4 of 10 cases demonstrated complete occlusion, and 5 displayed an 80–90% reduction in blood flow. In only one case, involving a basilar tip aneurysm, was the treatment unsuccessful in preventing eventual rupture and death. In cases where the morphology of the aneurysm is unclear, ARG can be considered indispensable for determining the treatment modality and safe performance of localized embolization of the neck by endovascular surgery. However, since coils used for embolization of giant aneurysms may move or become compacted, re-opening can occur so that applications may be limited, especially with terminal type lesions with intraluminal thrombus, and the necessity for long-term follow-up must be emphasized.

Experimental determination of minimal stimulation current and period for electrical thrombosis in dogs.

Endovascular surgery has been proposed as an alternative treatment for cerebral aneurysms. However, for wide neck and large sized lesions it is very difficult to obtain complete occlusion and tissue organization. The present study was conducted to examine the efficacy of electrical thrombosis for cerebral aneurysms and parent arterial occlusions using Interlocking Detachable Coils (IDCs), focusing on the minimum current volume and stimulation time required for stable electrical thrombosis formation. We used ten mixed-breed adult dogs (in the study body weights 9–12 kg; males: 5, females: 5). Guiding catheter sand microcatheters were introduced into both sides of the distal external carotid artery (ECA) and placed at the same level. To prevent migration, IDCs (4 mm × 12 cm) were placed in the ECA without being detached. After confirming no vessel occlusion, we applied a positive current (2–6 mA) to the coil on one side and performed angiography every ten minutes to observe whether vessel occlusion with electrothrombosis had occurred. It was determined that to achieve complete occlusion of the external carotid arteries in mixed-breed dogs, a minimum stimulation current of 4mA and a minimum stimulation time of ten to 20 minutes are required.

Pathophysiological evaluation of cerecyte coil embolization for experimental broad neck aneurysms.

Cerecyte second-generation coils feature inner surfaces coated with an absorbable polyglycolic acid (PGA) polymer. Their use is expected to accelerate aneurysm organization, but time course data are limited. The present experimental study was therefore conducted to clarify the processes by pathological examination. Methods. Two types of experimental aneurysms were initially generated in adult mongrel dogs, one bifurcation and another of lateral wall type. Long-term persistence of each was defined by follow-up angiography for more than 1 year. Embolization of the aneurysms was then performed using only cerecyte coils, and follow-up angiography was conducted after 2 and 4 weeks followed by pathological examination. Results. Organization of both types of broad neck aneurysm was apparent 4 weeks after embolization, which is earlier as compared with already reported data for bare coils.

Application of the Liquid Coil as an Embolic Material for Arteriovenous Malformations

The purpose of this paper is to clarify advantages and disadvantages of platinum liquid coils as an embolic material for AVMs. During the last eight years, 50 endovascular procedures using liquid coils were conducted in our institute for 19 cases with AVMs, 15 of which were located in the eloquent area. All but one presented with haemorrhage, the exception demonstrating repeated ischemic symptoms. Only liquid coils were used as the embolic material to obliterate the nidus and feeders. In ten of the 15 patients with AVMs located in the eloquent area and one case rejecting surgery, liquid coil embolization was applied one to 11 times (average 3.5 times) to achieve decrease in size and this was then followed by radiosurgery. The remaining eight AVM patients underwent total removal after liquid coil embolization. No complications were encountered during the peri-embolization period. In all cases, the purpose of embolization was to diminish the size to facilitate radiosurgery and decrease bleeding during surgery. The liquid coil has advantages as a material for embolization of AVMs; it is non-toxic and bioinart material; it seldom occludes normal minute vascular channels; when it used in a nidus, it seldom to migrates in the venous direction, and it has good radio-opacity and offers good marking for surgery. Appropriate applications include preoperative embolization or pre-radiosurgical embolization of AVMs, especially when staged embolizations are performed to reduce risk of perfusion pressure breakthrough in patients which are large or located in the eloquent area.