We reviewed 9 cases of brainstem cavernomas and evaluated the approach for each lesion, accessibility, respectability, and pre- and post operative neurological status. The dorsal lesions were treated with posterior approaches, such as the occipital transtentorial approach or trans-4th ventricle approach. The ventral lesions were treated with anterior approaches using skull base technique, but we needed some technique to access ventral lesions. We used transposition of the cranial nerve and VA, which lay across the surface of the cavernomas in 2 cases, and we performed two-staged surgery in 1 case. In all cases, we were able to access and remove the lesions safely.
Dorsal lesions with traditional posterior approaches and the ventral lesions require a skull-base approach and additional technique based on consideration of local anatomy and surrounding structures.

View full abstract

We reviewed the cases of brain stem cavernous malformation treated at Kyoto University Hospital between 1983 and 2007. We employed a midline suboccipital approach in 15 cases of a total 21 cases. Here we describe the pitfalls of this approach at our institute.

View full abstract

We investigated the usefulness of fluorescein cerebral angiography (FAG) and microvascular Doppler ultrasonography (MDU) for detecting the blood flow insufficiency in the perforating arteries during aneurysm surgery.
FAG was performed to confirm the patency of perforating arteries located deeply in the surgical field. After aneurysm clipping, the target arteries were illuminated using a beam from the pencil-type probe with a blue light-emitting diode at its tip. After intravenous administration of 5 ml of 10% fluorescein sodium, fluorescence in the vessels was clearly observed through a microscope and recorded on videotape. The excellent image quality and spatial resolution facilitated intraoperative real-time assessment of the patency of the perforating arteries and branches such as the posterior communicating artery, anterior choroidal artery, lenticulostriate artery, recurrent artery of Heubner, hypothalamic artery or posterior thalamoperforating artery.
Although MDU has generally been used in aneurysm surgery to assess the blood flow velocity before and after clipping, the complexity of keeping the MDU probe on the target vessel at the appropriate angle and degree of compression makes the detection of changes in flow velocity difficult. To overcome this problem, we continuously measured the blood flow velocity by MDU during aneurysmal clipping. The continuous MDU monitoring during aneurysm clipping enabled us to detect slight blood flow changes in real time.
The findings of this study suggest that the monitoring methods introduced here are safe and reliable for detecting intraoperative blood flow insufficiency in the perforating arteries and facilitate the prevention of unexpected postoperative cerebral infarction.

View full abstract

The purpose of this study was to determine the efficacy of various modifications for the remodeling technique, i.e., microcatheter tip re-shaping in the parent vessel, balloon setting with exchange microguidewire, balloon catheter navigation with another balloon in the targeted aneurysm, and retrograde approach of the balloon catheter. Remodeling technique is balloon assisted coil embolization for wide neck cerebral aneurysms, first documented by Jacques Moret. Under the neck protection with temporally inflated balloon in the parent vessel, platinum coils are delivered via another microcatheter. Not all wide neck aneurysms are suitable for remodeling technique because of the complex structure of the parent vessels surrounding the aneurysm orifice.
Some microcatheter tips could be re-shaped inside the normal artery at body temperature. Intensive bending of the microcatheter tip for a short while is of some help to difficult navigation. Occasionally, we find it difficult to navigate the stiff balloon catheter across the aneurysm neck. An exchange microguidewire of 300 cm length is useful if a supple microcatheter can be navigated in the same route as the balloon catheter is placed. A stiff balloon catheter can replace the microcatheter with the exchange guidewire. For a large aneurysm with wide neck, the balloon catheter can be navigated beyond the aneurysm with assistance of another balloon inflation inside the targeted aneurysm. Furthermore, retrograde navigation of the balloon catheter against the blood flow passing through the communicating vessels could be helpful under specific situations. During 2003-2006, 11 of these modifications were applied to 31 remodeling procedures. One hemorrhagic complication and 2 recurrences of treated aneurysms were observed. With illustrative cases, we report the details concerning these procedures.

View full abstract

We have treated ruptured aneurysms with Guglielmi Detachable Coils (GDC) as the first treatment. Of 575 patients of subarachnoid hemorrhage admitted to our hospital between March 1997 and December 2006, the condition of 201 patients was too poor to be treated. Eighty-eight patients were treated by neck clipping, and 286 cases were treated by GDC embolization. Among the latter patients, 229 (80%) were independent on discharge. During the follow-up period, aneurysmal rerupture occurred in 3 cases (1.5%). And 67 cases (33%) showed change of embolization status. We performed second embolizations in 34 cases (13%) to prevent aneurysmal rerupture.
These results suggest that embolization was safe and reliable. But new devices may be necessary to achieve more stable embolization status.

View full abstract

We report 4 cases with progressing stroke due to middle cerebral artery (MCA) occlusion, who were successfully treated by emergency superficial temporal artery (STA)-MCA anastomosis during the subacute stage. Surgical STA-MCA anastomosis is indicated by JET study to prevent the recurrence of severe ischemia. However, an indication for STA-MCA anastomosis to treat acute ischemic stroke due to main trunk artery occlusion is not established because of conflicting opinions regarding issues such as reperfusion injury. Nevertheless, the clinical outcome of occasional STA-MCA anastomosis performed at the subacute stage of progressing stroke is good. Four patients underwent emergency STA-MCA double anastomoses at our hospital between 1998 and 2005 to treat progressing stroke.
All patients were males aged 40-69 years (median, 51.8 years). The cause was low perfusion ischemia due to MCA occlusion caused by atherosclerosis, and a small ischemic lesion was depicted in the corona radiata or motor cortex. The duration from onset to surgery was 2 to 8 days (median, 4.75 days). The initial symptoms were progressive allophasis (n=3) and motor paresis (n=1). All 4 patients underwent emergency STA-MCA anastomoses. All of them slowly achieved obvious remission compared with symptoms on admission and returned to their jobs.
We therefore recommend STA-MCA bypass surgery for patients with progressive ischemia due to MCA occlusion even at the subacute stage.

View full abstract

When we treat a patient with progressing stroke, STA-MCA bypasses in the acute stage may be effective to minimize the lesion size. However, there was no evidence to support this hypothesis. The aim in this study is to investigate the potential risk and safety of acute stage bypass surgery to determine whether this treatment would be reasonable or not.
Over a 4-year period, from April 1 2002 to August 1 2006, we performed 55 STA-MCA bypasses, 23 in the acute stage and 32 in the chronic stage. The chronic stage patients were based on the selection standards of JET study (Japanese EC-IC bypass Trial). Each case was examined by IMP or Xe SPECT within 2 weeks of bypass surgery. Where hyperperfusion was evident, cases were divided into one of 2 groups, according to the location of the hyperperfusion: Group A demonstrating it locally, and Group B demonstrating it hemispherically. Symptomatic cases were also divided into 2 groups according to the degree of severity, with the mild group exhibiting such symptoms as headaches or transient psychological disturbance, and the severe group reporting convulsions or conscious disturbance, etc. We examined the frequency of hyperperfusion syndrome and the safety of STA-MCA bypasses performed in the acute stages.
Of the 23 acute stage bypasses, 7 cases (30.4%) were classified as Group A and 2 cases (8.7%) as Group B, affecting 9/23 cases, or 39.1% of the acute total. Of these, there were 3 mild symptomatic cases (13.0%), and 1 severe case (4.3%). Of the 32 chronic stage bypasses, 4 cases (12.5%) were classified as Group A and 1 case (3.1%) as Group B, affecting 5/32 cases, or 15.6% of the chronic total. Of these, there was 1 mild symptomatic case (3.1%), and 2 severe cases (6.3%). There were no hemorrhagic transformations. According to these results, acute stage bypasses did not differ significantly from chronic ones with regard to the occurrence of symptomatic cases. (p=0.435; Fisher exact method)
STA-MCA bypass surgery might be feasible in the acute stage for a little symptomatic hyperperfusion syndrome. More cases would be necessary to clarify the safety of acute stage bypass surgery.

View full abstract

It is important to pack the inflow zone of intracerebral aneurysm to prevent coil compaction or recanalization after coil embolization of the aneurysm. In this study, we report the usefulness of magnetic resonance angiography (MRA) to identify the inflow zone of the aneurysm.
Between November 2004 and March 2006, 21 patients (IC paraclinoid, 11 cases; BA tip, 3 cases; A-com, 4 cases; IC-top, 2 cases; P1, 1 case) underwent interventional coil embolization for cerebral aneurysms and MRA was used to try to depict the inflow zone of the aneurysm. We designed a 3D time-of-flight MRA technique targeted to the aneurysm with a large flip angle to emphasize the streamline into the aneurysm. We grasped the position of the inflow zone in the aneurysm by MRA before intervention. The inflow zone was packed by coils tightly with balloon neck remodeling technique and/or catheter assist technique, if necessary.
The inflow zone was depicted in all 21 cases by MRA. In sidewall type aneurysms, the inflow zone existed beside the distal neck in all cases. In terminal type aneurysms, the inflow zone existed on an extension line from patent artery. Dome filling was not detected in all cases after treatment. Small neck remnant was detected in 6 cases that slightly increased in 4 cases, vanished in 1 case, remained and unchanged in 1 case 6 months after treatment. None of the cases required additional treatment.
For effective coil embolization, it is important to grasp the position of the inflow zone of the aneurysm and to pack the point as tightly as possible. Identification of the inflow zone of aneurysm by MRA is useful for coil embolization.

View full abstract

Internal carotid artery (ICA) endovascular proximal occlusion and trapping with radial artery grafting is a favorable option in treating giant aneurysms in the cavernous portion of the ICA.
Even if ischemic tolerance is proven with the balloon test occlusion (BTO) procedure, treatment strategies will likely vary depending on the individual case. Should other aneurysms exist in collateral vessels, hemodynamic stress will occur on the collateral vessels and the aneurysm after the endovascular proximal occlusion, likely causing the aneurysm to enlarge. In such cases, neck clipping of these peripheral aneurysms should be performed before ICA proximal occlusion or trapping and vascular bypass.

View full abstract

Kyorin University Hospital covers a medical zone near the center of Tokyo, with a population of about 920,000. The hospital established a new urban-type stroke unit for this medical zone in May 2006. Reviewing the problems facing the previous system of treatment of stroke, the hospital decided to establish a new stroke care team to take care of all treatments for stroke patients at the hospital and ensure that intravenous t-PA therapy can be performed 24 hours a day. Over a 1-year period before the stroke unit opened, a total of 662 stroke patients were treated at the hospital, but about 80 patients with transient ischemic attack (TIA) or mild cerebral infarction could not be hospitalized. The major problems facing the hospital were that comprehensive management was not provided uniformly to stroke patients and attention was not being paid to patients with TIA or mild stroke who are at risk of severe stroke and its recurrence and require intervention the most.
The stroke unit opened with the following 4 strategies: 1) to accept patients with TIA or mild cerebral infarction non-selectively for short periods of time with close examination; 2) to apply an advanced hyperacute rehabilitation program to patients with moderate stroke for improved recovery of activities of daily living (ADL) and to achieve early intervention by social workers dedicated to the stroke unit to smooth the transition to rehabilitation hospitals; 3) to minimize medical complication in severe stroke patients by preventing aspiration pneumonia and decubitus by thorough body position management; and 4) to increase the awareness of a system for intravenous t-PA therapy among nearby hospitals and ambulance teams.
Using these strategies and measures, a total of 872 patients were admitted (549 men, 323 women; mean age, 70.2 years) over an 18-month period since the stroke unit opened. All the patients with TIA and mild cerebral infarction were hospitalized and actively managed for examination and treatment. Intravenous t-PA therapy was considered in 160 patients and finally performed on 66 patients according to the strict indication of the therapy.
Establishment of the intravenous t-PA therapy system has been very effective in improving overall management for stroke patients.

View full abstract

The pterional keyhole approach was used to clip 55 cases of relatively small unruptured aneurysms of the middle cerebral artery (MCA). Three-dimensional (3D) computed tomography angiography and 3D bone imaging with osteostomy technique were used for the pre-operative planning. The spatial relationship between the aneurysm dome and the sphenoid ridge is particularly important to determine the optimal location of the keyhole. The 55 MCA aneurysms were classified into 3 subgroups based on their relationship to the sphenoid ridge, namely sylvian type (25 cases), infra-sylvian type (22 cases), and supra-sylvian type (8 cases). The pterional keyholes were made according to the subtypes to perform minimally invasive clipping procedures. The optimal size and location of the keyholes were determined in each case. The diameter of the pterional mini-craniectomy was as small as 25 mm. One patient developed temporary mild hemiparesis, and 2 patients suffered from incomplete frontalis muscle weakness. No shaving of scalp hair, drain placement, or anticonvulsive agent administration were required. Most patients were discharged by the 3rd post-operative day without functional neurological deficits.
The pterional keyhole approach based on pre-operative imaging allows minimally invasive clipping surgery for unruptured MCA aneurysms.

View full abstract