Yoshie Hara

Two unusual cases of multiple dural arteriovenous fistulas

OBJECTIVE AND IMPORTANCE Two patients with dural arteriovenous fistulas involving the transverse sinus and superior sagittal sinus are described, with a focus on the unique type of venous drainage of the fistula. CLINICAL PRESENTATION Both patients presented with papilledema and progressive visual disturbance. Angiography and magnetic resonance imaging showed that the fistulas involving the superior sagittal sinus had a dilated venous channel, separate from the sinus lumen, located within the wall of the sinus. INTERVENTION Transvenous embolization of the venous channel of the fistula, proximal to its drainage into the superior sagittal sinus, resulted in closure of the fistula and restoration of the superior sagittal sinus function. The clinical symptoms were reversed; the symptoms are believed to have reflected venous hypertension in the superior sagittal sinus, resulting from the shunted flow and interfering with normal venous drainage. CONCLUSION This unique type of dural arteriovenous fistula may be a variant, occurring in the developmental process of the fistula. It is significant clinically because transvenous embolization can be used to close the fistula and restore sinus function.

Unruptured Cerebral Aneurysm Detected after Intravenous Tissue Plasminogen Activator for Stroke

Therapeutic guidelines of intravenous thrombolysis with tissue plasminogen activator (tPA) for hyperacute ischemic stroke are very strict. Because of potential higher risk of bleeding complications, the presence of unruptured cerebral aneurysm is a contraindication for systemic thrombolysis with tPA. According to the standard CT criteria, a 66-year-old woman who suddenly developed aphasia and hemiparesis received intravenous tPA within 3 h after ischemic stroke. Magnetic resonance angiography during tPA infusion was performed and the presence of a small unruptured cerebral aneurysm was suspected at the anterior communicating artery. Delayed cerebral angiography confirmed an aneurysm with a size of 7 mm. The patient did not experience any adverse complications associated with the aneurysm. Clinical experiences of this kind of accidental off-label thrombolysis may contribute to modify the current rigid tPA guidelines for stroke.

Post-licensed 1-year experience of systemic thrombolysis with tissue plasminogen activator for ischemic stroke in a Japanese neuro-unit

OBJECTIVE In Japan, intravenous thrombolysis with tissue plasminogen activator (tPA) for ischemic stroke within 3h of onset was officially approved in October 2005. METHODS We report initial 1-year clinical experience of intravenous alteplase at 0.6mg/kg in a Japanese neuro-unit. RESULTS Twenty patients received intravenous tPA, corresponding to 12% of all ischemic strokes (n=166) and 38% of ischemic strokes within 3h of onset (n=52). The mean age was 68 years old and 15% had pre-morbid dependency with modified Rankin Scale (mRS) of 3 or 4. The median baseline National Institute of Health Stroke Scale score was 19 points (range; 5-37). Average time from stroke onset to tPA delivery was 136 min (range; 87-180). Of 18 (90%) patients receiving pretreatment vascular imaging, 16 (80%) patients had a large arterial occlusion. At 3 months, excellent outcome with mRS of 0 or 1 was 25%, and good outcome with mRS of 0-2 was 35%. One patient (5%) developed symptomatic intracranial hemorrhage within 36 h. Mortality rate was 15%. CONCLUSIONS Intravenous tPA within 3h was safe and feasible, and possibly effective in clinical practice. The higher stroke severity in our cohort precluded to compare the sufficient effectiveness with clinical trials. In Japan, a post-licensed national surveillance is currently under way.

A very unusual case of fibromuscular dysplasia with multiple aneurysms of the vertebral artery and posterior inferior cerebellar artery

Fibromuscular dysplasia (FMD) is a noninflammatory and nonatheromatous arteriopathy that commonly affects the renal and cervical internal carotid arteries and sometimes the vertebral arteries (VAs). The association of FMD with intracranial aneurysms is widely known. The authors describe a rare case of FMD presenting with subarachnoid hemorrhage due to the rupture of 1 of 10 aneurysms located in the extra- and intracranial vertebral and posterior inferior cerebellar arteries. The FMD was treated successfully using flow reversal therapy, consisting of proximal occlusion of the VA with Guglielmi detachable coils, and was diagnosed histopathologically using a biopsy specimen of the distal superficial temporal artery. Originally FMD may be caused by a fragile arterial wall that may progress to the formation of an aneurysm due to hemodynamic stress. For this reason, FMD may be treatable by reducing this hemodynamic stress.

Angled rigid neuroendoscope for continuous intraoperative visual monitoring: technical note

We developed and tested a new, angled rigid endoscope as a tool for performing continuous visual monitoring during microsurgery. The shaft of the scope is angled 110 degrees at its midportion using a prism. We used the scope continuously in 30 cases including 15 pituitary tumours, 7 brain tumours, 7 cerebral aneurysms, and one hemifacial spasm. For pituitary tumours the tip of the scope was positioned in the sphenoid sinus or in the cavity formed by tumour removal; for cerebral aneurysms it was placed behind the parent artery or the aneurysmal neck. Image quality was acceptable for intraoperative monitoring. In no case did the neuroendoscope have a deleterious impact on th e proper function of the microscope or surgical instruments. This angled rigid scope was more effective for intraoperative monitoring than conventional straight scopes.

TRANSCRANIAL DOPPLER FINDINGS DURING BALLOON TEST OCCLUSION OF THE INTERNAL CAROTID ARTERY

The authors performed transcranial Doppler ultrasonography (TCD) during internal carotid artery (ICA) balloon test occlusion (BTO) and observed changes in mean flow velocity (Vm) in the middle cerebral artery (MCA), and pulsatility index (PI) while monitoring the stump pressure (Sp) of the internal carotid artery (ICA), and neurologic findings. A group of 17 patients requiring possible temporary or permanent occlusion of the ICA in the course of planned procedures first underwent BTO. A patient who either developed neurologic changes or maintained less than 60% of preocclusion Sp or Vm in the ipsilateral MCA during BTO was considered to have a positive test. Eleven patients had negative results, while in six patients, tests were positive. Mean flow velocity showed a decrease after occlusion in all cases but not to a remarkable extent in some patients. Stump pressure decreased in all negative cases after balloon inflation and than tended to increase progressively during 15 minutes of BTO. Pulsatility index tended to decrease gradually during BTO in all negative patients. However, in positive cases, PI and Sp fell steeply. Only one positive case had a neurologic symptom of severe headache. The decreased PI in the MCA reflected autoregulatory dilation of cerebral vessels to compensate for decreased absolute cerebral blood volume following ICA occlusion. Changes in PI are a good indicator for evaluating blood flow during BTO.

Combined transpetrosal and fronto-orbito-zygomatic approach to a giant skull based meningioma: a case report.

BACKGROUND Recently, various surgical approaches to skull base lesions have been developed. Skillful use of the combination of two standard approaches make possible the removal of large brain lesions, which conventionally had been considered inoperative. In this study, we present a case of a giant meningioma located in the cerebellopontine angle and middle cranial fossa. A near total resection was achieved using a combined transpetrosal and fronto-orbito-zygomatic approach. CASE REPORT A 15-year-old boy presented with a meningioma that caused a left hearing loss, dysarthria, and cerebellar ataxia. Preoperative magnetic resonance imaging revealed a giant meningioma located in the right cerebellopontine angle, middle fossa, and cavernous sinus. The patient underwent a near total resection of the tumor through a combined transpetrosal and fronto-orbito-zygomatic approach. He experienced a marked improvement postoperatively and entered high school the following year. CONCLUSIONS An approach from several angles was necessary for the giant skull based tumor presented here. A combination approach was selected for obtaining a wide operative field with minimal brain compression during resection of neoplasm. According to the individual features of each case, selection of the operative approach, decisions regarding the extent of excision, and postoperative treatment regimens should be adequately planned in the preoperative period.

Image-guided microsurgery with the Mehrkoordinaten Manipulator system for cerebral arteriovenous malformations.

Four patients with cerebral arteriovenous malformations (AVMs) underwent image-guided microsurgery with the Mehrkoordinaten Manipulator (MKM) system, which integrates a robotic microscope with a computer workstation. The patients were all male, from 8 to 51 years old (mean = 24), all presenting with intracerebral haemorrhage. The lesion was located in the deep sylvian fissure in one patient, the fronto-parieto-occipital area in one and the trigone in two. Stereotactic computed tomography and magnetic resource imaging of 1-mm slices were taken. The extent of AVM and the draining vein, predetermined with the MKM workstation, could be superimposed on the microscopic view, resulting in minimum scalp incision and craniotomy, as well as allowing for a stereotactic approach to deep-seated lesions. Superimposition of the contour of the lesion was also useful for resecting the lesion, although intraoperative diagnosis of the total resection required intraoperative digital subtraction angiography. In conclusion, image-guided microsurgery with the MKM system can assist minimally invasive and maximally effective microsurgery for cerebral AVMs.

Use of a split bone graft to correct the cosmetic deformity associated with the transpetrosal-transtentorial surgical approach: technical report.

OBJECTIVE Split bone graft reconstruction was performed after a standard transpetrosal-transtentorial approach to correct the cosmetic deformity in 18 patients. TECHNIQUE The split bone graft was made by dividing the inner table of the temporosuboccipital bone graft and covered the bone effect created by petrosectomy and mastoidectomy. The split bone graft was created and shaped during closure of the dura, so that the operation was not prolonged. RESULTS This technique produced excellent cosmetic results immediately after surgery; the results were maintained during the follow-up period of between 20 and 46 months. No complication associated with this technique was recognized. CONCLUSION Split bone graft reconstruction is a simple and safe technique for preventing the cosmetic deformity associated with a transpetrosal-transtentorial approach.

A new technique for intraoperative visual monitoring during spinal surgery: angiofiber and endoscopic ultrasonography

PURPOSE This paper is focused on our clinical use of endoscopic ultrasonography (EUS) and angiofiber (AF) for spinal microsurgery. METHODS EUS and AF were used in seven operations for syringomyelia and spinal tumor. We used EUS for extradural observation, and AF for extra and intra-dural, subarachnoid and intraluminal visual evaluation of the lesions. RESULTS EUS images of the spinal cord, roots and lesions were clear, providing precise evaluation of the lesion and the course of the shunt tube in real time during surgery. AF could provide clear vision of the syrinx lumen or subarachnoid space. Because these fine instruments could be advanced under the unresected laminae, sonographic and endoscopic images were obtained from beyond the extent of laminotomy, where the microscope could not reach. CONCLUSION Combined together, EUS and AF contributed to accurate and safe spinal surgery while minimising the laminotomy.