Haruo Yamashita

Utility of diffusion tensor imaging in the acute stage of mild to moderate traumatic brain injury for detecting white matter lesions and predicting long-term cognitive function in adults

OBJECT Traumatic brain injury (TBI) often impairs cognitive function. Diffusion tensor (DT) imaging, a novel modality, permits evaluation of the effects of head trauma on white matter nerve fibers. The objectives of the current study were to investigate where the white matter injury following mild to moderate TBI is specifically located on DT imaging in the acute disease stage and to examine the relationship between the severity of the white matter lesion on DT imaging in the acute stage of TBI and future cognitive function in the chronic disease stage. METHODS Twenty adult patients with mild to moderate TBI (Glasgow Coma Scale score between 9 and 15) underwent conventional MR and DT imaging a median of 3.5 days after injury, and 27 matched healthy controls also underwent both imaging modalities. The patients with TBI were further subdivided into 2 groups, that is, mild and more severe TBI groups, based on clinical (mild or moderate TBI), CT (diffuse brain injury [DBI] I or II), or MR imaging (normal or pathological appearance) classification. Fractional anisotropies (FAs) were compared between patients and controls using the region of interest method. Regions of interest were located in 8 different areas including the genu, stem, and splenium of the corpus callosum and the corona radiata (CR), anterior limb of the internal capsule (ALIC), posterior limb of the internal capsule (PLIC), frontal white matter (FWM), and occipital white matter (OWM) of the periventricular white matter. Eleven patients with TBI also underwent neuropsychological testing, which included the Trail Making Test, Wisconsin Card Sorting Test, Wechsler Adult Intelligence Scale-Revised, and P300 testing in the chronic disease stage (median 364 days). RESULTS Region of interest analysis demonstrated significantly lower FA values in the genu, stem, and splenium of the corpus callosum in more severe TBI groups (moderate TBI on clinical classification, DBI II on CT classification, and pathological appearance on MR imaging classification) than in controls. A significant difference was also observed in the FA of the splenium between controls and the mild TBI group of the clinical classification. No significant difference was observed in the FA of the CR, ALIC, PLIC, FWM, and OWM between controls and any of the TBI groups of clinical or imaging classifications. No significant difference was observed in the FA of any regions between mild and more severe TBI groups of the clinical or imaging classifications. Multiple regression analysis showed a statistically significant positive linear relationship between FA in the splenium and total IQ (r = 0.79, p = 0.004). A significant negative linear relationship between FA in the FWM and P300 latency was also observed (r = 0.62, p = 0.04). CONCLUSIONS Fractional anisotropy reductions in the splenium and FWM in the acute stage of mild to moderate TBI may be a useful prognostic factor for long-term cognitive dysfunction.

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.

In Vivo Cerebral Artery Microangiography in Rat and Mouse Using Synchrotron Radiation Imaging System

Microangiography with spatial resolution in the micrometer range was carried out to depict vascular responses of the cerebral artery and arterioles in rats and mice using a real-time imaging system and a third generation synchrotron radiation source at SPring-8. An X-ray direct-conversion type detector with 6-mum spatial resolution was developed for real-time biomedical imaging. The X-ray image is converted directly into an electrical signal in the photoconductive layer without image blurring. In synchrotron radiation radiography, a long source-to-object distance and a small source spot can produce high-resolution images. Microangiographic images were obtained without image blurring and were stored in a digital frame memory system with a 1024 x 1024-pixel, 10-bit format. In imaging experiments, vasoconstriction and vasodilatation of small cerebral arteries were visualized in response to hypercapnia, hemorrhagic hypotension, and vasoactive agents after iodine contrast agent injection into the carotid artery.

Cerebral hyperperfusion during surgical resection of high-flow arteriovenous malformations

Cerebral hemodynamics were evaluated in 16 patients with arteriovenous malformations (AVMs) using intraoperative thermogradient or laser Doppler flowmeter. The postexcision/preexcision blood flow ratio was determined. Two of seven patients with large AVMs (> or = 4 cm) developed a postoperative hematoma. Their flow ratios were larger than 1.9. In 4 patients with large AVMs, their blood flow ratios were reduced from an initial ratio exceeding 2.0 to less than 1.5 using carotid or special flow regulation clamps. These patients did not develop any hemorrhagic complication. In 9 patients of small AVMs (< 4 cm), the ratio was significantly low and there were no hemorrhagic complications.

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.

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.

Rapid tumor growth with glial differentiation of central neurocytoma after stereotactic radiosurgery

Although stereotactic radiosurgery (SRS) is effective for central neurocytoma (CN), the long-term outcome of SRS remains unclear. We present a case of recurrent CN that was diagnosed 10years after surgical resection and consecutive stereotactic radiotherapy. The patient was treated with SRS for the recurrent tumor, but underwent two-staged surgery once again due to rapid tumor growth. Histological features of the recurrent tumor were consistent with the diagnosis of CN. However, an increased Ki-67 proliferation index (3.4%), aberrant angiogenesis and glial differentiation of the tumor cells were observed, which were not identified in the initial CN. In addition, vascular endothelial growth factor (VEGF) and VEGF receptor were highly expressed in the recurrent tumor cells, as well as in the vascular endothelial cells. Our case suggests that malignant transition with aberrant angiogenesis and glial differentiation may be attributable to SRS.