Showing papers by "Miki Fujimura published in 2007"

Pressure-dependent effect of shock waves on rat brain: induction of neuronal apoptosis mediated by a caspase-dependent pathway.

Abstract: Object. Shock waves have been experimentally applied to various neurosurgical treatments including fragmentation of cerebral emboli, perforation of cyst walls or tissue, and delivery of drugs into cells. Nevertheless, the application of shock waves to clinical neurosurgery remains challenging because the threshold for shock wave‐induced brain injury has not been determined. The authors investigated the pressure-dependent effect of shock waves on histological changes of rat brain, focusing especially on apoptosis. Methods. Adult male rats were exposed to a single shot of shock waves (produced by silver azide explosion) at overpressures of 1 or 10 MPa after craniotomy. Histological changes were evaluated sequentially by H & E staining and terminal deoxynucleotidyl transferase‐mediated deoxyuridine triphosphate nick-end labeling (TUNEL). The expression of active caspase-3 and the effect of the nonselective caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (Z-VAD-FMK) were examined to evaluate the contribution of a caspase-dependent pathway to shock wave‐induced brain injury. High-overpressure (. 10 MPa) shock wave exposure resulted in contusional hemorrhage associated with a significant increase in TUNEL-positive neurons exhibiting chromatin condensation, nuclear segmentation, and apoptotic bodies. The maximum increase was seen at 24 hours after shock wave application. Low-overpressure (1 MPa) shock wave exposure resulted in spindle-shaped changes in neurons and elongation of nuclei without marked neuronal injury. The administration of Z-VAD-FMK significantly reduced the number of TUNEL-positive cells observed 24 hours after high-overpressure shock wave exposure (p , 0.01). A significant increase in the cytosolic expression of active caspase3 was evident 24 hours after high-overpressure shock wave application; this increase was prevented by Z-VAD-FMK administration. Double immunofluorescence staining showed that TUNEL-positive cells were exclusively neurons. Conclusions. The threshold for shock wave‐induced brain injury is speculated to be under 1 MPa, a level that is lower than the threshold for other organs. High-overpressure shock wave exposure results in brain injury, including neuronal apoptosis mediated by a caspase-dependent pathway. This is the first report in which the pressure-dependent effect of shock wave on the histological characteristics of brain tissue is demonstrated.

Symptomatic hyperperfusion after superficial temporal artery–middle cerebral artery anastomosis in a child with moyamoya disease

Abstract: Surgical revascularization for moyamoya disease prevents cerebral ischemic attacks by improving cerebral blood flow (CBF). It is undetermined, however, how rapid increase in CBF affects ischemic brain at acute stage, especially in children. A 4-year-old girl with moyamoya disease underwent right superficial temporal artery–middle cerebral artery (STA–MCA) anastomosis. She suffered temporary left facial palsy 5 days after surgery. Postoperative N-isopropyl-p-[123I]iodoamphetamine single-photon emission computed tomography (123I-IMP-SPECT) revealed focal intense increase in CBF at the sites of anastomosis. Magnetic resonance imaging/angiography showed the apparently patent STA–MCA anastomosis as a thick high signal without ischemic changes. Her symptom improved 9 days after surgery, and single-photon emission computed tomography (SPECT) 2 months later showed normalization of CBF. Surgical revascularization completely relieved the transient ischemic attack on her left hand that was seen before surgery. We demonstrated, for the first time, that delayed focal neurological deficit after STA–MCA anastomosis can be caused by focal hyperperfusion in childhood moyamoya disease.

Expression of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinase (TIMP) in cerebral cavernous malformations: immunohistochemical analysis of MMP-2, -9 and TIMP-2.

Abstract: Object. Hemorrhage from cerebral vascular malformations such as cerebral cavernous malformation (CCM) can result in significant mortality and morbidity, but its underlying mechanism is undetermined. Excessive degradation of the vascular matrix by matrix metalloproteinases (MMPs), proteolytic enzymes that degrade all the components of extracellular matrix, can lead to instability of the vascular structure and can thereby cause bleeding. Thus we examined the expression of MMPs and tissue inhibitors of metalloproteinase (TIMP) in CCM.

[Seizure following superficial temporal-middle cerebral artery anastomosis in patients with moyamoya disease: possible contribution of postoperative cerebral hyperperfusion].

Abstract: Surgical revascularization for moyamoya disease prevents cerebral ischemic attacks by improving cerebral blood flow (CBF). Seizure is known as a rare complication after revascularization for moyamoya disease, although its underlying mechanism is undetermined. We investigated the relationship between seizure attack and postoperative alteration in CBF in patients with moyamoya disease. CBF was routinely measured by N-isopropyl-p-[123I] iodpamphetamine (123I-IMP-SPECT) 1 and 7 days after superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis on 64 sides of the 44 consecutive patients (male:female = 13:31, 2-62 years old) with moyamoya disease. Three patients (male:female = 1:2, 40-55 years old) suffered from seizure attack at 1 to 10 days after surgery. Two of the three patients manifested as seizures at 8-10 days after surgery and presented transient neurologic deteriolation before seizure. Postoperative SPECT revealed significant increase in CBF at the sites of the anastomosis in all three patients. Postoperative magnetic resonance imaging showed no ischemic changes, and magnetic resonance angiography showed the apparently patent STA-MCA anastomosis as thick high signal intensity sign in all three patients. The anatomical location and the temporal profile of hyperperfusion were completely in accordance with the focus of seizure attack. Intensive blood pressure control and the use of antiepileptic agents were instituted. The neurologic deficits were resolved and no seizure attack recurred in three patients. Seizure following STA-MCA anastomosis can be caused by hyperperfusion in patients with moyamoya disease. When seizure attacks occur, routine CBF measurement is recommended to differentiate hyperperfusion and ischemia, since the treatments for these conditions are contradictory.

Association of cavernous malformation within vestibular schwannoma: immunohistochemical analysis of matrix metalloproteinase-2 and -9.

Abstract: A 65-year-old man presented with a rare case of cavernous malformation with hemorrhage located within vestibular schwannoma. He had suffered hearing impairment for 20 years, and was admitted to our hospital with vertigo and ataxic gait. Neurological examination revealed hearing loss, facial nerve paresis, and left cerebellar ataxia. Magnetic resonance imaging demonstrated a left vestibular schwannoma 35 mm in diameter, as well as a heterogeneous area associated with hypointense rim within the tumor, indicating intratumoral hemorrhage. Subtotal removal of the tumor together with the fibrously encapsulated hematoma was performed through a left retrosigmoid craniotomy. Histological examination of the surgical specimen revealed cavernous malformation within vestibular schwannoma. Immunohistochemistry for matrix metalloproteinase (MMP)-2 and -9, and tissue inhibitors of metalloproteinase-2 showed strong expression in the endothelial cells of the cavernous malformation, but not in the interstitial structures. His symptoms significantly improved after surgery and he underwent gamma-knife therapy for the residual tumor. Cavernous malformations may show dynamic characteristics such as repeated hemorrhage and de novo formation. MMP-2 and -9, which are implicated in angiogenesis and hemorrhage, may be upregulated in such tumors.

高感度赤外線画像システムiris-vを用いたもやもや病術中血行動態モニタリングによる術後過灌流の予測 : 2症例の検討

Abstract: Surgical revascularization for moyamoya disease prevents cerebral ischemic attacks by improving cerebral blood flow (CBF). But little is known about the change in intraoperative cerebral hemodynamics and its effect on postoperative neurological status, including symptomatic cerebral hyperperfusion. To address this issue, we applied a novel infrared imaging system (IRIS-V infrared imaging system) for intraoperative monitoring of surface hemodynamics in 2 patients with moyamoya disease. We investigated the correlation between clinical, radiological findings, and changes of the gradation value in infrared imaging using imaging software. The camera showed apparent revascularization during surgery in both cases. In case 1, a 36-year-old male who presented with transient ischemic attack (TIA) underwent superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis with pial synangiosis. His cerebrovascular reactivity was significantly compromised as shown by preoperative IMP-SPECT. Intraoperative infrared imaging disclosed an increase in brain surface temperature due to increase in blood flow around the anastomosis. The gradation value gradually increased after recanalization of bypass during several minutes. Postoperative IMP-SPECT showed a focal increase in CBF around the site of anastomosis 1 day after surgery. Beginning on the next day, he suffered fluctuated aphasia, numbness and fine movement disturbance on his right hand for 7 days. Intensive blood pressure control relieved his symptoms, and he was discharged without neurological deficit. The anatomical location and the temporal profile of hyperperfusion accorded with the neurological deficits. In case 2, a 29-year-old female who presented with TIA had already undergone surgical revascularization on the symptomatic right side. Then she underwent left STA-MCA anastomosis on the asymptomatic side with decreased cerebrovascular reserve capacity. Intraoperative infrared imaging disclosed no significant increase in brain surface color around the site of anastomosis except for the apparent revascularization through STA-MCA bypass. The gradation value did change significantly before or after recanalization of bypass. Postoperative IMP-SPECT showed a mild increase in CBF on the entire MCA territory without focal intense accumulation. Her postoperative course was uneventful, and she was discharged without neurological deterioration. Characteristic patterns of the intraoperative cerebral hemodynamics as delineated by IRIS-V may be the optimal predictor for postoperative transient symptomatic hyperperfusion after direct bypass in patients with moyamoya disease.