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Accurate and long-term transposition of offending vessels is required in microvascular decompression (MVD) for the treatment of hemifacial spasm (HFS) and trigeminal neuralgia (TN). We created ion-beam implanted of an expanded-polytetrafluoroethylene (i-ePTFE) surface to transpose offending vessels in MVD. In 13 patients with MVD, we concealed and transposed offending vessels with tape-shaped i-ePTFE, and relieved facial and trigeminal nerve compression by attaching the i-ePTFE to the dura with fibrin glue. After surgery, none of the patients reported further symptoms or experienced recurrence of symptoms up to 12 months post-surgery. Favorable surgical outcomes are obtainable, since i-ePTFE has high tissue affinity and is easy to manipulate, even under a narrow and deep operative field. Our results suggested that i-ePTFE is very useful for transposition in MVD.

A newly designed hydroxyapatite (HA) spacer for cervical laminoplasty is provided with a hole through which the titanium miniplate is passed. A new method of unilateral open-door laminoplasty with titanium miniscrew and miniplate through this HA spacer is described. Twenty-two patients with cervical stenotic disorders were treated by this procedure. Only the predominantly affected side of the laminae is exposed. The supraspinous and interspinous ligaments and the deep muscle layer in the contralateral side are left intact. A 4-mm wide gutter near the intervertebral joint is made and contralateral hinges are made under the deep muscle layer with minimum detachment of these muscles. The opened lamina is fixed with the titanium miniplate passed through the hole in the newly designed HA spacer. Mean operative time for the 22 operations was 193.5 minutes. Mean enlargement of the minimum spinal canal diameter was 50.9%. Neurological outcomes after 3 months were evaluated according to the Japanese Orthopaedic Association (JOA) scoring. Mean recovery rate of JOA score by Hirabayashi's method was 49.5%. Only 2 patients reported postoperative axial neck pain. Our method for unilateral open-door laminoplasty provides adequate decompression and tight fixation of laminae, and is less invasive to the posterior supporting elements of cervical spine.

A 20-year-old woman presented with subarachnoid hemorrhage (SAH) in the frontal interhemispheric fissure, and a cystic lesion in the left frontal lobe. Cerebral angiography demonstrated no aneurysm or vascular abnormalities. T(1)-weighted magnetic resonance imaging with contrast medium revealed an enhanced lesion along the falx. The lesion and cyst were removed, and histological examination revealed a pilocytic astrocytoma. Spontaneous intracranial hemorrhage from pilocytic astrocytoma is rare, with only 15 reported cases mostly involving intratumoral hemorrhage in the parenchyma of hypothalamic and cerebellar tumors. SAH caused by cerebral hemisphere pilocytic astrocytoma is extremely rare. This case suggests that interhemispheric fissure SAH, not associated with aneurysm or abnormal vascularity, could originate from small, low-grade glioma in the superficial cerebral hemisphere.

A 60-year-old man presented with a rare cerebellar inflammatory myofibroblastic tumor (IMT) manifesting as gait disturbance and dysarthria. Brain magnetic resonance imaging demonstrated an intra-axial round-shaped isointense mass homogeneously enhanced with gadolinium in the right cerebellar hemisphere, as well as perifocal edema extending to the brain stem and right thalamus. The tumor was elastic hard and was resected en bloc with a clear margin. Histological examination revealed IMT with spindle cells and collagen, but negative for anaplastic lymphoma kinase expression. IMT most commonly affects the lung, but may involve many other parts of the body. There is some debate regarding the disease entity of IMT in the central nervous system (IMT-CNS) because of its rarity and high frequency of recurrence. IMT-CNS is an important differential diagnosis among tumor-like intracranial lesions and total resection is required.

A 66-year-old man presented with complaints of numbness for the past 5 years and progressive motor weakness of the right leg for the previous 2 months. Magnetic resonance imaging revealed large intra- and extracranial tumors in the frontoparietal region. Physical examination suggested the extracranial lesion was a subcutaneous lipoma, which had been partially resected 60 years before, connected to the intracranial lesion via a defect of the skull. Gross total removal of the tumors was performed. Histological examination showed the intracranial lesion was epidermoid tumor, and connected to the extracranial lipoma by a lipoma bridge. The symptoms improved remarkably following surgery. This case of intracranial epidermoid tumor associated with intra-extracranial lipoma indicates that implantation of skin tissue in childhood carries the risk of epidermoid tumor even after several decades. Neuroimaging screening is recommended to detect the development of any intracranial components.

The concentrations and application methods of elastase in the rabbit aneurysm model were optimized to control the initiation of aneurysms and to cause rupture in a stepwise, controlled fashion. The common carotid artery of male Japanese albino rabbits was exposed. No aneurysm was generated if the adventitia was not dissected. After gentle removal of the adventitia, a two-fold dilution series of elastase was applied to the lesion and observed over a period of 2 hours. Various stages of aneurysmal lesions, from spindle-shaped enlargement to rupture, were produced in proportion to the elastase concentration. Application of elastase stock solution (5 U/mg of type I porcine pancreatic elastase) resulted in rupture within 30 minutes in all six animals. Elastase 1:2 solutions caused oozing in all animals, but subsequent rupture in only three of six animals. Histological examination found serious destruction of the internal elastic lamina and media, with expansion of the very thin wall. Elastase 1:4 to 1:16 solutions caused spindle-like distention of the entire artery and the development of tortuosity at the lesion. Elastase 1:32 or weaker solutions caused only localized dilatations. Overall, the destruction of the tunica media became less severe with decreased elastase concentration. Furthermore, the bursting pressure of the aneurysms decreased with increasing elastase concentrations. In particular, aneurysms produced by the elastase 1:2 solution ruptured at less than 150 mmHg, whereas aneurysms induced by the elastase 1:4 or weaker solutions did not rupture within the physiological range of blood pressure. The present aneurysm model requires shorter preparation time and enables accurate control of aneurysm development and rupture.

The role of endogenous nitric oxide (NO) synthesis was investigated in the regulation of the internal (ICA) and external carotid artery (ECA) beds of ventilated, anesthetized rats in a model in which the left common carotid artery was perfused from the aorta via an extracorporeal circuit under conditions of non-pulsatile controlled flow. The territories supplied by the extracranial ICA and ECA were studied separately following occlusion of the appropriate artery. An inhibitor of nitric oxide synthesis, N(G)-monomethyl-L-arginine (L-NMMA), and the NO synthase substrate L-arginine were administered via a jugular venous catheter. NO synthesis exerted an important influence on the pressure-flow relationships of the ICA and ECA circulations as L-NMMA increased input perfusion pressure at any given flow rate. However, in the presence of NO synthesis, hydraulic conductance increased rapidly with flow in the ICA, thereby stabilizing perfusion pressures over a wide range of flow rates, whereas this phenomenon was not evident in the ECA territory. Differences between the two circulations were further emphasized by observations that L-arginine antagonized the systemic hemodynamic response to L-NMMA and its effects on the conductance of the ECA bed, whereas the effects of L-NMMA were irreversible in the ICA territory.

The pathogenesis of sudden death during subarachnoid hemorrhage (SAH) still remains to be elucidated. A new rat common carotid artery-prechiasmal extracorporeal shunt model was designed to study the effect of different severities of SAH on intracranial pressure (ICP), regional cerebral blood flow (rCBF), and mortality. Different severities of SAH were induced by controlling the bleeding period (from 30 to 90 sec) and number of bleedings (one or three times). SAH caused a dramatic increase in ICP and immediate depression of rCBF, which recovered slowly to a certain extent. ICP increased sharply within the first 30 seconds and reached a plateau concomitant with nearly zero rCBF, which suggested the occurrence of cerebral circulation arrest. Bleeding of more than 60 seconds and increased ICP over 80 mmHg were directly correlated with the mortality. Respiratory arrest was the first sign of death, immediately followed by cardiac depression resulting in sudden death. This model combines arterial bleeding with systemic blood pressure and controlled bleeding time to simulate the acute period of SAH.

The authors report the clinicopathological findings in six cases of bacterial intracranial aneurysms. All patients received appropriate high-dose antibiotics, and four were treated surgically. One patient with multiple aneurysms of the main trunks died of disseminated intravascular coagulation. Autopsy disclosed no apparent aneurysm or inflammatory cell infiltration, but a partially interrupted internal elastic lamina and thickened intima were disclosed at the angiographical aneurysm sites. These findings suggest that 1) appropriate high-dose antibiotics are effective against inoperable bacterial aneurysms in the main trunks, 2) new aneurysms may be formed in patients with cyanotic congenital heart disease, because bacterial emboli can directly reach the cerebral circulation and reimplant on the fragile arterial walls after vasculitis. Histological examination of aneurysmal walls revealed inflammatory cell infiltration after resolution of clinical endocarditis. This suggests that both appropriate high-dose antibiotic therapy and surgery should be considered in patients with distal bacterial aneurysms.