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Reizo Shirane and Philip R. Weinstein

✓ The effects of pretreatment with mannitol on local cerebral blood flow (CBF) after permanent or temporary global cerebral ischemia were evaluated with 14C-iodoantipyrine autoradiography in rats under halothane-N2O endotracheal anesthesia. Blood pressure, pulse rate, arterial blood gas levels, and electroencephalographic (EEG) tracings were monitored throughout the experiments. After permanent occlusion of the basilar artery and both external carotid and pterygopalatine arteries, severe global ischemia was induced by permanent occlusion of the common carotid arteries (CCA's) or by a 30-minute temporary CCA occlusion followed by 5 minutes of reperfusion. Intravenous mannitol (25%, 1 gm/kg) or saline solution was administered 5 minutes before occlusion of the CCA's. Cerebral blood flow was measured in 24 anatomical regions.

The EEG tracings flattened within 2 to 3 minutes after the onset of ischemia, and no recovery was observed during reperfusion. In the mannitol-treated rats and the saline-treated controls, autoradiographic studies after permanent occlusion showed no CBF in the forebrain or cerebellum, although brain-stem and spinal cord CBF values were normal. After 5 minutes of reperfusion, CBF in the cortex, basal ganglia, and white matter was 100% to 200% higher in mannitol-treated rats and 50% to 100% higher in saline-injected rats than in the nonischemic anesthetized control group. Heterogeneously distributed areas of no-reflow were seen in all saline-injected rats but were observed in none of the mannitol-treated rats. Pretreatment with mannitol prevented postischemic obstruction of the microcirculation during 5 minutes of recirculation after 30 minutes of severe temporary ischemia, but the EEG signals did not recover. Further studies of the functional and morphological responses to longer periods of postischemic recirculation are needed to verify the extent to which these mannitol-induced effects are protective.

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Tomomi Kimiwada, Toshiaki Hayashi, Reizo Shirane and Teiji Tominaga

OBJECTIVE

Some pediatric patients with moyamoya disease (MMD) present with posterior cerebral artery (PCA) stenosis before and after anterior circulation revascularization surgery and require posterior circulation revascularization surgery. This study evaluated the factors associated with PCA stenosis and assessed the efficacy of posterior circulation revascularization surgery, including occipital artery (OA)–PCA bypass, in pediatric patients with MMD.

METHODS

The presence of PCA stenosis before and after anterior circulation revascularization surgery and its clinical characteristics were investigated in 62 pediatric patients (< 16 years of age) with MMD.

RESULTS

Twenty-three pediatric patients (37%) with MMD presented with PCA stenosis at the time of the initial diagnosis. A strong correlation between the presence of infarction and PCA stenosis before anterior revascularization was observed (p < 0.001). In addition, progressive PCA stenosis was observed in 12 patients (19.4%) after anterior revascularization. The presence of infarction and a younger age at the time of initial diagnosis were risk factors for progressive PCA stenosis after anterior revascularization (p < 0.001 and p = 0.002, respectively). Posterior circulation revascularization surgery, including OA-PCA bypass, was performed in 9 of the 12 patients with progressive PCA stenosis, all of whom showed symptomatic and/or radiological improvement.

CONCLUSIONS

PCA stenosis is an important clinical factor related to poor prognosis in pediatric MMD. One should be aware of the possibility of progressive PCA stenosis during the postoperative follow-up period and consider performing posterior circulation revascularization surgery.

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Toshiaki Hayashi, Reizo Shirane, Miki Fujimura and Teiji Tominaga

Object

Young patients with moyamoya disease frequently exhibit extensive cerebral infarction at the time of initial presentation, and even in the early postoperative period. To investigate clinical characteristics in the early postoperative period, the authors prospectively analyzed findings of MR imaging, MR angiography, and SPECT before and after surgery. The authors focused in particular on how postoperative neurological deterioration occurred.

Methods

Between August 2005 and June 2009, 22 patients younger than 18 years of age with moyamoya disease were treated at Miyagi Children's Hospital. The mean patient age (± SD) was 8.58 ± 4.55 years (range 2–17 years). Superficial temporal artery–middle cerebral artery bypass and indirect bypass of encephalosynangiosis between the brain surface and the temporal muscle, galea, and dura mater were performed in 35 hemispheres. Magnetic resonance imaging and MR angiography were performed before surgery, at 7 days postoperatively, and 3–6 months after surgery. A 123I-isopropyl iodoamphetamine SPECT scan was also obtained pre- and postoperatively.

Results

During the postoperative period, neurological deterioration was observed after 15 operations (10 cases of motor paresis, 1 of aphasia, and 4 of sensory disturbance) in 13 patients. All symptoms had resolved by the time of discharge, except in 2 patients who suffered cerebral infarction. All patients exhibited disappearance (94.3%) or reduction (5.7%) of transient ischemic attacks (TIAs) during the follow-up period. Perioperative studies revealed 2 different types of radiological findings, focal uptake decrease on SPECT indicative of cerebral ischemia due to dynamic change in cerebral hemodynamics caused by bypass flow, the so-called watershed shift, and perioperative edematous lesions on MR imaging due to cerebral hyperperfusion. The frequent occurrence of preoperative TIAs was significantly associated with watershed shift, whereas preoperative MR imaging findings and preoperative SPECT findings were not. Age at operation was the only factor significantly associated with postoperative hyperperfusion.

Conclusions

In young patients, moyamoya disease exhibits rapid progression, resulting in poor clinical outcome. The risk of postoperative neurological deterioration in very young moyamoya patients with frequent TIAs should be noted. The findings in this study showed that direct bypass is not completely safe in patients with moyamoya disease because it causes dynamic change in postoperative cerebral hemodynamics.

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Toshiki Endo, Yasuko Yoshida, Reizo Shirane and Takashi Yoshimoto

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Tomomi Kimiwada, Toshiaki Hayashi, Ayumi Narisawa, Reizo Shirane and Teiji Tominaga

OBJECT

Some pediatric patients with middle cranial fossa arachnoid cysts present with symptoms of increased intracranial pressure (ICP) and require shunt placement after a cyst fenestration. However, factors concerning increased ICP after fenestration followed by shunt placement have not been elucidated. This study evaluated factors that are associated with shunt placement following cyst fenestration in pediatric patients with middle cranial fossa arachnoid cysts.

METHODS

Twenty-six pediatric patients with middle cranial fossa arachnoid cysts who were surgically treated at a single institution between 2004 and 2013 were retrospectively identified. The surgical indications for middle cranial fossa arachnoid cysts were as follows: 1) arachnoid cysts associated with symptoms such as headache and abnormally enlarging head circumference; 2) progressively expanding arachnoid cysts; and 3) large arachnoid cysts such as Galassi Type III. A cyst fenestration was performed as a first-line treatment, and shunt placement was required if symptoms associated with increased ICP were found following fenestration. The risk factors evaluated included age, sex, presenting symptoms, the presence of head enlargement, progressive cyst expansion, and subdural hematoma/hygroma.

RESULTS

Four patients (15.4%) required shunt placement after cyst fenestration. Younger age, abnormal head enlargement, and progressive cyst expansion before fenestration were significantly associated with the need for shunt placement following fenestration. Arachnoid cysts decreased in size in 22 patients (84.6%) after fenestration and/or shunt placement. The presence of symptoms was not associated with postoperative cyst size in this study.

CONCLUSIONS

In this study, younger age, abnormal head enlargement, and progressive cyst expansion were risk factors for shunt placement after cyst fenestration in pediatric patients with middle cranial fossa arachnoid cysts. It is important to consider that cyst fenestration may not be effective because of a latent derangement of CSF circulation in patients with these risk factors.

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Reizo Shirane, Takeo Kondo, Yasuko K. Yoshida, Susumu Furuta and Takashi Yoshimoto

✓ A rare case of cerebral pseudoaneurysm located at the internal carotid artery (ICA) was caused by the removal of a ventricular catheter in an infant. This 4-month-old girl underwent ventriculoperitoneal shunt revision, during which the old ventricular catheter was removed from the posterior horn of the left lateral ventricle, but the choroid plexus was pulled out by the tip of the catheter. Intraventricular hemorrhage (IVH) and subarachnoid hemorrhage were observed postoperatively. Magnetic resonance (MR) angiography performed on the 12th postoperative day revealed ICA stenosis and aneurysm formation at the C1 portion of the left ICA. Contrast-enhanced computerized tomography (CT) scans obtained on the 21st postoperative day revealed recurrent IVH and enlargement of the lesion. The patient underwent surgery for treatment of the aneurysm. Operative findings revealed a pseudoaneurysm arising from the left ICA at the proximal end of the anterior choroidal artery (AChA). The aneurysm was removed and the wall of the ICA was reconstructed. Postoperative three-dimensional CT scanning and MR angiography demonstrated disappearance of the aneurysm and preservation of the ICA. The patient was discharged without additional neurological deficits.

Many complications, including IVH, are associated with removal of a ventricular catheter. This case shows that pseudoaneurysm formation can occur in a remote region due to avulsion of the AChA from the ICA. In most circumstances a ventricular catheter can be removed without difficulty. However, precision and caution should be exercised when removing a ventricular catheter.

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Toshiaki Hayashi, Reizo Shirane, Takahiro Kato and Teiji Tominaga

Object

Although a cerebrospinal fluid shunt procedure is one of the most frequently performed operations in pediatric neurosurgery, the infection rate due to the procedure is not low. The authors have hypothesized that the key to reducing surgical shunt infections is to reduce bacteria from the operating field and wound. This hypothesis has been tested in a prospective nonrandomized controlled study at the authors' department.

Methods

Beginning in August 2006, during shunt procedures the authors began routinely irrigating the operating field and wound with amikacin containing saline, using a jet of fluid from a syringe. Prior to this new routine no irrigation techniques were used, providing an adequate control group for comparing the effect of the irrigation technique. Data obtained in all patients undergoing shunt insertions or revisions for hydrocephalus performed between October 1, 2003, and November 30, 2007, were reviewed.

Results

A total of 101 shunt procedures were performed in 63 patients (34 females and 29 males) during the study period. The mean age of all patients was 48.2 ± 61.8 months. A total of 61 shunt procedures were performed before August 2006, and 40 were performed after August 2006. There was no statistical difference between the ages of patients in the 2 groups (p = 0.64). Eight total infections occurred during the 90 days of the postoperative period (7.9% overall infection rate). All 8 infections occurred before implementation of the irrigation technique (13.1% infection rate), but no infections were noted after beginning use of the irrigation procedure (0% infection rate). There was a statistically significant difference in the infection rate between the 2 groups (p = 0.021).

Conclusions

Use of an irrigation strategy aimed at reducing bacteria from the operating field and wound can be considered an effective procedure for preventing shunt infection.

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Atsuhiro Nakagawa, Ching-Chan Su, Kiyotaka Sato and Reizo Shirane

Object. Circulating blood volume (cBV) is reported to decrease in patients who suffer a subarachnoid hemorrhage (SAH), but little is known about the correlation between changes in cBV, and patient clinical condition and time course after SAH, especially during the very acute stage. To determine appropriate management of patients with SAH, the authors measured cBV by using pulse spectrophotometry immediately after patient admission. They also evaluated whether the timing of surgery influenced changes in cBV.

Methods.Circulating blood volume was measured in a total of 73 patients who were divided into the following three groups: Group A (very acute SAH) consisted of 14 SAH cases, Group B (acute SAH) included 34 SAH cases, and Group C (controls) included 25 other neurosurgical cases. All patients in Group A underwent aneurysm clipping within 6 hours after onset of SAH, whereas all patients in Group B underwent aneurysm clipping within 72 hours after onset. Hypervolemic therapy was not performed in patients with SAH.

Before surgery, cBV was significantly lower in patients in Group B than in those in Group C, but there was no significant difference in this parameter when comparing Groups A and C. Although there was a transient drop in cBV in Group B patients for at least 3 days after surgery, there was no significant change in cBV in Group A patients during the study period. None of the Group A patients suffered from symptomatic vasospasm; however, four Group B patients did experience symptomatic vasospasm.

Conclusions. The authors assert that normovolemic fluid management is appropriate for patients who undergo surgery during the very acute stage of SAH, whereas a relatively hypervolemic therapy is necessary for 3 to 5 days after operation to prevent early hypovolemia in patients who undergo surgery during the acute stage of SAH.

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Kenichi Sato, Hidefumi Jokura, Reizo Shirane, Tetsuya Akabane, Hiroshi Karibe and Takashi Yoshimoto

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Toshiaki Hayashi, Reizo Shirane, Michiko Yokosawa, Tomomi Kimiwada and Teiji Tominaga

Object

The rate of infection following shunt procedures is unacceptably high. The authors have hypothesized that the key to reducing the shunt infection rate is in reducing bacteria in the operating field and wound. This hypothesis has been tested in a prospective nonrandomized controlled manner.

Methods

Data obtained in all patients undergoing shunt insertions or revisions for hydrocephalus performed between October 1, 2003, and June 12, 2009, were reviewed. Starting in August 2006, we began routinely irrigating the operating field and wound with saline solution from a syringe. Prior to this, we had not used any irrigation techniques, providing an adequate control group (Group A) for the effect of the irrigation technique. Prior to November 2007, we used saline containing amikacin for irrigation (Group B). After that date, we used saline only for irrigation (Group C).

Results

A total of 150 shunt procedures were performed in 79 girls and 71 boys during the study period. The mean age of all patients was 44.0 ± 59.1 months. Groups A, B, and C comprised 61, 40, and 49 shunt procedures, respectively. There was no statistical difference in age among the 3 groups. Nine infections occurred within 90 days in the postoperative period. The overall infection rate was 6.0%. Eight infections occurred before introducing the irrigation procedure (infection rate 13.1%). One infection was noted after introducing irrigation (Group B [0.0%] + Group C [2.0%]; combined B and C infection rate = 1.1%). There was a statistical difference in the infection rate between Group A and Groups B and C combined (p = 0.003), Groups A and B (p = 0.021), and Groups A and C (p = 0.035). In contrast, no statistical difference was observed between Groups B and C (p > 0.99). Six of the 9 infections were due to staphylococcal species.

Conclusions

An irrigation technique used to reduce bacteria in the operating field and wound is effective for preventing shunt infection. Irrigation alone, and not antibiotics, contributed to the prophylaxis of shunt infection.