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D. Douglas Cochrane

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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, Tomomi Kimiwada, Reizo Shirane, and Teiji Tominaga

OBJECTIVE

Lipoma of the conus medullaris (LCM) causes neurological symptoms known as tethered cord syndrome (TCS). The symptoms can be seen at diagnosis and during long-term follow-up. In this report, pediatric patients with LCMs who underwent untethering surgery, under the policy of performing surgery if diagnosed regardless of symptoms, were retrospectively reviewed to evaluate long-term surgical outcomes. Possible risk factors for retethered cord syndrome (ReTCS) were evaluated in the long-term follow-up period.

METHODS

A total of 51 consecutive pediatric patients with LCMs who underwent a first untethering surgery and were followed for > 100 months were retrospectively analyzed. The surgery was performed with the partial removal technique. Pre- and postoperative clinical and radiological data were reviewed to analyze the outcomes of surgery and identify potential risk factors for ReTCS.

RESULTS

During follow-up, 12 patients experienced neurological deterioration due to ReTCS. The overall 10-year and 15-year progression-free survival rates were 82.3% and 75.1%, respectively. On univariate analysis, a lipoma type of lipomyelomeningocele (OR 11, 95% CI 2.50–48.4; p = 0.0014), patient age at the time of surgery (OR 0.41, 95% CI 0.14–1.18; p = 0.0070), and the mean patient growth rate after surgery (OR 2.00, 95% CI 1.12–3.41; p = 0.0040) were significant factors associated with ReTCS. Cox proportional hazard models showed that a lipoma type of lipomyelomeningocele (HR 5.16, 95% CI 1.54–20.1; p = 0.010) and the mean growth rate after surgery (HR 1.88, 95% CI 1.00–3.50; p = 0.040) were significantly associated with the occurrence of ReTCS.

CONCLUSIONS

More complex lesions and a high patient growth rate after surgery seemed to indicate increased risk of ReTCS. Larger prospective studies and registries are needed to define the risks of ReTCS more adequately.

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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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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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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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Toshiaki Hayashi, Akifumi Suzuki, Yasuji Yoshida, Hiromu Hadeishi, Takaaki Yoshida, and Nobuyuki Yasui

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Toshiaki Hayashi, Akifumi Suzuki, Jun Hatazawa, Iwao Kanno, Reizo Shirane, Takashi Yoshimoto, and Nobuyuki Yasui

Object. The mechanism of reduction of cerebral circulation and metabolism in patients in the acute stage of aneurysmal subarachnoid hemorrhage (SAH) has not yet been fully clarified. The goal of this study was to elucidate this mechanism further.

Methods. The authors estimated cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2), O2 extraction fraction (OEF), and cerebral blood volume (CBV) preoperatively in eight patients with aneurysmal SAH (one man and seven women, mean age 63.5 years) within 40 hours of onset by using positron emission tomography (PET). The patients' CBF, CMRO2, and CBF/CBV were significantly lower than those in normal control volunteers. However, OEF and CBV did not differ significantly from those in control volunteers. The significant decrease in CBF/CBV, which indicates reduced cerebral perfusion pressure, was believed to be caused by impaired cerebral circulation due to elevated intracranial pressure (ICP) after rupture of the aneurysm. In two of the eight patients, uncoupling between CBF and CMRO2 was shown, strongly suggesting the presence of cerebral ischemia.

Conclusions. The initial reduction in CBF due to elevated ICP, followed by reduction in CMRO2 at the time of aneurysm rupture may play a role in the disturbance of CBF and cerebral metabolism in the acute stage of aneurysmal SAH.

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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.

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Toshiaki Hayashi, Jun Takemoto, Tatsuhiro Ochiai, Tomomi Kimiwada, Reizo Shirane, Kiyohide Sakai, Haruo Nakagawa, and Teiji Tominaga

Object

After untethering of spinal dysraphism, some patients present with neurological deterioration, defined as retethered cord syndrome. It is known that surgical untethering is an option for improving the symptoms of retethered cord syndrome. Previous reports have shown that postoperative improvement in retethered cord syndrome was noted in the majority of patients presenting with pain, and in more patients with motor weakness than in those with urological symptoms. The authors speculate that subjective symptoms may be detected while symptoms are still reversible. In contrast, changes in urological function are less easy to diagnose, and delays in treatment may be complicated by advanced symptoms. In this study, patients with retethered cord syndrome were evaluated to investigate the benefits of performing routine urodynamic study to detect detrusor overactivity, which is considered to be a subclinical change of urological function, and to investigate the efficacy of early untethering surgery on the symptoms of retethered cord syndrome.

Methods

Surgical indications and outcomes of 78 untethering operations (20 for myelomeningocele, 58 for spinal lipoma) for retethered cord syndrome were examined. Diagnosis of retethered cord syndrome was defined by a multidisciplinary spina bifida team, and included routine urodynamic study.

Results

Preoperative symptoms included urological symptoms (70%), lower-extremity symptoms (45%), and others. The most frequent urological symptom was detrusor overactivity detected by urodynamic study (88.7%). Urinary incontinence was only found in 9.4% of patients. Postoperatively, progressive motor weakness improved in all patients, and sensory symptoms improved in 94%. Urological symptoms improved in 80% of the patients with urinary incontinence and in 75% of the patients with detrusor overactivity. Postoperative urodynamic study showed a significant increase in bladder volume (p < 0.05). The most common complication was temporary lower leg paresthesia that recovered at follow-up. Aggravated dysuria was noted in 3 patients.

Conclusions

Early untethering operations offer symptomatic relief to patients with retethered cord syndrome. Urodynamic study findings, especially detrusor overactivity, are considered to be the most significant indicators for early diagnosis of retethered cord syndrome.