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Fusao Ikawa, Akio Morita, Shinjiro Tominari, Takeo Nakayama, Yoshiaki Shiokawa, Isao Date, Kazuhiko Nozaki, Susumu Miyamoto, Takamasa Kayama, Hajime Arai and The Japan Neurosurgical Society for UCAS Japan Investigators

OBJECTIVE

The annual rupture rate of small (3–4 mm) unruptured cerebral aneurysms (UCAs) is 0.36% per year, however, the proportion of small ruptured aneurysms < 5 mm is 35%. This discrepancy is explained by the hypothesis that most acute subarachnoid hemorrhage (SAH) is from recently formed, unscreened aneurysms, but this hypothesis is without definitive proof. The authors aimed to clarify the actual number of screened, ruptured small aneurysms and risk factors for rupture.

METHODS

The Unruptured Cerebral Aneurysm Study Japan, a project of the Japan Neurosurgical Society, was designed to clarify the natural course of UCAs. From January 2001 through March 2004, 6697 UCAs among 5720 patients were prospectively registered. At registration, 2839 patients (49.6%) had 3132 (46.8%) small UCAs of 3–4 mm. The registered, treated, and rupture numbers of these small aneurysms and the annual rupture rate were investigated. The rate was assessed per aneurysm. The characteristics of patients and aneurysms were compared to those of larger unruptured aneurysms (≥ 5 mm). Cumulative rates of SAH were estimated per aneurysm. Risk factors underwent univariate and multivariate analysis.

RESULTS

Treatment and rupture numbers of small UCAs were 1132 (37.1% of all treated aneurysms) and 23 (20.7% of all ruptured aneurysms), respectively. The registered, treated, rupture number, and annual rupture rates were 1658 (24.8%), 495 (16.2%), 11 (9.9%), and 0.30%, respectively, among 3-mm aneurysms, and 1474 (22.0%), 637 (20.9%), 12 (10.8%), and 0.45%, respectively, among 4-mm aneurysms. Multivariate risk-factor analysis revealed that a screening brain checkup (hazard ratio [HR] 4.1, 95% confidence interval [CI] 1.2–14.4), history of SAH (HR 10.8, 95% CI 2.3–51.1), uncontrolled hypertension (HR 5.2, 95% CI 1.8–15.3), and location on the anterior communicating artery (ACoA; HR 5.0, 95% CI 1.6–15.5) were independent predictors of rupture.

CONCLUSIONS

Although the annual rupture rate of small aneurysms was low, the actual number of ruptures was not low. Small aneurysms that ruptured during follow-up could be detected, screened, and managed based on each risk factor. Possible selection criteria for treating small UCAs include a history of SAH, uncontrolled hypertension, location on the ACoA, and young patients. Further large prospective and longitudinal trials are needed.

Clinical trial registration no.: C000000418 (https://www.umin.ac.jp/ctr)

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Kentaro Mori, Kojiro Wada, Naoki Otani, Arata Tomiyama, Terushige Toyooka, Satoru Takeuchi, Takuji Yamamoto, Yasuaki Nakao and Hajime Arai

OBJECTIVE

Aneurysms of the middle cerebral artery (MCA) are still most often treated by clipping through standard craniotomy, but a longer hospital stay is one of the main drawbacks of this treatment. The authors developed a pterional keyhole clipping strategy for unruptured MCA aneurysms with the intention of minimizing hospital stay. In this paper, they report on their experience with this approach and analyze the long-term neurological and radiological outcomes.

METHODS

A total of 160 relatively small unruptured MCA aneurysms (mean 6.4 mm) were clipped through the pterional keyhole approach (19–30 mm, mean 24.6 mm) in 149 patients (aged 34–79 years, mean 62 years). Neurological and cognitive function were examined by several scales, including the modified Rankin Scale (mRS) and Mini–Mental State Examination (MMSE). Patients’ level of depression was assessed using the Beck Depression Inventory and Hamilton Depression Scale. The state of clipping was assessed at 1 year and then every few years after the operation.

RESULTS

The mean duration of postoperative hospitalization was 2.3 ± 3.4 days; in 31.3% of the cases, the patients were discharged on the day after the operation (overnight hospital stay) and in 93.2% within 3 days. Of the patients younger than 60 years, 40.4% required only an overnight stay. Complete aneurysm neck clipping was confirmed in 157 cases (98.1%). None of the completely clipped aneurysms showed any recurrence during the mean follow-up period of 5.0 years. The mean length of clinical follow-up was 5.4 years. After 2 (1.3%) of the surgical procedures, the patients showed persistent neurological deficits, defined as mRS score 1, but the overall operative morbidity based on the International Study of Unruptured Intracranial Aneurysms (ISUIA) definition (mRS score ≥ 2 or MMSE score < 24) was 0% at the last examination. Depression scores were significantly improved after surgery, and in 85.6% of the cases the patients were satisfied with their cosmetic results.

CONCLUSIONS

Pterional keyhole clipping is less invasive than clipping via standard craniotomy, minimizes hospital stay, and achieves durable treatment for relatively small unruptured MCA aneurysms.

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Kentaro Mori, Kojiro Wada, Naoki Otani, Arata Tomiyama, Terushige Toyooka, Satoru Takeuchi, Takuji Yamamoto, Yasuaki Nakao and Hajime Arai

OBJECTIVE

Aneurysms of the middle cerebral artery (MCA) are still most often treated by clipping through standard craniotomy, but a longer hospital stay is one of the main drawbacks of this treatment. The authors developed a pterional keyhole clipping strategy for unruptured MCA aneurysms with the intention of minimizing hospital stay. In this paper, they report on their experience with this approach and analyze the long-term neurological and radiological outcomes.

METHODS

A total of 160 relatively small unruptured MCA aneurysms (mean 6.4 mm) were clipped through the pterional keyhole approach (19–30 mm, mean 24.6 mm) in 149 patients (aged 34–79 years, mean 62 years). Neurological and cognitive function were examined by several scales, including the modified Rankin Scale (mRS) and Mini–Mental State Examination (MMSE). Patients’ level of depression was assessed using the Beck Depression Inventory and Hamilton Depression Scale. The state of clipping was assessed at 1 year and then every few years after the operation.

RESULTS

The mean duration of postoperative hospitalization was 2.3 ± 3.4 days; in 31.3% of the cases, the patients were discharged on the day after the operation (overnight hospital stay) and in 93.2% within 3 days. Of the patients younger than 60 years, 40.4% required only an overnight stay. Complete aneurysm neck clipping was confirmed in 157 cases (98.1%). None of the completely clipped aneurysms showed any recurrence during the mean follow-up period of 5.0 years. The mean length of clinical follow-up was 5.4 years. After 2 (1.3%) of the surgical procedures, the patients showed persistent neurological deficits, defined as mRS score 1, but the overall operative morbidity based on the International Study of Unruptured Intracranial Aneurysms (ISUIA) definition (mRS score ≥ 2 or MMSE score < 24) was 0% at the last examination. Depression scores were significantly improved after surgery, and in 85.6% of the cases the patients were satisfied with their cosmetic results.

CONCLUSIONS

Pterional keyhole clipping is less invasive than clipping via standard craniotomy, minimizes hospital stay, and achieves durable treatment for relatively small unruptured MCA aneurysms.

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Osamu Akiyama, Ken Matsushima, Maximiliano Nunez, Satoshi Matsuo, Akihide Kondo, Hajime Arai, Albert L. Rhoton Jr. and Toshio Matsushima

OBJECTIVE

The lateral recess is a unique structure communicating between the ventricle and cistern, which is exposed when treating lesions involving the fourth ventricle and the brainstem with surgical approaches such as the transcerebellomedullary fissure approach. In this study, the authors examined the microsurgical anatomy around the lateral recess, including the fiber tracts, and analyzed their findings with respect to surgical exposure of the lateral recess and entry into the lower pons.

METHODS

Ten cadaveric heads were examined with microsurgical techniques, and 2 heads were examined with fiber dissection to clarify the anatomy between the lateral recess and adjacent structures. The lateral and medial routes directed to the lateral recess in the transcerebellomedullary fissure approach were demonstrated. A morphometric study was conducted in the 10 cadaveric heads (20 sides).

RESULTS

The lateral recess was classified into medullary and cisternal segments. The medial and lateral routes in the transcerebellomedullary fissure approach provided access to approximately 140º–150º of the posteroinferior circumference of the lateral recess. The floccular peduncle ran rostral to the lateral recess, and this region was considered to be a potential safe entry zone to the lower pons. By appropriately selecting either route, medial-to-lateral or lateral-to-medial entry axis is possible, and combining both routes provided wide exposure of the lower pons around the lateral recess.

CONCLUSIONS

The medial and lateral routes of the transcerebellomedullary fissure approach provided wide exposure of the lateral recess, and incision around the floccular peduncle is a potential new safe entry zone to the lower pons.

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Kentaro Mori, Kojiro Wada, Naoki Otani, Arata Tomiyama, Terushige Toyooka, Kazuya Fujii, Kosuke Kumagai, Satoru Takeuchi, Satoshi Tomura, Takuji Yamamoto, Yasuaki Nakao and Hajime Arai

OBJECTIVE

Advanced age is known to be associated with a poor prognosis after surgical clipping of unruptured intracranial aneurysms (UIAs). Keyhole clipping techniques have been introduced for less invasive treatment of UIAs. In this study, the authors compared the complications and clinical and radiological outcomes after keyhole clipping between nonfrail elderly patients (≥ 70 years) and nonelderly patients.

METHODS

Keyhole clipping (either supraorbital or pterional) was performed to treat 260 cases of relatively small (≤ 10 mm) anterior circulation UIAs. There were 62 cases in the nonfrail elderly group (mean age 72.9 ± 2.6 years [± SD]) and 198 cases in the nonelderly group (mean age 59.5 ± 7.6 years). The authors evaluated mortality and morbidity (modified Rankin Scale score > 2 or Mini–Mental State Examination [MMSE] score < 24) at 3 months and 1 year after the operation, the general cognitive function by MMSE at 3 months and 1 year, anxiety and depression by the Beck Depression Inventory (BDI) and Hamilton Rating Scale for Depression (HAM-D) at 3 months, and radiological abnormalities and recurrence at 1 year.

RESULTS

Basic characteristics including comorbidities, frailty, and BDI and HAM-D scores were not significantly different between the 2 groups, whereas the MMSE score was slightly but significantly lower in the elderly group. Aneurysm location, largest diameter, type of keyhole surgery, neck clipping rate, and hospitalization period were not significantly different between the 2 groups. The incidence of chronic subdural hematoma was not significantly higher in the elderly group than in the nonelderly group (8.1% vs 4.5%, p = 0.332); rates of other complications including stroke and epilepsy were not significantly different. Lacunar infarction occurred in 3.2% of the elderly group and 3.0% of the nonelderly group. No patient in the elderly group required re-treatment or demonstrated recurrence of clipped aneurysms. The MMSE score at 3 months significantly improved in the nonelderly group but did not change in the elderly group. The BDI and HAM-D scores at 3 months were significantly improved in both groups. No patient died in either group. The morbidity at 3 months and 1 year in the elderly group (1.6% and 4.8%, respectively) was not significantly different from that in the nonelderly group (2.0% and 1.5%, respectively).

CONCLUSIONS

Keyhole clipping for nonfrail elderly patients with relatively small anterior circulation UIAs did not significantly increase the complication, mortality, or morbidity rate; hospitalization period; or aneurysm recurrence compared with nonelderly patients, and it was associated with improvement in anxiety and depression. Keyhole clipping to treat UIAs in the nonfrail elderly is an effective and long-lasting treatment.

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Osamu Akiyama, Ken Matsushima, Abuzer Gungor, Satoshi Matsuo, Dylan J. Goodrich, R. Shane Tubbs, Paul Klimo Jr., Aaron A. Cohen-Gadol, Hajime Arai and Albert L. Rhoton Jr.

OBJECTIVE

Approaches to the pulvinar remain challenging because of the depth of the target, surrounding critical neural structures, and complicated arterial and venous relationships. The purpose of this study was to compare the surgical approaches to different parts of the pulvinar and to examine the efficacy of the endoscope as an adjunct to the operating microscope in this area.

METHODS

The pulvinar was examined in 6 formalin-fixed human cadaveric heads through 5 approaches: 4 above and 1 below the tentorium. Each approach was performed using both the surgical microscope and 0° or 45° rigid endoscopes.

RESULTS

The pulvinar has a lateral ventricular and a medial cisternal surface that are separated by the fornix and the choroidal fissure, which wrap around the posterior surface of the pulvinar. The medial cisternal part of the pulvinar can be further divided into upper and lower parts. The superior parietal lobule approach is suitable for lesions in the upper ventricular and cisternal parts. Interhemispheric precuneus and posterior transcallosal approaches are suitable for lesions in the part of the pulvinar forming the anterior wall of the atrium and adjacent cisternal part. The posterior interhemispheric transtentorial approach is suitable for lesions in the lower cisternal part and the supracerebellar infratentorial approach is suitable for lesions in the inferior and medial cisternal parts.

The microscope provided satisfactory views of the ventricular and cisternal surfaces of the pulvinar and adjacent neural and vascular structures. The endoscope provided multi-angled and wider views of the pulvinar and adjacent structures.

CONCLUSIONS

A combination of endoscopic and microsurgical techniques allows optimal exposure of the pulvinar.

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Hiroshi Kageyama, Masakazu Miyajima, Ikuko Ogino, Madoka Nakajima, Kazuaki Shimoji, Ryoko Fukai, Noriko Miyake, Kenichi Nishiyama, Naomichi Matsumoto and Hajime Arai

OBJECT

The authors’ goal in this paper is to provide the first clinical, radiological, and genetic studies of panventriculomegaly (PaVM) defined by a wide foramen of Magendie and large cisterna magna.

METHODS

Clinical and brain imaging data from 28 PaVM patients (including 10 patients from 5 families) were retrospectively studied. Five children were included. In adult patients, the age at onset was 56.0 ± 16.7 years. Tetraventricular dilation, aqueductal opening with flow void on T2-weighted images, and a wide foramen of Magendie and large cisterna magna (wide cerebrospinal fluid space at the fourth ventricle outlet) were essential MRI findings for PaVM diagnosis. 3D fast asymmetrical spin echo sequences were used for visualization of cistern membranes. Time-spatial labeling inversion pulse examination was performed to analyze cerebrospinal fluid movement. Copy number variations were determined using high-resolution microarray and were validated by quantitative polymerase chain reaction with breakpoint sequencing.

RESULTS

Adult patients showed gait disturbance, urinary dysfunction, and cognitive dysfunction. Five infant patients exhibited macrocranium. Patients were divided into 2 subcategories, those with or without downward bulging third ventricular floors and membranous structures in the prepontine cistern. Patients with bulging floors were successfully treated with endoscopic third ventriculostomy. Genetic analysis revealed a deletion in DNAH14 that encodes a dynein heavy chain protein associated with motile cilia function, and which co-segregated with patients in a family without a downward bulging third ventricular floor.

CONCLUSIONS

Panventriculomegaly with a wide foramen of Magendie and a large cisterna magna may belong to a subtype of congenital hydrocephalus with familial accumulation, younger age at onset, and symptoms of normal pressure hydrocephalus. In addition, a family with PaVM has a gene mutation associated with dysfunction of motile cilia.

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Madoka Nakajima, Hidenori Sugano, Yasushi Iimura, Takuma Higo, Hajime Nakanishi, Kazuaki Shimoji, Kostadin Karagiozov, Masakazu Miyajima and Hajime Arai

A girl aged 2 years 10 months suddenly went into a deep coma and demonstrated left hemiplegia. At birth, she had exhibited a left-sided facial port-wine stain typical of Sturge-Weber syndrome (SWS) and involving the V1 and V2 distributions of the trigeminal nerve. Computed tomography showed a right thalamic hemorrhage with acute hydrocephalus. Magnetic resonance imaging with Gd enhancement 8 months before the hemorrhage had shown a patent superior sagittal sinus (SSS) and deep venous system. Magnetic resonance imaging and MR angiography studies 2 months before the hemorrhage had revealed obstruction of the SSS and right internal cerebral vein (ICV). Given that a digital subtraction angiography study obtained after the hemorrhage did not show the SSS or right ICV, the authors assumed that impaired drainage was present in the deep venous system at that stage. The authors speculated that the patient's venous drainage pattern underwent compensatory changes because of the occluded SSS and deep venous collectors, shifting outflow through other cortical venous channels to nonoccluded dural sinuses. Sudden congestion (nearly total to total obstruction) of the ICV may have caused the thalamic hemorrhage in this case, which is the first reported instance of pediatric SWS with intracerebral hemorrhage and no other vascular lesion. Findings suggested that the appearance of major venous sinus occlusion in a child with SWS could be a warning sign of hemorrhage.

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Ayato Hayashi, Masanobu Nishida, Hisakazu Seno, Masahiro Inoue, Hiroshi Iwata, Tomohiro Shirasawa, Hajime Arai, Ryoji Kayamori, Yuzo Komuro and Akira Yanai

Object

The authors have developed a technique for the treatment of facial paralysis that utilizes anastomosis of the split hypoglossal and facial nerve. Here, they document improvements in the procedure and experimental evidence supporting the approach.

Methods

They analyzed outcomes in 36 patients who underwent the procedure, all of whom had suffered from facial paralysis following the removal of large vestibular schwannomas. The average period of paralysis was 6.2 months. The authors used 5 different variations of a procedure for selecting the split nerve, including evaluation of the split nerve using recordings of evoked potentials in the tongue.

Results

Successful facial reanimation was achieved in 16 of 17 patients using the cephalad side of the split hypoglossal nerve and in 15 of 15 patients using the caudal side. The single unsuccessful case using the cephalad side of the split nerve resulted from severe infection of the cheek. Procedures using the ansa cervicalis branch yielded poor success rates (2 of 4 cases).

Some tongue atrophy was observed in all variants of the procedure, with 17 cases of minimal atrophy and 14 cases of moderate atrophy. No procedure led to severe atrophy causing functional deficits of the tongue.

Conclusions

The split hypoglossal-facial nerve anastomosis procedure consistently leads to good facial reanimation, and the use of either half of the split hypoglossal nerve results in facial reanimation and moderate tongue atrophy.

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Azusa Shimizu, Yuzo Komuro, Masakazu Miyajima and Hajime Arai

An otherwise healthy, developmentally normal 3-week-old male infant presented with complex multisuture craniosynostosis involving the metopic suture and bilateral coronal sutures with frontal prominence and hypotelorism. Frontal craniectomy and bilateral frontoorbital advancement remodeling were performed at the age of 5 months. The postoperative course was uneventful. The child's development was normal up to 8 months after the operation. His father and grandfather had similar specific deformities of the cranium, but no anomaly of the extremities was found, and conversation suggested that their intelligence was normal, excluding the possibility of syndromic craniosynostosis. A DNA analysis revealed large-scale copy number polymorphism of chromosome 4 in the patient and his family, which may include the phenotype of the cranium. Neither FGFR mutation nor absence of a TWIST1 mutation in the sequence from 291 to 1087, which includes DNA binding, Helix1, Loop, and Helix2, was identified. The patient apparently had a rare case of familial nonsyndromic craniosynostosis. The authors plan further genomic analysis of this family and long-term observation of the craniofacial deformity of this patient.