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Roberto C. Heros

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Shunya Hanakita, Tomoyuki Koga, Masahiro Shin, Hiroshi Igaki and Nobuhito Saito

OBJECT

Although stereotactic radiosurgery (SRS) has been accepted as a therapeutic option for arteriovenous malformations (AVMs) in children and adolescents, substantial data are still lacking regarding the outcomes of SRS for AVMs in this age group, especially long-term complications. This study aimed to clarify the long-term outcomes of SRS for the treatment of AVM in pediatric patients aged ≤ 18 years.

METHODS

Outcomes of 116 patients who were aged 4–18 years when they underwent SRS between 1990 and 2009 at the study institute were analyzed retrospectively.

RESULTS

The median follow-up period after SRS was 100 months, with 6 patients followed up for more than 20 years. Actuarial obliteration rates at 3 and 5 years after SRS were 68% and 88%, respectively. Five hemorrhages occurred in 851 patient-years of follow-up. The annual bleeding rate after SRS before obliteration was calculated as 1.3%, which decreased to 0.2% after obliteration. Shorter maximum nidus diameter (p = 0.02) and higher margin dose (p = 0.03) were associated with a higher obliteration rate. Ten patients experienced adverse events after SRS. Of them, 4 patients presented with delayed complications years after SRS (range 9–20 years after SRS).

CONCLUSIONS

SRS can reduce the risk of hemorrhage in pediatric and adolescent AVMs, with an acceptable risk of complications in the long term. However, adverse events such as expanding hematoma and radiation necrosis that can occur after substantial follow-up should be taken into account at the time that treatment decisions are made and informed consent is obtained.

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Douglas Kondziolka

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Bruce E. Pollock

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Masahiro Shin, Tetsuhiro Nishihara, Shigeo Iai and Tsuneyoshi Eguchi

✓ The introduction of magnetic resonance (MR) imaging to the field of neuroimaging has allowed detection of various lesions that cause aqueductal stenosis. The authors report the case of a 3-year-old boy in whom a benign ventricular cyst developed in the aqueduct. The patient became drowsy after having complained of headache and vomiting; MR imaging revealed mild triventricular dilation and a normal-sized fourth ventricle. Repeated MR imaging performed 1 week later revealed an aqueductal cyst that had markedly enlarged during the intervening period. An external ventricular drainage system was installed, but recovery of consciousness in the child was unsatisfactory and a new bilateral internuclear ophthalmoplegia developed. Fenestration of the cyst wall and placement of a ventriculocisternostomy in the third ventricle were performed simultaneously by using a flexible neuroendoscope. By 2 weeks postsurgery, the patient's neurological symptoms had completely resolved. This case illustrates that simple rerouting of ventricular cerebrospinal fluid (CSF) can aggravate the symptoms of this rare lesion by causing severe compression of periaqueductal structures by a cyst that maintains a high intracystic pressure. Endoscopic surgery was an excellent choice of treatment to achieve both cyst fenestration and normalization of intracranial CSF pressure by creating a ventriculocisternostomy.

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Masahiro Shin, Akio Morita, Shuichiro Asano, Keisuke Ueki and Takaaki Kirino

✓ Isolated fourth ventricle (IFV) is a rare complication in patients who undergo shunt placement, and it is not easily corrected by surgical procedures. The authors report a case of IFV that was successfully treated with an aqueductal stent placed under direct visualization by using a neuroendoscope. This 36-year-old suffered meningitis after partial resection of a brainstem pilocytic astrocytoma, and subsequently developed hydrocephalus for which a ventriculoperitoneal shunt was placed. Nine months later, the patient presented with progressive cerebellar ataxia, and magnetic resonance imaging revealed slitlike supratentorial ventricles and a markedly enlarged fourth ventricle, which were compatible with the diagnosis of IFV. The surgical procedure described was performed under visualization through a styletlike slim optic fiberscope inserted into a ventricular catheter. The catheter, with the endoscope inside it, was passed through the foramen of Monro and then through the aqueduct to reach the enlarged fourth ventricle, where membranous occlusion of the foramen of Magendie was clearly visualized. The tip of the catheter was placed in the fastigium of the fourth ventricle. After the procedure, the size of the fourth ventricle was reduced and the patient's symptoms improved. Thus, it is concluded that endoscopic aqueductal stent placement is a simple and safe surgical procedure for treatment of IFV.

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Masahiro Shin, Kenji Kondo, Shunya Hanakita, Keigo Suzukawa, Taichi Kin, Masaaki Shojima, Daichi Nakagawa and Nobuhito Saito

OBJECT

In recent years, application of endoscopic transnasal surgery (ETS) has been expanded to orbital lesions, and preliminary results have started to be published for medially located soft mass lesions. However, reports on experience with endoscopic intraorbital surgery aimed at resection of invasive skull base tumors remains quite limited. This report presents the authors’ experience with ETS for locally aggressive tumors involving the orbit.

METHODS

ETS was performed for 15 cases of aggressive tumors involving the orbit: 5 meningiomas (meningothelial, n = 3; atypical, n = 1; anaplastic, n = 1), 4 chordomas, 2 chondrosarcomas, and 4 others (metastasis from systemic myxofibrosarcoma, schwannoma, inverted papilloma, and acinic cell carcinoma, n = 1 each). Among these, 9 tumors were located outside the periorbita and 6 inside the periorbita. In 6 intraperiosteal tumors, 5 were intraconal lesions, of which 3 arose in the muscle cone (anaplastic meningioma, optic sheath meningioma, and metastatic myxofibrosarcoma), and 2 meningothelial meningioma had invaded from the sphenoid ridge or the cavernous sinus into the muscle cone through the optic canal and the superior orbital fissure. A case of schwannoma originated around the cavernous sinus and pterygopalatine fossa and extended extraconally into the periorbita. Intraoperatively, ethmoid air cells and the lamina papyracea were removed, and extraperiosteal tumors were safely approached. For intraperiosteal tumors, the periorbita was widely opened, and the tumors were approached through the surgical window between the rectus and oblique muscles.

RESULTS

Gross-total resection was achieved for 12 of the 15 tumors, including 2 intraconal lesions. After surgery, exophthalmos resolved in all 8 patients with this symptom, and diplopia resolved in 5 of 6 patients. Improvement of visual symptoms was reported by 4 of 5 patients with loss of visual acuity or constriction of the visual field. Postoperatively, 1 patient showed mild, transient worsening of existing facial dysesthesia, and another showed transient ptosis and mild hypesthesia of the forehead on the affected side. All those symptoms resolved within 3 months. No patients showed enophthalmos, worsening of diplopia or visual function, or impairment of olfaction after surgery.

CONCLUSIONS

ETS appears acceptable as a less-invasive alternative for treating aggressive tumors involving the orbit. For extraperiosteal tumors, gross-total removal can generally be achieved without neurological complications. For intraperiosteal tumors, surgical indications should be carefully discussed, considering the relationship between the tumor and normal anatomy. Wide opening of the periorbital window is advocated to create a sufficient surgical pathway between the extraocular muscles, allowing a balance between functional preservation and successful tumor resection.

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Kenichi Usami, Kensuke Kawai, Tomoyuki Koga, Masahiro Shin, Hiroki Kurita, Ichiro Suzuki and Nobuhito Saito

Object

Despite the controversy over the clinical significance of Gamma Knife surgery (GKS) for refractory mesial temporal lobe epilepsy (MTLE), the modality has attracted attention because it is less invasive than resection. The authors report long-term outcomes for 7 patients, focusing in particular on the long-term complications.

Methods

Between 1996 and 1999, 7 patients with MTLE underwent GKS. The 50% marginal dose covering the medial temporal structures was 18 Gy in 2 patients and 25 Gy in the remaining 5 patients.

Results

High-dose treatment abolished the seizures in 2 patients and significantly reduced them in 2 others. One patient in this group was lost to follow-up. However, 2 patients presented with symptomatic radiation necrosis (SRN) necessitating resection after 5 and 10 years. One patient who did not need necrotomy continued to show radiation necrosis on MRI after 10 years. One patient died of drowning while swimming in the sea 1 year after GKS, before seizures had disappeared completely.

Conclusions

High-dose treatment resulted in sufficient seizure control but carried a significant risk of SRN after several years. Excessive target volume was considered as a reason for delayed necrosis. Drawbacks such as a delay in seizure control and the risk of SRN should be considered when the clinical significance of this treatment is evaluated.

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Shunya Hanakita, Atumi Takenobu, Atsushi Kambe, Takashi Watanabe, Masahiro Shin and Akira Teraoka

The authors present a case of germinoma that was initially found in the pineal region and recurred 15 years later in the intramedullary cervical spinal cord after intensive chemo- and radiotherapy and diagnosis of complete remission.

This 28-year-old man initially presented with seizures. Hydrocephalus and a pineal tumor were found on radiological examination, and partial resection of the tumor was performed. Histological diagnosis showed a pure germinoma. Following surgery, the patient received a combination of chemo- and radiotherapy, and a complete remission was shown. However, after 15 years of follow-up, he presented with gait disturbances. Spinal MRI showed an intramedullary mass lesion in the cervical spinal cord. The cervical lesion was biopsied, and histological examination again revealed a pure germinoma.

With germinomas, the possibility of a drop metastasis from an intracranial lesion to the spinal cord must be considered during follow-up. However, in the present case, analysis of a CSF sample showed no abnormalities as in previously published cases. In recent years, multidisciplinary treatments have demonstrated good event-free survival rates in cases of pure germinomas, but long-term outcomes over the decades are not fully known. Continual follow-up of such cases is recommended even after complete remission has been achieved.