Kenichi Nishiyama

Nationwide investigation of the current status of therapeutic neuroendoscopy for ventricular and paraventricular tumors in Japan: Clinical article

OBJECT The authors report their investigation on the current status of neuroendoscopic biopsy for ventricular and paraventricular tumors as well as treatment for associated hydrocephalus in Japan. METHODS Patients who had undergone therapeutic neuroendoscopy between 2005 and 2009 were included in this study. The main items examined were age; sex; localization of tumor; pathological diagnosis using biopsy; the presence, treatment, and efficacy of treatment of associated hydrocephalus; perioperative complications; activities of daily living (ADL) before and after therapeutic neuroendoscopy; and the presence of dissemination during the postoperative course. RESULTS Seven hundred fourteen patients from 123 sites (462 male and 252 female patients, mean age 33.3 years) were enrolled. Localization of the tumor was mainly classified into the lateral ventricle in 91 patients, the third ventricle in 339, the fourth ventricle in 18, the suprasellar region in 75, and other paraventricular areas in 191 patients. The most commonly observed tumors were germ cell tumors in the third ventricle (177 cases [39%]), cystic lesions in the suprasellar region (56 cases [75%]), and astrocytic tumors in the thalamus-basal ganglia (71 cases [38%]). Although 641 (92.8%) of 691 patients could receive neuroendoscopic diagnosis using biopsy, the diagnosis obtained with endoscopic biopsy differed from the final diagnosis based on subsequent craniotomy in 18 patients and clinical course in 3 patients. Of these 21 patients, 7 had astrocytic tumors, 4 had pineal tumors, 6 had germ cell tumors, and 4 had other tumors. The final diagnostic accuracy rate was 89.7%. Associated hydrocephalus was observed in 517 patients (72.4%), of whom 316 and 39 underwent third ventriculostomy and fenestration of the septum, respectively. The response rates were 96.2% and 89.7%, respectively. Third ventriculostomy was required for recurrence of hydrocephalus in 41 patients (13.0%), and the long-term response rate was therefore 83.2% (263 of 316 patients). Perioperative complications other than fever, such as new onset of or progressive hydrocephalus, infection due to CSF leakage, and bleeding in the ventricle or tumor, were found in 81 patients (11.3%). The median Karnofsky Performance Scale score before endoscopic surgery was 80, but it increased to 90 after surgery. The score was thus significantly increased after surgery (p < 0.0001, Mann-Whitney U-test). Activities of daily living after surgery decreased due to perioperative complications in 15 patients (2.1%). The incidence of new dissemination after endoscopic biopsy was 6.8% and not high compared with routine surgical treatment. CONCLUSIONS The authors concluded that neuroendoscopic diagnosis using biopsy for ventricular and paraventricular tumors is adequately accurate and safe. It was demonstrated that endoscopic procedures play important roles not only in the treatment of hydrocephalus associated with intra- and paraventricular tumors but also in significantly improving ADL. Furthermore, the long-term outcome of endoscopic third ventriculostomy was clearly favorable.

Endoscopic stent placement for treatment of secondary bilateral occlusion of the Monro foramina following endoscopic third ventriculostomy in a patient with aqueductal stenosis

Nontumoral bilateral occlusion of the Monro foramina is a rare clinical condition. Treatment includes shunt placement, endoscopic procedures, or both. The authors describe the case of a 22-year-old woman who had previously undergone placement of a ventriculoperitoneal shunt via a right frontal approach for management of triventricular dilation due to aqueductal stenosis. Six years postoperatively she presented with right-sided slit-ventricle syndrome and stenosis of the right Monro foramen, which was treated with an endoscopic third ventriculostomy and fenestration of the septum pellucidum. Two years later she presented with bilateral lateral ventricular dilation. Inspection of the right lateral ventricle with a fiberscope revealed occlusion of the septum pellucidum fenestration; on observation, the right Monro foramen was covered by thick, tough granulation tissue and the left was occluded by thin membranous tissue. Repeated fenestration of the septum pellucidum and left Monro foraminoplasty were therefore performed by perforating this thin tissue. A stent was then introduced into the third ventricle via the right lateral ventricle, the fenestration in the septum pellucidum, and the left Monro foramen. The authors note that fiberscopes are in general more maneuverable than rigid endoscopes and conclude that they are particularly useful for the treatment of this type of hydrocephalus.

A fourth ventricle atypical teratoid/rhabdoid tumor in an infant

Atypical teratoid/rhabdoid tumor (AT/RT), a recently established central nervous system tumor entity, occurs in children and is more malignant than medulloblastoma/primitive neuroectodermal tumors (PNET). We report here a case of AT/RT in a male infant who was 9 months old at the time of diagnosis. Magnetic resonance imaging revealed that the tumor occupied the fourth ventricle, and at surgery it was found to adhere to the floor of the fourth ventricle. After subtotal removal of the tumor mass, chemotherapy and radiotherapy were performed, but the patient died about 8 months after the diagnosis following rapid regrowth of the residual tumor. Light-microscopically, the tumor was composed mainly of nests of rhabdoid cells with fields of PNET. Occasional mesenchymal and epithelial fields were also evident. Immunohistochemically, these rhabdoid cells were positive for vimentin, epithelial membrane antigen, smooth-muscle actin, cytokeratin, and S-100 protein, and less frequently for glial fibrillary acidic protein. Electron-microscopically, the typical rhabdoid cells contained whorled bundles of intermediate filaments in their cytoplasm. Occasionally, such rhabdoid cells were covered partially by basal lamina at their stromal interface. These findings are typical of AT/RT. Although it is well known that AT/RT often arises in the posterior fossa, detailed reports of cases affecting the fourth ventricle are rare. In this case, the ultrastructural relationship between rhabdoid cells and the basal lamina, which has not so far been described in AT/RT, was of great interest when the nature of the rhabdoid cells was considered.

A case of congenital supratentorial tumor: atypical teratoid/rhabdoid tumor or primitive neuroectodermal tumor?

Two embryonal CNS tumors, atypical teratoid/rabdoid tumor (AT/RT) and primitive neuroectodermal tumor (PNET), may be confused with each other and misdiagnosed. Here we report an infant with a congenital supratentorial tumor, which was detected by fetal MRI at 37 weeks gestation. On routine histological examination, the tumor was composed mainly of small undifferentiated cells, among which many rhabdoid cells and occasional sickle‐shaped embracing cells were observed. No mesenchymal or epithelial areas were evident. Our impression was that the tumor was an atypical example of AT/RT. Immunohistochemically, almost all the tumor cells were strongly positive for vimentin. However, epithelial membrane antigen was notably negative, and most of the tumor cell nuclei were clearly positive for INI1. In addition, many tumor cells were positive for neurofilament protein. There were also occasional small areas containing many tumor cells positive for glial fibrillary acidic protein. Finally, a diagnosis of PNET, with a rhabdoid phenotype and expression of neuronal and glial markers, was made. In the present case, application of INI1 immunostaining was very helpful for distinguishing PNET from AT/RT.

Intraspinal lesions associated with sacrococcygeal dimples.

UNLABELLED OBJECT.: Sacrococcygeal dimples in the gluteal fold, also known as coccygeal pits, are observed in 2%-4% of newborns. Sacrococcygeal dimples are not generally considered to be associated with a significant risk of intraspinal anomalies and therefore are not thought to require further radiographic evaluation. Accordingly, the precise incidence and nature of intraspinal lesions that may be associated with sacrococcygeal dimples is unclear. This study was conducted to determine the incidence of intraspinal lesions in patients with intergluteal dimples. METHODS In this study, the authors used MRI to evaluate 103 children who were seen at the Niigata University Medical and Dental Hospital between 2006 and 2011 because of skin abnormalities in the lumbosacral region. Of these children, 14 were excluded as having a subcutaneous fatty mass, and 5 were excluded because the dimples were above the gluteal fold or did not end at the coccyx. The remaining 84 patients were classified according to whether the bottom of the dimple was visible (shallow) or not (deep). The authors also retrospectively examined other skin abnormalities and coexisting anomalies. RESULTS The mean age at the time of MRI evaluation was 11.7 months. Magnetic resonance imaging led to the identification of fibrolipoma of the terminal filum (FTF) in 14 cases (16.7%); 6 of these patients also had a low conus. Classified by depth, there were 58 cases with shallow and 26 with deep dimples. Fibrolipoma of the terminal filum was found in significantly more patients with deep dimples (9 [34.6%]) than in those with shallow dimples (5 [8.6%]). The frequency of other congenital anomalies was significantly higher in patients with FTF-associated dimples (6 [42.9%] of 14) than in those with dimples that were not associated with FTF (9 [12.9%] of 70). CONCLUSIONS Fibrolipoma of the terminal filum was identified by MRI in 16.7% of patients with sacrococcygeal dimples. The risk of FTF increased when the dimples were deeply excavated or were accompanied by congenital anomalies. Magnetic resonance imaging should be performed to identify intraspinal lesions when there are high risk factors for intraspinal abnormalities, or when an ultrasound screening suggests intraspinal abnormalities.

Current status of neuroendoscopic surgery in Japan and discussion on the training system

ObjectivesThe objectives of this study was to investigate the current status of neuroendoscopic surgery in Japan and to discuss the issue disclosed by the survey.MethodsWe delivered questionnaires about neuroendoscopic surgeries to 1,237 of Japan Neurosurgical Society certified training institutions.ResultsOf these institutions, 592 (47.9%) returned completed questionnaires, and 316 (53.4%) among them experienced neuroendoscopic surgeries in the past. Two hundred seventy-six institutions had at least one procedure in the year 2003, but 208 (75.5%) had only one to ten procedures per year. Total number of procedures was 2,796, and trans-sphenoidal surgery was performed most frequently (705). Aneurysmal neck clipping (637) was second, and the third place was third ventriculostomy (ETV, 357). ETV was performed at 126 institutions, and 112 (88.9%) of them had only five cases or under per year.DiscussionNeuroendoscopic surgeries are performed at many institutions, but little experience per institution was reported. We refer to the on-going project of the Japanese Society for Neuroendoscopy on establishing training system of neuroendoscopic surgeries.

Adult Cerebellopontine Angle Medulloblastoma Originating in the Pons Mimicking Focal Brainstem Tumor

We herein report a rare case of cerebellopontine angle (CPA) medulloblastoma originating in the brainstem that demonstrated a very unusual clinical presentation and radiological appearances. A 25‐year‐old female was admitted to our hospital with a right hearing disturbance and a right facial palsy. A small non‐enhanced lesion having minimal mass effect in the right CPA was identified by using a 1.5‐tesla‐MR system, whose size remained almost unchanged a year. The 3‐tesla MR images revealed that the precise region was in the right side of the tegmentum of the lower pons to the inferior cerebellar peduncle and the flocculus. MR spectroscopic images using a 3‐tesla system revealed a high ratio of choline‐to‐N‐acetylaspartate in the region of interest in comparison to the contra‐lateral side. Craniotomy and biopsy were performed. The histopathological diagnosis was medulloblastoma. The patient received craniospinal irradiation and chemotherapy, and achieved complete remission by the time of the follow‐up MR images. She is now doing well with a full recovery of the right facial palsy. MR spectroscopic imaging is considered to be quite useful for the management of this rare type of brainstem tumor.

A case of split cord malformation associated with myeloschisis

IntroductionSplit cord malformation (SCM) associated with myeloschisis is a very rare form of spinal dysraphism. We encountered a case of SCM associated with myeloschisis showing split neural placodes (hemicords) in the upper lumbar region.ResultsRadiological examinations, including prenatal MRI and postnatal CT scan, clearly demonstrated a bony spur between the two hemicords as well as myeloschisis, which facilitated a precise preoperative diagnosis of this complex anomaly. Resection of the spur, closure of the myeloschisis, and untethering of the thickened filum terminale were successfully accomplished in one stage. The presence of SCM associated with myeloschisis is consistent with the hypothesis of an ontogenic basis of neural development, and we emphasize the importance of early imaging including prenatal MRI for diagnosing this complex anomaly.

Entrapment of the inferior horns of the lateral ventricle with enlargement of the bilateral choroid plexus.

The patient, a 61-year-old woman, was admitted to a hospital because of a 2-month history of personality alteration, memory disturbance and disorientation. A serological examination revealed a normal CRP value and a normal WBC count, with no detectable antibodies against hepatitis B virus (HBV), HCV or HIV. The CSF showed an increased cell count of 52/μL with predominance of lymphocytes, 547 mg/dL protein, 37 mg/dL glucose and 6397 ng/mL β2 microglobulin. A brain MRI study revealed marked dilatation of the inferior horns of the lateral ventricle on both sides, and enlargement of the bilateral choroid plexus with marked gadolinium enhancement (Fig. 1). A whole-body CT scan disclosed no mass lesions anywhere in the body or visceral organs, and there was no evidence of lymphadenopathy or infectious lesions. The patient had no family history of neurological disorders nor any evidence of contact with bird droppings and never owned any pets. Following a tentative diagnosis of choroid plexus tumor, an endoscopic biopsy of the bilateral masses was performed for histopathological diagnosis. The bilateral choroid plexus observed through the endoscope window was markedly enlarged, constituting a solid, whitish mass (Fig. 2).

An organic light-emitting diode display for use in neuroendoscopic surgery in the ventricle

The organic light-emitting diode (OLED) display delivers a bright and high-contrast image compared to the liquid crystal display. The first experience of neuroendoscopic surgery using an OLED display was reported and its stereoscopic effect emphasized.