Brainstem Surgery: Functional Surgical Anatomy with the Use of an Advanced Modern Intraoperative Neurophysiological Procedure.

Intraoperative neurophysiology (ION) in brainstem surgery evolved as brainstem surgery advanced.The original idea of brainstem mapping (BSM) is a neurophysiological procedure to locate cranial nerve motor nuclei (CNMN) on the floor of the fourth ventricle. With the introduction of various skull base approaches to the brainstem, BSM is carried out on any surface of the brainstem to expose the safe entry zone to the intrinsic brainstem lesion. It is the modern concept of BSM, a broader definition of BSM. BSM enables to avoid direct damage to the CNMN when approaching the brainstem through the negative mapping region.The corticobulbar tract (CBT) motor evoked potential (MEP) is another ION procedure in brainstem surgery. It enables monitoring of the functional integrity of the whole cranial motor pathway without interrupting surgical procedures. Combined application of both BSM and CBT-MEP monitoring is indispensable for the functional preservation of the CNMN and their supranuclear innervation during the brainstem surgery.In this paper, the neurophysiological aspect of BSM and the CBT-MEP was fully described. Normal anatomical background of the floor of the fourth ventricle and the detail of the CBT anatomy were demonstrated to better understand their clinical usefulness, limitations, and surgical implications derived from ION procedures. Finally, a future perspective in the role of ION procedures in brainstem surgery was presented. The latest magnetic resonance imaging (MRI) technology can allow surgeons to find an "on the image" safe entry zone to the brainstem. However, the role of BSM and the CBT-MEP monitoring in terms of safe brainstem surgery stays unshakable. Special attention was paid for the recent trend of management in diffuse intrinsic pontine gliomas. A new role of BSM during a stereotactic biopsy was discussed.It is the authors' expectation that the paper enhances the clinical application of a contemporary standard of the ION in brainstem surgery and supports safer brainstem surgery more than ever and in the future.

Surgery for spina bifida occulta: spinal lipoma and tethered spinal cord.

The technical evolution of the surgery for spina bifida occulta (SBO) over the course of a half-century was reviewed with special foci placed on the spinal lipoma and tethered spinal cord. Looking back through history, SBO had been included in spina bifida (SB). Since the first surgery for spinal lipoma in the mid-nineteenth century, SBO has come to be recognized as an independent pathology in the early twentieth century. A half-century ago, the only option available for SB diagnosis was the plain X-ray, and pioneers of the time persevered in the field of surgery. The classification of spinal lipoma was first described in the early 1970s, and the concept of tethered spinal cord (TSC) was proposed in 1976. Surgical management of spinal lipoma with partial resection was the most widely practiced approach and was indicated only for symptomatic patients. After understanding TSC and tethered cord syndrome (TCS), more aggressive approaches became preferred. A PubMed search suggested that there was a dramatic increase of publications on the topic beginning around 1980. There have been immense academic achievements and technical evolutions since then. From the authors' viewpoint, landmark achievements in this field are listed as follows: (1) establishment of the concept of TSC and the understanding of TCS; (2) unraveling the process of secondary and junctional neurulation; (3) introduction of modern intraoperative neurophysiological mapping and monitoring (IONM) for surgery of spinal lipomas, especially the introduction of bulbocavernosus reflex (BCR) monitoring; (4) introduction of radical resection as a surgical technique; and (5) proposal of a new classification system of spinal lipomas based on embryonic stage. Understanding the embryonic background seems critical because different embryonic stages bring different clinical features and of course different spinal lipomas. Surgical indications and selection of surgical technique should be judged based on the background embryonic stage of the spinal lipoma. As time flows forward, technology continues to advance. Further accumulation of clinical experience and research will open the new horizon in the management of spinal lipomas and other SBO in the next half-century.

Physiological defects of lumbosacral vertebral arches on computed tomography images in children.

OBJECTIVE: Physiological midline defects of the lumbosacral vertebral arches on radiographs must be distinguished from pathological spina bifida. To date, however, this has not been examined, except for some reports based on plain radiography. The aim of this study is to accurately define the rate and distribution of physiological defects by computed tomography (CT) imaging. METHODS: A total of 115 patients aged 0 months to 16 years (median age, 4 years) who underwent CT scans for abdominopelvic disorder not involving the lumbosacral spine were retrospectively analyzed. The lumbosacral spines were collaterally identified on these images. RESULTS: In the lumbosacral spine excluding the sacral hiatus, the rate of physiological defects was 66.1% (95% confidence interval [CI]: 56.7-74.7%), and the mean number of defective vertebral arches was 1.6 per patient (95% CI: 1.3-1.9). The rate and mean number of defects were significantly higher in the group of patients less than 6 years old (84.3%, 2.2/patient) than that of patients 6 years old or older (37.8%, 0.5/patient) (p < 0.001 and p < 0.001, respectively). The defect rates by spinal level were S3 (57.4%), S1 (47.8%), S2 (34.8%), L5 (13.0%), L4 (2.6%), and L3 (0.9%) in descending order. CONCLUSIONS: Physiological defects were found more commonly at an earlier age and predominantly existed adjacent to the sacral hiatus (S3) and around S1. Understanding the detection rate and distribution features of defects more precisely on CT images will contribute clinically supportive information to distinguish between physiological defects and pathological spina bifida.

Fronto-orbital advancement in a patient with Marshall-Smith syndrome: a case report and review of the literature.

OBJECTIVE: The present report aimed to document the clinical features of a case of Marshall-Smith syndrome (MSS), an extremely rare embryonic developmental disorder with associated craniosynostosis. PATIENT AND METHOD: We presented herein a case of a 2-year-old female patient with MSS who underwent fronto-orbital advancement for multisuture craniosynostosis. RESULTS: The patient's proptosis improved after surgery, and no further surgical intervention was required for corneal exposure. A second FOA followed by revision tarsorrhaphy further improved eye closure. CONCLUSION: Surgical procedures to correct dysplastic features and limit neurological impairment are a worthwhile supportive treatment for improving the quality of life and general condition of patients with MSS.

Deleterious fibronectin type III-related gene variants may induce a spinal extradural arachnoid cyst: an exome sequencing study of identical twin cases.

PURPOSE: Despite numerous studies, the etiology of spinal extradural arachnoid cyst (SEDAC), a lesion associated with neurological symptoms, remains unknown. In this genomic twin study, we investigated the genetic etiology of SEDACs. METHODS: The subjects were identical twins who developed notably similar SEDACs at the same vertebral level. Accordingly, we performed whole-exome sequencing analyses of genomic material from the twins and their parents using a next-generation sequencer. Additionally, we determined their detailed family history and analyzed the family pedigree. RESULTS: The pedigree analysis suggested the potential presence of SEDACs in certain family members, indicating a genetic disease. Sequenced data were analyzed and filtered using a purpose-built algorithm, leading to the identification of 155 novel single-nucleotide polymorphisms (SNPs), of which 118 encoded missense or nonsense variants. A functional analysis of the proteins encoded by these SNP alleles revealed strong enrichment for the fibronectin type III (FN3) protein domain (q = 0.00576). Specifically, the data indicated that a missense variant affecting the FN3 protein domain of fibronectin 1 (FN1, p.P969S) can be the causal mutation underlying the SEDACs. CONCLUSION: The data suggest that deleterious mutations in fibronectin-related genes may cause SEDACs. In particular, it was suspected that a variant of FN1 may be the cause of the SEDACs in the twin cases studied herein. Detailed studies with a larger number of cases are needed.

Pudendal mapping of S1 rootlets in a functional posterior rhizotomy: when an S1 posterior root shows a high pudendal dorsal action potential-a technical note.

BACKGROUND: The standard level for lesioning in a functional posterior rhizotomy (FPR) ranges from L2 to S1/S2. Lesioning of the S1 and S2 rootlets strongly correlates with a reduction in ankle spasticity. In the Japanese population, the S2 root often shows the highest dorsal root action potentials (DAPs) in the afferent fibers of the pudendal nerve and is not lesioned to preserve postoperative urinary function. Thus, cutting of the S1 root plays a key role in reducing ankle spasticity in FPR. However, on rare occasions, even an S1 root may show high DAP in the afferent fibers of the pudendal nerve. PURPOSE: The present, brief, technical note aimed to describe how an S1 root with a relatively high DAP in the afferent fibers of the pudendal nerve may be handed. METHODS: In the procedure, the S1 root is divided into several rootlets, and each rootlet is tested for the pudendal mapping. A train of electrical stimuli is delivered to each rootlet in the standard FPR. If electromyography (EMG) findings after electrical stimulation are highly abnormal while the pudendal mapping demonstrates no or a relatively low DAPs, the rootlet is cut. In contrast, even if the rootlet shows highly abnormal EMG findings, it is preserved if mapping demonstrates a relatively high DAP. CONCLUSION: The S1 pudendal mapping is combined with EMG findings to achieve satisfactory reduction in ankle spasticity while preserving urological function.

Clinically practical formula for preoperatively estimating the cutting rate of the spinal nerve root in a functional posterior rhizotomy.

OBJECTIVE: A functional posterior rhizotomy (FPR) ideally involves minimal cutting of the posterior root while providing maximal reduction of disabling spasticity. However, the ideal cutting rate has yet to be determined. It was hypothesized that the cutting rate of the posterior root would negatively correlate with preoperative motor function in children with spasticity. METHODS: Children who underwent an FPR between March 1996 and March 2017 and whose pre- and postoperative data were followed more than a year were enrolled. The preoperative Gross Motor Function Measure (GMFM) score and the overall cutting rate of the posterior root were plotted on a scatter plot, and a simple linear regression analysis was performed. The rationale for the cutting rate of the posterior root was tested by postoperative chronological changes in the GMFM score up to 5 years after the FPR. The Gross Motor Function Classification System (GMFCS) was used to group the children. The postoperative and preoperative GMFM were compared at each GMFCS level. RESULTS: One hundred thirty-seven children (aged 2 to 19 years old, mean 5.9 years old) met the selection criteria. The cutting rate of the posterior root ranged from 17 to 83%, (mean 48.3%). A scatter plot was then made using GMFM scores between 10 and 90. The formula for the simple linear regression analysis was y = - 0.5539x + 73.896 (x, GMFM score; y, overall cutting rate (%)). The formula was further approximated based on the scatter plot findings as y = 100 - x. The postoperative GMFM showed an improved average score for all GMFCS levels although statistically significant improvement at postoperative 5 years was confirmed in only the GMFCS level 1 group. CONCLUSIONS: The findings of this study supported the hypothesis of the negative correlation of the cutting rate of the posterior root with preoperative motor function in children with spasticity. The amount of posterior nerve root/rootlet cutting during FPR negatively correlated with the preoperative GMFM score. The approximated formula is simple, practical for clinical use, and helpful for preoperatively estimating the required overall cutting rate for the posterior root. The suggested cutting rate induced by the approximated formula should be used as a reference value and be modified according to preoperative motor function, severity and distribution of spasticity, the result of intraoperative neurophysiology, and other factors.

Characteristics of Recurrent Congenital Sinus Pericranii: Case Report and Review of the Literature.

INTRODUCTION: Sinus pericranii (SP) involves transosseous vessels that connect the intra- and extracranial venous systems. Accessory-type SP can be cured by surgical or endovascular treatment. Reports of recurrence are, however, rare. CASE: A boy presented with a soft-tissue mass on the left parietal region of the head. Computed tomography and magnetic resonance imaging revealed the congenital SP with several small transosseous vessels surrounded by an area of thin bone. At the initial surgery, the vascular mass was completely excised by coagulating and cutting the -transosseous vessels. The skull defect was filled with bone wax. Two years later, SP recurred at the same site. At the second surgery, the skull defect and surrounding area were sealed with acrylic resin. The boy has been followed up for 6 years without recurrence. DISCUSSION: Potential risk factors for recurrence proposed in the existing literature include an unusually large number of emissary veins, rich circulation between intra- and extracranial venous systems, large bone defects, raised intracranial pressure, and association of other developmental venous anomalies. Our case demonstrates that thin skull bone around the original lesion can be another risk factor for recurrence. CONCLUSION: Removing all abnormal vessels and sealing the skull defect as well as the surrounding thin bone area are important to prevent recurrence of congenital SP.

Reversible diffusion weighted imaging hyperintensities during the acute phase of ischemic stroke in pediatric moyamoya disease: a case report.

BACKGROUND: Moyamoya disease is one of the primary causes of pediatric ischemic stroke, especially in East Asia. Areas of high signal intensity on diffusion weighted imaging (DWI) with decreased apparent diffusion coefficient (ADC) values usually point to irreversible ischemic damage. Reversibility of these DWI hyperintensities during the acute phase of ischemic stroke in pediatric moyamoya disease has not previously been reported. CASE REPORT: A 3-year-old girl was admitted to our emergency department due to sudden onset speech impairment and right hemiplegia. Computed tomography (CT) revealed a multilobal low-density area in the left cerebral hemisphere. The area was hyperintense on DWI with decreased ADC values. Magnetic resonance (MR) angiography revealed stenosis of the bilateral internal carotid artery bifurcations and their branches. Acute cerebral infarction due to moyamoya disease was diagnosed. MR images taken 4 days later showed resolution of most of the DWI hyperintensity areas. The initial decline in the ADC of the reversible DWI hyperintensities was less severe compared to the irreversible lesion. Within several days after onset, the patient became ambulatory although the follow-up MR fluid attenuated inversion recovery (FLAIR) images taken 2 weeks after onset revealed thinning of the corresponding cortical gyri. CONCLUSION: These findings indicate that a wide area of DWI hyperintensity during the acute phase of ischemic stroke can be reversed by appropriate treatment in pediatric moyamoya disease. To the best of our knowledge, this is the first report of reversible DWI hyperintensities over a wide cortical area during the acute phase of ischemic stroke in pediatric moyamoya disease.

Pediatric intraventricular arachnoid cysts in the body of lateral ventricle: surgical outcome and its embryologic background.

PURPOSE: The aim of this study is for the surgical treatment and outcome of the endoscopic fenestration of the arachnoid cyst located in the ventricular body to trigone in the pediatric population. Special concern was paid for the developmental origin of the intraventricular cysts estimated from the postoperative follow-up neuroimagings. PATIENTS AND METHODS: Between July 2002 and June 2015, we performed endoscopic and partly CT/MRI navigated fenestrations of intraventricular arachnoid cysts located at the body to trigone of the lateral ventricle in ten pediatric patients aged 2 months to 5 years. Based on the long axis of the cyst, we have opted for two surgical approaches: anterior approach via burr hole at Kocher's point and posterior approach via burr hole at the posterior occipital region. Fenestration was performed based on the intraoperative findings, either ventriculocystostomy, ventriculocystoventriculostomy, or ventriculocystocisternostomy. RESULTS: Intraventricular arachnoid cysts located in the body-trigone region showed a favorable outcome after endoscopic fenestration. All of the cysts shrank postoperatively. Follow-up neuroimagings taken between 6 and 126 months after surgery strongly suggested its relationship with the midline cisterns. Of our ten cases, eight were suggestive for originating from the velum interpositum cistern while two seemed to root from the quadrigeminal cistern. CONCLUSION: In the present study, we found that endoscopic fenestration of intraventricular arachnoid cysts in the body to trigone is a safe procedure with a satisfactory outcome. In our limited experience, there are two anatomic backgrounds; velum interpositum cistern and quadrigeminal cistern. Differentiation can be possible by neuroimagings, especially those obtained after surgery.

[Respiratory complications in children with Chiari malformation type II associated with myelomeningocele].

BACKGROUND: Management of life-threatening respiratory complications of Chiari malformation type II (CM II) is important in patients with myelomeningocele (MMC). The objective of this study is to determine the clinical features and outcome of respiratory complications in MMC. METHODS: The study was a retrospective chart review of 50 patients with MMC who were treated from birth between 2002 and 2013 at the National Center for Child Health and Development, Tokyo Japan. Respiratory complications were divided into three types; upper airway obstruction, sleep-disordered breathing (SDB) and prolonged expiratory apnea with cyanosis (PEAC). SDB was further divided into two subtypes: sleep apnea type and central hypoventilation type. RESULTS: Twelve (24%) of the 50 MMC patients had respiratory complications. Among them, most had at least two types of complications; six had upper airway obstruction, 10 had SDB, and 10 had PEAC. The respiratory complications appeared during the first six months in most patients. Surgical decompression was performed 11 of the patients during 10 and 60 days after respiratory symptoms appeared; of which, four required invasive respiratory support in spite of decompression surgery. Three patients with central hypoventilation type SDB required ventilator support with tracheostomy, and one with upper airway obstruction needed tracheostomy. In the patients with PEAC, the frequency of apneic spells decreased over time. There was no death in the patients with respiratory complications of MMC. CONCLUSIONS: In addition to surgical decompression for CM II, management of respiratory complications may improve mortality outcome. Such screening should be performed in patient with MMC particularly in the first six months.

Apparent diffusion coefficient of intracranial germ cell tumors.

The role of diffusion weighted imaging and apparent diffusion coefficient in intracranial germ cell tumors has not been fully elucidated. The aim of this study was to evaluate whether the ADC correlates with the histologic subtypes of germ cell tumors. We also aimed to investigate whether the ADC values can predict treatment response. The authors retrospectively analyzed the ADC values of the enhancing and solid regions of germ cell tumors. The absolute ADC values and the normalized ADC values were compared among different histologic diagnoses. The ADC values before and after the first course of chemotherapy were also compared between the different prognostic groups. Ten patients were included in the study. The median age at diagnosis was 9.3 years (range 5.3-13.8 years). There were four patients with germinoma and six patients with nongerminomatous germ cell tumor (NGGCT) including five mixed germ cell tumors and one immature teratoma. The mean absolute and normalized ADC values (×10(-3) mm(2)/s) were significantly lower in germinomas [0.835 ± 0.065 (standard deviation) and 1.11 ± 0.096, respectively] than in NGGCTs (1.271 ± 0.145 and 1.703 ± 0.223, respectively) (p = 0.01). The ADC values before and after the first course of chemotherapy were available in four patients. The ADC value after the first chemotherapy had a tendency to increase more in patients who eventually demonstrated complete response with chemotherapy than in patients who required second-look surgery. Assessment of the ADC values of germ cell tumors is considered to facilitate differentiation of histological subtypes of germ cell tumors. Evaluation of the ADC may also be useful for predicting treatment response.

Awareness of folic acid use increases its consumption, and reduces the risk of spina bifida.

The majority of neural tube defects were believed to be folic acid (FA)-preventable in the 1990s. The Japanese government recommended women planning pregnancy to take FA supplements of 400 µg/d in 2000, but the incidence of spina bifida has not decreased. We aimed to evaluate the OR of having an infant with spina bifida for women who periconceptionally took FA supplements and the association between an increase in supplement use and possible promoters for the increase. This is a case-control study which used 360 case women who gave birth to newborns afflicted with spina bifida, and 2333 control women who gave birth to healthy newborns during the first 12 years of this century. They were divided into two 6-year periods; from 2001 to 2006 and from 2007 to 2012. Logistic regression analyses were conducted to compute OR between cases and controls. The adjusted OR of having an infant with spina bifida for supplement users was 0.48 in the first period, and 0.53 in the second period. The proportion of women who periconceptionally consumed supplements significantly increased from 10 % in the first period to 30 % in the second period. Awareness of the preventive role of FA was a promoter for an increase in supplement use, and thus an FA campaign in high school seems rational and effective. The failure of the current public health policy is responsible for an epidemic of spina bifida. Mandatory food fortification with FA is urgent and long overdue in Japan.

Characteristic expression of p57/Kip2 in balloon cells in focal cortical dysplasia.

Balloon cells are a pathognomonic cellular feature of various cortical malformations, including focal cortical dysplasia type IIb (FCD IIb), cortical tubers of tuberous sclerosis (TSC) and hemimegalencephaly (HME). In the present study, we investigated the immunohistochemical expression of p57/Kip2, a member of the Cip/Kip family of cyclin-dependent kinase inhibitory proteins, in balloon cells in surgical specimens taken from 26, 17 and six patients with FCD IIb, TSC and HME, respectively. Characteristic dot-like reactivity with a faint, intense, reticular and process-like pattern was confined to the proximal portion of the cytoplasmic processes of the cells. Immunoelectron microscopy revealed the p57/Kip2 reactivity on intermediate filaments in the proximal portion of the processes. The immunohistochemical profile appeared similar to that of CD34; however, a double immunofluorescence study demonstrated that no cells showed reactivity for both p57/Kip2 and CD34. The frequencies of the p57/Kip2-positive cells in FCD IIb and HME were significantly higher than those in TSC, suggesting that the balloon cells may be heterogeneous. These findings suggest some functional significance of the protein on the cytoplasmic processes of balloon cells and appear consistent with the notion that the cells are abnormally differentiated progenitor cells.

[Scintigraphic imaging in the diagnosis of failed intrathecal baclofen therapy: a case report of a 7-year-old boy with ventriculoperitoneal shunt].

Intrathecal baclofen (ITB) therapy is popular for the management of intractable spasticity. In 2007, the indications of ITB therapy expanded to include spasticity of children in Japan. In this report, we assessed the utility of radioisotopic scintigraphy in the diagnosis of failed ITB therapy. A 7-year-old boy with schizencephaly, hydrocephalus, and spastic quadriplegia had an ITB pump implanted. In his infancy, he had undergone ventriculoperitoneal shunt implantation. One month after the ITB operation, the ITB therapeutic effect diminished. Several examinations confirmed that the pump function was normal and catheter failure had not occurred. However, radioisotopic scintigraphy revealed that the baclofen had been washed out to blood circulation more rapidly than is typically observed. We considered two possible causes for this; obstruction of the cerebrospinal space due to kyphosis and excessive washout of celebrospinal fluid through the ventriculoperitoneal shunt. The catheter was moved to a more caudal site surgically, and his spasticity improved. The use of radioisotopic scintigraphy to identify the distribution of baclofen is an effective technique for investigation of baclofen pump system malfunction.

[Intrathecal baclofen treatment for spasticity in childhood . initial report of long-term follow up in Japan].

OBJECTIVE: Initial outcome of intrathecal baclofen (ITB) treatment in Japan is being reported on. METHODS: Chronological change of the Ashworth scale and complications after surgery were analyzed. Data were obtained from 71 children with severe spasticity who had received ITB screening tests by the end of March 2012. RESULTS: Pump implantations for ITB treatment were performed in 43 children out of 62 whose spasticity reduced after baclofen injection at the screening tests. Postoperative evaluations of ITB treatment were carried out within one year and, in some cases, more than 2 years after surgery. Complications related to baclofen were reported on 19 occasions in 12 children within one year of ITB pump implantation, and on 9 occasions in 4 children of the 21 who were followed for more than 2 years. Main complications were hypertonia of muscle, liver dysfunction, and low blood pressure. The frequency of complications was lower than that reported previously. There was no apparent evidence to indicate that complications developed more in children than in adults in this study. The postoperative values of Ashworth scale in the upper and lower extremities were reduced markedly when compared with preoperative levels, and the improvements were statistically significant (P < 0.05). CONCLUSIONS: This is the first report of outcome of ITB for severely disabled children with spasticity in Japan. It was confirmed that ITB for children with severe spasticity is a safe and effective treatment.

Risk factors for the occurrence of spina bifida (a case-control study) and the prevalence rate of spina bifida in Japan.

BACKGROUND: The Japanese government recommended in 2000 that women planning pregnancy should take 400 µg of folic acid daily to decrease the risk of having an infant with spina bifida. We aimed to identify risk factors for the occurrence of spina bifida and to evaluate how the prevalence rate has altered over the past 3 decades. METHODS: Subjects comprised 360 women who gave birth to spina bifida-affected offspring and 2333 women who gave birth to offspring without spina bifida between 2001 and 2012. A self-administered questionnaire was used to collect data, which were analyzed by multiple logistic regression models. The prevalence rate of spina bifida was obtained through data provided by international and domestic organizations. RESULTS: Four variables were significantly associated with the increased risk of having newborns afflicted with spina bifida: not taking folic acid supplements (odds ratios [OR], 2.50; 95% confidence interval [CI], 1.72-3.64), presence of spina bifida patients within third-degree relatives (OR, 4.26; 95% CI, 1.12-16.19), taking anti-epileptic drugs without folic acid (OR, 20·20; 95% CI, 2.06-198.17), and low birth weight in the newborns ≤ 2500 g (OR, 4.21; 95% CI, 3.18-5.59). The prevalence rate of spina bifida has remained 5 to 6 per 10,000 total births and has not shown any decreasing trend over the past 11 years. CONCLUSION: Four risk factors were identified among Japanese women. Because recommendations and information have not decreased the occurrence of spina bifida, the Japanese government should implement mandatory food fortification.

The efficacy of a biopsy of intrinsic brainstem lesions for decision making of the treatments.

OBJECT: The diagnosis of diffuse intrinsic pontine gliomas (DIPGs) has been generally made mainly by magnetic resonance imaging (MRI) and clinical course. However, the accuracy of MRI-based diagnosis has not been fully confirmed yet. Our aim was to review efficacy of biopsy for decision making of the treatments. METHODS: We retrospectively analyzed pediatric patients undergoing biopsy for intrinsic brainstem lesions which were considered atypical for DIPGs by MRI findings. The lesion was evaluated atypical when it extended beyond the pons or it had a well-margined localized enhancing portion. RESULTS: Seven patients underwent biopsy. Preoperative MRI revealed a lesion extending beyond the pons in five patients and a focal enhancing lesion in four. Two patients had both of these. Open biopsy was performed via midline suboccipital approach in six patients and retrosigmoid approach in one. No intraoperative complications were observed. Histopathological examination revealed diffuse brainstem glioma in five patients, primitive neuroectodermal tumor (PNET) in one, and pilocytic astrocytoma in one. In the case with PNET, chemotherapy and radiotherapy were effective and the patient had been stable for 12 months without recurrence. The patient with pilocytic astrocytoma did not undergo radiotherapy and has been stable without regrowth of the tumor for 9 months. CONCLUSIONS: Open biopsy of intrinsic brainstem lesions is considered to be safe and effective for selecting an appropriate course of therapy. Patients with intrinsic pontine lesions which extend beyond the pons or with localized enhancing portion seem to be benefited from the biopsy.

Endoscopic transaqueductal or interventricular stent placement for the treatment of isolated fourth ventricle and pre-isolated fourth ventricle.

OBJECT: The aim of our study is to evaluate the effectiveness of endoscopic transaqueductal or interventricular stent placement into the fourth ventricle for isolated fourth ventricle (IFV) and pre-isolated fourth ventricle (PIFV), in which occlusion of the fourth ventricle outlets and dilation of the fourth ventricle are seen while the aqueduct is still patent. METHODS: We retrospectively analyzed pediatric patients who underwent endoscopic stent placement for IFV or PIFV. RESULTS: Five patients with IFV and four patients with PIFV underwent endoscopic stent placement. The mean age was 11.5 months. Three patients with IFV underwent aqueductoplasty with stent connected to an extracranial shunt system. Two patients with IFV and supratentorially protruded fourth ventricle underwent interventriculostomy with stent. In these patients, the stent was not connected to the shunt system as functional shunt had been already placed using the contralateral ventricle. In four patients with PIFV, transaqueductal stent was placed and connected to the extracranial shunt system. In all patients, preoperative symptoms improved and magnetic resonance imaging demonstrated reduction of the size of the fourth ventricle. The mean follow-up period was 49.6 months (range 5 to 99 months). Three patients (33 %) underwent reoperation due to obstruction of the abdominal catheter, partial occlusion of the ventricular catheter, and retraction of the fourth ventricular catheter. CONCLUSION: The endoscopic transaqueductal or interventricular stent placement into the fourth ventricle for the treatment of IFV is considered to be effective and safe. The transaqueductal stent placement for PIFV is also considered to be effective for resolution of symptoms and prevent progression into IFV.