Infratentorial choroid plexus tumors in children

OBJECTIVE

Choroid plexus tumors (CPTs) are rare pediatric intracranial neoplasms, and mostly occur in the lateral ventricle. CPTs located in the infratentorial location are considered to be rare in the pediatric population. We present a series of eight patients treated in the last decade at our institution focusing on clinical presentations and their outcome after excision.

METHODS

We performed an institutional retrospective review of patients who underwent surgical resection of infratentorial CPTs during the period from 2008 to 2017. Patients' charts were reviewed for demographic data, clinical presentation, surgical treatment, and follow-up.

RESULTS

There were eight patients (6 females and 2 males), with mean age for the cohort at presentation was 9.0 years. They represent 75% of 12 CPTs of all locations treated at the same period in our institution. These 8 infratentorial CPTs were in the fourth ventricle in seven, and in the cerebellopontine angle (CPA) in one. Seven patients had choroid plexus papillomas (WHO grade I) and 1 had an atypical choroid plexus papilloma (WHO grade II). Gross total resection was attempted in all patients. However, two of 3 patients with fourth ventricle floor invasion had subtotal resection with a thin layer of tumor left on the floor. The remaining 6 had a gross total resection. Six patients with preoperative hydrocephalus had a perioperative external ventricular drainage but none required permanent shunting after tumor resection. None showed recurrence/tumor progression without adjuvant therapy during the follow-up period of 20 months to 11 years.

CONCLUSION

Infratentorial dominance among pediatric CPTs in this series contradicts previous reports. Infratentorial CPTs are amenable to surgical resection. Unresected small residuals due to invasion to the fourth ventricle floor showed no regrowth during 2 to 3 years follow-up without adjuvant therapy. However, these patients with incomplete resection need watchful observations.

EXTH-18. PEPTIDE NANO-STRUCTURES ENHANCE PEDIATRIC BRAIN TUMOR CHEMOTHERAPEUTIC EFFICACY

Pediatric gliomas, particularly high-grade gliomas, which include diffuse intrinsic pontine gliomas (DIPGs), are among the most formidable and devastating cancers in children. These tumors remain incurable, despite many treatment approaches. We recently identified a small population of glioma cells with stem-like features in pediatric gliomas (glioma stem cells: GSCs), that may be responsible, for therapeutic resistance. Bone morphogenetic protein 4 (BMP4), essential for CNS development, increases GSC therapeutic sensitivity and is a promising adjuvant for glioma treatment. Mechanisms through which BMP4 increases therapeutic sensitivity need to be elucidated, as this can lead to identification of additional treatment targets and delivery systems for BMP4 administration in a clinical setting. Additionally, extension of BMP4 short half-life would enhance its’ clinical application. Here we show that BMP4 increases chemosensitivity by decreasing H3K4me3 at the promoter of multidrug resistant gene 1 (MDR1), resulting in decreased MDR1 expression. BMP4 appears to bring about this effect by decreasing hSETD1A, an H3K4me3 methyltransferase. Our work also demonstrates the first use of a novel sulfated glycopeptide (glyco-PA) nanostructure as a vector for BMP4 delivery. Glyco-PA markedly extended and enhanced BMP4 function, and increased chemotherapeutic anti-tumor activity against pediatric malignant glioma cells in culture. Overall, this work illuminates BMP4 effects on pediatric glioma therapeutic sensitivity through epigenetic mechanisms, and demonstrates the potential of bioactive glyco-PA nanostructures as a delivery mechanism for treating pediatric malignant gliomas and other tumors.

Management of Chiari I malformation in children: personal opinions

PURPOSE

This manuscript describes our management philosophy of Chiari I malformation in children based on a single neurosurgeon's personal experience.

METHODS

Based on 61 infants and children with Chiari I malformation treated from 2007 to 2017, typical symptoms, surgical indications, types of surgery, and evaluation of surgical decompression are reviewed.

RESULTS

Sixty-one patients had 69 decompressions, with 90% having symptom improvement. Seven (11.5%) needed reoperation, 1 of which needed 2 reoperations for recurrence. The recurrence rates were 20% (5 of 25) after dural scoring and 5.6% (2 of 36) after duraplasty (p = 0.1116, Fisher's exact test). Six (16%) of 36 patients developed pseudomeningocele or CSF leak.

CONCLUSIONS

We recommend surgical intervention for Chiari I malformation for clearly symptomatic patients and those with significant hydromyelia regardless of symptoms. A bony decompression with dural scoring is recommended for patients with typical occipital headaches with a lesser degree of tonsillar descent, while an expansile duraplasty is standard for those with high-grade tonsillar descent, medullary kink, or hydromyelia. Intraoperative ultrasound is often helpful to ensure the adequacy of the decompression. Most patients will have improvements in symptom and imaging after either type of decompressive surgery.

Pediatric primary spinal atypical teratoid rhabdoid tumor: a case series and review of the literature

Atypical teratoid rhabdoid tumors (ATRTs) are rare malignant central nervous system tumors, commonly occurring before 3 years of age. Median overall survival (OS) of patients with these tumors is about 1 year, despite aggressive multimodal therapy. Pediatric primary spinal ATRTs are even more rare, with fewer than 50 cases reported. The authors present a series of four patients who were treated at Ann and Robert H. Lurie Children's Hospital of Chicago in the period from 1996 to 2017.These patients, with ages 2-11 years, presented with pain and a decline in motor functions. They were found to have lesions in the lumbar, thoracic, and/or cervical spine. One patient's tumor was intramedullary with exophytic components, while another patient's tumor had both intra- and extradural components. All patients underwent resection followed by chemotherapy (systemic and intrathecal). Two patients had fractionated radiation therapy and one had an autologous stem cell transplant. Three patients are known to be deceased (OS 8.5-45 months). The fourth patient was in remission 19 years after her initial diagnosis. To the authors' knowledge, this is the largest series of pediatric primary spinal ATRTs documented at a single institution. These cases illustrate a variety of presentations of spinal ATRT and add to the body of literature on this aggressive pathology.A systematic MEDLINE search was also conducted using the keywords "atypical teratoid rhabdoid tumor," "pediatric spinal rhabdoid tumor," and "malignant rhabdoid tumor spine." Reports were included for patients younger than 21 years, without evidence of intracranial or systemic disease at the time of diagnosis. Clinical characteristics and outcomes of the four institutional cases were compared to those in the literature. This review yielded an additional 48 cases of primary pediatric spinal ATRTs reported in the English-language literature. Patients (ages 2 months to 19 years) presented with symptoms of pain, regression of motor function, and spinal cord compression. The majority of tumors were intradural (14 extramedullary, 8 intramedullary, 1 both). Eleven cases in the literature described tumors limited to extradural structures, while 10 tumors involved the intra- and extradural spine. Four reports did not specify tumor location. Although rare, spinal ATRT should be considered in the differential diagnosis of pediatric patients presenting with a new spinal mass.

A Phenotypic Switch of Differentiated Glial Cells to Dedifferentiated Cells Is Regulated by Folate Receptor α

In a previous study, we showed that folate receptor‐α (FRα) translocates to the nucleus where it acts as a transcription factor and upregulates Hes1, Oct4, Sox2, and Klf4 genes responsible for pluripotency. Here, we show that acetylation and phosphorylation of FRα favor its nuclear translocation in the presence of folate and can cause a phenotypic switch from differentiated glial cells to dedifferentiated cells. shRNA‐FRα mediated knockdown of FRα was used to confirm the role of FRα in dedifferentiation. Ocimum sanctum hydrophilic fraction‐1 treatment not only blocks the folate mediated dedifferentiation of glial cells but also promotes redifferentiation of dedifferentiated glial cells, possibly by reducing the nuclear translocation of ~38 kDa FRα and subsequent interaction with chromatin assembly factor‐1. stem cells2019;37:1441–1454

Abstract 2871: Global reduction of H3K4me3 improves chemotherapeutic efficacy for pediatric ependymomas

Background Ependymomas (EPNs) are the third most common brain tumor in children. These tumors are resistant to available chemotherapeutic treatments, therefore new effective targeted therapeutics must be identified. Increasing evidence shows epigenetic alterations including histone posttranslational modifications (PTMs), are associated with malignancy, chemotherapeutic resistance and prognosis for pediatric EPNs. In this study we examined histone PTMs in EPNs and identified potential targets to improve chemotherapeutic efficacy.

Methods Global histone H3 lysine 4 trimethylation (H3K4me3) levels were detected in pediatric EPN tumor samples with immunohistochemistry and immunoblots. Candidate genes conferring therapeutic resistance were profiled in pediatric EPN tumor samples with micro-array. Promoter H3K4me3 occupancy was examined for two candidate genes, CCND1 and ERBB2, with chromatin-immunoprecipitation coupled with real-time PCR (ChIP-PCR). These methods and MTS assay were used to verify a relationship between H3K4me3 levels and CCND1 and ERBB2, and to investigate cell viability in response to chemotherapeutic drugs in primary cultured pediatric EPN cells.

Results H3K4me3 levels positively correlate with WHO grade malignancy in pediatric EPNs and are associated with progression free survival in patients with posterior fossa group A EPNs (PF-EPN-A). Reduction of H3K4me3 by silencing its methyltransferase SETD1A, in primary cultured EPN cells, increased cell response to chemotherapy.

Conclusions Our results support the development of a novel treatment that targets H3K4me3 to increase chemotherapeutic efficacy in pediatric PF-EPN-A tumors.

Key words: promoter, H3K4me3, human SETD1A, chemotherapy, pediatric ependymoma

Citation Format: Guifa Xi, Nitin Wadhwani, Rintaro Hashizume, Barbara Mania-Farnell, Marcelo Bento Soares, Charles D. James, Tadanori Tomita. Global reduction of H3K4me3 improves chemotherapeutic efficacy for pediatric ependymomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2871.

Evaluation of Protein Kinase Inhibitors with PLK4 Cross-Over Potential in a Pre-Clinical Model of Cancer

Polo-like kinase 4 (PLK4) is a cell cycle-regulated protein kinase (PK) recruited at the centrosome in dividing cells. Its overexpression triggers centrosome amplification, which is associated with genetic instability and carcinogenesis. In previous work, we established that PLK4 is overexpressed in pediatric embryonal brain tumors (EBT). We also demonstrated that PLK4 inhibition exerted a cytostatic effect in EBT cells. Here, we examined an array of PK inhibitors (CFI-400945, CFI-400437, centrinone, centrinone-B, R-1530, axitinib, KW-2449, and alisertib) for their potential crossover to PLK4 by comparative structural docking and activity inhibition in multiple established embryonal tumor cell lines (MON, BT-12, BT-16, DAOY, D283). Our analyses demonstrated that: (1) CFI-400437 had the greatest impact overall, but similar to CFI-400945, it is not optimal for brain exposure. Also, their phenotypic anti-cancer impact may, in part, be a consequence of the inhibition of Aurora kinases (AURKs). (2) Centrinone and centrinone B are the most selective PLK4 inhibitors but they are the least likely to penetrate the brain. (3) KW-2449, R-1530 and axitinib are the ones predicted to have moderate-to-good brain penetration. In conclusion, a new selective PLK4 inhibitor with favorable physiochemical properties for optimal brain exposure can be beneficial for the treatment of EBT.

Global Reduction of H3K4me3 Improves Chemotherapeutic Efficacy for Pediatric Ependymomas

BACKGROUND

Ependymomas (EPNs) are the third most common brain tumor in children. These tumors are resistant to available chemotherapeutic treatments, therefore new effective targeted therapeutics must be identified. Increasing evidence shows epigenetic alterations including histone posttranslational modifications (PTMs), are associated with malignancy, chemotherapeutic resistance and prognosis for pediatric EPNs. In this study we examined histone PTMs in EPNs and identified potential targets to improve chemotherapeutic efficacy.

METHODS

Global histone H3 lysine 4 trimethylation (H3K4me3) levels were detected in pediatric EPN tumor samples with immunohistochemistry and immunoblots. Candidate genes conferring therapeutic resistance were profiled in pediatric EPN tumor samples with micro-array. Promoter H3K4me3 was examined for two candidate genes, CCND1 and ERBB2, with chromatin-immunoprecipitation coupled with real-time PCR (ChIP-PCR). These methods and MTS assay were used to verify a relationship between H3K4me3 levels and CCND1 and ERBB2, and to investigate cell viability in response to chemotherapeutic drugs in primary cultured pediatric EPN cells.

RESULTS

H3K4me3 levels positively correlate with WHO grade malignancy in pediatric EPNs and are associated with progression free survival in patients with posterior fossa group A EPNs (PF-EPN-A). Reduction of H3K4me3 by silencing its methyltransferase SETD1A, in primary cultured EPN cells increased cell response to chemotherapy.

CONCLUSIONS

Our results support the development of a novel treatment that targets H3K4me3 to increase chemotherapeutic efficacy in pediatric PF-EPN-A tumors.

Polo-Like Kinase 4 (PLK4) Is Overexpressed in Central Nervous System Neuroblastoma (CNS-NB)

Neuroblastoma (NB) is the most common extracranial solid tumor in pediatrics, with rare occurrences of primary and metastatic tumors in the central nervous system (CNS). We previously reported the overexpression of the polo-like kinase 4 (PLK4) in embryonal brain tumors. PLK4 has also been found to be overexpressed in a variety of peripheral adult tumors and recently in peripheral NB. Here, we investigated PLK4 expression in NBs of the CNS (CNS-NB) and validated our findings by performing a multi-platform transcriptomic meta-analysis using publicly available data. We evaluated the PLK4 expression by quantitative real-time PCR (qRT-PCR) on the CNS-NB samples and compared the relative expression levels among other embryonal and non-embryonal brain tumors. The relative PLK4 expression levels of the NB samples were found to be significantly higher than the non-embryonal brain tumors (p-value < 0.0001 in both our samples and in public databases). Here, we expand upon our previous work that detected PLK4 overexpression in pediatric embryonal tumors to include CNS-NB. As we previously reported, inhibiting PLK4 in embryonal tumors led to decreased tumor cell proliferation, survival, invasion and migration in vitro and tumor growth in vivo, and therefore PLK4 may be a potential new therapeutic approach to CNS-NB.

Erythropoietin-mediated activation of aquaporin-4 channel for the treatment of experimental hydrocephalus

OBJECTIVE

In this study, we investigate a neuroprotective agent, erythropoietin (EPO), in animal hydrocephalus model and its potential reversal effects on hydrocephalus by altering the expression of aquaporin-4 (AQP4).

METHODS

Obstructive hydrocephalus was induced in 2-week-old rat pups by injecting kaolin (50 μl, 10 mg/ml in saline) into the cisterna magna, while the control pups received only saline. Kaolin-injected pups were divided into two groups on the fifth day after kaolin injection; one group received intra-peritoneal (i.p.) EPO (1 μg/pup) for 5 consecutive days, while other group received i.p. saline for 5 days. The effects of EPO on hydrocephalus were investigated by studying cerebral ventricle size and structural ependymal changes. We examined also the EPO effects on AQP4 expression and microRNA expression.

RESULTS

EPO treatment significantly reduced dilation of the cerebral ventricle and denudation of ependymal line in hydrocephalic pups comparing with the control group. Increased expression of AQP4 in periventricular ependymal lining and cultured astrocytes and increased vascular formation were noted after EPO treatment. Additionally, we identified miR-668 as an endogenous regulator of AQP4 in response to EPO. Anti-miR-668 dampened EPO-induced activation of AQP4 expression.

CONCLUSIONS

Together, our results show that EPO-mediated upregulation of AQP4 significantly reduces dilation of the cerebral ventricles in obstructive hydrocephalus pups and may lead to potential therapeutic options for hydrocephalus.

Prospective feasibility and safety assessment of surgical biopsy for patients with newly diagnosed diffuse intrinsic pontine glioma

Background

Diagnosis of diffuse intrinsic pontine glioma (DIPG) has relied on imaging studies, since the appearance is pathognomonic, and surgical risk was felt to be high and unlikely to affect therapy. The DIPG Biology and Treatment Study (DIPG-BATS) reported here incorporated a surgical biopsy at presentation and stratified subjects to receive FDA-approved agents chosen on the basis of specific biologic targets.

Methods

Subjects were eligible for the trial if the clinical features and imaging appearance of a newly diagnosed tumor were consistent with a DIPG. Surgical biopsies were performed after enrollment and prior to definitive treatment. All subjects were treated with conventional external beam radiotherapy with bevacizumab, and then stratified to receive bevacizumab with erlotinib or temozolomide, both agents, or neither agent, based on O6-methylguanine-DNA methyltransferase status and epidermal growth factor receptor expression. Whole-genome sequencing and RNA sequencing were performed but not used for treatment assignment.

Results

Fifty-three patients were enrolled at 23 institutions, and 50 underwent biopsy. The median age was 6.4 years, with 24 male and 29 female subjects. Surgical biopsies were performed with a specified technique and no deaths were attributed to the procedure. Two subjects experienced grade 3 toxicities during the procedure (apnea, n = 1; hypertension, n = 1). One subject experienced a neurologic deficit (left hemiparesis) that did not fully recover. Of the 50 tumors biopsied, 46 provided sufficient tissue to perform the study assays (92%, two-stage exact binomial 90% CI: 83%-97%).

Conclusions

Surgical biopsy of DIPGs is technically feasible, associated with acceptable risks, and can provide biologic data that can inform treatment decisions.

Resection of an Embolized Cirsoid Aneurysm With Intracranial Venous Drainage: 2-Dimensional Operative Video

Cirsoid aneurysms, also known as scalp arteriovenous malformations (AVM), are rare congenital extracranial vascular anomalies that often present as an enlarging pulsatile scalp mass. A 14-yr-old male presented with a pulsatile scalp lesion that was first noticed 3 yr prior and had progressively enlarged. No history of trauma was reported. MRI demonstrated a 4 cm wide and 2 cm tall nidus and catheter angiography was performed to further define the vascular supply and drainage. The patient underwent transvenous endovascular embolization followed by surgical excision via a bicoronal incision, as shown in this operative video. Care was taken to identify, cauterize, and transect feeding vessels from the superficial temporal, supratrochlear, and supraorbital arteries circumferentially to completely devascularize and resect the galeal nidus from overlying scalp tissue and underlying pericranium. Previously unreported in the literature, transosseous emissary veins partially draining the lesion were noted on angiography and were waxed thoroughly during surgery. Six-month follow-up examination demonstrated a well-healed incision without evidence of AVM recurrence. The unique venous drainage of this cirsoid aneurysm highlights the value of diagnostic angiography to fully characterize these rare and complex vascular lesions prior to pursuing definitive treatment.

 IRB approval was obtained from the Ann & Robert H. Lurie Children's Hospital of Chicago Institutional Review Board (IRB #2018-1799). The IRB waives the requirement of obtaining informed consent for this study in accordance with 45 CFR 46.116(d).

Abstract 3175: Sulfated glycopeptide nanostructures activate and extend bone morphogenetic protein 4 ability to increase pediatric malignant glioma chemotherapeutic efficacy

Pediatric gliomas, particularly high-grade gliomas, are among the most formidable and devastating cancers in children. These tumors have remained incurable, regardless of the many treatment approaches attempted. We recently identified a small population of glioma cells with stem-like features in pediatric gliomas (glioma stem cells: GSCs), that may be responsible, for therapeutic resistance in pediatric gliomas. Signaling by bone morphogenetic protein 4 (BMP4), an essential molecule for central nervous system (CNS) development, increases GSC therapeutic sensitivity, and whose activation is a promising adjuvant for glioma treatment. Mechanisms through which BMP4 increases therapeutic sensitivity need to be elucidated as this can lead to the identification of additional targets for treating malignant gliomas in children. Delivery systems for administering BMP4 in a clinical setting also need to be developed. Here, we show that BMP4 increases chemosensitivity by decreasing H3 lysine 4 trimethylation (H3K4me3) at the promoter of multidrug resistant gene 1 (MDR1) that, in turn, results in increased BMP4 expression. This appears to be the result of BMP4 decreasing levels of hSETD1A, a critical methyltransferase for H3K4me3. Our work also demonstrates the first use of a novel sulfated glycopeptide (glycol-PA) nanostructure as a vector for delivery of BMP4. Glycol-PA markedly extended and enhanced BMP4 function, and increased chemotherapeutic anti-tumor activity against pediatric malignant glioma cells in culture. Overall, our results expand understanding of how BMP4 brings about glioma therapeutic sensitization through epigenetic mechanisms, and show that highly bioactive glyco-PA nanostructures have potential as a novel delivery mechanism for treating pediatric malignant glioma, as well as other tumors.

Citation Format: Guifa Xi, Benjamin Best, Sonali Nayak, Mark McClendon, Barbara Mania-Farnell, John Kessler, Charles David James, Samuel Stupp, Tadanori Tomita. Sulfated glycopeptide nanostructures activate and extend bone morphogenetic protein 4 ability to increase pediatric malignant glioma chemotherapeutic efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3175.

Abstract 2084: Reprogramming the epigenome as an effective treatment option for neurofibromatosis1 associated malignant peripheral nerve sheath tumors

Neurofibromatosis type 1 (NF1) is common, occurring in 1 in 3000 live births, and results in skin pigmentation and the growth of tumors along nerves in the skin, brain, and other parts of the body. It arises from a mutated and non-functional tumor suppressor gene NF1. Tumors of the peripheral nerves, called neurofibromas and of the main eye nerve, called optic glioma, are debilitating and deadly. Epigenetic mechanisms have been shown to play an important role in the progression of neurofibromas to malignant peripheral nerve sheath tumors (MPNSTs). MPNSTs with polycomb repressive complex 2 (PRC2) loss showed complete loss of trimethylation at lysine 27 of histone H3 (H3K27me3). We hypothesized that owing to the loss of this repressive complex PRC2, there is an overexpression of genes related to tumorigenesis in MPNSTs because of reciprocal gain of the activation marks such as trimethylation at lysine 4 of histone H3 (H3K4me3) and acetylation of lysine 27 of histone H3 (H3K27Ac) at their promoters. Using RT-PCR, we observed an increase in the expression of candidate oncogenes genes PAX2, FOXN4, IGF2 and TLX1 in NF1 associated MPNST cell line ST88-14 versus the normal Schwann cells and normal human fibroblasts. Western blots using purified histones revealed that there was an increase in the expression of H3K4me3, H3K9me2, H3K18Ac and H3K27Ac. Recently, aqueous extracts of Ocimum Sanctum has been used as investigational cancer preventive drug. We wanted to know the effects of extracts of O. Sanctum on MPNST cell line ST88-14. Treatment of ST88-14 cells with the hydrophilic fraction of methanolic extract of Ocimum Sanctum (OSHP-1) not only showed a dose dependent decrease in the above histone marks but also showed an increase in the expression of N-CAM 140KD, characteristic of mature Schwann cells, in addition to a significant decline in proliferation. Further evaluation of the nuclear extracts showed that OSHP-1 treatment increased the expression of HDAC2, a component of NuRD complex and decreased that of lysine acetyl transferase 7 (KAT7) in a dose dependent manner suggesting that both HDAC2 and KAT7 may be responsible for the decrease in the acetylation of H3K27Ac and therefore reversal of the tumorigenic MPNSTs to a differentiated Schwann cell phenotype. Chromatin immunoprecipitation (ChIP) data revealed H3K27Ac occupancy on candidate genes (PAX2, FOXN4, IGF2 and TLX1) promoters was reduced by OSHP-1 treatment. In conclusion, OSHP-1 reprograms the epigenome and may be an effective treatment option for NF1 associated MPNSTs.

Citation Format: Chandra S. Mayanil, Mariam M. Khan, Vineet Mohanty, Raj Kumar, Guifa Xi, Shunsuke Ichi, Bal Ram Singh, Barbara Mania-Farnell, Tadanori Tomita. Reprogramming the epigenome as an effective treatment option for neurofibromatosis1 associated malignant peripheral nerve sheath tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2084.

In vivo three-dimensional kinematics of normal knees during different high-flexion activities

Aims

In Asia and the Middle-East, people often flex their knees deeply in order to perform activities of daily living. The purpose of this study was to investigate the 3D kinematics of normal knees during high-flexion activities. Our hypothesis was that the femorotibial rotation, varus-valgus angle, translations, and kinematic pathway of normal knees during high-flexion activities, varied according to activity.

Materials and Methods

We investigated the in vivo kinematics of eight normal knees in four male volunteers (mean age 41.8 years; 37 to 53) using 2D and 3D registration technique, and modelled the knees with a computer aided design program. Each subject squatted, kneeled, and sat cross-legged. We evaluated the femoral rotation and varus-valgus angle relative to the tibia and anteroposterior translation of the medial and lateral side, using the transepicodylar axis as our femoral reference relative to the perpendicular projection on to the tibial plateau. This method evaluates the femur medially from what has elsewhere been described as the extension facet centre, and differs from the method classically applied.

Results

During squatting and kneeling, the knees displayed femoral external rotation. When sitting cross-legged, femurs displayed internal rotation from 10° to 100°. From 100°, femoral external rotation was observed. No significant difference in varus-valgus angle was seen between squatting and kneeling, whereas a varus position was observed from 140° when sitting cross-legged. The measure kinematic pathway using our methodology found during squatting a medial pivoting pattern from 0° to 40° and bicondylar rollback from 40° to 150°. During kneeling, a medial pivot pattern was evident. When sitting cross-legged, a lateral pivot pattern was seen from 0° to 100°, and a medial pivot pattern beyond 100°.

Conclusion

The kinematics of normal knees during high flexion are variable according to activity. Nevertheless, our study was limited to a small number of male patients using a different technique to report the kinematics than previous publications. Accordingly, caution should be observed in generalizing our findings.

Cite this article: Bone Joint J 2018;100-B:50–5.

Chiari type I malformation of infants and toddlers

OBJECTIVES

Chiari I malformation has been a well-recognized clinical entity; however, its occurrence among infants and toddlers is unusual. Their clinical presentations may be different from other age groups due to their lack of effective verbal communication. The authors analyze their personal series of patients focusing on symptomatology and MRI characteristics. Treatment methods, results, and outcome are analyzed in order to identify appropriate surgical management among infants and toddlers with Chiari I malformation.

METHODS

The authors retrospectively reviewed 16 patients who were diagnosed and surgically treated between 2007 and 2014 during the first 3 years of life with minimum follow-up of 3 years. We focused on the presenting symptoms, magnetic resonance imaging findings, and surgical techniques used for posterior fossa decompression (PFD) and their postoperative outcome.

RESULTS

Twelve patients (75%) presented with signs of headaches such as irritability, inconsolable crying, head grabbing, and/or arching back. Ten patients (62.5%) presented with oropharyngeal and/or respiratory symptoms such as emesis, choking, gagging, snoring, sleep apnea, breathing pause, and/or vocal cord palsy. Only one patient had segmental cervical hydromyelia. At the first surgery, ten patients had PFD with dural scoring (Type 1 procedure), while six others had PFD with duraplasty (Type 2 procedure) with thermal reduction of the cerebellar tonsils in four. Following the first operation, all initially had varying degrees of symptomatic improvement; however, seven patients subsequently had symptomatic recurrence. Persistent crowding at the PFD site on the postoperative imaging indicated greater risk of recurrences in both Type 1 procedure and Type 2 procedure groups. Of seven patients who needed a second operation, fivewere after Type 1 procedure and the two were after Type 2 procedure. The difference of recurrence rates between these two groups is not significant. CSF-related complications occurred in 4 out of 11 patients who had Type 2 procedure (one after primary decompression and three after the second decompression for recurrence).

CONCLUSION

Young patients lacking effective verbal communication often present their Chiari I malformation differently from olderage groups. Behavioral changes indicative of headaches/irritability and oropharyngeal/respiratory symptoms are the primary presenting symptoms. The recurrence rate tends to be higher among the patients after Type 1 procedure (particularly those younger than 18 months) than after Type 2 procedure. We observed that duraplasty at primary or at redo PFD provides for better decompression and long-term outcome. However, one should keep it in mind that there is risk of CSF-related complications following duraplasty, particularly higher tendency after redo PFD.