Ependymoma from Benign to Highly Aggressive Diseases: A Review.

Ependymomas comprise biologically distinct tumor types with respect to age distribution, (epi)genetics, localization, and prognosis. Multimodal risk-stratification, including histopathological and molecular features, is essential in these biologically defined tumor types. Gross total resection (GTR), achieved with intraoperative monitoring and neuronavigation, and if necessary, second-look surgery, is the most effective treatment. Adjuvant radiation therapy is mandatory in high-risk tumors and in case of residual tumor. There is yet growing evidence that some ependymal tumors may be cured by surgery alone. To date, the role of chemotherapy is unclear and subject of current studies.Even though standard therapy can achieve reasonable survival rates for the majority of ependymoma patients, long-term follow-up still reveals a high probability of relapse in certain biological entities.With increasing knowledge of biologically distinct tumor types, risk-adapted adjuvant therapy gains importance. Beyond initial tumor control, and avoidance of therapy-induced morbidity for low-risk patients, intensified treatment for high-risk patients comprises another challenge. With identification of specific risk features regarding molecular alterations, targeted therapy may represent an option for individualized treatment modalities in the future.

Long-term results of minimally invasive strip craniectomy without helmet therapy for scaphocephaly - a single-centre experience.

Scaphocephaly is the most common type of craniosynostosis and various surgical techniques are used for treatment. Due to late postoperative changes of the head shape, long-term outcome data is important for evaluating any new surgical technique. At our institution, minimally invasive strip craniectomy without regular helmet therapy is the standard treatment in scaphocephalic patients. Between October 2021 and February 2023, we retrospectively examined the skull shape of patients who underwent minimally invasive strip craniectomy for scaphocephaly using a 3D surface scan technique. The cephalic index (CI), the need for helmet therapy and additional cosmetic outcome parameters were investigated. We included 70 patients (72.5% male). The mean follow-up time was 46 (10-125) months and the mean CI was 75.7 (66.7-85.2). In 58 patients, the final cosmetic result was rated as "excellent/good" (mean CI: 76.3; 70.4-85.0), in 11 as "intermediate" (mean CI: 73.3; 66.7-77.6), and in one case as "unsatisfactory" (CI 69.3). The presence of a suboccipital protrusion was associated with a "less than good" outcome. The CI correlated significantly with the overall outcome, the presence of frontal bossing, and the interval between scan and surgery (age at scan). Minimally invasive strip craniectomy is an elegant and safe method to correct scaphocephaly. Our data show good cosmetic results in the long term even without regular postoperative helmet therapy.

A suspected case of shaken baby syndrome-clinical management in Germany: a case-based overview.

PURPOSE: Each year, between 100 and 200 cases with shaken baby syndrome (SBS) are hospitalized in Germany. The reported incidence is 14 in 100,000 children. About 10 to 30% of the affected children do not survive. A high number of unreported cases are assumed. The rate of lifelong disability is high. The current situation in respect of abusive head injuries in infants has been investigated. MATERIAL AND METHODS: A case-based overview on the management of SBS in a German reference center for pediatric neurosurgery is presented and discussed against the background of forensic data and child protection network institutions and guidelines. RESULTS: The presented case is an example of a typical SBS presentation. All necessary diagnostic and therapeutic steps are explained and evaluated according to the existing guidelines in Germany. The authors state that hospital SOP can help to detect suspected cases of SBS and define the role of the pediatric neurosurgeon. Although the abusive mechanism of a head trauma is clear in most cases, forensic methods lack the precision to identify a perpetrator in all of them. According to an analysis of a multi-center study on criminal proceedings in Germany, 50% of the proceedings were closed without judgment due to lack of suspicion. Out of the remaining half with judgment, in 17%, the court decided on acquittal since the perpetration could not be assigned to a specific individual. CONCLUSION: Prevention is the most important factor to protect children from death and disability caused by inflicted brain injury. Pediatric healthcare professionals must be aware of typical signs of suspected child abuse, SBS in particular, and institutional SOP can help to improve management and outcome in these children. Forensic methods lack the precision to identify a perpetrator in every case.

Clinical variety and prognosis of intracranial arachnoid cysts in children.

Arachnoid cysts (AC) occur in different intracranial locations. Management and prognosis depend on the clinical presentation and treatment guidelines do not exist. With this study, we want to demonstrate the clinical variety of arachnoid cysts in children and place a focus on outcome factors in operated cases. This retrospective study of a consecutive single unit series of children, who underwent AC surgery between January 2010 and September 2019, provides demographic, clinical, imaging data, and information about surgical treatment and outcome. Overall, 63 patients (71.4 male) underwent surgery. Mean age was 50 months (0-191). Mean follow-up was 40 months (0-121). Eighty-one percent of patients presented with symptoms/signs of raised ICP. Focal neurological deficits were present in 15.9%, headache in 11.1% of children. Galassi cysts represented the predominant type (30.2%), followed by suprasellar (14.3%), quadrigeminal (12.7%), retrocerebellar, CPA and midline (each 11.1%), and hemispheric cysts (7.9%). Endoscopic and microsurgical fenestrations were performed in 27% and 58.7%, stent or shunt insertion in 6.3%/57.9% of the cases. In 33.3% of the cases one and in 12.7%, a second reintervention became necessary. Reoperation rate was significantly higher in children < 1 year (p = 0.003). Cyst volume decreased in 85.7%. Seventy percent of the patients were symptom free, 5% suffered from headache, and 22% from developmental disorders. All focal neurological symptoms resolved. Complication rate and outcome are depending on age and cyst location. Recurrence and revision rates are significantly higher in young infants (p = 0.003). Midline cysts with CCA are associated with developmental disorders.

Essential Management of Pediatric Brain Tumors.

Brain tumors are the most common solid tumors in children and are associated with high mortality. The most common childhood brain tumors are grouped as low-grade gliomas (LGG), high grade gliomas (HGG), ependymomas, and embryonal tumors, according to the World Health Organization (WHO). Advances in molecular genetics have led to a shift from pure histopathological diagnosis to integrated diagnosis. For the first time, these new criteria were included in the WHO classification published in 2016 and has been further updated in the 2021 edition. Integrated diagnosis is based on molecular genomic similarities of the tumor subclasses, and it can better explain the differences in clinical courses of previously histopathologically identical entities. Important advances have also been made in pediatric neuro-oncology. A growing understanding of the molecular-genetic background of tumorigenesis has improved the diagnostic accuracy. Re-stratification of treatment protocols and the development of targeted therapies will significantly affect overall survival and quality of life. For some pediatric tumors, these advances have significantly improved therapeutic management and prognosis in certain tumor subgroups. Some therapeutic approaches also have serious long-term consequences. Therefore, optimized treatments are greatly needed. Here, we discuss the importance of multidisciplinary collaboration and the role of (pediatric) neurosurgery by briefly describing the most common childhood brain tumors and their currently recognized molecular subgroups.

Diagnosis and treatment of Chiari malformation type 1 in children: the International Consensus Document.

BACKGROUND: Chiari malformation type 1 (CM1) is a rare condition where agreed classification and treatment are still missing. The goal of this study is to achieve a consensus on the diagnosis and treatment of CM1 in children. METHODS: A multidisciplinary panel formulated 57 provisional statements based on a review of the literature. Thirty-four international experts (IE) participated in a Delphi study by independently rating each statement on a 4-point Likert scale ("strongly disagree," "disagree," "agree," "strongly agree"). Statements that were endorsed ("agree" or "strongly agree") by < 75% of raters were re-formulated, or new statements were added, and another Delphi round followed (up to a maximum of three). RESULTS: Thirty-five IE were contacted and 34 agreed to participate. A consensus was reached on 30/57 statements (52.6%) after round 1. Three statements were added, and one removed. After round 2, agreement was reached on 56/59 statements (94.9%). Finally, after round 3, which took place during the 2019 Chiari Consensus Conference (Milan, Italy), agreement was reached on 58/59 statements (98.3%) about four main sections (Definition and Classification, Planning, Surgery, Isolated Syringomyelia). Only one statement did not gain a consensus, which is the "definition of radiological failure 24 month post-surgery." CONCLUSIONS: The consensus document consists of 58 statements (24 on diagnosis, 34 on treatment), serving clinicians and researchers following children with CM1. There is a clear need for establishing an international network and registry and to promote collaborative studies to increase the evidence base and optimize the long-term care of this patient population.

Spinal Cord Ependymomas With MYCN Amplification Show Aggressive Clinical Behavior.

Adult spinal cord ependymomas are typically low grade and have a relatively favorable clinical course following gross total resection. We report 4 cases of anaplastic spinal cord ependymoma with MYCN amplification, an exceptionally rare finding. All cases occurred in the spinal cord of adolescent and young adult women and had morphological and immunohistochemical features of anaplastic ependymomas (World Health Organization grade III). Chromosomal microarray analysis demonstrated amplification of 2p24 (including MYCN) in all cases. One patient died 6 months after surgery. Another patient recently had removal of metastatic nodules in the thoracic region, following gross total resection and adjuvant radiation therapy of a lumbar ependymoma 1 year previously. One patient responded well after chemotherapy but died after multiple relapses 82 months after diagnosis. We found MYCN amplification reported in 2 other ependymomas, both anaplastic and arising in the spinal cord of adult females (Brain Pathol 2001;11:133-43). One patient had multiple recurrences in the spinal cord and an intracranial metastasis. Although MYCN amplification is rare in ependymomas, the current and previously reported cases suggest that this is associated with higher-grade histology, spinal location, and often unfavorable prognosis. The clinical significance and therapeutic implications of MYCN amplification in ependymomas require further evaluation.

"Management: opinions from different centers"-the Sankt Augustin experience.

OBJECTIVE: In this "how we do it" survey, we review our management regimen of symptomatic CM1 and provide an analysis of our institutional case series of "bony only" decompression of the craniocervical junction without dural opening. METHODS: In regard to the latter clinical symptomatology, neurological status, electrophysiology data, and pre- and post-surgical MRI were analyzed. Surgery was performed in standard fashion under IOM, evaluated by intraoperative ultrasound. RESULTS: We reviewed 22 patients (mean age at surgery 13 ± 7 years; 11 female, 11 male). Neck pain, occipital headaches, sensory symptoms, and dizziness were the predominating symptoms; 9% had central apnea, 5 patients had scoliosis, and 2 patients had a history of premature synostosis. On MRI, preoperative mean tonsillar herniation was 16.55 ± 6.19, compared to 14.25 ± 6.75 after surgery. About half of patients with syringomyelia (n = 11) experienced imagining improvement after surgery. Patients with neck pain, occipital headaches, dizziness, and sensory abnormalities benefited most from surgery. Of the 6 cases that presented with pathological SSEPs, 4 exhibited improved measurements after surgery. There were no postoperative complications. CONCLUSION: To conclude bony decompression for CM1 resulted in clinical and imaging wise improvement and can be viewed as a safe first-lane option for symptomatic CM1.

Childhood supratentorial ependymomas with YAP1-MAMLD1 fusion: an entity with characteristic clinical, radiological, cytogenetic and histopathological features.

Ependymoma with YAP1-MAMLD1 fusion is a rare, recently described supratentorial neoplasm of childhood, with few cases published so far. We report on 15 pediatric patients with ependymomas carrying YAP1-MAMLD1 fusions, with their characteristic histopathology, immunophenotype and molecular/cytogenetic, radiological and clinical features. The YAP1-MAMLD1 fusion was documented by RT-PCR/Sanger sequencing, and tumor genomes were studied by molecular inversion probe (MIP) analysis. Significant copy number alterations were identified by GISTIC (Genomic Identification of Significant Targets in Cancer) analysis. All cases showed similar histopathological features including areas of high cellularity, presence of perivascular pseudo-rosettes, small to medium-sized nuclei with characteristic granular chromatin and strikingly abundant cells with dot-like cytoplasmic expression of epithelial membrane antigen. Eleven cases presented features of anaplasia, corresponding to WHO grade III. MRI showed large supratentorial multinodular tumors with cystic components, heterogeneous contrast enhancement, located in the ventricular or periventricular region. One of two variants of YAP1-MAMLD1 fusions was detected in all cases. The MIP genome profiles showed balanced profiles, with focal alterations of the YAP1 locus at 11q22.1-11q21.2 (7/14), MAMLD1 locus (Xp28) (10/14) and losses of chromosome arm 22q (5/14). Most patients were female (13/15) and younger than 3 years at diagnosis (12/15; median age, 8.2 months). Apart from one patient who died during surgery, all patients are alive without evidence of disease progression after receiving different treatment protocols, three without postoperative further treatment (median follow-up, 4.84 years). In this to date, largest series of ependymomas with YAP1-MAMLD1 fusions we show that they harbor characteristic histopathological, cytogenetic and imaging features, occur mostly in young girls under 3 years and are associated with good outcome. Therefore, this genetically defined neoplasm should be considered a distinct disease entity. The diagnosis should be confirmed by demonstration of the specific fusion. Further studies on large collaborative series are warranted to confirm our findings.

Conservative and operative management of iatrogenic craniocerebral disproportion-a case-based review.

INTRODUCTION: Craniocerebral disproportion (CCD) can occur as a sequela after shunting in early infancy. It can be understood as a disorder closely related to slit ventricle syndrome and chronic overdrainage syndrome. Here, we present two exemplary cases and summarize the pathophysiological, diagnostic, and therapeutic approaches to CCD. CLINICAL PRESENTATION: Two premature babies underwent shunting for posthemorrhagic hydrocephalus and presented in later childhood with recurrent episodes of symptomatic raised intracranial pressure (ICP) at 2 and 8 years of age, respectively. DIAGNOSIS AND MANAGEMENT: Both patients had unchanged ventricular size on cranial imaging and fulfilled the clinical diagnostic criteria of CCD. After confirming shunt patency, ICP monitoring was performed to diagnose intermittent intracranial hypertension. Different treatment pathways were pursued: While readjustment of a programmable shunt valve was sufficient to alleviate the raised ICP in the first case, a cranial expansion surgery was necessary in the second case. OUTCOME AND CONCLUSIONS: Both children were treated successfully after thorough assessment and careful choice of treatment approaches. This review provides detailed insight into CCD and highlights the importance of individual and critical decision-making in these complex patients.

Prophylactic antibiotics in pediatric neurological surgery.

PURPOSE: Surgical antibiotic prophylaxis (SAP) in pediatric neurosurgery has poorly been characterized until now. This review gives an overview on the current literature extracting recommendations and guidelines. METHODS: The current literature on SAP with special forcus on pediatric neurosurgerical procedures was reviewed. Further, available recommendations in online databases were checked. Clean neurosurgical, shunt, and implant surgeries are considered separately. RESULTS: To date, evidence-based data on SAP in pediatric neurosurgery remain sparse and there are no standardized approaches to an adequate use of antimicrobial agents for SSI prevention for this age group. CONCLUSION: Due to statistical needs, multi-center surveillance studies are needed for implementing SAP recommendations in pediatric neurosurgery.

Head circumference - a useful single parameter for skull volume development in cranial growth analysis?

BACKGROUND: The measurement of maximal head circumference is a standard procedure in the examination of childrens' cranial growth and brain development. The objective of the study was to evaluate the validity of maximal head circumference to cranial volume in the first year of life using a new method which includes ear-to-ear over the head distance and maximal cranial length measurement. METHODS: 3D surface scans for cranial volume assessment were conducted in this method comparison study of 44 healthy Caucasian children (29 male, 15 female) at the ages of 4 and 12 months. RESULTS: Cranial volume increased from measurements made at 4 months to 12 months of age by an average of 1174 ± 106 to 1579 ± 79 ml. Maximal cranial circumference increased from 43.4 ± 9 cm to 46.9 ± 7 cm and the ear-to ear measurement increased from 26.3 ± 21 cm to 31.6 ± 18 cm at the same time points. There was a monotone association between maximal head circumference (HC) and increase in volume, yet a backwards inference from maximal circumference to the volume had a predictive value of only 78% (adjusted R2). Including the additional measurement of distance from ear to ear strengthened the ability of the model to predict the true value attained to 90%. The addition of the parameter skull length appeared to be negligible. CONCLUSION: The results demonstrate that for a distinct improvement in the evaluation of a physiological cranial volume development, the additional measurement of the ear-to ear distance using a measuring tape is expedient, and, especially for cases with pathological skull changes, such as craniosynostosis, ought to be conducted.

Bite force and electromyography evaluation after cranioplasty in patients with craniosynostosis.

OBJECTIVE: This long-term follow-up investigation aimed to assess masticatory muscle function in 15 patients with craniosynostosis with detachment of the temporal muscle during fronto-orbital advancement 6 years after cranioplasty compared with a non-operative stomatognathic healthy cohort in the same age group (n = 25). STUDY DESIGN: The follow-up assessment for the operated children occurred on average 5.2 ± 1.7 years after surgery at the age of 7 ± 1.6 years. The maximum bite force was assessed, in addition to the bilateral function of both temporal and masseter muscles, which were analyzed using superficial electromyography. RESULTS: The maximum bite force was 257 ± 89 N 255 ± 88 N (right/left), respectively, in the group of operated children and 212 ± 61 N and 203 ± 57 N (right/left), respectively, in the control group, without clinical relevant difference between groups. The surface electromyography signal of the temporal muscle correlated positively with the bite force and showed a slightly lower average resting tone activity in the control group, whereas muscle fatigue occurred slightly faster in the operated children in both muscles without statistically significant difference between the 2 groups. CONCLUSIONS: There was no measurable dysfunction in the temporal muscle after the operative correction of craniosynostosis compared with a healthy population of children.

The self-defining axis of symmetry: A new method to determine optimal symmetry and its application and limitation in craniofacial surgery.

PURPOSE: Analysis of symmetry represents an essential aspect of plastic-reconstructive surgery. For cases in which reference points are either not fixed or are changed due to corrective intervention the determination of a symmetry axis is sometimes almost impossible and a pre-defined symmetry axis would not always be helpful. To assess cranial shape of surgical patients with craniosynostosis, a new algebraic approach was chosen in which deviation from the optimal symmetry axis could be quantified. MATERIALS AND METHODS: Optimal symmetry was defined based on a single central point in the fronto-orbital advancement (FOA) hyperplane and a corresponding landmark pair. The forehead symmetry evaluation was based on 3D-scans series of 13 children, on whom cranioplasty with FOA was performed and 15 healthy children who served as control group. RESULTS: Children with plagiocephaly showed considerable improvement in symmetry postoperatively, with stable values over one year, while those with trigonocephaly and brachycephaly showed constant good symmetry in the forehead both pre- and postoperatively. CONCLUSIONS: With the help of an optimally calculated symmetry axis this new analysis method offers a solution, which is independent of preset dimensions. Patients can be evaluated according to their individual needs regarding symmetry and also be compared with one another.

Comparison between piezosurgery and conventional osteotomy in cranioplasty with fronto-orbital advancement.

BACKGROUND: Cranioplasty of patients with craniosynostosis requires rapid, precise and gentle osteotomy of the skull to avoid complications and benefit the healing process. The aim of this prospective clinical study was to compare two different methods of osteotomy. Piezosurgery and conventional osteotomy were compared using an oscillating saw and high speed drill while performing cranioplasties with fronto-orbital advancement. METHODS: Thirty-four children who required cranioplasty with fronto-orbital advancement were recruited consecutively. The operations were conducted using piezosurgery or a conventional surgical technique, alternately. Operative time, blood count, CRP and transfusion rate, as well as soft tissue injuries, postoperative edema, pain development and secondary bone healing were investigated. RESULTS: The average age of patients was 9.7 months. The following indications for craniosynostosis were surgically corrected: trigonocephaly (23), anterior plagiocephaly (8), brachycephaly (1), and syndromic craniosynostosis (2). Piezosurgery was utilized in 18 cases. There were no group differences with regard to the incidence of soft tissue injuries (dura, periorbita), pain, swelling, blood loss or bony integration. The duration of osteotomy was significantly longer in the piezosurgery group, leading to slightly increased blood loss, while the postoperative CRP increase was higher using the conventional method. CONCLUSIONS: The piezosurgery method is a comparatively safe surgical method for conducting osteotomy during cranioplasty. With regard to soft tissue protection and postoperative clinical course, the same procedural precautions and controls are necessary as those needed for conventional methods. The osteotomy duration is considerably longer using piezosurgery, although it is accompanied by lower initial postoperative CRP values.

Myelomeningocele - a single institute analysis of the years 2007 to 2015.

BACKGROUND: After the introduction of folate supplementation, the number of open spinal dysraphism was successfully reduced over time. In 2007, the department for pediatric neurosurgery was established in the children's hospital. Since then, newborns with myelomeningocele (MMC), the most common form of open neural tube defects (NTD), are treated here. The aim of this study is to present the concepts applied to and experiences resulting from treatment of MMC. METHODS: Records of all newborns with MMC treated surgically during the period January 2007 to August 2015 in our institution were analyzed. Children, who were previously operated in utero were excluded. The type of neural tube defect, its location, associated comorbidities, and ambulation were recorded. RESULTS: Forty-eight children (25 males, 23 females) with spinal dysraphism were included in the analysis. In nearly 90 % of the cases, the repair of the MMC was done on the day of delivery. The follow-up period ranges from 9 weeks to 8 9/12 years (loss of follow-up in 2 cases). In 19 %, the defect remained undetected during gestation and in one case, carbamazepine was taken despite pregnancy. In 36 children (75 %), we found a Chiari malformation type II (CMII) associated with myelomeningocele. 85.4 % suffered from hydrocephalus and implantation of a shunt was necessary. In cases of bladder impairment, an intermittent catheterization was the most common management (83.3 %); no bladder augmentation was required. Twelve children required orthopedic surgery. Twenty-three of 33 patients (70 %) are ambulatory w/wo orthoses and devices. The 13 children who are younger than 2 years were considered separately to assess the motor activity safely. CONCLUSIONS: Our data show that neural tube defects to this day can remain undetected despite medical care during pregnancy. The most common associated diseases with MMC are Chiari II malformations and hydrocephalus. In the seven cases of simultaneous repair of MMC with shunt implantation, no additional complications were encountered. An interdisciplinary approach was allowed in a high percentage independence and social continence.

High-resolution genomic analysis does not qualify atypical plexus papilloma as a separate entity among choroid plexus tumors.

Choroid plexus tumors are rare neoplasms that mainly affect children. They include papillomas, atypical papillomas, and carcinomas. Detailed genetic studies are rare, and information about their molecular pathogenesis is limited. Molecular inversion probe analysis is a hybridization-based method that represents a reliable tool for the analysis of highly fragmented formalin-fixed paraffin-embedded tissue-derived DNA. Here, analysis of 62 cases showed frequent hyperdiploidy in papillomas and atypical papillomas that appeared very similar in their cytogenetic profiles. In contrast, carcinomas showed mainly losses of chromosomes. Besides recurrent focal chromosomal gains common to all choroid plexus tumors, including chromosome 14q21-q22 (harboring OTX2), chromosome 7q22 (LAMB1), and chromosome 9q21.12 (TRPM3), Genomic Identification of Significant Targets in Cancer analysis uncovered focal alterations specific for papillomas and atypical papillomas (e.g. 7p21.3 [ARL4A]) and for carcinomas (16p13.3 [RBFOX1] and 6p21 [POLH, GTPBP2, RSPH9, and VEGFA]). Additional RNA expression profiling and gene set enrichment analysis revealed greater expression of cell cycle-related genes in atypical papillomas in comparison with that in papillomas. These findings suggest that atypical papillomas represent an immature variant of papillomas characterized by increased proliferative activity, whereas carcinomas seem to represent a genetically distinct tumor group.

Primary and secondary management of the Chiari II malformation in children with myelomeningocele.

OBJECT: Chiari malformation type II is almost exclusively found in patients with open spinal dysraphism. Etiology and pathophysiology are not yet completely understood, and management guidelines regarding the best follow-up and treatment of this pathological entity do not exist. In order to assess essential management aspects, literature and a series of secondary neurosurgical interventions in Chiari II patients have been reviewed. METHODS: A literature review regarding etiology, diagnostics, pathophysiology, and management of Chiari malformation type II (CMII) and a retrospective evaluation of a series (2009-2012) of secondary interventions in Chiari II patients have been performed. Inclusion criteria were ICD for myelomeningocele with or without hydrocephalus and ICD for Chiari malformation and neurosurgical OR procedure. Evaluated parameters were: patient demographics, primary management, secondary neurosurgical operations (cranio-cervical decompression, shunt revision, myelolysis) as well as specific findings pre- and postoperatively. Essential results from literature review and patients' series are compiled in order to define management recommendations. RESULTS: Fifty patients (28 f, 22 m; mean age, 7.1 years (range, 0.5-26 years)) with myelomeningocele-associated Chiari malformation type II were operated on between 2009 and 2012. Twenty-four patients had syringomyelia and scoliosis each, and 12 suffered from both. Orthopedic surgery for scoliosis or kyphosis had been performed in 13 cases. Shunt revision was performed in 38 cases, myelolysis in 17, and decompression of the foramen magnum in 14 (28 %). After a mean follow-up of 1.9 years, syringomyelia decreased from 24 to 16 cases. There was a postoperative reduction of neck pain (one third), sensorimotor (two fifths), and cranial nerve deficits (one half). CSF flow at the foramen magnum did not change visibly after surgery. Ventricular size improved in about half of the patients. Slit-like ventricles were found in nine (6 pre-surgical) and enlarged ventricles in nine (23 pre-surgical). Complication rate was 6 % (3/50) per cases, and no patient died or deteriorated neurologically after surgery. CONCLUSION: CMII-related management guidelines are not well defined, since clinical constellations and presentations are varying. Often associated findings are syringomyelia, hydrocephalus, and scoliosis, and symptomatic CMII may be triggered by more than one underlying condition. According to literature and clinical experience, management recommendations can be defined. The most important finding is that hydrocephalus is often involved in symptomatic CMII and must always be considered first in any symptomatic patient. Intrinsic brain stem dysfunctions cannot be treated surgically, and monitoring of vital functions is sometimes the only clinical means that can be offered to the patient. Knowledge of the complex background has led to improved follow-up programs for the affected children and thus also improved longtime survival.