Tonsillar herniation and cervical syringomyelia in association with posterior fossa tumors in children: a case-based update

Chiari I malformation in defined genetic syndromes in children: are there common pathways?

PURPOSE

Chiari malformation type I (CMI) is a common pediatric neurologic anomaly that can be associated with a variety of genetic disorders; however, it is not always clear whether the observed associations are real or random. The knowledge of the real associations could provide useful guidance to clinicians. Furthermore, it could be of help to better understand the still unknown genetic etiology of CMI.

METHODS

With the aim of implementing such insights, we retrospectively reviewed clinical, neuroradiological, and genetic data of patients harboring CMI evaluated at the Child Neurology Unit of our institution between January 2008 and December 2018.

RESULTS

The cohort consists of 205 patients (111 males and 94 females), with a mean age at diagnosis of 6.3 years (range 0-18 years). 188 patients completed an average follow-up period of 5.2 years (range one month-18 years). Mean age at last assessment was 11.4 years (range nine months-23 years). 127 (62%) children have been classified as syndromic due to the presence of neurodevelopmental disorders, phenotypic anomalies, or malformations. Among syndromic CMI children, a molecular diagnosis was identified in 35/127 (27.6%) (20 males and 15 females). The most common diagnoses were syndromic craniosynostosis in 8/35 children (22.9%), among which sevenare FGFR-related and one ERF-related craniosynostosis; disorders of the RAS/MAPK pathway, termed RASopathies or RAS/MAPK syndromes in 9/35 (25.7%); disorders of the PTEN-PI3K/AKT signal transduction cascade, termed PTENopathies in 3/35 children (8.6%); and chromosomal rearrangements in 6/35 patients (17.1%), two of whom with del16p11.2.

CONCLUSIONS

We polarized our attention on the defined genetic diagnoses focusing not only on the phenotypic hallmarks but also on the phenotypic overlapping features. In addition, we discussed the pathophysiological mechanisms leading to progressive cerebellar ectopia and the involved molecular pathways. Along with the recent literature evidence, we suppose that interactions between FGFR and RAS/MAPK pathway and between RAS/MAPK and PTEN-PI3K/AKT pathways could explain some phenotypic overlapping features and could have a significant role in the pathogenesis of CMI.

Chiari I Malformation: Opinions on Diagnostic Trends and Controversies from a Panel of 63 International Experts

BACKGROUND

Chiari I malformation (CMI) and the topics concerning it have been the subject of numerous discussions and polarizing controversies over the course of the last 20 years.

METHODS

The opinions of 63 recognized international CMI experts from 4 continents, with a collective surgical experience of >15,000 CMI cases, were gathered through a detailed questionnaire.

RESULTS

Three facts emerged from the analysis of the results: 1) Most of the replies showed a high level of consensus on most CMI-related topics. 2) Several topics, which had been considered controversial as recently as 10 years ago, are now more widely accepted. 3) The so-called 5-mm rule was rejected by 88.5% of the CMI experts who responded to the questionnaire.

CONCLUSIONS

Sixty three recognized international CMI experts from 4 continents, with a collective surgical experience of >15,000 CMI cases were polled about a number of CMI topics. The results showed a high level of consensus, as well as a paradigm shift.

Secondary sacral tethered cord syndrome after treatment of secondary cervical syringomyelia

A female patient operated at the age of 11 on a pilocytic astrocytoma in the posterior fossa, was re-operated for a recurrence 9 years later. A Torkildsen drain was placed in the 4th ventricle and she remained asymptomatic for 15 years before presenting again with acute hydrocephalus, tonsillar herniation, and a massive cervicothoracic syrinx. The symptoms retreated following craniocervical untethering and decompression. Two weeks later, however, she suffered from debilitating radiculopathy provoked by tethering of the cauda equina. Again, symptoms retreated completely after microsurgical intervention. This combination of a secondary Chiari-like malformation with cervical syringomyelia and tethering of the cauda equina in a single patient as a delayed complication of posterior fossa surgery has not been reported before. Diagnosis and treatment of lower tethered cord syndrome may be obscured and delayed in complex clinical situations. In particular, awareness to symptoms that are not related to syringomyelia is important in patients with a known syrinx and a history of posterior fossa surgery.

Syringomyelia Associated with a Huge Retrocerebellar Arachnoid Cyst: A Case Report

Occasionally, a posterior fossa arachnoid cyst can induce compression of the spinal cord and cause syringomyelia. Here, we report the case of a 29-year-old man with both progressive shoulder pain and gait disturbance, who was found to have a huge retrocerebellar arachnoid cyst associated with syringomyelia. Accordingly, posterior fossa decompression and arachnoid cyst excision were performed. Post-operative MRI showed a marked reduction in the size of the arachnoid cyst and syringomyelia. The patient's symptoms were clearly improved compared to before surgery. In our view, treatment in such patients should focus on decompressing the foramen magnum and include the removal of the coexistent arachnoid cyst walls, which appear to be the crucial factor in development of syringomyelia. In this report, we discuss the pathogenic mechanisms underlying syringomyelia-associated retrocerebellar arachnoid cyst and review the current literature on this topic.

Giant posterior fossa arachnoid cyst causing tonsillar herniation and cervical syringomyelia

Acquired cerebellar tonsillar herniation and syringomyelia associated with posterior fossa mass lesions is an exception rather than the rule. In the present article, we describe the neuroimaging findings in a case of 28-year-old female patient presented with a history of paraesthesia involving right upper limb of 8-month duration. Magnetic resonance imaging showed a giant retrocerebellar arachnoid causing tonsillar herniation with cervical syringomyelia. The findings in the present case supports that the one of the primary mechanism for the development of syringomyelia may be the obstruction to the flow of cerebrospinal fluid causing alterations in the passage of extracellular fluid in the spinal cord and leading to syringomyelia.

Cervicothoracic syringohydromyelia associated with a prosencephalic mass in a dog

A five-year-old, female, neutered boxer, with neuroanatomical signs consistent with a C1-C5 myelopathy, was diagnosed with a prosencephalic mass and associated severe cervicothoracic syringohydromyelia. After treatment with corticosteroids and lomustine, neurological examination was normal. Imaging repeated three months later showed significant reduction in both the size of the mass and the syringohydromyelia. To the authors' knowledge, this is the first reported case of a dog with syringohydromyelia secondary to a rostral brain mass that had clinical signs on presentation solely due to the syrinx, and the first reported case in a dog of partial resolution of syringohydromyelia after treatment solely with chemotherapy.

Foramen magnum arachnoid cyst induces compression of the spinal cord and syringomyelia: case report and literature review

It is very rare that a foramen magnum arachnoid cyst induces compression of the spinal cord and syringomyelia, and currently there are few treatment experiences available. Here we reported the case of a 43-year-old male patient who admitted to the hospital due to weakness and numbness of all 4 limbs, with difficulty in urination and bowel movement. MRI revealed a foramen magnum arachnoid cyst with associated syringomyelia. Posterior fossa decompression and arachnoid cyst excision were performed. Decompression was fully undertaken during surgery; however, only the posterior wall of the arachnoid cyst was excised, because it was almost impossible to remove the whole arachnoid cyst due to toughness of the cyst and tight adhesion to the spinal cord. Three months after the surgery, MRI showed a reduction in the size of the arachnoid cyst but syrinx still remained. Despite this, the symptoms of the patient were obviously improved compared to before surgery. Thus, for the treatment of foramen magnum arachnoid cyst with compression of the spinal cord and syringomyelia, if the arachnoid cyst could not be completely excised, excision should be performed as much as possible with complete decompression of the posterior fossa, which could result in a satisfying outcome.

Symptomatic syringomyelia occurring as a late complication of posterior fossa medulloblastoma removal in infancy in a boy also suffering from scaphocephaly

INTRODUCTION

The association of a medulloblastoma and a syringomyelia has been already described in rare instances albeit without symptoms related to the syrinx.

CASE REPORT

The case of a 23-year-old man operated in infancy for a medulloblastoma and then treated solely with adjuvant chemotherapy is reported. He was also operated in infancy for a scaphocephaly. With a very long time delay, he has developed a Chiari I and a symptomatic cervico-dorsal syringomyelia. The symptoms attributed to the syrinx consisted of a unilateral prurigo over the left arm which was so severe to lead to self-mutilation.

DISCUSSION

Clinical and magnetic resonance imaging follow-up after cervico-dorsal decompression shows a significant improvement of the symptoms together with a reduction of the size of the syrinx. This case is discussed in the light of the presumed pathophysiology of the syrinx and its exceptional clinical presentation.

Posterior fossa arachnoid cyst, tonsillar herniation, and syringomyelia in trichorhinophalangeal syndrome Type I

The authors report the case of a patient with Chiari malformation Type I (CM-I) and syringomyelia probably caused by a retrocerebellar arachnoid cyst. The patient's phenotype corresponded to trichorhinophalangeal syndrome Type I. The authors attributed the origin of both the retrocerebellar cyst and the abnormal posterior fossa to endochondral ossification anomalies that occur in this syndrome. The patient's spinal pain was most likely a result of the combination of CM-I and syringomyelia. To the best of the authors' knowledge, this is the first report on the association of CM-I and syringomyelia with a retrocerebellar arachnoid cyst occurring in a patient with trichorhinophalangeal syndrome Type I. The authors discuss the pathogenetic mechanisms involved in the production of tonsillar descent and syringomyelia in this patient, and review the current literature on related conditions that can result in this association.