Special Issue "Chiari 1 Malformation, Syringomyelia and Related Disorders: Advances in Diagnosis and Treatment for Adults and Children"

A special issue of Journal of Clinical Medicine (ISSN 2077-0383). This special issue belongs to the section "Clinical Neurology".

Deadline for manuscript submissions: 20 September 2023 | Viewed by 7028

Special Issue Editor

Neuroscience Department, Azienda Ospedaliera - Universitaria Città della Salute e della Scienza di Torino, Turin, Italy
Interests: rare diseases; Chiari malformation; syringomyelia; clinical neurophysiology; neuropathic pain; disability

Special Issue Information

Dear Colleagues,

Chiari 1 Malformation (CM1) is classically defined as a caudal displacement of the cerebellar tonsils through the foramen magnum into the spinal cord, but modern imaging techniques and experimental studies disclose a different aetiology. Other disorders, such as syringomyelia,  hydrocephalus, craniocervical instability can be associated at the time of the diagnosis or appear secondarily. Syringomyelia (Syr) is morphologically defined at magnetic resonance imaging (MRI) as the presence of a single or multiple fluid-filled cavities within the spinal cord and/or the bulb (Syringobulbia) and classified as a neurological rare disease (ORPHA3280). CM1 is classified as a rare disease (ORPHA268882), but epidemiology has been scarcely investigated. When CM1 is defined by cerebellar tonsil position 5 mm or more below the foramen magnum, MRI prevalence studies estimate prevalence at between 0.24 and 3.6% of the population; the discrepancy between these estimates is a result of the different age groups analysed, as the prevalence is substantially higher in children and young adults compared with older adults. Chiari can present with a wide variety of symptoms, also non-specific, with consequent controversies on diagnosis and surgical decision-making. The potential anatomy changes during maturation influence the decision to treat a younger versus an older patient with Chiari, particularly in asymptomatic o minimally symptomatic.

In this background, the aim of this Special Issue of Journal of Clinical Medicine is to attract high-quality studies covering pathogenesis, diagnosis and management of Chiari and Syringomyelia.

Contributors are encouraged to submit articles describing novel results, models, methodological innovations or reviews. We will strive to ensure that the articles of the Special Issue collectively present a cohesive picture of the state-of-the-art in the field and help to advance our understanding and management of these conditions.

The topics we wish to cover include but are not limited to:

  • Epidemiology of Chiari Malformation, syringomyelia and related disorders
  • Pathophysiology of Chiari: Hydrodynamics of Cerebro-Spinal Fluid flow
  • Pathogenesis of Syringomyelia: lessons from observations in dogs
  • The role of genetics in Chiari Malformation and Syringomyelia
  • Clinical phenotypes in Chiari and in Syringomeylia
  • Diagnostic investigations: old and new neurophysiological  methods
  • Neuroradiological definitions of Chiari  Malformation, Syringomyelia and related disorders
  • Advances in neuroradiological techniques in the diagnosis of Chiari Malformations and Syringomyelia
  • Surgery in Chiari  1 Malformation with and without Syringomyelia
  • Surgical strategies in isolated Syringomyelia
  • Outcome measures in Chiari and Syringomyelia long-term follow up

Dr. Palma Ciaramitaro
Guest Editor

Manuscript Submission Information

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Keywords

  •  chiari maformation
  •  syringomyelia
  •  epidemiology genetics
  •  hydrodynamics
  •  cerebro-spinal fluid
  •  MRI
  •  neurophysiology
  •  diagnosis
  •  surgery
  •  outcome measures
  •  adults
  •  children
  •  clinical outcome

Published Papers (7 papers)

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Research

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Article
Compromised Cranio-Spinal Suspension in Chiari Malformation Type 1: A Potential Role as Secondary Pathophysiology
J. Clin. Med. 2022, 11(24), 7437; https://doi.org/10.3390/jcm11247437 - 15 Dec 2022
Viewed by 815
Abstract
In Chiari Malformation Type I (CM1), low-lying tonsils obstruct the cisterna magna at the foramen magnum, thereby compromising the essential juncture between the cranial and spinal compartments. The anatomical obstruction of the cisterna magna inhibits bi-directional CSF flow as well as CSF pulse [...] Read more.
In Chiari Malformation Type I (CM1), low-lying tonsils obstruct the cisterna magna at the foramen magnum, thereby compromising the essential juncture between the cranial and spinal compartments. The anatomical obstruction of the cisterna magna inhibits bi-directional CSF flow as well as CSF pulse pressure equilibration between the intracranial compartment and the intraspinal compartment in response to instances of increased intracranial pressure. Less understood, however, are the roles of the spinal cord suspension structures at the craniocervical junction which lend viscoelastic support to the spinal cord and tonsils, as well as maintain the anatomical integrity of the cisterna magna and the dura. These include extradural ligaments including the myodural bridges (MDBs), as well as intradural dentate ligaments and the arachnoid framework. We propose that when these elements are disrupted by the cisterna magna obstruction, tonsillar pathology, and altered CSF dynamics, there may arise a secondary pathophysiology of compromised and dysfunctional cranio-spinal suspension in CM1. We present intraoperative images and videos captured during surgical exposure of the craniocervical junction in CM1 to illustrate this proposal. Full article
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Article
Chiari 1 Malformation and Epilepsy in Children: A Missing Relationship
J. Clin. Med. 2022, 11(20), 6182; https://doi.org/10.3390/jcm11206182 - 20 Oct 2022
Viewed by 798
Abstract
Purpose: Once believed a result of pathophysiological correlations, the association between Chiari 1 malformation (CM1) and epilepsy has since been considered as a coincidence, due to missing etiologic or clinical matching points. At present, the problem is being newly debated because of [...] Read more.
Purpose: Once believed a result of pathophysiological correlations, the association between Chiari 1 malformation (CM1) and epilepsy has since been considered as a coincidence, due to missing etiologic or clinical matching points. At present, the problem is being newly debated because of the increasing number of CM1 diagnoses, often among children with seizures. No specific studies on this topic are available yet. The present study aimed at updating the information on this topic by reporting on a series of children specifically enrolled and retrospectively analyzed for this purpose. Methods: All children admitted between January 2015 and June 2020 for epilepsy and CM1 were considered (Group 1). They were compared with children admitted in the same period for symptoms/signs related to CM1 and/or syringomyelia (Group 2). Syndromic patients were excluded, as well as those with tumoral or other overt intracranial lesions. All patients received a complete preoperative work-up, including MRI and EEG. Symptomatic children with CM1/syringomyelia were operated on. The pertinent literature was reviewed. Results: Group 1 was composed of 29 children (mean age: 6.2 years) showing CM1 and epilepsy with several types of seizures. A share of 27% had CM1-related symptoms and syringomyelia. The mean tonsillar ectopia was 7.5 mm. Surgery was performed in 31% of cases. Overall, 62% of children are currently seizure-free (including 5/9 children who were operated on). Tonsillar herniation and syringomyelia regressed in 4/9 cases and 4/8 cases, improved in 4/9 cases and 3/8 cases, and remained stable in 1/9 and 1/8 cases, respectively. CM1 signs/symptoms regressed completely in 6/8 cases and improved or remained stable in one case in each of the two remaining patients. Group 2 consisted of 77 children (mean age: 8.9 years) showing symptoms of CM1 (75%) and/or syringomyelia (39%). The mean tonsillar ectopia was 11.8 mm. Non-specific EEG anomalies were detected in 13 children (17%). Surgery was performed in 76.5% of cases (18 children were not operated on because of oligosymptomatic). Preoperative symptoms regressed in 26%, improved in 50%, remained stable 22%, and worsened in 2%; CM1 radiologically regressed in 39%, improved in 37%, remained unchanged in 22%, and worsened in 2%; and syringomyelia/hydromyelia regressed in 61%, improved in 30%, and was stable in 9%. No statistically significant differences between the two groups were detected regarding the M/F ratio, presence of syringomyelia/hydromyelia, or CM1/syringomyelia outcome; moreover, no correlation occurred between seizure-free condition and PF decompression in Group 1, or between disappearance of EEG anomalies and PF decompression in Group 2. A significant difference between the two groups was noticed regarding the mean age at admission (p = 0.003), amount of tonsillar herniation (p < 0.00001), and PF decompression (p = 0.0001). Conclusions: These findings do not support clinical correlations between CM1 and epilepsy. Their course depends on surgery and antiepileptic drugs, respectively. The analysis of the literature does not provide evidence of a relationship between seizures and cerebellar anomalies such as CM1. Rather than being linked to a syndrome that could explain such an association, the connection between the two now has to be considered to be random. Full article
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Article
Insights on the Hydrodynamics of Chiari Malformation
J. Clin. Med. 2022, 11(18), 5343; https://doi.org/10.3390/jcm11185343 - 12 Sep 2022
Cited by 1 | Viewed by 782
Abstract
Background: We propose that the appearance of a ptosis of the cerebellar tonsils and syringomyelia is linked to its own hemohydrodynamic mechanisms. We aimed to quantify cerebrospinal fluid (CSF) and cerebral blood flow to highlight how neurofluid is affected by Chiari malformations type [...] Read more.
Background: We propose that the appearance of a ptosis of the cerebellar tonsils and syringomyelia is linked to its own hemohydrodynamic mechanisms. We aimed to quantify cerebrospinal fluid (CSF) and cerebral blood flow to highlight how neurofluid is affected by Chiari malformations type 1(CMI) and its surgery. Methods: We retrospectively included 21 adult patients with CMI who underwent pre- and postoperative phase contrast MRI (PCMRI) during the period from 2001 to 2017. We analyzed intraventricular CSF, subarachnoid spaces CSF, blood, and tonsils pulsatilities. Results: In preoperative period, jugular venous drainage seems to be less preponderant in patients with syringomyelia than other patients (venous correction factor: 1.49 ± 0.4 vs. 1.19 ± 0.1, p = 0.05). After surgery, tonsils pulsatility decreased significantly (323 ± 175 μL/cardiac cycle (CC) vs. 194 ± 130 μL/CC, p = 0.008) and subarachnoid CSF pulsatility at the foramen magnum increased significantly (201 ± 124 μL/CC vs. 363 ± 231 μL/CC, p = 0.02). After surgery, we found a decrease in venous flow amplitude (5578 ± 2469 mm3/s vs. 4576 ± 2084 mm3/s, p = 0.008) and venous correction factor (1.98 ± 0.3 vs. 1.20 ± 0.3 mm3/s, p = 0.004). Conclusions: Phase-contrast MRI could be a useful additional tool for postoperative evaluation and follow-up, and is complementary to morphological imaging. Full article
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Article
Neurophysiological Correlates in Patients with Syringomyelia and Chiari Malformation: The Cortico-Diaphragmatic Involvement
J. Clin. Med. 2022, 11(17), 5080; https://doi.org/10.3390/jcm11175080 - 29 Aug 2022
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Abstract
Purpose. Brainstem syndromes have frequently been reported in Chiari syndrome and in syringobulbia; previous studies have shown that determining the central motor conduction time (CMCT) along the circuit of the phrenic nerve makes the assessment of the voluntary control of the respiratory pathway [...] Read more.
Purpose. Brainstem syndromes have frequently been reported in Chiari syndrome and in syringobulbia; previous studies have shown that determining the central motor conduction time (CMCT) along the circuit of the phrenic nerve makes the assessment of the voluntary control of the respiratory pathway possible. In our study, we evaluated the transcranial magnetic stimulation (TMS) of the phrenic nerve in patients affected by Chiari syndrome and/or syringomyelia (Syr) with the aim of identifying subclinical neurophysiological alterations. Methods. One hundred patients (75 females; average age: 51 ± 13.08 SD; range: 18–76) affected by Chiari syndrome and/or Syr without dyspnea were selected. The magnetic stimulation of the second motor neuron correlating with the phrenic nerve was performed using cervical magnetic stimulation (C5-MEP); the cortical MEP after magnetic stimulation (Cz-MEP) was recorded by magnetic stimulation of the motor cortex (areas corresponding to the diaphragm). The CMCT was calculated. The differences between the patients and controls were calculated (Student’s t test). Results. In 13% of the patients, the Cz-MEP were absent bilaterally, and the CMCT was not evaluable. In all these cases, bulbar/cervical Syr was present at MRI; in 10 of them, this was associated with CM1. A bilateral response was obtained in all the other patients (87%), and the CMCTs were normal. All the patients with alterations/absence of Cz-MEP presented bulbar/cervical Syr at MRI. The C5-MEP latency was prolonged or absent in 48%; of these, 84% presented bulbar/cervical Syr associated with CM1 at MRI. The C5-MEP latency values were significantly higher in the group of patients. Conclusions. Neurophysiological alterations of the diaphragmatic pathway were recorded in a group of Chiari syndrome and, particularly, in bulbar/cervical Syr. Future studies with larger cohorts of patients are needed to further assess the specific role of the TMS of the phrenic nerve in CM/Syr patients. Full article
Article
Surgical Management of Chiari Malformation Type I Associated with Syringomyelia: Outcome of Surgeries Based on the New Classification and Study of Cerebrospinal Fluid Dynamics
J. Clin. Med. 2022, 11(15), 4556; https://doi.org/10.3390/jcm11154556 - 04 Aug 2022
Cited by 1 | Viewed by 1003
Abstract
Introduction: The mainstay of treatment of syringomyelia associated with Chiari malformation type I (CM-I) is the management of CM-I to normalize the cerebrospinal fluid (CSF) flow at the foramen magnum. CM-I is classified into three independent types. Surgical treatment was selected based on [...] Read more.
Introduction: The mainstay of treatment of syringomyelia associated with Chiari malformation type I (CM-I) is the management of CM-I to normalize the cerebrospinal fluid (CSF) flow at the foramen magnum. CM-I is classified into three independent types. Surgical treatment was selected based on the mechanism of hindbrain ptosis in each CM-I type. Materials and Methods: Foramen magnum decompression (FMD: 213 cases), expansive suboccipital cranioplasty (ESCP: 87 cases), and craniocervical fixation (CCF: 30 cases) were performed. CSF flow dynamics were assessed pre- and post-surgery using cine phase contrast magnetic resonance imaging. During surgery, CSF flow dynamics were examined using color Doppler ultrasonography (CDU). Results: ESCP and FMD demonstrated high rates of improvement in neurological symptoms and signs (82.7%), whereas CCF demonstrated a high rate of improvement in neurological symptoms (89%). The pre-operative maximum flow velocity (cm/s) was significantly lower in patients than in controls and increased post-operatively. During surgery, CDU indicated that the volume of the major cistern was 8 mL, and the maximum flow velocity was >3 mL/s. Conclusions: An appropriate surgical treatment should be selected for CM-I to correct hindbrain ptosis. In addition, it is necessary to confirm the normalization of CSF flow at the foramen of Magendie. Full article
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Article
Surgical Management after Chiari Decompression Failure: Craniovertebral Junction Revision versus Shunting Strategies
J. Clin. Med. 2022, 11(12), 3334; https://doi.org/10.3390/jcm11123334 - 10 Jun 2022
Cited by 2 | Viewed by 929
Abstract
Revision surgery after posterior fossa decompression for Chiari malformation is not uncommon and poses both strategic and technical challenges. We conducted a single-center retrospective cohort study including all adult patients who underwent revision surgery after posterior fossa decompression for Chiari type I malformation [...] Read more.
Revision surgery after posterior fossa decompression for Chiari malformation is not uncommon and poses both strategic and technical challenges. We conducted a single-center retrospective cohort study including all adult patients who underwent revision surgery after posterior fossa decompression for Chiari type I malformation between 2010 and 2019. Among 311 consecutive patients operated on for Chiari malformation at our institution, 35 patients had a least one revision surgery with a mean follow-up of 70.2 months. Mean delay for revision was 28.8 months. First revision surgery was performed at the level of the foramen magnum in 25/35 cases and consisted in duraplasty revision in all cases, arachnolysis (51.4%), additional bone decompression (37.1%), tonsillar coagulation or resection (25.7%), 4th ventricle to cervical subarachnoid spaces shunt (5.7%). Most repeat revisions consisted in CSF diversion procedures, with either ventriculo-peritoneal or syringo-peritoneal shunts. Mean number of interventions per patient was 3.2, with 22.9% of patients undergoing 4 or more surgeries. Based on our experience, we propose that revision at the level of the foramen magnum should be considered as a first-line strategy for Chiari decompression failure. Shunting procedures can be performed in case of extensive arachnoiditis or repeated failures. Full article
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Review

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Review
The Small Posterior Cranial Fossa Syndrome and Chiari Malformation Type 0
J. Clin. Med. 2022, 11(18), 5472; https://doi.org/10.3390/jcm11185472 - 17 Sep 2022
Viewed by 1061
Abstract
Patients showing typical Chiari malformation type 1 (CM1) signs and symptoms frequently undergo cranial and cervical MRI. In some patients, MRI documents >5 mm of cerebellar tonsillar herniation (TH) and the diagnosis of CM1. Patients with 3–5 mm TH have “borderline” CM1. Patients [...] Read more.
Patients showing typical Chiari malformation type 1 (CM1) signs and symptoms frequently undergo cranial and cervical MRI. In some patients, MRI documents >5 mm of cerebellar tonsillar herniation (TH) and the diagnosis of CM1. Patients with 3–5 mm TH have “borderline” CM1. Patients with less than 3 mm of TH and an associated cervical syrinx are diagnosed with Chiari “zero” malformation (CM0). However, patients reporting CM1 symptoms are usually not diagnosed with CM if MRI shows less than 3–5 mm of TH and no syrinx. Recent MRI morphometric analysis of the posterior fossa and upper cervical spine detected anatomical abnormalities in and around the foramen magnum (FM) that explain these patients’ symptoms. The abnormalities include a reduced size of the posterior fossa, FM, and upper cervical spinal canal and extension of the cerebellar tonsils around the medulla rather than inferior to the foramen magnum, as in CM1. These morphometric findings lead some neurologists and neurosurgeons to diagnose CM0 in patients with typical CM1 signs and symptoms, with or without cervical syringes. This article reviews recent findings and controversies about CM0 diagnosis and updates current thinking about the clinical and radiological relationship between CM0, borderline CM1, and CM1. Full article
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