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: 31 March 2024 | Viewed by 38178

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

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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 (22 papers)

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14 pages, 4742 KiB  
Article
Developing Semiautomated Methods to Measure Pre- and Postoperative Syrinx Volumes
J. Clin. Med. 2023, 12(21), 6725; https://doi.org/10.3390/jcm12216725 - 24 Oct 2023
Viewed by 534
Abstract
Neurosurgeons evaluate MRI scans to document whether surgical treatment has reduced syrinx size. Manual measurement of syrinx volume is time-consuming and potentially introduces operator error and bias. Developing convenient semiautomated volumetric analysis methods may encourage their clinical implementation and improve syringomyelia monitoring. We [...] Read more.
Neurosurgeons evaluate MRI scans to document whether surgical treatment has reduced syrinx size. Manual measurement of syrinx volume is time-consuming and potentially introduces operator error and bias. Developing convenient semiautomated volumetric analysis methods may encourage their clinical implementation and improve syringomyelia monitoring. We analyzed 30 SPGR axial MRI scans from 15 pre- and postoperative Chiari I and syringomyelia patients using two semiautomated (SCAT and 3DQI) methods and a manual Cavalieri (CAV) method. Patients’ spinal cord and syrinx volumes pre- and postoperatively were compared by paired t-test. A decrease in syrinx volume (mm3) after surgery was detected across all methods. Mean syrinx volume (± SD) measured by CAV (n = 30) was, preoperatively, 4515 mm3 ± 3720, postoperatively 1109 ± 1469; (p = 0.0004). SCAT was, pre, 4584 ± 3826, post, 1064 ± 1465; (p = 0.0007) and 3DQI was, pre, 4027 ± 3805, post, 819 ± 1242; (p = 0.001). 3DQI and CAV detected similar mean spinal cord volumes before (p = 0.53) and after surgery (p = 0.23), but SCAT volumes differed significantly (p = 0.005, p = 0.0001). The SCAT and 3DQI semiautomated methods recorded surgically related syrinx volume changes efficiently and with enough accuracy for clinical decision-making and research studies. Full article
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15 pages, 1837 KiB  
Article
Mobility Assessment Using Multi-Positional MRI in Children with Cranio-Vertebral Junction Anomalies
J. Clin. Med. 2023, 12(21), 6714; https://doi.org/10.3390/jcm12216714 - 24 Oct 2023
Viewed by 576
Abstract
Objective: This study aimed to assess the relevance of using multi-positional MRI (mMRI) to identify cranio-vertebral junction (CVJ) instability in pediatric patients with CVJ anomalies while determining objective mMRI criteria to detect this condition. Material and Methods: Data from children with CVJ anomalies [...] Read more.
Objective: This study aimed to assess the relevance of using multi-positional MRI (mMRI) to identify cranio-vertebral junction (CVJ) instability in pediatric patients with CVJ anomalies while determining objective mMRI criteria to detect this condition. Material and Methods: Data from children with CVJ anomalies who underwent a mMRI between 2017 and 2021 were retrospectively reviewed. Mobility assessment using mMRI involved: (1) morphometric analysis using hierarchical clustering on principal component analysis (HCPCA) to identify clusters of patients by considering their mobility similarities, assessed through delta (Δ) values of occipito-cervical parameters measured on mMRI; and (2) morphological analysis based on dynamic geometric CVJ models and analysis of displacement vectors between flexion and extension. Receiver operating characteristics (ROC) curves were generated for occipito-cervical parameters to establish instability cut-off values. (3) Additionally, an anatomical qualitative analysis of the CVJ was performed to identify morphological criteria of instability. Results: Forty-seven patients with CVJ anomalies were included (26 females, 21 males; mean age: 10.2 years [3–18]). HCPCA identified 2 clusters: cluster №1 (stable patients, n = 39) and cluster №2 (unstable patients, n = 8). ΔpB-C2 (pB-C2 line delta) at 2.5 mm (AUC 0.98) and ΔBAI (Basion-axis Interval delta) 3 mm (AUC 0.97) predicted instability with 88% sensibility and 95% specificity and 88% sensitivity and 85% specificity, respectively. Geometric CVJ shape analysis differentiated patients along a continuum, from a low to a high CVJ motion that was characterized by a subluxation of C1 in the anterior direction. Qualitative analysis found correlations between instability and C2 anomalies, including fusions with C3 (body p = 0.032; posterior arch p = 0.045; inferior articular facets p = 0.012; lateral mass p = 0.029). Conclusions: We identified a cluster of pediatric patients with CVJ instability among a cohort of CVJ anomalies that were characterized by morphometric parameters with corresponding cut-off values that could serve as objective mMRI criteria. These findings warrant further validation through prospective case–control studies. Full article
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12 pages, 2553 KiB  
Article
Hemodynamic and Hydrodynamic Pathophysiology in Chiari Type 1 Malformations: Towards Understanding the Genesis of Syrinx
J. Clin. Med. 2023, 12(18), 5954; https://doi.org/10.3390/jcm12185954 - 13 Sep 2023
Cited by 1 | Viewed by 561
Abstract
Background: The pathophysiology of this association of type 1 Chiari malformation (CM1) and syrinxes is still unknown. There is an alteration in the dynamics of neurofluids (cerebrospinal fluid, arterial and venous blood) during the cardiac cycle in CM1. Our objective is to quantify [...] Read more.
Background: The pathophysiology of this association of type 1 Chiari malformation (CM1) and syrinxes is still unknown. There is an alteration in the dynamics of neurofluids (cerebrospinal fluid, arterial and venous blood) during the cardiac cycle in CM1. Our objective is to quantify CSF or arterial blood or venous blood flow in patients with Chiari syndrome (CS) with and without syrinxes using phase-contrast MRI (PCMRI). Methods: We included 28 patients with CM1 (9 with syrinxes, 19 without). Morphological MRI with complementary PCMRI sequences was performed. We analyzed intraventricular CSF, subarachnoid spaces CSF, blood, and tonsillar pulsatility. Results: There is a highly significant correlation (p < 0.001) between cerebral blood flow, cerebral vascular expansion volume and venous drainage distribution. Venous drainage distribution is significantly inversely correlated with oscillatory CSF volume at the level of the foramen magnum plane [−0.37 (0.04)] and not significantly correlated at the C2C3 level [−0.37 (0.05)] over our entire population. This correlation maintained the same trend in patients with syrinxes [−0.80 (<0.01)] and disappeared in patients without a syrinx [−0.05 (0.81)]. Conclusion: The distribution of venous drainage is an important factor in intracranial homeostasis. Impaired venous drainage would lead to greater involvement of the CSF in compensating for arterial blood influx, thus contributing to syrinx genesis. Full article
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20 pages, 6351 KiB  
Article
Intraoperative Neurophysiological Monitoring in Syringomyelia Surgery: A Multimodal Approach
J. Clin. Med. 2023, 12(16), 5200; https://doi.org/10.3390/jcm12165200 - 10 Aug 2023
Cited by 1 | Viewed by 738
Abstract
Syringomyelia can be associated with multiple etiologies. The treatment of the underlying causes is first-line therapy; however, a direct approach to the syrinx is accepted as rescue treatment. Any direct intervention on the syrinx requires a myelotomy, posing a significant risk of iatrogenic [...] Read more.
Syringomyelia can be associated with multiple etiologies. The treatment of the underlying causes is first-line therapy; however, a direct approach to the syrinx is accepted as rescue treatment. Any direct intervention on the syrinx requires a myelotomy, posing a significant risk of iatrogenic spinal cord (SC) injury. Intraoperative neurophysiological monitoring (IONM) is crucial to detect and prevent surgically induced damage in neural SC pathways. We retrospectively reviewed the perioperative and intraoperative neurophysiological data and perioperative neurological examinations in ten cases of syringomyelia surgery. All the monitored modalities remained stable throughout the surgery in six cases, correlating with no new postoperative neurological deficits. In two patients, significant transitory attenuation, or loss of motor evoked potentials (MEPs), were observed and recovered after a corrective surgical maneuver, with no new postoperative deficits. In two cases, a significant MEP decrement was noted, which lasted until the end of the surgery and was associated with postoperative weakness. A transitory train of neurotonic electromyography (EMG) discharges was reported in one case. The surgical plan was adjusted, and the patient showed no postoperative deficits. The dorsal nerve roots were stimulated and identified in the seven cases where the myelotomy was performed via the dorsal root entry zone. Dorsal column mapping guided the myelotomy entry zone in four of the cases. In conclusion, multimodal IONM is feasible and reliable and may help prevent iatrogenic SC injury during syringomyelia surgery. Full article
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15 pages, 1023 KiB  
Article
Syringomyelia Associated with Chiari 1 Malformation in Adults: Positive Outcome Predictors after Posterior Fossa Decompression with Duraplasty
J. Clin. Med. 2023, 12(8), 3019; https://doi.org/10.3390/jcm12083019 - 21 Apr 2023
Cited by 4 | Viewed by 1296
Abstract
Background: Syringomyelia (Syr) in patients with Chiari 1 malformation (CM1) may be attributable to abnormal dynamics of cerebrospinal fluid (CSF) in the upper cervical segment; fourth ventricle enlargement has been reported in association with a worse clinical and radiological presentation, independently of the [...] Read more.
Background: Syringomyelia (Syr) in patients with Chiari 1 malformation (CM1) may be attributable to abnormal dynamics of cerebrospinal fluid (CSF) in the upper cervical segment; fourth ventricle enlargement has been reported in association with a worse clinical and radiological presentation, independently of the posterior fossa volume. In this study, we analyzed presurgery hydrodynamic markers to evaluate if their changes could be associated with clinical and radiological improvement after posterior fossa decompression and duraplasty (PFDD). As a primary endpoint, we aimed to correlate improvement in the fourth ventricle area with positive clinical outcomes. Methods: In total, in this study, we enrolled 36 consecutive adults with Syr and CM1 who were followed by a multidisciplinary team. All the patients were prospectively evaluated with clinical scales and neuroimaging, including CSF flow, the fourth ventricle area, and the Vaquero Index by using a phase-contrast MRI before (T0) and after surgical treatment (T1-Tlast, with a range of 12–108 months). The CSF flow at the craniocervical junction (CCJ), the fourth ventricle area, and the Vaquero Index changes were statistically analyzed and compared to the clinical and quality of life improvement after surgery. The good outcome prediction ability of presurgical radiological variables was tested. Results: Surgery was associated with positive clinical and radiological outcomes in more than 90% of cases. The fourth ventricle area significantly reduced after surgery (T0-Tlast, p = 0.0093), but no significant associations with clinical improvement were found. The presurgical presence of CSF flow at the CCJ was able to predict a good outcome (AUC = 0.68, 95% CI 0.50–0.87 and LH+ = 2.1, IC 95% 1.16–3.07) and was also significantly associated with post-surgical pain relief (rho = 0.61 and p = 0.0144). Conclusions: Presurgery CSF flow at the CCJ is proposed as a radiological marker with the ability to predict a positive outcome after PFDD in adults with syringomyelia and CM1. Measurements of the fourth ventricle area could be useful additional information for evaluating surgical long-term follow-up; further experience on larger cohorts is required to better define the prognostic yield of this radiological parameter. Full article
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17 pages, 2743 KiB  
Article
Reoperation in Chiari-1 Malformations
J. Clin. Med. 2023, 12(8), 2853; https://doi.org/10.3390/jcm12082853 - 13 Apr 2023
Viewed by 1806
Abstract
(1) Background: The issue of unsuccessful surgery for Chiari-1 malformation (CM-1), as well as its potential causes and possible solutions, remains poorly documented and studied. (2) Methods: From a retrospective review of a personal series of 98 patients undergoing treatment for CM-1 during [...] Read more.
(1) Background: The issue of unsuccessful surgery for Chiari-1 malformation (CM-1), as well as its potential causes and possible solutions, remains poorly documented and studied. (2) Methods: From a retrospective review of a personal series of 98 patients undergoing treatment for CM-1 during the past 10 years, we created two study groups. Group 1: 8 patients (8.1%) requiring additional surgeries owing to postoperative complications (7 cerebrospinal fluid leakage, 1 extradural hematoma); 7 patients (7.1%) undergoing reoperations for failed decompression during the follow-up. Group 2: During the same period, we also managed 19 patients who had previously been operated on elsewhere: 8 patients who required adequate CM-1 treatment following extradural section of the filum terminale; 11 patients requiring reoperations for failed decompression. Failed decompression was managed by adequate osteodural decompression, which was associated with tonsillectomy (6 cases), subarachnoid exploration (8 cases), graft substitution (6 cases), and occipito-cervical fixation/revision (1 case). (3) Results: There was no mortality or surgical morbidity in Group 1. However, one patient’s condition worsened due to untreatable syrinx. In Group 2, there were two cases of mortality, and surgical morbidity was represented by functional limitation and pain in the patient who needed revision of the occipitocervical fixation. Twenty patients improved (58.8%), 6 remained unchanged (32.3%), 1 worsened (2.9%) and 2 died (5.9%). (4) Conclusions: The rate of complications remains high in CM-1 treatment. Unfortunately, a certain rate of treatment failure is unavoidable, but it appears that a significant number of re-operations could have been avoided using proper indications and careful technique. Full article
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13 pages, 2093 KiB  
Article
Cerebellar Tonsillar Descent Mimicking Chiari Malformation
J. Clin. Med. 2023, 12(8), 2786; https://doi.org/10.3390/jcm12082786 - 09 Apr 2023
Viewed by 4181
Abstract
Chiari I malformation has been defined as cerebellar tonsillar descent greater than 5 mm below the foramen magnum. Suboccipital decompression remains the mainstay of treatment for symptomatic patients. Other conditions sometimes have imaging features that mimic Chiari I malformation. These patients are at [...] Read more.
Chiari I malformation has been defined as cerebellar tonsillar descent greater than 5 mm below the foramen magnum. Suboccipital decompression remains the mainstay of treatment for symptomatic patients. Other conditions sometimes have imaging features that mimic Chiari I malformation. These patients are at risk of misdiagnosis and mismanagement, including surgery that may be unnecessary or may even worsen the underlying condition. The aim of this study was to analyse a series of Chiari I malformation mimics and identify differentiating imaging features. The mimics are categorised as post-traumatic cranio-cervical junction arachnoiditis, dural band, spontaneous intracranial hypotension, idiopathic intracranial hypertension, and cysts. Better understanding of these conditions will assist with diagnosis and optimal management, including avoiding unnecessary surgery. Full article
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16 pages, 1704 KiB  
Article
Audiovestibular Findings in a Cohort of Patients with Chiari Malformation Type I and Dizziness
J. Clin. Med. 2023, 12(8), 2767; https://doi.org/10.3390/jcm12082767 - 07 Apr 2023
Viewed by 1362
Abstract
Chiari Malformation Type I (CM1) is a neurological condition in which the cerebellar tonsils extend past the foramen magnum. While many studies have reported dizziness symptoms in patients with CM1, the prevalence of peripheral labyrinthine lesions is largely unknown. This study aimed to [...] Read more.
Chiari Malformation Type I (CM1) is a neurological condition in which the cerebellar tonsils extend past the foramen magnum. While many studies have reported dizziness symptoms in patients with CM1, the prevalence of peripheral labyrinthine lesions is largely unknown. This study aimed to comprehensively describe the audiovestibular phenotype in a cohort of patients with CM1 expressly referred for dizziness. Twenty-four patients with CM1 and a complaint of dizziness/vertigo were evaluated. Hearing and auditory brainstem tract function were essentially normal. While vestibular abnormalities were most prevalent during rotational testing (33%), abnormal functional balance was the most common finding (40%). Patients with CM1 had a greater likelihood of exhibiting an abnormal sensory organization test (SOT) postural stability score for fixed platform conditions, and for the somatosensory analysis score. While no significant associations were identified between tonsillar ectopia extent and any vestibular/balance outcome measure, a significant negative association was identified between neck pain and the somatosensory sensory analysis score. Abnormal functional balance in the somatosensory domain was remarkable, with poorer scores associated with neck pain. An isolated peripheral vestibulopathy was present in only 8% of patients. Despite the low prevalence of vestibulopathy, vestibular/balance assessment is warranted to identify patients who may benefit from referral to specialized medical disciplines. Full article
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12 pages, 3940 KiB  
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
Cited by 1 | Viewed by 1746
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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19 pages, 2229 KiB  
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 2399
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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11 pages, 925 KiB  
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 6 | Viewed by 1606
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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7 pages, 232 KiB  
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
Cited by 1 | Viewed by 1099
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
19 pages, 12731 KiB  
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 2 | Viewed by 3130
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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7 pages, 1459 KiB  
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 5 | Viewed by 1571
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

Jump to: Research, Other

43 pages, 2532 KiB  
Review
The Role of Neurophysiology in Managing Patients with Chiari Malformations
J. Clin. Med. 2023, 12(20), 6472; https://doi.org/10.3390/jcm12206472 - 11 Oct 2023
Viewed by 942
Abstract
Chiari malformation type 1 (CM1) includes various congenital anomalies that share ectopia of the cerebellar tonsils lower than the foramen magnum, in some cases associated with syringomyelia or hydrocephalus. CM1 can cause dysfunction of the brainstem, spinal cord, and cranial nerves. This functional [...] Read more.
Chiari malformation type 1 (CM1) includes various congenital anomalies that share ectopia of the cerebellar tonsils lower than the foramen magnum, in some cases associated with syringomyelia or hydrocephalus. CM1 can cause dysfunction of the brainstem, spinal cord, and cranial nerves. This functional alteration of the nervous system can be detected by various modalities of neurophysiological tests, such as brainstem auditory evoked potentials, somatosensory evoked potentials, motor evoked potentials, electromyography and nerve conduction studies of the cranial nerves and spinal roots, as well as brainstem reflexes. The main goal of this study is to review the findings of multimodal neurophysiological examinations in published studies of patients with CM1 and their indication in the diagnosis, treatment, and follow-up of these patients, as well as their utility in intraoperative monitoring. Full article
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Graphical abstract

31 pages, 4694 KiB  
Review
A Critical Update of the Classification of Chiari and Chiari-like Malformations
J. Clin. Med. 2023, 12(14), 4626; https://doi.org/10.3390/jcm12144626 - 11 Jul 2023
Cited by 1 | Viewed by 1458
Abstract
Chiari malformations are a group of craniovertebral junction anomalies characterized by the herniation of cerebellar tonsils below the foramen magnum, often accompanied by brainstem descent. The existing classification systems for Chiari malformations have expanded from the original four categories to nine, leading to [...] Read more.
Chiari malformations are a group of craniovertebral junction anomalies characterized by the herniation of cerebellar tonsils below the foramen magnum, often accompanied by brainstem descent. The existing classification systems for Chiari malformations have expanded from the original four categories to nine, leading to debates about the need for a more descriptive and etiopathogenic terminology. This review aims to examine the various classification approaches employed and proposes a simplified scheme to differentiate between different types of tonsillar herniations. Furthermore, it explores the most appropriate terminology for acquired herniation of cerebellar tonsils and other secondary Chiari-like malformations. Recent advances in magnetic resonance imaging (MRI) have revealed a higher prevalence and incidence of Chiari malformation Type 1 (CM1) and identified similar cerebellar herniations in individuals unrelated to the classic phenotypes described by Chiari. As we reassess the existing classifications, it becomes crucial to establish a terminology that accurately reflects the diverse presentations and underlying causes of these conditions. This paper contributes to the ongoing discussion by offering insights into the evolving understanding of Chiari malformations and proposing a simplified classification and terminology system to enhance diagnosis and management. Full article
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12 pages, 1327 KiB  
Review
Overview of Spontaneous Intracranial Hypotension and Differential Diagnosis with Chiari I Malformation
J. Clin. Med. 2023, 12(9), 3287; https://doi.org/10.3390/jcm12093287 - 05 May 2023
Viewed by 1714
Abstract
Spontaneous intracranial hypotension (SIH) occurs due to a leakage of the cerebrospinal fluid (CSF) lowering the pressure of subarachnoid space, mostly caused by a dural breach or discogenic microspur. As a result of less support provided by CSF pressure, intracranial structures are stretched [...] Read more.
Spontaneous intracranial hypotension (SIH) occurs due to a leakage of the cerebrospinal fluid (CSF) lowering the pressure of subarachnoid space, mostly caused by a dural breach or discogenic microspur. As a result of less support provided by CSF pressure, intracranial structures are stretched downward, leading to a constellation of more or less typical MRI findings, including venous congestion, subdural effusions, brainstem sagging and low-lying cerebellar tonsils. Clinic examination and an MRI are usually enough to allow for the diagnosis; however, finding the location of the dural tear is challenging. SIH shares some MRI features with Chiari malformation type I (CM1), especially low-lying cerebellar tonsils. Since SIH is likely underdiagnosed, these findings could be interpreted as signs of CM1, leading to a misdiagnosis and an incorrect treatment pathway. Medical treatment, including steroids, bed rest, hydration caffeine, and a blind epidural blood patch, have been used in this condition with variable success rates. For some years, CSF venous fistulas have been described as the cause of SIH, and a specific diagnostic and therapeutic pathway have been proposed. The current literature on SIH with a focus on diagnosis, treatment, and differential diagnosis with CM1, is reviewed and discussed. Full article
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13 pages, 1453 KiB  
Review
A Systematic Review of Non-Opioid Pain Management in Chiari Malformation (Type 1) Patients: Current Evidence and Novel Therapeutic Opportunities
J. Clin. Med. 2023, 12(9), 3064; https://doi.org/10.3390/jcm12093064 - 23 Apr 2023
Cited by 1 | Viewed by 2944
Abstract
Chiari Malformation Type I (CM) includes a range of cranial abnormalities at the junction of the skull with the spine, with common symptoms including pain and headaches. Currently, CM pain is managed medically through anti-inflammatory drugs, muscle relaxants, and opioids, while surgical management [...] Read more.
Chiari Malformation Type I (CM) includes a range of cranial abnormalities at the junction of the skull with the spine, with common symptoms including pain and headaches. Currently, CM pain is managed medically through anti-inflammatory drugs, muscle relaxants, and opioids, while surgical management includes posterior fossa decompression. Given the adverse effects of opioid use, and an ongoing opioid epidemic, there is a need for safe, non-opioid alternatives for clinical pain management. This systematic review was performed to provide an update on the current literature pertaining to the treatment of CM pain with non-opioid alternatives. A literature search was performed in June 2022 utilizing the PubMed and Google Scholar databases, and articles were identified that included information regarding non-opioid pain management in CM patients. A total of 90 articles were obtained from this search, including 10 relevant, drug-specific studies. Two independent reviewers selected and included all relevant articles based on the chosen search criteria to minimize bias risk. Currently available treatments for neurosurgical pain management include anticonvulsants, corticosteroids, NSAIDs, anti-inflammatory drugs, NMDA receptor antagonists, local anesthetics, nerve blocks, scalp blocks, and neuromuscular blocks. While more information is needed on the use of non-opioid pain management, the present literature provides potential evidence of its efficacy amongst the CM patient population, on account of the success that non-opioid pain management has demonstrated within other neurological pain syndromes. Further research into non-pharmacological pain management would also benefit the CM population and could be generalized to related conditions. Full article
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13 pages, 4163 KiB  
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
Cited by 3 | Viewed by 2587
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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Other

Jump to: Research, Review

10 pages, 564 KiB  
Systematic Review
Chiari Syndrome: Advances in Epidemiology and Pathogenesis: A Systematic Review
J. Clin. Med. 2023, 12(20), 6694; https://doi.org/10.3390/jcm12206694 - 23 Oct 2023
Viewed by 805
Abstract
Arnold Chiari syndrome is a rare congenital disease of unknown prevalence and whose origin is still under study. It is encompassed within the posterior cranial malformations, showing a wide spectrum of symptomatology that can range from severe headache, dizziness, and paresthesia to complete [...] Read more.
Arnold Chiari syndrome is a rare congenital disease of unknown prevalence and whose origin is still under study. It is encompassed within the posterior cranial malformations, showing a wide spectrum of symptomatology that can range from severe headache, dizziness, and paresthesia to complete asymptomatology. It is for this reason that early diagnosis of the disease is difficult, and it is usually diagnosed in adolescence. Treatment is based on remodeling and decompression of the malformed posterior cranial fossa, although the risk of residual symptoms after surgery is high. The aim of this review is to update all the existing information on this pathology by means of an exhaustive analysis covering all the scientific literature produced in the last 5 years. In addition, it has been carried out following the PRISMA model and registered in PROSPERO with code CRD42023394490. One of the main conclusions based on the results obtained in this review is that the origin of the syndrome could have a genetic basis and that the treatment of choice is the decompression of the posterior cerebral fossa. Full article
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7 pages, 494 KiB  
Brief Report
Treatment of Chiari Malformation and Concomitant Paediatric Scoliosis Long-Term Follow-Up in One Major Referral Centre in the UK
J. Clin. Med. 2023, 12(10), 3409; https://doi.org/10.3390/jcm12103409 - 11 May 2023
Viewed by 1393
Abstract
Objective: Paediatric scoliosis (PS) and Chiari malformation type 1 (CM-1) have been reported to be associated with each other. Scoliosis curvature is a common finding among patients operated for CM-1, and curve development has been related to it. We report a cohort of [...] Read more.
Objective: Paediatric scoliosis (PS) and Chiari malformation type 1 (CM-1) have been reported to be associated with each other. Scoliosis curvature is a common finding among patients operated for CM-1, and curve development has been related to it. We report a cohort of PS and CM-1 patients managed with posterior fossa and upper cervical decompression (PFUCD) by a single surgeon, with an average of two years of follow-up. Methods: We present a retrospective cohort in a single referral centre for patients with CM-1 and PS. Results: From 2011 to 2018, we identified fifteen patients with CM-1 and PS; eleven underwent PFUCD, ten had symptomatic CM-1, and one had asymptomatic CM-1 but showed curve progression. The remaining four CM-1 patients were asymptomatic and were hence treated conservatively. The average follow-up post-PFUCD was 26.2 months. Scoliosis surgery was performed in seven cases; six patients underwent PFUCD prior to the scoliosis correction. One scoliosis case underwent surgery in the presence of mild CM-1 treated conservatively. The remaining four cases were scheduled for scoliosis correction surgery, while three were managed conservatively, with one case lost to follow-up. The average time between PFUCD and scoliosis surgery was 11 months. None of the cases had intraoperative neuromonitoring alerts or perioperative neurological complications. Conclusion: CM-1 with concomitant scoliosis can be found. Symptomatic CM-1 might require surgery, but as we discovered, PFUCD had negligible effect on curve progression and the future need for scoliosis surgery. Full article
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11 pages, 1851 KiB  
Perspective
Post-Operative Complications after Foramen Magnum Decompression with Duraplasty Using Different Graft Materials in Adults Patients with Chiari I Malformation: A Systematic Review and Meta-Analysis
J. Clin. Med. 2023, 12(10), 3382; https://doi.org/10.3390/jcm12103382 - 10 May 2023
Cited by 1 | Viewed by 1461
Abstract
Despite extensive investigations, the choice of graft material for reconstructive duraplasty after foramen magnum decompression for Chiari type I malformation (CMI) is still a topic of discussion. The authors performed a systematic review and meta-analysis of the literature examining the post-operative complications in [...] Read more.
Despite extensive investigations, the choice of graft material for reconstructive duraplasty after foramen magnum decompression for Chiari type I malformation (CMI) is still a topic of discussion. The authors performed a systematic review and meta-analysis of the literature examining the post-operative complications in adult patients with CMI after foramen magnum decompression and duraplasty (FMDD) using different graft materials. Our systematic review included 23 studies with a total of 1563 patients with CMI who underwent FMDD with different dural substitutes. The most common complications were pseudomeningocele (2.7%, 95% CI 1.5–3.9%, p < 0.01, I2 = 69%) and CSF leak (2%, 95% CI 1–2.9%, p < 0,01, I2 = 43%). The revision surgery rate was 3% (95% CI 1.8–4.2%, p < 0.01, I2 = 54%). A lower rate of pseudomeningocele was observed with autologous duraplasty when compared with synthetic duraplasty (0.7% [95% CI 0–1.3%] vs. 5.3% [95% CI 2.1–8.4%] p < 0.01). The rate of CSF leak and revision surgery was lower after autologous duraplasty than after non-autologous dural graft (1.8% [95% CI 0.5–3.1%] vs. 5.3% [95% CI 1.6–9%], p < 0.01 and 0.8% [95% CI 0.1–1.6%] vs. 4.9% [95% CI 2.6–7.2%] p < 0.01, respectively). Autologous duraplasty is associated with a lower rate of post-operative pseudomeningocele and reoperation. This information should be considered when planning duraplasty after foramen magnum decompression in patients with CMI. Full article
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