A Systematic Review of Cognition in Chiari I Malformation

Moving Beyond Morphometrics and Alignment: Prospective Longitudinal Study on Cognition, Quality of Life, and Diffusion Metrics in Congenital Craniovertebral Junction Anomalies

BACKGROUND AND OBJECTIVES

Chiari type I malformation (CMI) has been implicated to cause cognitive impairment. Unusual for a craniovertebral junction (CVJ) anomaly, this phenomenon is postulated to be related to microstructural changes across the brain. However, this has not been confirmed in a longitudinal study, in bony CVJ anomalies, or in the context of quality of life (QOL). This study aimed to analyze cognition, QOL, and diffusion tensor imaging (DTI) metrics before and after surgery for congenital CVJ anomalies and evaluate their correlations with conventional clinico-radiological factors.

METHODS

Fifty-seven patients with congenital CVJ anomalies-CMI, atlantoaxial dislocation (AAD), and basilar invagination (BI)-were evaluated in this prospective longitudinal study over 3 years with a neuropsychological battery, QOL and functional scores, and DTI metrics. A total of 43 patients (23 with CMI; 20 with AAD or BI) with 1-year postsurgical data were included in the final analysis.

RESULTS

Cognitive dysfunction in one or more domains was noted in 15 (65%) of the patients with CMI and 16 (80%) of the patients with AAD/BI. Memory and visual motor perception were the most-affected domains in both the cohorts. At the 1-year follow-up, the proportion of patients demonstrating an overall cognitive dysfunction did not change significantly (P > .05). All patients demonstrated significant postoperative improvement in functional and QOL scores at follow-up. DTI metrics improved in many regions postoperatively, but did not correlate with functional or cognitive changes (P > .05).

CONCLUSION

Cognition is affected in a majority of patients with CMI, AAD, or BI. These patients experience good functional and QOL outcomes after surgery but most of them continue to exhibit cognitive impairment. DTI metrics improve after surgery, but do not correlate with cognitive changes. These findings underline the multidimensional nature of the pathology of these anomalies that complicate achieving the concept of a "successful" surgery.

Relationship of Morphometrics and Symptom Severity in Female Type I Chiari Malformation Patients with Biological Resilience

In the present study we report the relationship among MRI-based skull and cervical spine morphometric measures as well as symptom severity (disability-as measured by Oswestry Head and Neck Pain Scale and social isolation-as measured by the UCLA Loneliness scale) on biomarkers of allostatic load using estrogen, interleukin-6, C-reactive protein, and cortisol in a sample of 46 CMI patients. Correlational analyses showed that McRae line length was negatively associated with interleukin-6 and C-reactive protein levels, and Analysis of Variance (ANOVA) showed joint effects of morphometric measures (McRae line length, anterior CSF space) and symptom severity (disability and loneliness) on estrogen and intereukin-6 levels. These results are consistent with allostatic load. That is, when the combination of CSF crowding and self-report symptom (disability and loneliness) severity exceed the capacity of biological resilience factors, then biomarkers such as neuroprotective estrogen levels drop, rather than rise, with increasing symptom severity.

Intellectual Functioning of Children With Isolated PRS, PRS-Plus, and Syndromic PRS

OBJECTIVE

Describe the intelligence quotient (IQ) of children with Pierre Robin sequence (PRS).

DESIGN

Prospective cohort study.

SETTING

Neurodevelopmental follow-up clinic within a hospital.

PATIENTS

Children with PRS (n = 45) who had been in the Neonatal Intensive Care Unit (NICU) were classified by a geneticist into 3 subgroups of isolated PRS (n = 20), PRS-plus additional medical features (n = 8), and syndromic PRS (n = 17) based on medical record review and genetic testing.

MAIN OUTCOME MEASURE

Children with PRS completed IQ testing at 5 or 8 years of age with the Wechsler Preschool and Primary Scale of Intelligence, Third Edition (WPPSI-III) or Fourth Edition (WPPSI-IV) or the Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV) or Fifth Edition (WISC-V).

RESULTS

IQ scores were more than 1 to 2 standard deviations below the mean for 36% of the overall sample, which was significantly greater compared to test norms (binomial test P = .001). There was a significant association between PRS subtype and IQ (Fisher's exact P = .026). While only 20% of children with isolated PRS were within 1 standard deviation below average and 35% of children with syndromic PRS were below 1 to 2 standard deviations, 75% of PRS-plus children scored lower than 1 to 2 standard deviations below the mean.

CONCLUSION

PRS subgroups can help identify children at risk for cognitive delay. The majority of children with PRS-plus had low intellectual functioning, in contrast to the third of children with syndromic PRS who had low IQ and the majority of children with isolated PRS who had average or higher IQ.

Human genetics and molecular genomics of Chiari malformation type 1

Chiari malformation type 1 (CM1) is the most common structural brain disorder involving the craniocervical junction, characterized by caudal displacement of the cerebellar tonsils below the foramen magnum into the spinal canal. Despite the heterogeneity of CM1, its poorly understood patho-etiology has led to a 'one-size-fits-all' surgical approach, with predictably high rates of morbidity and treatment failure. In this review we present multiplex CM1 families, associated Mendelian syndromes, and candidate genes from recent whole exome sequencing (WES) and other genetic studies that suggest a significant genetic contribution from inherited and de novo germline variants impacting transcription regulation, craniovertebral osteogenesis, and embryonic developmental signaling. We suggest that more extensive WES may identify clinically relevant, genetically defined CM1 subtypes distinguished by unique neuroradiographic and neurophysiological endophenotypes.

Cognition in Chiari Malformation Type I: an Update of a Systematic Review

Chiari malformation has been classified as a group of posterior cranial fossa disorders characterized by hindbrain herniation. Chiari malformation type I (CM-I) is the most common subtype, ranging from asymptomatic patients to those with severe disorders. Research about clinical manifestations or medical treatments is still growing, but cognitive functioning has been less explored. The aim of this systematic review is to update the literature search about cognitive deficits in CM-I patients. A literature search was performed through the following electronic databases: MEDLINE, PsychINFO, Pubmed, Cochrane Library, Scopus, and Web of Science. The date last searched was February 1, 2023. The inclusion criteria were as follows: (a) include pediatric or adult participants with a CM-I diagnosis, (b) include cognitive or neuropsychological assessment with standardized tests, (c) be published in English or Spanish, and (d) be empirical studies. Articles that did not report empirical data, textbooks and conference abstracts were excluded. After the screening, twenty-eight articles were included in this systematic review. From those, twenty-one articles were focused on adult samples and seven included pediatric patients. There is a great heterogeneity in the recruited samples, followed methodology and administered neurocognitive protocols. Cognitive functioning appears to be affected in CM-I patients, at least some aspects of attention, executive functions, visuospatial abilities, episodic memory, or processing speed. However, these results require careful interpretation due to the methodological limitations of the studies. Although it is difficult to draw a clear profile of cognitive deficits related to CM-I, the literature suggests that cognitive dysfunction may be a symptom of CM-I. This suggest that clinicians should include cognitive assessment in their diagnostic procedures used for CM-I. In summary, further research is needed to determine a well-defined cognitive profile related to CM-I, favoring a multidisciplinary approach of this disorder.

Revisiting the factor structure of the Short-Form McGill Pain Questionnaire-2 (SF-MPQ-2): Evidence for a bifactor model in individuals with Chiari malformation

The Short-Form McGill Pain Questionnaire-2 (SF-MPQ-2; Dworkin et al., 2009) is intended to measure the multidimensional qualities of pain (i.e., continuous, intermittent, neuropathic, and affective) as well as total pain. Using structural equation modeling, we evaluated the fit of four competing measurement models of the SF-MPQ-2-an oblique 4-factor model, a 1-factor model, a higher-order model, and a bifactor model-in 552 adults diagnosed with Chiari malformation, a chronic health condition whose primary symptoms include head and neck pain. Results revealed the strongest support for the bifactor model, suggesting that SF-MPQ-2 item responses are due to both a general pain factor and a specific pain factor that is orthogonal to the general pain factor. Additional bifactor analyses of the SF-MPQ-2's model-based reliability and dimensionality revealed that most of the SF-MPQ-2's reliable variance is explained by a general pain factor, and that the instrument can be modeled unidimensionally and scored as a general pain measure. Results also indicated that the general and affective pain factors in the bifactor model uniquely predicted pain-related external criteria (e.g., depression, anxiety, and stress); however, the continuous, intermittent, and neuropathic factors did not.

Association between resistance to cerebrospinal fluid flow and cardiac-induced brain tissue motion for Chiari malformation type I

PURPOSE

Chiari malformation type I (CMI) patients have been independently shown to have both increased resistance to cerebrospinal fluid (CSF) flow in the cervical spinal canal and greater cardiac-induced neural tissue motion compared to healthy controls. The goal of this paper is to determine if a relationship exists between CSF flow resistance and brain tissue motion in CMI subjects.

METHODS

Computational fluid dynamics (CFD) techniques were employed to compute integrated longitudinal impedance (ILI) as a measure of unsteady resistance to CSF flow in the cervical spinal canal in thirty-two CMI subjects and eighteen healthy controls. Neural tissue motion during the cardiac cycle was assessed using displacement encoding with stimulated echoes (DENSE) magnetic resonance imaging (MRI) technique.

RESULTS

The results demonstrate a positive correlation between resistance to CSF flow and the maximum displacement of the cerebellum for CMI subjects (r = 0.75, p = 6.77 × 10-10) but not for healthy controls. No correlation was found between CSF flow resistance and maximum displacement in the brainstem for CMI or healthy subjects. The magnitude of resistance to CSF flow and maximum cardiac-induced brain tissue motion were not statistically different for CMI subjects with and without the presence of five CMI symptoms: imbalance, vertigo, swallowing difficulties, nausea or vomiting, and hoarseness.

CONCLUSION

This study establishes a relationship between CSF flow resistance in the cervical spinal canal and cardiac-induced brain tissue motion in the cerebellum for CMI subjects. Further research is necessary to understand the importance of resistance and brain tissue motion in the symptomatology of CMI.

Chiari I malformation: management evolution and technical innovation

BACKGROUND AND DEFINITION

In recent years thanks to the growing use of radiological assessment, Chiari I malformation became one of the major diseases for a neurosurgeon to deal with. CIM can be classified according to the extent of cerebellar tonsil tip into the foramen magnum being a protrusion over five mm considered pathological. Such a disease is a heterogeneous condition with a multifactorial pathogenetic mechanism that can subdivided into a primary and secondary form. Regardless of the form, it seems that CIM is the result of an imbalance between the volume of the braincase and its content. Acquired CIMs are secondary to conditions causing intracranial hypertension or hypotension while the pathogenesis of primary forms is still controversial.

PATHOGENESIS AND TREATMENT

There are several theories in the literature but the most accepted one implies an overcrowding due to a small posterior cranial fossa. While asymptomatic CIM do not need treatment, symptomatic ones prompt for surgical management. Several techniques are proposed being the dilemma centered in the need for dural opening procedures and bony decompression ones.

CONCLUSION

Alongside the paper, the authors will address the novelty presented in the literature on management, diagnosis and pathogenesis in order to offer a better understanding of such a heterogeneous pathology.

Management of Adult Chiari I Patients Based on CSF Flow Magnetic Resonance Imaging: Experience of Two Neurosurgical Centers

BACKGROUND AND STUDY AIMS

 Chiari malformation type 1 (CM1) is one of the most discussed neurosurgical disorders. No consensus exists how to manage adult CM1 patients. We aimed to evaluate all adult CM1 patients consecutively managed at our institutions and discuss our approach based on the phase-contrast (PC) magnetic resonance imaging (MRI).

PATIENTS AND METHODS

 The medical charts of adult patients diagnosed with CM1 at two referral neurosurgical centers between 2010 and 2017 were reviewed. The patients were either managed conservatively or surgically. We evaluated the patients clinically with the Chicago Chiari Outcome Scale (CCOS). The radiologic diagnosis was based on both craniocervical and PC-MRI.

RESULTS

 Ninety adult CM1 patients were managed conservatively. Conservative treatment failed in 5 of these 90 patients. Seventy-two patients (including those 5 patients who did not benefit from conservative treatment) underwent posterior fossa decompression with duraplasty. Eighty-five patients (94.4%) from the conservative group and 61 patients (84.7%) from the surgical group were treated successfully. An aqueductal stroke volume (ASV) value of 12 µL was found as the cutoff value for surgical candidates. A strong positive correlation between the increase in ASV values and clinical improvement was observed.

CONCLUSIONS

 PC-MRI can help in the management and follow-up of adult CM1 patients. Conservative management is possible in selected symptomatic CM1 patients with a high ASV (ASV > 15 µL). Surgery should be considered in patients with an ASV ≤ 12 µL. CM1 patients with ASV ≤12 to >15 μL require close follow-up. Long-standing symptoms, severe sleep apnea, symptoms influencing functionality, and syrinx are factors that affected outcomes negatively.

Chiari Malformation Type 1 and Syringomyelia: Why Do Patients Claim for International Guidelines? Commentary on the 2021 Chiari and Syringomyelia Consensus Document

The diagnosis of Chiari malformation type 1 (CM1) and Syringomyelia (Syr) has become increasingly common during the past few years. Contemporarily, the body of literature on these topics is growing, although randomized controlled studies on significant case series to drive guidelines are missing in the pediatric and adult populations. As a result of the different opinions about surgical indications and techniques raised by CM1-Syr, an increasing number of well-informed but disoriented patients is emerging. To bridge this gap, an International Consensus Conference on CM1-Syr held in Milan in November 2019 aimed to find a consensus among international experts, to suggest some recommendations that, in the near future, could lead to guidelines. Here, we comment on the most relevant recommendations about the definition, diagnosis, surgical management, failures and re-intervention, and outcome. We also focus on some "wrong" indications or techniques that, although widely disapproved by the experts, and negatively experienced by many patients, are still largely in use.

Chiari Type 1 Malformation and Syringomyelia in Children: Classification and Treatment Options

Chiari type 1 malformation (CIM) is defined as tonsillar ectopia of >5 mm, while syringomyelia (SM) is defined as a cerebrospinal fluid (CSF)-filled cavity larger than 3 mm dissecting the spinal cord. Over the last decades, our understanding of these pathologies has grown; however, many controversies still exist almost in every aspect of CIM and SM, including etiology, indication for treatment, timing of treatment, surgical technique, follow-up regime, and outcome. This chapter provides a comprehensive overview on different aspects of CIM and SM and on the still existing controversies, based on the evidence presently available. Future directions for clinical research concerning CIM and SM treatment and outcome are elaborated and discussed as well.

A Clinical Study on the Treatment of Recurrent Chiari (Type I) Malformation with Syringomyelia Based on the Dynamics of Cerebrospinal Fluid

Objective. Combining the dynamics of cerebrospinal fluid, our study investigates the clinical effects of syringomyelia after the combination of fourth ventricle-subarachnoid shunt (FVSS) for recurrent Chiari (type I) malformations after cranial fossa decompression (foramen magnum decompression (FMD)). Methods. From December 2018 to December 2020, 15 patients with recurrent syringomyelia following posterior fossa decompression had FVSS surgery. Before and after the procedure, the clinical and imaging data of these individuals were retrospectively examined. Results. Following FVSS, none of the 15 patients experienced infection, nerve injury, shunt loss, or obstruction. 13 patients improved dramatically after surgery, while 2 patients improved significantly in the early postoperative period, but the primary symptoms returned 2 months later. The Japanese Orthopedic Association (JOA) score was $12.67\pm 3.95$ , which was considerably better than preoperatively ( $t=3.69$ , $P$ 0.001). The MRI results revealed that the cavities in 13 patients were reduced by at least 50% compared to the cavities measured preoperatively. The shrinkage rate of syringomyelia was 86.67% (13/15). One patient’s cavities nearly vanished following syringomyelia. The size of the cavity in the patient remain unchanged, and the cavity’s maximal diameter was significantly smaller than the size measured preoperatively ( $P<0.001$ ) PC-MRI results indicated that the peak flow rate of cerebrospinal fluid at the central segment of the midbrain aqueduct and the foramen magnum in patients during systole and diastole were significantly reduced after surgery ( $P<0.05$ ). Conclusion. After posterior fossa decompression, FVSS can effectively restore the smooth circulation of cerebrospinal fluid and alleviate clinical symptoms in patients with recurrent Chiari (type I) malformation and syringomyelia. It is a highly effective way of treatment.

Accuracy of Palpation Procedures for Locating the C1 Transverse Process and Masseter Muscle as Confirmed by Computed Tomography Images

OBJECTIVE

The purpose of this study was to examine the accuracy of palpation methods for locating the transverse processes of the first cervical vertebra and masseter muscle using radiographic images as the gold-standard method and the association between personal characteristics with the observed accuracy.

METHODS

This was a single-blinded, diagnostic accuracy study. Ninety-five participants (49 women, 58 ± 16 years of age) were enrolled in this study. A single examiner palpated the neck and face region of all participants to identify the transverse processes of the first cervical vertebra and masseter muscles bilaterally. In sequence, participants underwent a multislice computed tomography scan for assessment of the superimposed inner body structure. Two radiologists assessed the computed tomography images using the same criteria and were blinded regarding each other's assessment and the anatomic landmarks under investigation. The palpation accuracy was calculated as the proportion of the correctly identified landmarks in the studied sample. The correlation of the palpation outcome (correct = 1; incorrect = 0) with age, sex (male = 1; female = 0), and body mass index was investigated using the point-biserial correlation coefficient.

RESULTS

The right and left transverse processes were correctly located in 76 (80%) and 81 (85%) participants, respectively, and bilaterally in 157 events (83%), as evaluated by the consensus of the 2 radiologists. The masseter muscles were correctly localized bilaterally in 95 of 95 (100%) participants. Body mass showed statistical evidence of a weak, positive correlation with the correct location of the transverse processes of the first cervical vertebra at the right body side (r = .219; 95% confidence interval, 0.018-0.403; P = .033).

CONCLUSION

Palpation methods used in this study accurately identified the location of the first cervical vertebra spinous processes and the masseter muscles.

Conservative Treatment of Chiari Malformation Type I Based on the Phase-Contrast MRI: A Retrospective Study

BACKGROUND

The phase-contrast magnetic resonance image (PC-MRI) use is interestingly increased in diagnosis and follow-up patients with Chiari Type I Malformation (CM1). The current study aimed to elaborate the benefits of conservative treatment by evaluating consecutively treated adult patients with CM1 who were selected on basis of the PC-MRIs.

METHODS

Medical records of patients diagnosed with CM1 were retrospectively reviewed at two neurosurgical centers spanning eight years (2010-2017). Adult patients with CM1, who were treated conservatively and met study criteria, were selected to be the core sample for this study. Between-groups (benefited vs non-benefited) comparisons were performed to understand the factors that may affect the outcomes.

RESULTS

Ninety (68 females and 22 males) adult patients received conservative treatment for CM1. The mean age was 40.6. Headaches and pinprick loss were the most commonly recorded symptoms and clinical findings which were recorded in 58 (64.4%) and 31 (34.4%) patients, respectively. Eleven patients were presented with a syrinx. The mean aqueductal stroke volume (ASV) was 16.5 μl. The conservative treatment failed in treating five (5.6%) patients who underwent surgical intervention. The means of ASV in the benefited and non-benefited groups were 16.7 and 13.2 μl, respectively (p=0.004).

CONCLUSION

Conservative approaches (prescriptive medications, physical therapy, Pilates, and swimming) can improve the life quality of non-surgical candidate adult patients with CM1. Conservative treatment can be useful in selected patients with variably CM1 (ASV=16.7 μl). The presence of heavy sleep apnea or/and functional symptoms were prognostic factors that were affected the conservative treatment negatively.

The factors affecting the outcomes of conservative and surgical treatment of chiari i adult patients: a comparative retrospective study

BACKGROUND

The prognosis of the Chiari malformation type 1 (CM1) demonstrates a variant spectrum that varies from full recovery to complicated worse neurological disability.

OBJECTIVE

To investigate the factors affecting the outcomes of conservative and surgical treatment for CM1 by evaluating adult patients consecutively managed at our institutions.

MATERIALS AND METHODS

We retrospectively reviewed the medical records of patients diagnosed with CM1 at two reference neurosurgical centers for eight years (2010-2017). We selected all CM1 adult patients who managed conservatively or surgically as the core sample for this study. For clinical evaluation, we used a Chicago Chiari Outcome Scale (CCOS). For radiological assessment, we adopted both craniocervical and contrast-phase MRIs. We investigate factors such as age, sex, pretreatment symptoms, symptoms duration, and radiological findings in both groups.

RESULTS

Ninety patients were treated conservatively. After a progression, five of them were treated surgically later and included in a total of 72 patients who underwent decompressive surgery. We successfully managed 85 patients (94.4%) of the conservative group and 64 patients (88.9%) of the surgical group. We found that patients with aqueductal stroke volume (ASV) of 12 µl are surgical candidates. We observed a strong positive correlation between clinical improvement and the increase in ASV values.

CONCLUSIONS

ASV≤12 µl is a significant predictor for surgical intervention. The presence of heavy sleep apnea or/and functional symptoms, tonsillar herniation >13.4 mm on coronal images, low ASV, long symptom durations, and a syrinx are the independent prognostic factors that affected outcomes negatively.

Surgical Outcomes of C1-2 Posterior Stabilization in Patients With Chiari Malformation Type 1

STUDY DESIGN

Retrospective chart review.

OBJECTIVES

Chiari malformation (CM) is characterized by a downward displacement of the cerebellar tonsils through the foramen magnum. This tonsillar herniation may sometimes be accompanied by syringomyelia and/or basilar invagination (BI). In this study, we examined the surgical outcomes of patients by underwent C1-2 reduction + fixation (C1-2RF), which is a new method defined by Goel, in the literature.

METHODS

Between 2015 and 2018, 21 patients (mean age and duration of follow-up: 39 years and 20 months, respectively) with CM were treated with atlantoaxial fixation. We found syringomyelia in all patients and BI in 9 of them. In all cases, radiography, computed tomography, and magnetic resonance imaging were performed radiologically. C1-2RF was performed in all patients. Preoperative and postoperative clinical Japanese Orthopaedic Association scores were obtained. Syrinx size and cerebrospinal fluid flow rate were compared radiologically.

RESULTS

All patients were treated with C1-2RF. None of the patients underwent foramen magnum decompression or intervention for the syrinx. Occipital bone and subaxial spinal structures were not included in the fixation. In addition to significant clinical improvement, significant improvement in syringomyelia and cerebrospinal fluid flow rate was seen on the radiographs of all patients.

CONCLUSIONS

Although posterior fossa decompression and/or duraplasty is a common treatment modality in CM, we propose that the C1-2RF method described by Goel is a radiologically and clinically effective treatment method, whether or not BI and/or syringomyelia in CM are present. This article is the first article of central and axial atlantoaxial dislocation, except for Goel's writings in the literature.

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.

Cognitive and Psychological Functioning in Chiari Malformation Type I Before and After Surgical Decompression - A Prospective Cohort Study

BACKGROUND

Chiari Malformation Type I (CM-I) is defined as cerebellar tonsil displacement more than 5 mm below the foramen magnum. This displacement can alter cerebrospinal fluid flow at the cervicomedullary junction resulting in Valsalva-induced headaches and syringomyelia and compress the brainstem resulting in bulbar symptoms. However, little is known about cognitive and psychological changes in CM-I.

OBJECTIVE

To prospectively assess cognitive and psychological performance in CM-I and determine whether changes occur after surgical decompression.

METHODS

Blinded evaluators assessed symptomatic CM-I patients ages ≥18 with a battery of neuropsychological and psychological tests. Testing was conducted preoperatively and 6 to 18 mo postoperatively. Data were converted to Z-scores based on normative data, and t-tests were used to analyze pre-post changes.

RESULTS

A total of 26 patients were included, with 19 completing both pre- and post-op cognitive assessments. All patients had resolution of Valsalva-induced headaches and there was improvement in swallowing dysfunction (P < .0001), ataxia (P = .008), and sleep apnea (P = .021). Baseline performances in visual perception and construction (z = -1.11, P = .001) and visuospatial memory (z = -0.93, P = .002) were below average. Pre-post comparisons showed that CM-I patients had stable cognitive and psychological functioning after surgery, without significant changes from preoperative levels.

CONCLUSION

CM-I patients had below average performance in visuospatial and visuoconstructional abilities preoperatively. Prospective longitudinal data following surgery demonstrated improved neurologic status without any decline in cognition or psychological functioning. Routine pre- and postoperative formal neuropsychological assessment in CM-I patients help quantify cognitive and behavioral changes associated with surgical decompression.

Surgical Outcomes of Adult Chiari Malformation Type 1: Experience at a Tertiary Institute

Background

Chiari type I malformation (CM1) is a herniation of the caudal cerebellum and/or medulla oblongata into the upper spinal canal, occurring in pediatric and adult populations. We aimed to analyze the surgical outcomes of adult patients with CM1 consecutively treated with a posterior fossa decompression and duraplasty (PFDD) in a tertiary institution.

Patients and methods

We retrospectively reviewed the medical charts of 45 adult patients with CM1 who underwent PFDD at the Neurosurgery Department of our institution between January 2012 and December 2017. Radiological evaluation was based on pre- and postoperative syrinx/cord ratio, syrinx length, and regression of the ectopic cerebellar tonsils on coronal and sagittal magnetic resonance imaging (MRI) images, and clinical assessment of the patients was performed with the Chicago Chiari Outcome Scale (CCOS).

Results

Of the 45 patients included in the study, 25 (four men, 21 women) were diagnosed with symptomatic CM1 with an age average of 36.6±11.4 (18-66) years. Headache was the most common symptom (72.0%), while pinprick losses were prevalent in 13 (52.0%) patients. The mean postoperative CCOS score was 14.7±2.0 (8-16). Symptoms improved in 20 patients (80.0%) at the last follow-up. The mean regression in ectopic tonsils on midsagittal and coronal images were 9.1±1.8 (range: 0-16.5) mm and 8.3±1.2 (0-12.0) mm, respectively (p<0.05). The syrinxes had regressed completely or significantly in 7 (87.5%) of eight patients with syrinx.

Conclusion

Our findings showed that PFDD is sufficient to relieve most of the major symptoms and resolve the syrinx cavity without additional surgical interventions. The CCOS keeps its measurability of assessment of the clinical outcomes. A reliable radiological evaluation should be performed on midsagittal and coronal MRI images.

The executive functions, intellectual capacity, and psychiatric disorders in adolescents with Chiari malformation type 1

PURPOSE

In the last two decades, the non-motor functions of the cerebellum have become the centre of attention for researchers. Anecdotal observations of cognitive and psychiatric manifestations of cerebellar lesions have increased this interest. We aimed to investigate the executive function (EF), intellectual capacity, and comorbid psychiatric disorders in adolescents with Chiari malformation type 1 (CM1), which is a pathological manifestation of posterior cranial fossa structures include the cerebellum.

METHODS

The Chiari group consisted of ten adolescents aged 12-18 years old, and the control group consisted of 13 healthy adolescents with similar age and sex with patients. Stroop test (ST), trail making test (TMT), and Behaviour Rating Inventory of Executive Function-Parent form (BRIEF) were used to evaluate EF; Kent EGY and Porteus Maze Test was used to measuring the intelligence quotient (IQ), and a semi-structured interview was used to determine the psychiatric disorders.

RESULTS

EF test scores were found comparable between the two groups. IQ scores of the Chiari group were found in the normal range, but significantly lower than controls. No significant difference was revealed in terms of comorbid psychiatric disorders between the two groups.

CONCLUSION

In this study, we did not observe an impairing effect of CM1 on EF and intelligence. Also, we found that CM1 did not cause more psychiatric disorders compared to controls. Further studies need to support our findings in adolescents diagnosed with CM1.

Functional connectivity abnormalities in Type I Chiari: associations with cognition and pain

There is initial evidence of microstructural abnormalities in the fibre-tract pathways of the cerebellum and cerebrum of individuals diagnosed with Type I Chiari malformation. However, it is unclear whether abnormal white matter architecture and macro-level morphological deviations that have been observed in Chiari translate to differences in functional connectivity. Furthermore, common symptoms of Chiari include pain and cognitive deficits, but the relationship between these symptoms and functional connectivity has not been explored in this population. Eighteen Type I Chiari patients and 18 age-, sex- and education-matched controls underwent resting-state functional MRI to measure functional connectivity. Participants also completed a neuropsychological battery and completed self-report measures of chronic pain. Group differences in functional connectivity were identified. Subsequently, pathways of significant difference were re-analyzed after controlling for the effects of attention performance and self-reported chronic pain. Chiari patients exhibited functional hypoconnectivity between areas of the cerebellum and cerebrum. Controlling for attention eliminated all deficits with the exception of that from the posterior cerebellar pathway. Similarly, controlling for pain also eliminated deficits except for those from the posterior cerebellar pathway and vermis VII. Patterns of Chiari hyperconnectivity were also found between regions of the cerebellum and cerebrum in Chiari patients. Hyperconnectivity in all regions was eliminated after controlling for attention except between left lobule VIII and the left postcentral gyrus and between vermis IX and the precuneus. Similarly, hyperconnectivity was eliminated after controlling for pain except between the default mode network and globus pallidus, left lobule VIII and the left postcentral gyrus, and Vermis IX and the precuneus. Evidence of both hyper- and hypoconnectivity were identified in Chiari, which is posited to support the hypothesis that the effect of increased pain in Chiari draws on neural resources, requiring an upregulation in inhibitory control mechanisms and resulting in cognitive dysfunction. Areas of hypoconnectivity in Chiari patients also suggest disruption in functional pathways, and potential mechanisms are discussed.

Adult Age Differences in Self-Reported Pain and Anterior CSF Space in Chiari Malformation

Chiari malformation type I (CMI) is a neural disorder with sensory, cognitive, and motor defects, as well as headaches. Radiologically, the cerebellar tonsils extend below the foramen magnum. To date, the relationships among adult age, brain morphometry, surgical status, and symptom severity in CMI are unknown. The objective of this study was to better understand the relationships among these variables using causal modeling techniques. Adult CMI patients (80% female) who either had (n = 150) or had not (n = 151) undergone posterior fossa decompression surgery were assessed using morphometric measures derived from magnetic resonance images (MRI). MRI-based morphometry showed that the area of the CSF pocket anterior to the cervico-medullary junction (anterior CSF space) correlated with age at the time of MRI (r =  - .21). Also, self-reported pain increased with age (r = .11) and decreased with anterior CSF space (r =  - .18). Age differences in self-reported pain were mediated by anterior CSF space in the cervical spine area-and this effect was particularly salient for non-decompressed CMI patients. As CMI patients age, the anterior CSF space decreases, and this is associated with increased pain-especially for non-decompressed CMI patients. It is recommended that further consideration of age-related decreases in anterior CSF space in CMI patients be given in future research.

Evidence of Neural Microstructure Abnormalities in Type I Chiari Malformation: Associations Among Fiber Tract Integrity, Pain, and Cognitive Dysfunction

BACKGROUND

Previous case-control investigations of type I Chiari malformation (CMI) have reported cognitive deficits and microstructural white matter abnormalities, as measured by diffusion tensor imaging (DTI). CMI is also typically associated with pain, including occipital headache, but the relationship between pain symptoms and microstructure is not known.

METHODS

Eighteen CMI patients and 18 adult age- and education-matched control participants underwent DTI, were tested using digit symbol coding and digit span tasks, and completed a self-report measure of chronic pain. Tissue microstructure indices were used to examine microstructural abnormalities in CMI as compared with healthy controls. Group differences in DTI parameters were then reassessed after controlling for self-reported pain. Finally, DTI parameters were correlated with performance on the digit symbol coding and digit span tasks within each group.

RESULTS

CMI patients exhibited greater fractional anisotropy (FA), lower radial diffusivity, and lower mean diffusivity in multiple brain regions compared with controls in diffuse white matter regions. Group differences no longer existed after controlling for self-reported pain. A significant correlation between FA and the Repeatable Battery for the Assessment of Neuropsychological Status coding performance was observed for controls but not for the CMI group.

CONCLUSIONS

Diffuse microstructural abnormalities appear to be a feature of CMI, manifesting predominantly as greater FA and less diffusivity on DTI sequences. These white matter changes are associated with the subjective pain experience of CMI patients and may reflect reactivity to neuroinflammatory responses. However, this hypothesis will require further deliberate testing in future studies.

Association Between Resistance to Cerebrospinal Fluid Flow Near the Foramen Magnum and Cough-Associated Headache in Adult Chiari Malformation Type I

Cough-associated headaches (CAHs) are thought to be distinctive for Chiari malformation type I (CMI) patients and have been shown to be related to the motion of cerebrospinal fluid (CSF) near the foramen magnum (FM). We used computational fluid dynamics (CFD) to compute patient-specific resistance to CSF motion in the spinal canal for CMI patients to determine its accuracy in predicting CAH. Fifty-one symptomatic CMI patients with cerebellar tonsillar position (CTP) ≥ 5 mm were included in this study. The patients were divided into two groups based on their symptoms (CAH and non-CAH) by review of the neurosurgical records. CFD was utilized to simulate CSF motion, and the integrated longitudinal impedance (ILI) was calculated for all patients. A receiver operating characteristic (ROC) curve was evaluated for its accuracy in predicting CAH. The ILI for CMI patients with CAH (776 dyn/cm5, 288-1444 dyn/cm5; median, interquartile range) was significantly larger compared to non-CAH (285 dyn/cm5, 187-450 dyn/cm5; p = 0.001). The ILI was more accurate in predicting CAH in CMI patients than the CTP when the comparison was made using the area under the ROC curve (AUC) (0.77 and 0.70, for ILI and CTP, respectively). ILI ≥ 750 dyn/cm5 had a sensitivity of 50% and a specificity of 95% in predicting CAH. ILI is a parameter that is used to assess CSF blockage in the spinal canal and can predict patients with and without CAH with greater accuracy than CTP.

Social Cognition in Chiari Malformation Type I: a Preliminary Characterization

Chiari malformation type I (CM-I) is a neurological disorder in which cerebellar tonsils are herniated through the foramen magnum into the spinal canal. A wide spectrum of cognitive deficits underlying this pathology has been reported, but the literature about social cognition is insufficient. Clinical research has pointed out the cerebellar role in Theory of Mind (ToM), indicating that there are several disorders with cerebellar pathology that reveal a poorer performance in social cognition tasks. The main purpose of this study is to compare the performance on ToM tasks between CM-I patients and healthy controls. The protocol includes Faux Pas test, Happé's Strange Stories test, Ice-Cream Van task, the FEEL test, and the Word Accentuation Test. In order to eliminate the possible influence of covariables, physical pain and anxious-depressive symptomatology have been controlled for. According to the results, CM-I patients performed worse than matched healthy controls on ToM tasks, except for facial emotion recognition. These differences remained even after controlling for the neuropsychiatric variables and physical pain. Thus, it can be suggested that patients with CM-I are impaired in their social skills related to their performance on ToM tasks. These findings can be considered to be a preliminary approach to the specific study of social cognition in relation to CM-I since it is similar to other cerebellar pathologies and to previous literature on the cerebellum's role in social cognition.

Management of Rare Causes of Pediatric Chronic Respiratory Failure

The need for long-term noninvasive positive pressure ventilation (NiPPV) in children with chronic respiratory failure is rapidly growing. This article reviews pediatric-specific considerations of NiPPV therapy. Indications for NiPPV therapy can be categorized by the cause of the respiratory failure: (1) upper airway obstruction, (2) musculoskeletal and/or neuromuscular disease, (3) lower respiratory tract diseases, and (4) control of breathing abnormalities. The role of NiPPV therapy in select rare conditions (spinal muscular atrophy, congenital central hypoventilation syndrome, cerebral palsy, scoliosis, and Chiari malformations) is also reviewed.

Clinical and radiological evaluation of treated Chiari I adult patients: retrospective study from two neurosurgical centers

Chiari malformation type I (CM1) is a common neurosurgical disorder. It often causes debilitation in the affected patients. CM1 is a herniation of the caudal cerebellum into the spinal canal. This study aimed to evaluate the clinical and radiological outcomes of posterior fossa decompression and duraplasty (PFDD) in treated CM1 patients. In retrospective design, we reviewed the medical records of diagnosed patients with CM1 at two neurosurgical centers spanning 8 years from 2010 to 2017. We selected all CM1 patients who underwent PFDD surgery (n = 72) as the core sample for this study. We used the Chicago Chiari Outcome Scale (CCOS) to evaluate clinical outcomes. Pre- and postoperatively, we assessed the syrinx/cord ratio, the syrinx length, and the improvement of aqueductal stroke volume (ASV) on CSF flow MRIs. The mean value of CCOS was 14.1 ± 2.1. On midsagittal MRIs, the mean regression in ectopia tonsils was 9.4 ± 1.9 mm (i.e., mean pre- and postoperative tonsil herniation was 13.1 ± 3.1 mm and 4.0 ± 1.6 mm, respectively; p < 0.001). On coronal MRIs, the mean regression in ectopia tonsils was 8.4 ± 1.5 mm (i.e., mean pre- and postoperative tonsil herniation was 13.9 ± 2.4 mm and 5.8 ± 1.0 mm, respectively; p < 0.001). A strong positive correlation was observed between clinical improvement and the increase in ASV values. CSF flow MRIs can help in the surgical decision and follow-up of CM1 patients. ASV ≤ 12 μl is a significant predictor for surgical intervention. Full clinical and radiological evaluation utilizing CSF flow MRI are essential. Most syrinx cavities have regressed following PFDD.

Correlation of a new hydrodynamic index with other effective indexes in Chiari I malformation patients with different associations

This study aimed to find a new CSF hydrodynamic index to assess Chiari type I malformation (CM-I) patients’ conditions and examine the relationship of this new index with morphometric and volumetric changes in these patients and their clinical symptoms. To this end, 58 CM-I patients in four groups and 20 healthy subjects underwent PC-MRI. Ten morphometric and three volumetric parameters were calculated. The CSF hydrodynamic parameters were also analyzed through computational fluid dynamic (CFD) simulation. The maximum CSF pressure was identified as a new hydrodynamic parameter to assess the CM-I patients’ conditions. This parameter was similar in patients with the same symptoms regardless of the group to which they belonged. The result showed a weak correlation between the maximum CSF pressure and the morphometric parameters in the patients. Among the volumetric parameters, PCF volume had the highest correlation with the maximum CSF pressure, which its value being higher in patients with CM-I/SM/scoliosis (R² = 65.6%, P = 0.0022) than in the other patients. PCF volume was the more relevant volumetric parameter to assess the patients’ symptoms. The values of PCF volume were greater in patients that headache symptom was more obvious than other symptoms, as compared to the other patients.

Working Memory Impairments in Cerebellar Disorders of Childhood

The cerebellum is a crucial center for motor control and integration. Increasing evidence supports the notion that the cerebellum is also involved in nonmotor functions. Along these lines, multiple cerebellar disorders of childhood and adulthood are associated with behavioral and cognitive symptoms, including impairments in memory. One form of memory commonly affected in cerebellar disorders is working memory, which uses attention to manipulate information that is immediately available to execute cognitive tasks. This article reviews the literature illustrating that working memory impairments are frequently observed in acquired, congenital, and genetic/developmental cerebellar disorders of childhood. Functional neuroimaging studies demonstrate that working memory tasks engage many posterior regions of the cerebellar hemispheres and vermis. Thus, the cerebellum acts as one important node in the working memory circuit, and when the cerebellum is involved in childhood disorders, deficits in working memory commonly occur.

Neuroanatomic Correlates for the Neuropsychological Manifestations of Chiari Malformation Type I

Chiari malformation comprises a spectrum of congenital malformations characterized by a herniation of the cerebellar tonsils below the foramen magnum. Chiari malformation type I (CM-I) is the most prevalent subtype seen in clinical practice. This condition variably compresses the cerebellum and medulla-spinal cord junction secondary to malformation of the posterior fossa. Most neurologists and neurosurgeons recognize the sensorimotor and lower brainstem manifestations that result in the clinical picture of CM-I. The effects of CM-I on cognitive functioning, however, and their impact on neuropsychological performance are poorly understood, despite having long been recognized. This article reviews neuropsychological deficits demonstrated by individuals with CM-I, and explores cerebellocortical neuroanatomic pathways to provide possible rationale for the neurocognitive impairments present in affected individuals.

Clinical diagnosis-part II: what is attributed to Chiari I

PURPOSE

Chiari malformation type I is identified as radiological appearance of cerebellar tonsil herniation below the foramen magnum. The wide spectrum of clinical manifestations variably associated sometimes encompasses signs and symptoms whose correlation with the malformation remains debatable. However, a correct clinical framework is relevant in tailoring the strategy of management, and in particular, establishing the appropriate surgical intervention.

METHODS

An analysis of relevant articles on this issue was performed, involving both single case reports and case series. The papers were obtained from electronic databases including PubMed/MEDLINE and Google Scholar, as well as direct contact with some authors.

RESULTS

This review focuses on those unusual clinical pictures attributed to Chiari malformation type I (CMI), investigating their actual relationship with the morphological condition. Supposed physiopathogenetic mechanisms and clinical relevance are discussed along with an analysis on the surgical indications and results.

CONCLUSION

There is no clear explanation on why some patients may exhibit uncommon symptoms, often in association with the most frequent ones, but even reported as single initial clinical occurrence. Their actual incidence may have been roughly underestimated in the literature so far, because of wide heterogeneity of selection and analysis among different studies. Most of the authors appear sharing the impression that CMI surgical decompression plays a significant role in controlling the majority of these unusual symptoms, stressing their actual occurrence in relation with the malformation. A routinely multidisciplinary clinical approach has become advisable to encompass the diversity of conditions potentially associated with CMI and improve the care of CMI patients.

Comparative Volumetric Analysis of the Brain and Cerebrospinal Fluid in Chiari Type I Malformation Patients: A Morphological Study

BACKGROUND

Chiari Type I malformation (CM-I) is defined as the migration of cerebellar tonsils from the foramen magnum in the caudal direction and is characterized by the disproportion of the neural structures. The aim of this study was to investigate the brain volume differences between CM-I patients and normal population using a comparative volumetric analysis.

METHODS

140 patients with CM-I and 140 age- and sex-matched healthy controls were included in this study. The magnetic resonance imaging (MRI) data of both groups were analyzed with an automated MRI brain morphometry system. Total intracranial, cerebrum, cerebellum, brainstem, cerebrospinal fluid (CSF), and lateral ventricle volumes as well as cerebrum and cerebellum gray/white matter (GM/WM) volumes were measured. Statistical analysis was performed.

RESULTS

Both total CSF and lateral ventricle volumes and volume percentages (Pct) were found significantly higher in CM-I patients compared to the control group. However, there were significant decreases in cerebrum and cerebellum volume Pct in CM-I patients. Although there were no significant differences in cerebrum WM volumes and volume Pct, cerebrum GM volume Pct were found to be significantly lower in CM-I patients.

CONCLUSIONS

Revealing the increased CSF and lateral ventricle volume, and volume Pct supported concomitant ventricular enlargement and hydrocephalus in some CM-I patients. Decreased cerebrum GM volume Pct compared to the control group might be the underlying factor of some cortical dysfunctions in CM-I patients.

Fourth Ventricle Enlargement in Chiari Malformation Type I

OBJECTIVE

How Chiari malformation type I (CM-I) affects posterior fossa brain structures and produces various symptoms remains unclear. The fourth ventricle is surrounded by critical structures required for normal function. The foramen of Magendie can be obstructed in CM-I; therefore, fourth ventricle changes may occur. To test this hypothesis, we assessed fourth ventricle volume in CM-I compared with healthy controls.

METHODS

Using our database from 2007-2016, we studied 72 patients with CM-I and 30 age-matched healthy control subjects. Fourth and lateral ventricle volumes and posterior fossa volumes (PFV) were assessed and correlated with clinical signs and symptoms. Statistical analysis was performed.

RESULTS

Patients with CM-I had larger fourth ventricle volumes compared with control subjects (1.31 vs. 0.95 mL; P = 0.012). There were no differences in lateral ventricle volume or PFV. CM-I fourth ventricle volume was associated with tonsillar descent (P = 0.030). CM-I fourth ventricle volume variance was larger than healthy controls (F_71,29 = 8.33; P < 0.0001). Patients with CM-I with severe signs and symptoms had a significantly larger fourth ventricle than patients with CM-I with mild signs and symptoms (1.565 vs. 1.015 mL; P = 0.0002).

CONCLUSIONS

The fourth ventricle can be enlarged in CM-I independent of lateral ventricle size and is associated with greater tonsillar descent. Most importantly, fourth ventricle enlargement was associated with a worse clinical and radiographic presentation independent of PFV. Fourth ventricle enlargement can affect critical structures and may be a mechanism contributing to symptoms unexplained by tonsil descent. Fourth ventricle enlargement is a useful adjunct in assessing CM-I.

Quantification of changes in brain morphology following posterior fossa decompression surgery in women treated for Chiari malformation type 1

PURPOSE

While 84% of patients surgically treated for Chiari malformation type 1 (CM1) demonstrate improved quality of life after posterior fossa decompression surgery, there are many risks associated with this surgery. Surgical planning to identify candidates likely to improve postoperatively may benefit from an improved understanding of morphological changes after decompression surgery. To evaluate these changes, we quantified 59 morphological parameters on 42 CM1 adult female patients before and after CM1 decompression surgery.

METHODS

Fifty-nine morphological parameters in the posterior cranial fossa, cranio-cervical, and intracranial regions in the midsagittal plane were evaluated using 42 T1-weighted magnetic resonance images of female CM1 patients before and after surgery, and 42 healthy female controls. Morphological differences before and after surgery were compared through the development of a technique to establish the opisthion location, a key reference point not present after surgery.

RESULTS

In addition to the expected reduction of the cranio-caudal dimension of the cerebellum, objective analyses showed a significant increase in the area of the cerebrospinal fluid spaces, posterior (6×) and inferior (2.6×) to the cerebellum (+ 112 ± 102 and + 140 ± 127 mm2, respectively). This increased area was primarily impacted by an average reduction in the occipital bone length of 24.5 ± 7.3 mm following surgery. Based on multiple angles, results demonstrated a 2°-4° anterior rotation of the cerebellum after surgery.

CONCLUSION

Our results show that decompression surgery results in significant changes in the cerebellum and cerebrospinal fluid spaces. Further investigation should determine how these morphological changes impact clinical outcomes.

Quantification of Cerebellar Crowding in Type I Chiari Malformation

This study was focused on a semi-automated morphometric analysis of the cerebellum in the mid-sagittal plane as an alternative to tonsillar descent alone in the evaluation of Chiari malformation type 1 (CMI) patients. Morphometric analyses of posterior fossa structures were performed on mid-sagittal MRI images of 375 individuals (females, > 18 years, 235 CMI and 140 healthy controls). Twenty-six parameters including linear, angular and area measurements together with non-dimensional ratios were calculated. Eighteen parameters were found to be significantly different between CMI and control subjects. Smaller posterior cranial fossa (PCF) area in CMI subjects was attributed to a smaller PCF area anterior to the brainstem. The cerebellar area was found to be larger in CMI subjects as compared to controls (15.1%), even without inclusion of the tonsillar area below the foramen magnum (FM) (8.4%). The larger cerebellar area in CMI subjects was due to cranial-caudal elongation of the cerebellum, predominately below the fastigium. The cerebrospinal fluid spaces below the FM were smaller in CMI subjects as compared to controls. Overall, greater cerebellar crowding was identified in CMI subjects relative to healthy controls. These observations may improve our understanding of the pathophysiology of CMI in adult female patients.