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BACKGROUND: Chiari (type I) malformations are typically congenital. Occasionally, however, tonsillar herniation can arise secondary to cerebrospinal fluid leakage, posterior fossa or intraventricular mass lesions, or other etiologies. We present the first-ever case of an intramedullary subependymoma at the cervicomedullary junction associated with vertebral bone abnormalities and an acquired secondary Chiari malformation. CASE DESCRIPTION: A 60-year-old woman presented with a 3-year history of occipital, tussive headaches. Preoperative imaging was negative for mass lesions but demonstrated a Chiari malformation. She was recommended posterior fossa decompression with tonsillar shrinkage. During surgery, an intramedullary mass was incidentally observed, obstructing the obex at the cervicomedullary junction. Histopathological analysis of the resected lesion revealed a diagnosis of subependymoma. CONCLUSION: Subependymomas can sometimes present a diagnostic challenge due to their subtle appearance in neuroimaging. Only rarely are such masses associated with an acquired Chiari malformation. No such case has previously been reported. We present a literature review on acquired Chiari malformations and discuss their management.

Chiari malformation type 1 (CM1) is a structural defect that involves the herniation of the cerebellar tonsils through the foramen magnum, causing mild to severe neurological symptoms. Little is known about the molecular and developmental mechanisms leading to its pathogenesis, prompting current efforts to elucidate genetic drivers. Inherited genetic disorders are reported in 2–3% of CM1 patients; however, CM1, including familial forms, is predominantly non-syndromic. Recent work has focused on identifying CM1-asscoiated variants through the study of both familial cases and de novo mutations using exome sequencing. This article aims to review the current understanding of the genetics of CM1. We discuss three broad classes of CM1 based on anatomy and link them with genetic lesions, including posterior fossa-linked, macrocephaly-linked, and connective tissue disorder-linked CM1. Although the genetics of CM1 are only beginning to be understood, we anticipate that additional studies with diverse patient populations, tissue types, and profiling technologies will reveal new insights in the coming years. [ABSTRACT FROM AUTHOR]

Background: Chiari malformation type 1 (CM1) remains a complex neurosurgical condition with ongoing debate regarding its optimal management. Methods: This narrative review examines key controversies surrounding the pathophysiology, surgical indications, and treatment strategies for CM1. Results: We highlight the challenges posed by the wide spectrum of CM variants and the evolving understanding of its association with syringomyelia, basilar invagination, and craniovertebral instability. Emerging surgical techniques, including minimally invasive approaches and the use of new technologies such as endoscopes and exoscopes, are evaluated for their potential to improve outcomes. Recent consensus guidelines are also discussed. Conclusions: The need for individualized treatment plans for CM1 is emphasized, with special focus put on the connection between novel pathophysiological insights, technological advancements and opportunities for a more nuanced surgical management. Further research is necessary to establish solid foundations for more individualized treatments. [ABSTRACT FROM AUTHOR]

Background: Chiari malformation is a rare congenital condition in which the cerebellar tonsils herniate through the foramen magnum, causing symptoms related to compression of the surrounding structures. Rehabilitation plays a key role in the pre- and post-operative management of the syndrome, as it can improve strength, range of motion, motor coordination, pain management, and performance of activities of daily living. Methods: This article presents the case of a 43-year-old woman with Chiari malformation 1B who underwent resection of the filum terminale. She presented as an outpatient at the University Hospital "G. Martino" in Messina, complaining of difficulty walking, balance problems, lumbar pain, and heaviness in the lower limbs. Following a multidisciplinary assessment, she underwent an 11-month rehabilitation protocol based on cognitive therapeutic exercise. Results: The patient achieved significant improvements in pain, mental confusion, and quality of life after treatment and at the 12-month follow-up. Conclusions: The results of this study highlight the significant benefits of cognitive therapeutic exercises in Chiari malformation, with improvements in several key areas, including quality of life, pain management, and ability to perform activities of daily living. [ABSTRACT FROM AUTHOR]

Chiari I malformation (CM-I) is defined as the extension of brain tissue into the spinal cord. This study aimed to refine the methodology for the acquisition of 3-dimensional measurements of the posterior fossa and introduce occipital keel size as a new marker and its impact in patients with CM. In this retrospective study, all patients who underwent Chiari decompression surgery at Montefiore Medical Center from April 2012 to April 2022 were included. Perioperative clinical information was obtained in addition to maximal keel thickness (KT), foramen magnum area, and preoperative and postoperative posterior fossa volumes for each patient and age-matched controls. Volumetric measurements were obtained using artificial intelligence-based semiautomated segmentation. A total of 107 patients with CM including 37 males, and 70 females were studied with a mean age of 26.56 ± 17.31 compared with 103 controls without CM. The comparison between the CM and the general population groups demonstrated a significantly increased keel size in Chiari patients. Keel size had a significant relationship with dysphagia, paresthesia, and intraoperative blood loss, while posterior volume change had a significant relationship with sex and early symptomatic improvement. The Foramen magnum area was related to tonsillar descent and more prominent in patients with spina bifida. The Keel of Goodrich is a new anatomical factor that should be taken into consideration when evaluating preoperative symptoms, and intraoperative complications in patients with CM-I. Volumetric analyses demonstrated that posterior fossa volume change had a significant impact on early symptom improvement in patients with Chiari, as did the choice of operative approach. The routine use of semiautomated segmentation of the posterior fossa may help stratify Chiari patients in the future and should be implemented in routine clinical care. [ABSTRACT FROM AUTHOR]

Introduction: Chiari malformation (CIM) is a congenital anomaly characterized by herniation of hindbrain structures through the foramen magnum into the cervical spinal canal (CSC). Although the pathogenesis of CIM has not been clearly defined, its relationship with the posterior fossa and CSC morphology is unclear. In this study, we aimed to perform morphometric analysis of both the posterior fossa and the CSC in CIM to investigate the correlation of measurements with each other and to reveal their effects on the development of syringomyelia (SM), which has not been previously reported. Methods: Magnetic resonance imaging images of 90 patients and 30 healthy individuals were retrospectively analyzed. Posterior fossa parameters and CSC diameters at all cervical vertebral levels were measured for each patient. The taper ratio of CSC was calculated separately for each group at the C1-C4 and C1-C7 levels. The average CSC shape was drawn for each group. Results: No statistically significant difference was detected between the age groups. A steeper taper ratio was detected when CIM was accompanied by SM. In addition, the posterior fossa had a narrower volume than the normal fossa in CIM. Conclusion: Morphometric analysis of both the posterior fossa and the CSC was performed using CIM for the first time in the literature. This is the first study to present the term “tapering” with an illustration.

Objective Imaging parameters of Chiari malformation type I (CMI) development are not well established. This study aimed to collect evidence of general or specific imaging measurements in patients with CMI, analyze indicators that may assist in determining the severity of CMI, and guide its diagnosis and treatment. Methods A comprehensive search was conducted across various databases including the Cochrane Library, PubMed, MEDLINE, Scopus, and Embase, covering the period from January 2002 to October 2023, following predefined inclusion criteria. Meta-analyses were performed using RevMan (ver. 5.4). We performed a quantitative summary and systematic analysis of the included studies. This study was registered in the PROSPERO (International Prospective Register of Systematic Reviews) prior to initiation (CRD42023415454). Results Thirty-three studies met our inclusion criteria. The findings indicated that out of the 14 parameters examined, 6 (clivus length, basal angle, Boogard’s angle, supraocciput lengths, posterior cranial fossa [PCF] height, and volume) exhibited significant differences between the CMI group and the control group. Furthermore, apart from certain anatomical parameters that hold prognostic value for CMI, functional parameters like tonsillar movement, obex displacement, and cerebrospinal fluid dynamics serve as valuable indicators for guiding the clinical management of the disease. Conclusion We collated and established a set of linear, angular, and area measurements deemed essential for diagnosing CMI. However, more indicators can only be analyzed descriptively for various reasons, particularly in prognostic prediction. We posit that the systematic assessment of patients’ PCF morphology, volume, and other parameters at a 3-dimensional level holds promising clinical application prospects.

Introduction: Rubinstein-Taybi syndrome (RTS) is a rare genetic condition with a distinctive set of physical features. This case series reports a single institutional experience of RTS cases, highlighting the role of neurosurgery in the comprehensive management of RTS patients. Methods: A retrospective review of patients with genetically confirmed RTS presenting between 2010 and 2023 at Children’s Hospital of Pittsburgh was performed. Patient demographics, genetic profile, clinical symptoms, radiographic characteristics, and neurosurgical management were recorded for all patients. Results: Twenty-one patients (13 females, 8 males) aged 0 to 22 years presented for formal genetic counseling and diagnosis. Twenty patients (95%) had CREBBP pathogenic variants (RTS type 1), and 1 patient (5%) had EP300 pathogenic variants (RTS type 2). Ten patients (48%) had a low-lying conus medullaris, and 3 patients (30%) underwent subsequent spinal cord detethering. Four patients (19%) had a Chiari malformation, and three (75%) underwent Chiari decompression surgeries. One patient (5%) had Chiari-associated syringomyelia. Conclusions: RTS patients have an increased rate of tethered cord syndrome requiring detethering. The incidence of symptomatic Chiari I malformation requiring decompression has not been previously reported. The RTS series presented here demonstrates a high incidence of symptomatic Chiari I malformation in addition to tethered cord syndrome. [ABSTRACT FROM AUTHOR]

Foramen magnum decompression (FMD) is an established technique for patients with Chiari-1 malformation. However, the extent of decompressive surgery is controversial, in particular whether dural opening is undertaken. In this study, we report outcomes with our technique utilising intraoperative ultrasound (iOU) findings. Decision to proceed for further decompression was based on CSF flow around foramen magnum and visualisation of tip of tonsils. Review of adults with CM-1 undergoing FMD 2013–2018. Patients underwent a suboccipital craniectomy ± partial C1 superior laminectomy ± duraplasty in a stepwise manner. Favourable iOU findings of CSF flow around the foramen magnum and pulsation of the tonsillar tips were sought at each step. Post-operative outcomes were assessed using the Chicago Chiari Outcome Score (CCOS). Fifty-seven patients were included. The mean age was 47 years (range 18–77 years). There was a strong female preponderance (48 females to nine males). The mean follow-up was 3.2 years (range 1–5 years). Surgery included: suboccipital craniectomy (52/57, 91%), plus partial C1 superior laminectomy (2/57, 4%), and plus duraplasty (3/57, 6%). Redo surgery was undertaken in 7/57 patients (12%). At final follow-up, 56/57 (98%) patients achieved a good (CCOS 13–16) or satisfactory (CCOS 9–12) outcome based on COSS. A patient centred approach to surgery utilising findings from iOU can achieve favourable outcomes. Dural opening is not routinely required. [ABSTRACT FROM AUTHOR]

Purpose: Chiari Malformation Type I (CM1) is characterized by the downward displacement of the cerebellar tonsils below the foramen magnum. The standard surgical treatment for CM1 is foramen magnum decompression and atlas laminectomy (FMD-AL). However, there is a growing interest in exploring minimally invasive techniques, such as neuroendoscopically assisted FMD-AL, to optimize surgical outcomes. The aim is to present the results of the less invasive neuroendoscopic-assisted system application as an alternative to decompression surgery in patients with CM-1 with/without syringomyelia. Patients and methods: A retrospective analysis was conducted on 76 patients with CMI who underwent either neuroendoscopic-assisted FMD-AL (n = 23) or open surgery (n = 53). Preoperative and postoperative assessments were performed, including pain levels, functional assessment, outcome and serum creatinine kinase (CK) levels. Surgical parameters and radiological imaging were also evaluated and compared. Results: Both surgical groups showed improvements in pain levels and increase in postoperative CK levels. There were no statistically significant differences between the groups in terms of postoperative JOA scores, VAS scores, CCOS, or syrinx resolution. However, the neuroendoscopic group had significantly lower CK levels, shorter hospital stays, less blood loss, and shorter operation times compared to the open surgery group, indicating reduced muscle damage and potential benefits of the neuroendoscopic assisted approach. Conclusion: Both neuroendoscopy and open surgery groups can effectively alleviate symptoms and improve outcomes in patients with CM1. The neuroendoscopic assisted technique offers the advantage of reduced muscle damage and shorter hospital stays. The choice of surgical technique should be based on individual patient characteristics and preferences. Level of evidence: 3 (Retrospective case–control study) according to using the Oxford Centre for Evidence-Based Medicine (CEBM) Table. [ABSTRACT FROM AUTHOR]

Introduction: Chiari malformation (CIM) is a congenital anomaly characterized by herniation of hindbrain structures through the foramen magnum into the cervical spinal canal (CSC). Although the pathogenesis of CIM has not been clearly defined, its relationship with the posterior fossa and CSC morphology is unclear. In this study, we aimed to perform morphometric analysis of both the posterior fossa and the CSC in CIM to investigate the correlation of measurements with each other and to reveal their effects on the development of syringomyelia (SM), which has not been previously reported. Methods: Magnetic resonance imaging images of 90 patients and 30 healthy individuals were retrospectively analyzed. Posterior fossa parameters and CSC diameters at all cervical vertebral levels were measured for each patient. The taper ratio of CSC was calculated separately for each group at the C1-C4 and C1-C7 levels. The average CSC shape was drawn for each group. Results: No statistically significant difference was detected between the age groups. A steeper taper ratio was detected when CIM was accompanied by SM. In addition, the posterior fossa had a narrower volume than the normal fossa in CIM. Conclusion: Morphometric analysis of both the posterior fossa and the CSC was performed using CIM for the first time in the literature. This is the first study to present the term "tapering" with an illustration. [ABSTRACT FROM AUTHOR]

We compared the diameter of the jugular foramen (JF) between normal individuals and those with a diagnosis of craniovertebral junction abnormalities, such as Chiari malformation type I (CMI) and/or basilar invagination (BI). This cross-sectional analytical study measured the diameter of the right and left JF on magnetic resonance imaging scans of patients divided into 4 groups: 68 with combined CMI and BI (CMI+BI), 42 with isolated BI, 45 with isolated CMI, and 102 control cases. The t test determined sex differences, and univariate analysis of variance with Tukey's post hoc test assessed JF differences between groups. Considering all combinations of laterality and sex, the CMI+BI group had a JF narrower than their respective control groups. The JF was bilaterally narrower in the BI group than in the control group only in the women. Regardless of laterality, the CMI group had a wider JF than did the CMI+BI group in men and did not differ from that of the control group. In the female patients with CMI, the right JF did not differ from that of the controls and was wider than that in the CMI+BI group. Also, the left JF was narrower than that in the control group and did not differ from that in the CMI+BI group. JF narrowing is associated with CMI and BI when combined in the same patient. When CMI or BI are detected separately, they do not imply evident changes in JF morphometry. It is expected that these findings could bring empiric substrate to support theories that claim a possible role of intracranial pressure disturbances as a triggering factor for CMI. [ABSTRACT FROM AUTHOR]

Background: Chiari malformation type 1 (CM-1) involves the cerebellar tonsils' descent below the foramen magnum. In Chiari malformation type 1.5 (CM-1.5), both the cerebellar tonsils and the brainstem are herniated. Common symptoms include headaches and cervical pain, often associated with conditions like syringomyelia and hydrocephalus. Surgical treatment is not performed in asymptomatic patients, while the presence of syringomyelia represents an indication for surgery. Methods: This study retrospectively examined pediatric patients with CM-1 and CM-1.5 at Giannina Gaslini Hospital from 2006 to 2020, analyzing demographics, radiological findings, surgical interventions, and outcomes. Results: Out of 211 patients who underwent surgery, 83.9% were diagnosed with CM-1 and 16.1% with CM-1.5. Headaches were prevalent (69%) and cerebellar signs were noted in 29% of patients. Syringomyelia and hydrocephalus were present in 28.4% and 8% of cases, respectively. Intraoperative ultrasonography guided interventions, with 59.8% requiring bony and ligamentous decompression, and 27.1% undergoing duraplasty. Conclusions: The surgical treatment of CM-1/CM-1.5 involves posterior cranial fossa decompression. Choosing between bony decompression alone and its combination with duraplasty has always been controversial in the pediatric population. If we consider as surgical endpoint the restoration of cerebrospinal fluid (CSF) flux, intraoperative ultrasound may be a real-time helpful tool in orienting the surgical strategy, yet refinement with quantitative measures is needed. [ABSTRACT FROM AUTHOR]

Background: Chiari malformation type 1 (CM1) is a congenital hindbrain malformation characterized by herniation of the cerebellar tonsils below the foramen magnum. The term Chiari type 1.5 is used when herniation of the brainstem under the McRae line and anomalies of the craniovertebral junction are also present. These conditions are associated with several symptoms and signs, including headache, neck pain, and spinal cord syndrome. For symptomatic patients, surgical decompression is recommended. When radiographic indicators of craniovertebral junction (CVJ) instability or symptoms related to ventral brainstem compression are present, CVJ fixation should also be considered. Case description: We report the case of a 13-year-old girl who presented with severe tetraparesis after posterior decompression for Chiari malformation type 1.5, followed 5 days later by partial C2 laminectomy. Several months after the initial surgery, she underwent two fixations, first without and then with intraoperative cervical traction, leading to significant neurological improvement. Discussion and conclusion: This case report underscores the importance of meticulous radiological analysis before CM surgery. For CM 1.5 patients with basilar invagination, CVJ fixation is recommended, and C2 laminectomy should be avoided. In the event of significant clinical deterioration due to nonadherence to these guidelines, our findings highlight the importance of traction with increased extension before fixation, even years after initial destabilizing surgery. [ABSTRACT FROM AUTHOR]

Objective: Imaging parameters of Chiari malformation type I (CMI) development are not well established. This study aimed to collect evidence of general or specific imaging measurements in patients with CMI, analyze indicators that may assist in determining the severity of CMI, and guide its diagnosis and treatment. Methods: A comprehensive search was conducted across various databases including the Cochrane Library, PubMed, MEDLINE, Scopus, and Embase, covering the period from January 2002 to October 2023, following predefined inclusion criteria. Meta-analyses were performed using RevMan (ver. 5.4). We performed a quantitative summary and systematic analysis of the included studies. This study was registered in the PROSPERO (International Prospective Register of Systematic Reviews) prior to initiation (CRD42023415454). Results: Thirty-three studies met our inclusion criteria. The findings indicated that out of the 14 parameters examined, 6 (clivus length, basal angle, Boogard's angle, supraocciput lengths, posterior cranial fossa [PCF] height, and volume) exhibited significant differences between the CMI group and the control group. Furthermore, apart from certain anatomical parameters that hold prognostic value for CMI, functional parameters like tonsillar movement, obex displacement, and cerebrospinal fluid dynamics serve as valuable indicators for guiding the clinical management of the disease. Conclusion: We collated and established a set of linear, angular, and area measurements deemed essential for diagnosing CMI. However, more indicators can only be analyzed descriptively for various reasons, particularly in prognostic prediction. We posit that the systematic assessment of patients' PCF morphology, volume, and other parameters at a 3-dimensional level holds promising clinical application prospects. [ABSTRACT FROM AUTHOR]

Arief Cahyadi,1,2 Riyadh Firdaus,2 Hansen Angkasa2 1Department of Anestesiology, Univesitas Padjajaran, Hasan Sadikin General Hospital, Bandung, Indonesia; 2Department of Anesthesiology and Intensive Care, Faculty of Medicine University of Indonesia, Cipto Mangunkusumo General Hospital, Jakarta, IndonesiaCorrespondence: Arief Cahyadi, Hasan Sadikin General Hospital, Pasteur Road, No. 38, Bandung, West Java, 40161, Indonesia, Email ariefcahyadi@gmail.comAbstract: Arnold–Chiari malformation is a displacement of the brain into the spinal canal, often leading to hemodynamic distress. Arnold-Chiari malformation type III (CM III) is a rare and severe type that requires early detection to prevent complications. We aim to report this rare presentation of CM III. A 16-month-old girl with a massive tumor of the occiput suspected to be a meningoencephalocele with CM III was referred to the neurosurgery department. The patient was assessed with class 3 American Society of Anesthesiologist classification, posed challenges due to a difficult airway and the presence of a meningoencephalocele. The patient was scheduled for an elective surgery. Preoperative, the patient was lethargic with an abnormal heart rate and blood pressure. Induction was performed while preserving spontaneous ventilation, but was assisted by an oropharyngeal airway due to a short neck and obesity. The patient later developed laryngospasm thus, muscle relaxant and propofol were administered. A rescue laryngeal mask airway was inserted due to desaturation. Intubation was performed with video laryngoscope. When the surgeon opened the cele and removed the cerebrospinal fluid, the blood pressure began to decline. Resection of brain tissue caused the patient started to bleed, fluid and blood products were administered. At the end of surgery, the patient had stable hemodynamics and was transferred to the pediatric intensive care for monitoring. In patients with massive occipital meningoencephalocele and CM III, anesthetic management requires smooth intubation and prevention of excessive manipulation of the cervical joint to prevent increased intracranial pressure. The patient was not extubated because the brainstem could not be sufficiently reduced coupled with significant autonomic dysfunction.Keywords: Chiari malformation, children, management anesthesia, meningoencephalocele

Chiari malformation is characterized by inferior displacement of the cerebellar tonsils through the foramen magnum, frequently resulting in strain related headaches, and motor/sensory dysfunction. Chiari decompression technique varies significantly, possibly contributing to frequent revisions. We reviewed revision Chiari decompressions at our institution to determine the primary indications for revision and outcomes after revision. We retrospectively reviewed patients who underwent revision of Chiari decompression at our institution from 2005 to 2020. Demographics, indications for revision surgery, operative techniques, imaging findings, and preoperative/postoperative symptoms were collected. χ2 test was performed to determine statistical significance using a P < 0.05. Independent predictors of operative outcomes were identified. A total of 46 patients (91% females, mean age 38.8 years) were included for analysis. The median time to revision surgery was 69.1 months (range 0–364 months) with headache (n = 37, 80%) being the most commonly recurring symptom. Large craniectomy (n = 28, 61%) was the most frequent indication for revision surgery. Thirty-two (70%) patients underwent cranioplasty, 20 (43%) required duraplasty, 15 (33%) required arachnoid dissection, and 15 (33%) required tonsillar reduction during revision surgery. Postrevision follow-up (at 8.9 ± 5.2 months average, range 1–18 months), revealed an average reduction in all Chiari-related symptoms relative to symptoms before the revision. The most common indication for revision Chiari decompression was a large craniectomy resulting in cerebellar ptosis. We found that tonsillar reduction paired with modest craniectomy achieved near-complete resolution of symptoms with minimal complications. For patients with recurrent or persistent sequelae of Chiari malformation after decompression, revision may reduce symptom severity. [ABSTRACT FROM AUTHOR]

This study extended research on Psychology of Working Theory (PWT) by examining the connection of decent work to work fulfillment and general well-being in 346 predominantly U.S. adult workers diagnosed with Chiari malformation (CM), a chronic health condition involving a structural malformation affecting the posterior region and base of the skull, and commonly presenting with chronic head and neck pain and related physical (e.g., fatigue) and psychological (e.g., anxiety, depression) complications. Participants completed an online survey containing measures of PWT's outcomes of decent work constructs as well as the domain-specific marginalization constructs of condition severity and workplace limitations. Results of structural equation modeling analyses supported 12 of 19 hypotheses. Decent work directly and positively predicted survival, social contribution, and self-determination needs; social contribution and self-determination needs directly and positively predicted work fulfillment; survival and self-determination needs directly and positively predicted general well-being; decent work indirectly (via social contribution and self-determination needs) and positively predicted work fulfillment and indirectly (via survival and self-determination needs) and positively predicted general well-being; and condition severity directly and negatively predicted general well-being. Consistent with PWT, attaining decent work contributes to meeting needs for survival, social contribution, and self-determination, which in turn contributes to greater work fulfillment and general well-being in workers with CM. [ABSTRACT FROM AUTHOR]

Introduction: Chiari 1 malformation and hind brain hernia can be associated with skull base and craniocervical anomalies. One of the more recently associated anomalies is a retroverted or retroflexed odontoid process or dens. We conducted a retrospective study of our operated symptomatic and conservatively managed asymptomatic Chiari cohort to assess the impact of dens retroflexion on rate of revision or cerebrospinal fluid diversion following primary foramen magnum decompression (FMD). Methods: We undertook a retrospective study of all foramen magnum decompression (FMD) cases for Chiari type 1 malformation performed over a 15-year period in a single tertiary paediatric neurosurgical unit. For comparison, non-operated asymptomatic Chiari cases were considered as reference cohort. Information gathered included: demographics, age, sex, length of cerebellar tonsils below McRae's line, pB-C2 distance (a line drawn perpendicular to one drawn between the basion and the posterior aspect of the C2 body), angle of retroflexion (angle formed between a line drawn through the odontoid synchondrosis and its intersection with a line drawn from the tip of the odontoid process) and angle of retroversion (angle formed between the line drawn from the base of C2 and its intersection with a line drawn from the tip of the odontoid process). Grade of retroflexion was measured using pre-operative mid-sagittal MR images and classified as grade 0 (> 90°), grade 1 (85°–89°); grade 2 (80°–84°) and grade 3 (< 80°). The rates for redo surgery or need for cerebrospinal fluid (CSF) diversion were obtained from clinical records and compared in the operated and non-operated groups. Results: One hundred twenty-six Chiari 1 patients were included in this study with adequate imaging. Sixty-five patients were in the non-operated asymptomatic cohort with 61 patients in the operated symptomatic cohort. Mean age of non-operated cohort was 10.2 years with M:F ratio (30:35). Mean cerebellar tonsillar length below McRae's line was 10.3 mm. 7.7% of this cohort had associated syrinx. Mean angles of retroversion and retroflexion were 76 and 78°, respectively. Retroflexion grades included (9.2% grade 1, 35% grade 2 and 52.3% grade 3). pB-C2 distance was 6.8 mm. Mean age of operated cohort was 11.3 years, with M:F ratio (21:40). Mean cerebellar tonsillar length below McRae's line was 15 mm. 45.9% of this cohort had associated syrinx. Mean angles of retroversion and retroflexion were 73 and 74.5°, respectively. Retroflexion grades included (4.9% grade 1, 16.5% grade 2 and 78.6% grade 3). pB-C2 distance was 6.9 mm. No association was identified between retroflexion grade and rate of revision or CSF diversion following primary foramen magnum decompression. Conclusion: The operated Chiari 1 cohort had more retroflexed dens, longer tonsils and associated syrinx compared to the non-operated asymptomatic cohort. [ABSTRACT FROM AUTHOR]

Background: Segmentation tools continue to advance, evolving from manual contouring to deep learning. Researchers have utilized segmentation to study a myriad of posterior fossa-related conditions, such as Chiari malformation, trigeminal neuralgia, post-operative pediatric cerebellar mutism syndrome, and Crouzon syndrome. Herein, we present a summary of the current literature on segmentation of the posterior fossa. The review highlights the various segmentation techniques, and their respective strengths and weaknesses, employed along with objectives and outcomes of the various studies reported in the literature. Methods: A literature search was conducted in PubMed, Embase, Cochrane, and Web of Science up to November 2023 for articles on segmentation techniques of posterior fossa. The two senior authors searched through databases based on the keywords of the article separately and then enrolled joint articles that met the inclusion and exclusion criteria. Results: The initial search identified 2205 articles. After applying inclusion and exclusion criteria, 77 articles were selected for full-text review after screening of titles/abstracts. 52 articles were ultimately included in the review. Segmentation techniques included manual, semi-automated, and fully automated (atlas-based, convolutional neural networks). The most common pathology investigated was Chiari malformation. Conclusions: Various forms of segmentation techniques have been used to assess posterior fossa volumes/pathologies and each has its advantages and disadvantages. We discuss these nuances and summarize the current state of literature in the context of posterior fossa-associated pathologies. [ABSTRACT FROM AUTHOR]

Objective The aim this study is to present the results of the minimal invasive neuroendoscopic-assisted system application as an alternative to traditional surgery in patients with Chiari malformation type 1 (CM type 1) with/without syringomyelia. Design, Setting, and Participants In the study, data of 22 symptomatic patients were prospectively collected. Before and after the operation, patient characteristics, computed tomography, magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) flow dynamics MRI, and outcome scales scores were recorded. Foramen magnum decompression and C1 total laminectomy were performed. The fibrous band at the craniocervical junction was opened and a durotomy was performed. In patients with a syrinx, the pre- and postoperative axial and sagittal lengths of the syrinx were measured and compared. Results The mean age of the patients was 32 ± 5 years. There were eight male patients. Ten patients had syrinx. The mean visual analog scale (VAS) score before and after surgery was 8 ± 1.06 and 2.18 ± 1.13, respectively. When evaluated according to the Chicago Chiari Outcome Scale, there was improvement in 20 patients, while there was no change in 2 patients. Syrinx resolved completely in 3 of 10 (13.6%) patients with syringomyelia, and the syrinx volume decreased in 3 patients (13.6%). In 4 of 10 (18.1%) patients, there was no significant change in the syrinx volume. The average operation time was 105 minutes (80–150 minutes). The average blood loss was 40 mL (20–110 mL). Conclusion Although the study was limited due to the small number of patients with a short follow-up, endoscopic decompression was a safe and effective technique for surgery in CM type 1 patients. [ABSTRACT FROM AUTHOR]

We sought to identify social determinants of health (SDoH) for adult patients undergoing Chiari decompression surgery and to analyze their association with postoperative outcomes, including length of stay (LOS), return to the system within 30 days, and the Chicago Chiari Outcomes Score (CCOS). This is a retrospective study of adult patients who underwent Chiari decompression surgery between June 2021 and January 2023. Data was gathered through electronic medical record review and telephone surveys. Descriptive statistics were used to evaluate demographics of all patients meeting inclusion criteria. Fisher's exact tests and logistic regression were used for data analysis. A total of 37 patients underwent Chiari decompression (23 CCOS/SDoH survey respondents): 48% bony decompression only, 30% bony decompression plus intradural exploration, and 22% occipitocervical fusion. Seven patients (30%) had a LOS > 2 days, 1 patient (4%) required inpatient rehabilitation postoperatively, 4 patients (17%) returned to the system within 30 days, 10 patients (43%) had an extremely favorable CCOS (15–16), and 11 patients (48%) reported interaction with a Chiari support group. Mean follow-up was 9.5 months. Patients with occipitocervical fusion were more likely to have a LOS > 2 days (p = 0.03), patients who exercised ≥ 3 days per week were more likely to have a favorable CCOS (p = 0.04), and patients who participated in a Chiari support group were less likely to have a favorable CCOS (p = 0.03). Chiari decompression plus occipitocervical fusion may be associated with increased LOS. While more frequent exercise may be associated with better post-surgical outcomes, participation in a Chiari support group may be correlated with worse outcomes. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to determine the values of volumetric and morphological parameters in Chiari malformation type 1 (CM1) patients in the Turkish population. Methods: This retrospective study was conducted at a single center and included patients diagnosed with CM1 between 2013 and 2023. The patients were separated into two groups: the group CM1 and the control group comprising healthy individuals (group control). The morphometric measurements were clivus length, supraocciput length, foramen magnum diameters, distance between the midbrain-pons junction and midbrain-medullospinal junction, cerebellar hemisphere height, tentorium angle, clivus angle, clivus-tentorium angle, posterior fossa volume (PFV), and cerebellar tonsillar morphology. Results: The cerebellar tonsillar herniation was 11.43±2.09 mm in group CM1 and -2.64±2.37 mm in the control group. The mean clivus and supraocciput length were 34.26±4.76 mm and 41.26±4.33 mm in group CM1 and 36.85±3.23 mm and 42.21±2.86 mm in the control group, respectively. The mean foramen magnum diameters were 31.41±3.28 mm in group CM1 and 35.64±2.32 mm in the control group (p<0.05). The mean PFV was 153.91±5.02 mL in group CM1 and 180.70±11.62 mL in the control group (p<0.05). Conclusion: Two parameters were statistically significantly decreased in CM1 patients (PFV and foramen magnum diameters), indicating the main morphometric change that guides diagnosis and treatment in CM1 patients. All other parameters examined in this study were deemed unnecessary because there was no significant difference between CM1 and the average population. [ABSTRACT FROM AUTHOR]

Objective To evaluate the value of magnetic resonance imaging (MRI) in prenatal diagnosis of fetal Chiari malformation. Methods The prenatal MRI findings of 27 cases of Chiari malformation confirmed by follow-up in Obstetrics and Gynecology Hospital,Fudan University from Feb 2010 to Feb 2022 were retrospectively analyzed and compared with ultrasound findings. Results Twenty-seven pregnant women, aged from 16-36 years ( average 28.0 years) and 27 fetuses with gestation from 15.3-38.4 weeks (average 24.3 weeks) were studied. There were 18 cases of Chiari Ⅱ (Chiari malformation type Ⅱ,CM Ⅱ), 3 cases of Chiari Ⅲ (CM Ⅲ), 6 cases of Chiari Ⅳ (CM Ⅳ) . CM Ⅱ and CMⅢ images showed brain herniation, descending pons, narrowing or disappearance of the posterior fossa cistern and the fourth ventricle,the subarachnoid space disappears. There were 17 cases of hydrocephalus, 2 cases of cerebrospinal fluid loss, 17 cases of“ lemon head” and“ banana cerebellar” signs,4 cases of encephalocele, 15 cases of spinal bifida, 3 cases of lower spinal cord and 2 cases of spinal cavity, 4 cases of spinal angular deformity and 6 cases of other malformations. In CM Ⅳ, there were 2 cases of undeveloped cerebellum and 4 cases of cerebellum and brainstem dysplasia, hydrocephalus in 5 cases, posterior fossa cistern widening in 4 cases, and other malformations in 4 cases. MRI showed the posterior fossa structure and spinal cord more clearly than ultrasound, and could find lesions not detected by ultrasound. Conclusion Prenatal MRI can be used as a complementary examination of ultrasound, which can improve the accuracy of diagnosis of Chiari malformation, reduce the rate of missed diagnosis, and clarify the classification of Chiari malformation. [ABSTRACT FROM AUTHOR]

Chiari malformation (CM) 1 is the most common of all types and is often found incidentally. Neurological symptoms occur due to compression of the cerebellum or medulla at the foramen magnum and/or development of syrinx. Psychiatric symptoms have also been reported. We report a case of CM who underwent decompression surgery but developed self-biting of fingers first on the left hand, which resolved and then on the right hand with extensive mutilation and tissue damage. He improved with oral amitriptyline, but the cause of his self-biting remains unexplained. It is not uncommon to find psychiatric disorders in patients with neurological disorders; therefore, a detailed history and a holistic approach are warranted.

Chiari malformation (CM) is a common neurological disorder with foramen magnum decompression (FMD) as a commonly accepted treatment. The authors present a case of CM-1 wherein there was no radiological instability preoperatively and FMD was done as a treatment, after which the patient improved transiently only to deteriorate further. Atlantoaxial fixation was done as a second-stage procedure, after which the patient improved clinically and radiologically. The knowledge of this case and surgical entity should be borne in mind before the formulation of a treatment plan. It is important that the solution is to identify and treat the underlying pathology rather than to decompress and directly manipulate the tonsils.

Chiari malformation (CM) is characterized by herniation of the cerebellar tonsil(s) and/or medulla oblongata into the spinal canal, resulting in various morphometric abnormalities. The current study aimed to evaluate the magnetic resonance imaging (MRI) findings and morphometric features of the craniocervical region in patients who underwent surgery for CM. Demographic and radiological data were collected from 59 patients who underwent surgery for CM and a control group of 58 randomly selected nonsurgical patients. For between-group comparisons, Continuous variables were described as the mean (±SD) or median (IQR) and categorical variables as frequency (%). The mean age of the control group participants was 33.38 years. The mean age of patients in the CM group at the time of surgery was 33.83 years. The diameter of the foramen magnum, the maximum anteroposterior diameter of the C1 vertebra, the maximum diameter of the spinal canal at the C2 vertebra, and the atlantodental interval were all positively correlated with the total cerebellar tonsil length [r=0.54, 0.37, 0.42, 0.71]. Comparisons of total cerebellar tonsil length with other morphological and clinical variables, including contact between the brainstem and clivus, basilar invagination, preoperative hydrocephalus, remnant cartilage between the odontoid and C2 corpus, and associated craniovertebral junction anomalies, revealed no other significant correlations. CM is associated with many structural anomalies in the brain. However, there is relatively little detail in the existing literature on the morphometric parameters associated with the malformation. The findings of this study provide insights for future research and contribute to knowledge of the morphometric features of CMs in general and CMs in patients requiring surgical management in particular. [Med-Science 2023; 12(4.000): 1066-73]

Background: Chiari malformation type 1 (CM1) remains a complex neurosurgical condition with ongoing debate regarding its optimal management. Methods: This narrative review examines key controversies surrounding the pathophysiology, surgical indications, and treatment strategies for CM1. Results: We highlight the challenges posed by the wide spectrum of CM variants and the evolving understanding of its association with syringomyelia, basilar invagination, and craniovertebral instability. Emerging surgical techniques, including minimally invasive approaches and the use of new technologies such as endoscopes and exoscopes, are evaluated for their potential to improve outcomes. Recent consensus guidelines are also discussed. Conclusions: The need for individualized treatment plans for CM1 is emphasized, with special focus put on the connection between novel pathophysiological insights, technological advancements and opportunities for a more nuanced surgical management. Further research is necessary to establish solid foundations for more individualized treatments.

Objective To explore the application value of transcranialcerebral vessel Doppler (TVD) ultrasonography in the diagnoses and postoperative evaluations of type Ⅰ Chiari malformation in children. Methods From March 2018 to December 2021, the relevant clinical data were retrospectively reviewed for 27 children with type Ⅰ Chiari malformation. Based upon age, they were assigned into two groups of preschool (aged 1-6 year, n=15) and school-age (aged 7-16 year, n=12). TVD was detected at pre-operation, 24 h post-operation and 1 month post-operation. Posterior cerebral artery (PCA), bilateral vertebral artery (VA) and basilar artery (BA) in posterior cranial fossa were selected as target vessels. Peak systolic velocity (PSV), end-diastolic velocity (EVD) and pulsative index (PI) of the corresponding target vessels were monitored. Hemodynamic profiles of posterior cranial fossa were compared in different age groups at pre-operation versus post-operation. The accuracy of diagnosis was compared with magnetic resonance imaging (MRI) at pre-operation and the consistency of efficacy compared with Tator evaluation post-operation. Results PSV of bilateral PCA post-operation spiked in preschool group as compared with that pre-operation [left (44.25±13.06) vs. (66.76±14.45) cm/s, t=5.148, P=0.023; right (45.12±13.41) cm/s vs. (65.33±10.12) cm/s, t=5.389, P=0.021) and PI declined [left (1.18±0.42) vs. (0.91±0.18), t=4.545, P=0.033; right (1.24±0.48) vs. (0.92±0.13), t=4.776, P=0.028), bilateral VA PSV [left (43.50±11.99) vs. (70.94±7.56) cm/s, t=7.042, P=0.008; right (44.56±8.45) vs. (68.82±9.02) cm/s, t=6.833, P=0.009], preoperative EVD rose [left (19.01±9.22) vs. (27.18±8.53) cm/s, t=4.587, P=0.032; right (18.28±5.77) vs. (28.32±7.26) cm/s, t=4.683, P=0.030]and preoperative bilateral PI dropped [left (1.12±0.45) vs. (0.86±0.19), t=4.712, P=0.029; right (1.31±0.46) vs. (0.84±0.31) cm/s, t=5.277, P=0.022], BA PSV [(48.75±16.57) vs. (69.17±11.86) cm/s, t=5.413, P=0.019], preoperative EVD increased [(27.73±7.34) vs. (27.18±8.53) cm/s, t=4.738, P=0.027) and preoperative PI decreased [(1.13±0.55) vs. (0.90±0.28), t=4.721, P=0.030]; PSV of bilateral VA after surgery in school-age group was higher than that pre-operation [left (48.16±18.47) vs. (53.77±24.73)cm/s, t=4.187, P=0.045; right [(45.72±18.53) vs. (56.31±19.82) cm/s, t=3.872, P=0.036)], BA PSV [(48.50±11.44) vs. (58.17±18.86) cm/s, t=5.108, P=0.024], preoperative EVD increased [(18.63±9.91) vs. (23.19±10.63) cm/s, t=4.763, P=0.029]and preoperative PI declined [(1.06±0.42) vs. (0.92±0.25), t=4.572, P=0.032]. Preoperative TVD detection rate of 27 cases was lower than that of MRI (χ²=5.511, P=0.019). At 1 month after Tator efficacy evaluation, there were improvements (n=19, 70.4%) and non-improvements (n=8, 29.6%). TVD ultrasonic monitoring parameters improved (n=22, 81.5%) and stagnated (n=5, 18.5%). There was consistency between TVD ultrasound and Tator efficacy evaluation [χ²=0.911, P=0.340]. Conclusions MRI is a gold diagnostic standard for Chiari type Ⅰ malformation in children. However, TVD ultrasound has some accuracy and auxiliary effects. It can effectively depict the hemodynamic changes of posterior fossa artery and indirectly and non-invasively assess intracranial pressures. Thus it enables clinicians to make a timely diagnosis, offer a proper treatment and make an accurate assessment of outcomes. [ABSTRACT FROM AUTHOR]

Background: The role of reduced intracranial compliance (ICC) in the outcome after foramen magnum decompression (FMD) was demonstrated in adults with Chiari malformation Type 1 (CMI). However, similar observations from children treated for CMI are missing. Methods: We reviewed pediatric cases of CMI referred to FMD between 2006 and 2022. Children with clinical and/or radiological signs suggesting reduced ICC (Group A) underwent overnight measurements of the pulsatile intracranial pressure (ICP): mean ICP wave amplitude (MWA) served as a surrogate marker of ICC. Children with more typical symptoms of CMI (Group B) underwent FMD without preoperative ICC estimation. This study presents the clinical, radiological, and outcome differences between these groups. Results: Sixty-four children (mean age 11.1 ± 4.3 years) underwent FMD: In Group A (n = 30), the finding of reduced ICC as estimated from preoperative ICP measurement resulted in CSF diversion (ventriculoperitoneal shunt) before FMD in 11 children. Two patients required shunt due to complications after FMD (total shunt rate 43%). In Group B (n = 34) treated with FMD without preoperative ICC estimation, five children (15%) required shunting due to complications. In Group A, we found a significantly higher frequency of headache, nausea, fatigue, and dizziness. The outcome assessed by the modified Chicago Chiari Outcome Scale (mean follow-up 83 ± 57 months) was comparable between the groups, but the complication rate after FMD was significantly lower in Group A (7% vs. 32%; p = 0.011). The number of procedures (ICP measurement, FMD, shunt, re-do FMD, shunt revisions) was significantly higher in Group A (2.6 ± 0.9 vs. 1.5 ± 1.1 per patient; p < 0.001). Conclusion: In symptomatic children with CMI, the preoperative estimation of ICC from the overnight measurement of pulsatile ICP was more reliable for identifying those with reduced ICC than clinical and radiological assessment alone. When children with abnormally reduced ICC were identified and treated with CSF diversion before FMD, the complication rate was significantly reduced. [ABSTRACT FROM AUTHOR]

Chiari malformation (CM) is a common neurological disorder with foramen magnum decompression (FMD) as a commonly accepted treatment. The authors present a case of CM-1 wherein there was no radiological instability preoperatively and FMD was done as a treatment, after which the patient improved transiently only to deteriorate further. Atlantoaxial fixation was done as a second-stage procedure, after which the patient improved clinically and radiologically. The knowledge of this case and surgical entity should be borne in mind before the formulation of a treatment plan. It is important that the solution is to identify and treat the underlying pathology rather than to decompress and directly manipulate the tonsils. [ABSTRACT FROM AUTHOR]

Background: Chiari (type I) malformations are typically congenital. Occasionally, however, tonsillar herniation can arise secondary to cerebrospinal fluid leakage, posterior fossa or intraventricular mass lesions, or other etiologies. We present the first-ever case of an intramedullary subependymoma at the cervicomedullary junction associated with vertebral bone abnormalities and an acquired secondary Chiari malformation. Case Description: A 60-year-old woman presented with a 3-year history of occipital, tussive headaches. Preoperative imaging was negative for mass lesions but demonstrated a Chiari malformation. She was recommended posterior fossa decompression with tonsillar shrinkage. During surgery, an intramedullary mass was incidentally observed, obstructing the obex at the cervicomedullary junction. Histopathological analysis of the resected lesion revealed a diagnosis of subependymoma. Conclusion: Subependymomas can sometimes present a diagnostic challenge due to their subtle appearance in neuroimaging. Only rarely are such masses associated with an acquired Chiari malformation. No such case has previously been reported. We present a literature review on acquired Chiari malformations and discuss their management. [ABSTRACT FROM AUTHOR]

Sleep apnoea is common in patients with Basilar Invagination with Arnorld Chiari Malformation (ACM). Various studies have shown its incidence in the range of 60-70% among such patients. Most of the studies have shown improvement in sleep disturbances after decompressive surgeries for Chiari Malformations. There is no report of postoperative deterioration due to sleep apnoea in these patients. Authors report two cases of basilar invagination associated with ACM and Platybasia, who deteriorated probably due to worsening of pre-existing sleep disorders on 3rd and 7th postoperative days after their surgeries, despite clinico-radiological improvements during their early post-operative courses. Authors discuss literature related to sleep apnoea in basilar invagination associated with Chiari Malformations and share precautions, which are relevant and should be undertaken in such patients especially during early post-operative periods to avoid alarming complication which may occur even in experienced hands. [ABSTRACT FROM AUTHOR]

Background: Chiari I malformation is defined by tonsillar herniation through the foramen magnum. There is no consensus on the treatment of Chiari malformation. A simple follow-up is recommended for asymptomatic cases. The classic approach is the midline sub-occipital craniotomy. Methods: For four years, we operated on six patients with Chiari malformation I using our endoscopic minimally invasive sub-occipital approach. We compared the results with six other patients operated by the classical sub-occipital approach. Results: Patients operated by endoscopic approach had shorter hospital stays, and wounds healed faster and smoother. Mid-term results were similar in the two groups. Conclusion: This paper proposes a new endoscopic Minimally invasive paramedian sub-occipital approach for Chiari malformation I. Although the number of cases is limited, the results look promising. We need to gather more cases to have significant numbers to perform a global comparison between the two approaches and assess the advantages and disadvantages of each technique. [ABSTRACT FROM AUTHOR]

Purpose: Hydrocephalus after craniovertebral decompression (CVD) for Chiari I malformation (CM-1) is a well-recognised complication. The mainstay of management involves medical management with high-dose steroids and/or acetazolamide, repeated lumbar punctures, external ventricular drainage (EVD) or insertion of a ventriculoperitoneal shunt (VPS). Endoscopic third ventriculostomy (ETV) has only been used a handful of times to treat this type of hydrocephalus with controversial outcomes. Not much is known about this or the technical nuances of this procedure. We report our experience. Methods: All children who underwent ETV to treat hydrocephalus post CVD done for CM-1 were identified from a prospectively kept database. Results: Three children were identified (13F, 11F, 13F). The average time to presentation of hydrocephalus was 8 days after craniovertebral decompression. Two were successfully treated with ETV with brain imaging showing a reduction in the size of the ventricles post-operatively and not requiring any further cerebrospinal fluid drainage. In one patient, the procedure had to be abandoned after the peel away catheter was introduced into the right ventricle because CSF egressed under high pressure with ventricle walls collapse resulting in an obstructed view. This child ultimately required a VPS. Conclusion: ETV can be used to successfully treat post CVD hydrocephalus in CM-1 patients depending on the aetiology of the hydrocephalus. There are technical and anatomical commonalities between these cases which make it more challenging than an ETV performed in "typical" obstructive hydrocephalus. We describe our experience and review the cases previously reported in the literature. [ABSTRACT FROM AUTHOR]

Chiari malformation (CM) is characterized by herniation of the cerebellar tonsil(s) and/or medulla oblongata into the spinal canal, resulting in various morphometric abnormalities. The current study aimed to evaluate the magnetic resonance imaging (MRI) findings and morphometric features of the craniocervical region in patients who underwent surgery for CM. Demographic and radiological data were collected from 59 patients who underwent surgery for CM and a control group of 58 randomly selected nonsurgical patients. For between-group comparisons, Continuous variables were described as the mean (±SD) or median (IQR) and categorical variables as frequency (%). The mean age of the control group participants was 33.38 years. The mean age of patients in the CM group at the time of surgery was 33.83 years. The diameter of the foramen magnum, the maximum anteroposterior diameter of the C1 vertebra, the maximum diameter of the spinal canal at the C2 vertebra, and the atlantodental interval were all positively correlated with the total cerebellar tonsil length [r=0.54, 0.37, 0.42, 0.71]. Comparisons of total cerebellar tonsil length with other morphological and clinical variables, including contact between the brainstem and clivus, basilar invagination, preoperative hydrocephalus, remnant cartilage between the odontoid and C2 corpus, and associated craniovertebral junction anomalies, revealed no other significant correlations. CM is associated with many structural anomalies in the brain. However, there is relatively little detail in the existing literature on the morphometric parameters associated with the malformation. The findings of this study provide insights for future research and contribute to knowledge of the morphometric features of CMs in general and CMs in patients requiring surgical management in particular. [ABSTRACT FROM AUTHOR]

Introduction Syringomyelia is a chronic disease characterized by the presence of intramedullary cavity. Chiari malformation (CM) and basilar impression (BI) are conditions usually associated with syringomyelia. Its prevalence has wide geographical variation, being higher in the Northeast of Brazil, making it relevant to study the subject in this region.

Chiari malformation (CM) 1 is the most common of all types and is often found incidentally. Neurological symptoms occur due to compression of the cerebellum or medulla at the foramen magnum and/or development of syrinx. Psychiatric symptoms have also been reported. We report a case of CM who underwent decompression surgery but developed self-biting of fingers first on the left hand, which resolved and then on the right hand with extensive mutilation and tissue damage. He improved with oral amitriptyline, but the cause of his self-biting remains unexplained. It is not uncommon to find psychiatric disorders in patients with neurological disorders; therefore, a detailed history and a holistic approach are warranted. [ABSTRACT FROM AUTHOR]