Cerebral anomalies and Chiari type 1 malformation

Noonan syndrome and type 1 Chiari malformation: Possible association

Noonan syndrome (NS) is mostly an autosomal dominant genetic disorder that affects between 1 in 1000 and 1 in 2500 people. Type 1 Chiari malformations (CM1) have an estimated prevalence of <1 in 1000 people. Though NS typically spares the posterior fossa, there have been 11 past instances of patients with NS having a concurrent CM1 that have been published in the literature. Each of these 11 cases occurred sporadically, in an isolated individual with no published family history of CM1. This case report presents a three generational family with four members having both NS and concurrent CM1. All affected family members share a pathogenic variant in PTPN11. A literature review was performed to identify and compile data regarding all past published cases of NS and CM1 occurring concurrently. Since 1982, a dozen case reports have detailed NS with concurrent CM1. Where molecular genetic data was presented, seven had a variant in PTPN11, and only one had a variant in another gene. The clustering of NS with CM1 within a single family that shares the same genotype, along with the exclusion of both NS and CM1 in other family members, may indicate that CM1 is a part of the NS phenotype.

Chiari 1 Malformation and Epilepsy in Children: A Missing Relationship

Purpose: Once believed a result of pathophysiological correlations, the association between Chiari 1 malformation (CM1) and epilepsy has since been considered as a coincidence, due to missing etiologic or clinical matching points. At present, the problem is being newly debated because of the increasing number of CM1 diagnoses, often among children with seizures. No specific studies on this topic are available yet. The present study aimed at updating the information on this topic by reporting on a series of children specifically enrolled and retrospectively analyzed for this purpose. Methods: All children admitted between January 2015 and June 2020 for epilepsy and CM1 were considered (Group 1). They were compared with children admitted in the same period for symptoms/signs related to CM1 and/or syringomyelia (Group 2). Syndromic patients were excluded, as well as those with tumoral or other overt intracranial lesions. All patients received a complete preoperative work-up, including MRI and EEG. Symptomatic children with CM1/syringomyelia were operated on. The pertinent literature was reviewed. Results: Group 1 was composed of 29 children (mean age: 6.2 years) showing CM1 and epilepsy with several types of seizures. A share of 27% had CM1-related symptoms and syringomyelia. The mean tonsillar ectopia was 7.5 mm. Surgery was performed in 31% of cases. Overall, 62% of children are currently seizure-free (including 5/9 children who were operated on). Tonsillar herniation and syringomyelia regressed in 4/9 cases and 4/8 cases, improved in 4/9 cases and 3/8 cases, and remained stable in 1/9 and 1/8 cases, respectively. CM1 signs/symptoms regressed completely in 6/8 cases and improved or remained stable in one case in each of the two remaining patients. Group 2 consisted of 77 children (mean age: 8.9 years) showing symptoms of CM1 (75%) and/or syringomyelia (39%). The mean tonsillar ectopia was 11.8 mm. Non-specific EEG anomalies were detected in 13 children (17%). Surgery was performed in 76.5% of cases (18 children were not operated on because of oligosymptomatic). Preoperative symptoms regressed in 26%, improved in 50%, remained stable 22%, and worsened in 2%; CM1 radiologically regressed in 39%, improved in 37%, remained unchanged in 22%, and worsened in 2%; and syringomyelia/hydromyelia regressed in 61%, improved in 30%, and was stable in 9%. No statistically significant differences between the two groups were detected regarding the M/F ratio, presence of syringomyelia/hydromyelia, or CM1/syringomyelia outcome; moreover, no correlation occurred between seizure-free condition and PF decompression in Group 1, or between disappearance of EEG anomalies and PF decompression in Group 2. A significant difference between the two groups was noticed regarding the mean age at admission (p = 0.003), amount of tonsillar herniation (p < 0.00001), and PF decompression (p = 0.0001). Conclusions: These findings do not support clinical correlations between CM1 and epilepsy. Their course depends on surgery and antiepileptic drugs, respectively. The analysis of the literature does not provide evidence of a relationship between seizures and cerebellar anomalies such as CM1. Rather than being linked to a syndrome that could explain such an association, the connection between the two now has to be considered to be random.

Long-term surgical outcome of Chiari type-I malformation-related syringomyelia: an experience of tertiary referral hospital

OBJECTIVE

Syringomyelia is a common condition seen in patients with Chiari type-I malformation (CM1). The purpose of this retrospective study was to evaluate the long-term clinical and radiological outcomes of posterior fossa decompression with duraplasty (PFDD) with coagulation of tonsillar ectopia in consecutive surgically treated adult patients with CM1-related syringomyelia (CRS).

METHODS

Over 9 years' duration (1993-2001), medical charts of diagnosed patient with CM1 at our neurosurgical center were reviewed retrospectively. This study included adult patients with CM1 who had syringomyelia and underwent PFDD with coagulation of tonsillar ectopia surgery. The differences between the pre- and postoperative syrinx/cord ratio (S/C), the syrinx length, and the regression of herniated cerebellar tonsils on coronal and midsagittal MRIs were evaluated.

RESULTS

A total of 87 surgical procedures (46 primary operations, 7 ventriculoperitoneal shunts, and 34 additional operations) for CRS were performed on 24 males and 22 females. The mean preoperative S/C was 0.59 ± 0.12. The means of regression in herniated cerebellar tonsils on mid-sagittal and coronal images were 11.8 ± 2.3 mm and 10.2 ± 2.2 mm (p < 0.0001), respectively. 35 (76.1%) patients were discharged after showing signs of recovery or improvement. Different complications occurred in 16 (34.8%) patients. Negative correlations were noticed between postoperative recovery/improvement and the long symptoms' duration, the herniated tonsils' extent, S/C, and the persistence of the herniated tonsils on the coronal images.

CONCLUSION

Early diagnosis of patients with CRS can improve surgical outcomes. Due to its efficacy in resolving clinical symptoms and syrinx cavities, PFDD is still an optimal surgical approach for CRS.

Persistent Syringomyelia After Posterior Fossa Decompression for Chiari Malformation

BACKGROUND

Chiari malformation (CM) is often comorbid with syringomyelia. The treatment of CM via posterior fossa decompression (PFD) may not improve syringomyelia in up to 40% of patients, based on historical cohorts. Management of these patients is problematic, as both reoperation and syrinx shunting have high failure rates in the long term.

METHODS

We retrospectively reviewed our cases in which patients with CM type 1 or 1.5 and syringomyelia underwent PFD without postoperative improvement in syringomyelia. Symptomatology and radiographic measurements were collected at presentation and on the first and latest available postoperative scans and analyzed. We present 2 cases to illustrate the challenges in the management of these patients.

RESULTS

Our cohort consisted of 48 consecutive patients with CM and syringomyelia who underwent PFD. Of these, 41 patients had postoperative improvement in or resolution of syringomyelia. We subsequently studied the cohort of 7 patients who underwent PFD with (n = 5) or without (n = 2) durotomy and demonstrated worsening of syringomyelia following surgery. This cohort had mean (±SEM) preoperative syrinx area of 23.9 ± 10.0 mm². Postoperatively, the mean syrinx area increased to 40.5 ± 9.6 mm² and 57.3 ± 12.5 mm² on the first and latest postoperative scans available (P = 0.02), for an increase of 106.9% ± 94.4% and 186.0% ± 107.4% (P = 0.04). Presenting symptoms included occipital headache, paresthesias, visual deterioration, and paraspinal pain. On last follow-up (mean 13.9 ± 4.9 months), the majority of symptoms were resolved in this cohort, despite persistence of syringomyelia.

CONCLUSIONS

In this small cohort of unique patients, syrinx resolution was not achieved via decompression surgery. Despite "radiographic failure," good symptom control was achieved, with most patients remaining or becoming asymptomatic postoperatively, thus supporting our rationale for what has largely been a conservative approach in this population.

Management opinions from different centers (Rio de Janeiro)

INTRODUCTION

The surgical treatment of Chiari type 1 (CM1) malformation is controversial and depends largely on the preference of the surgeon. The evolution of neuroimaging resulted in an increased number of asymptomatic patients incidentally diagnosed.

PURPOSE

To study retrospectively a population of 24 symptomatic patients with CM1 operated between 1999 and 2017 in which intraoperative ultrasonography (IOUS)-assisted posterior fossa-C1 decompression was used to decide whether the dura mater should be opened (CVD+) or not (CVD).

RESULTS

Most of the patients complained of headache or neck pain, 15 had hydrosyringomyelia and 14 had some spinal cord involvement. Patients were categorized in improved, unchanged, or worse according the preoperative signs and symptoms. Overall, 19 patients improved, 3 deteriorated, and 2 remained unchanged. Among these, 4 out 5 had syringohydromyelia.

CONCLUSIONS

IOUS-assisted posterior fossa-C1 decompression is our preferred option to treat CM1. Children submitted to intradural procedures, initially or subsequently, had increased postoperative complications. CSF fistula or pseudomeningocele was the major cause of complication. The final result seems to correlate with the preoperative neurological status.

Chiari malformation and atlantoaxial instability: problems of co-existence

BACKGROUND

Association of Chiari malformation and atlantoaxial subluxation varies. There is a complex relationship between the two, bony and soft tissue pathologies.

METHODS

This is a review of various articles available from the literature on the management of Chiari and its association with atlantoaxial instability.

RESULTS

We have an experience of operating on 86 cases of paediatric atlantoaxial subluxation, of which 12 had Chiari malformation diagnosed preoperatively (13.95%). Of the 76 children with Chiari malformations operated on by us, 11 had associated atlantoaxial subluxation diagnosed on imaging (14.47%).

CONCLUSIONS

Re-alignment and reduction with fixation may be effective in achieving decompression in cases where reduction is possible from posterior approach. In these cases, posterior fixation is all that is required. If reduction is not possible from posterior and there is "fixed" ventral compression, anterior decompression needs to be combined with posterior fixation. In most cases, direct posterior decompression is warranted.

Chiari Type I Malformation Associated With Verbal Fluency Impairment

PURPOSE

Chiari malformation (CM) Type I is a rare disorder that implies an anomaly in the craniocervical junction, where one or both cerebellar tonsils are displaced below the foramen magnum into the cervical spinal channel. Research carried out regarding cognitive symptoms such as verbal fluency is scarce. The aim of this study was to investigate whether verbal fluency is impaired in a CM clinical group compared to a group of healthy control individuals while controlling for depression and anxiety symptomatology.

METHOD

For this purpose, 101 individuals were enrolled to take part in the study (51 CM, 50 healthy controls). The Controlled Oral Word Association Test (Benton, de Hamsher, & Sivan, 1983) and the Hospital Anxiety and Depression Scale (Zigmond & Snaith, 1983) were administered.

RESULTS

Results showed significantly lower scores for the CM group in verbal fluency compared to the control group (p < .005). After performing an analysis of covariance to eliminate depression and anxiety symptomatology tendencies, it was observed that verbal fluency could not be predicted by this variable (p > .005).

CONCLUSIONS

From the results of this study, it can be concluded that people suffering from CM exhibit less verbal fluency than healthy control individuals and that this difference is not caused by depression or anxiety.

Geometric morphometrics reveal altered corpus callosum shape in pyridoxine-dependent epilepsy

OBJECTIVE

To evaluate the features and maturational changes in overall callosal shape in patients with pyridoxine-dependent epilepsy (PDE).

METHODS

Measurements were conducted through landmark-based geometric morphometrics applied on cerebral MRIs of patients with PDE and age-matched control subjects. The outline of the corpus callosum was manually traced in the midsagittal plane. Three hundred semi-landmarks along the outline were collected and underwent statistical generalized Procrustes analysis. An allometric regression was applied to evaluate the callosal shape due to growth over time.

RESULTS

Thirty-eight patients with PDE and 38 age- and sex-matched control subjects were included. Mean age at the time of the MRI in the patient group was 9.3 years (median 6.3 years, range 0.01-48 years). Significant differences (p < 0.01) in the mean callosal shape between patients and controls were found. The allometric regression model revealed significant shape variations (p < 0.01) between the 2 study groups across the developmental course after controlling for the effect of callosal size on shape. This latter effect turned out to be significant as well (p < 0.001).

CONCLUSIONS

Patients with PDE show an altered callosal shape and variations in callosal ontogeny, which are likely secondary to the underlying genetic defect with abnormal function of antiquitin, the product of the ALDH7A1 gene.

Chiari 1 Malformation in a Child with Febrile Seizures, Parasomnias, and Sleep Apnea Syndrome

Introduction

The type I is the most common Chiari malformation in children. In this condition, the lower part of the cerebellum, but not the brain stem, extends into the foramen magnum at the base of the skull leading to disturbances in cerebrospinal fluid circulation and to direct compression of nervous tissue.

Case report

We describe a 4-year-old Caucasian female child with febrile seizures, headache, parasomnias, and a delay of speech. The child underwent a magnetic resonance imaging to investigate these neurological signs, disclosing a Chiari malformation type 1. The polysomnography showed a mild-moderate sleep-disordered breathing, increased number of central sleep apneas, and generalized spike waves at sleep onset.

Conclusions

Seizures have been seldom described in CM1 patients. The main reasons for performing MRI in this case were frequent seizures, a delay of speech, and headache, leading to an unexpected diagnosis of CM1. Polysomnography detected a discrete SDB.

Chiari type 1 malformation, corpus callosum agenesis and patent craniopharyngeal canal in an 11-year-old boy

We describe the neuroimaging findings of an 11-year-old boy who presented with mild occipital headache and precocious puberty. This child was found to have a combination of various midline anomalies including a Chiari type 1 malformation, corpus callosum agenesis and patent craniopharyngeal canal with adjacent intracranial dermoid cyst.

Clinical significance of changes in pB-C2 distance in patients with Chiari Type I malformations following posterior fossa decompression: a single-institution experience

OBJECT The coexistence of Chiari malformation Type I (CM-I) and ventral brainstem compression (VBSC) has been well documented, but the change in VBSC after posterior fossa decompression (PFD) has undergone little investigation. In this study the authors evaluated VBSC in patients with CM-I and determined the change in VBSC after PFD, correlating changes in VBSC with clinical status and the need for further intervention. METHODS Patients who underwent PFD for CM-I by the senior author from November 2005 to January 2013 with complete radiological records were included in the analysis. The following data were obtained: objective measure of VBSC (pB-C2 distance); relationship of odontoid to Chamberlain's, McGregor's, McRae's, and Wackenheim's lines; clival length; foramen magnum diameter; and basal angle. Statistical analyses were performed using paired t-tests and a mixed-effects ANOVA model. RESULTS Thirty-one patients were included in the analysis. The mean age of the cohort was 10.0 years. There was a small but statistically significant increase in pB-C2 postoperatively (0.5 mm, p < 0.0001, mixed-effects ANOVA). Eleven patients had postoperative pB-C2 values greater than 9 mm. The mean distance from the odontoid tip to Wackenheim's line did not change after PFD, signifying postoperative occipitocervical stability. No patients underwent transoral odontoidectomy or occipitocervical fusion. No patients experienced clinical deterioration after PFD. CONCLUSIONS The increase in pB-C2 in patients undergoing PFD may occur as a result of releasing the posterior vector on the ventral dura, allowing it to relax posteriorly. This increase appears to be well-tolerated, and a postoperative pB-C2 measurement of more than 9 mm in light of stable craniocervical metrics and a nonworsened clinical examination does not warrant further intervention.

Molecular Diversity and Associated Phenotypic Spectrum of Germline CBL Mutations

Noonan syndrome (NS) is a relatively common developmental disorder with a pleomorphic phenotype. Mutations causing NS alter genes encoding proteins involved in the RAS-MAPK pathway. We and others identified Casitas B-lineage lymphoma proto-oncogene (CBL), which encodes an E3-ubiquitin ligase acting as a tumor suppressor in myeloid malignancies, as a disease gene underlying a condition clinically related to NS. Here, we further explored the spectrum of germline CBL mutations and their associated phenotype. CBL mutation scanning performed on 349 affected subjects with features overlapping NS and no mutation in NS genes allowed the identification of five different variants with pathological significance. Among them, two splice-site changes, one in-frame deletion, and one missense mutation affected the RING domain and/or the adjacent linker region, overlapping cancer-associated defects. A novel nonsense mutation generating a v-Cbl-like protein able to enhance signal flow through RAS was also identified. Genotype-phenotype correlation analysis performed on available records indicated that germline CBL mutations cause a variable phenotype characterized by a relatively high frequency of neurological features, predisposition to juvenile myelomonocytic leukemia, and low prevalence of cardiac defects, reduced growth, and cryptorchidism. Finally, we excluded a major contribution of two additional members of the CBL family, CBLB and CBLC, to NS and related disorders.

[Idiopathic intracranial hypertension in a patient with Chiari I malformation]

CASE REPORT

The case involves a 22-year-old woman who presented with headache and decreased vision. She showed asymmetric papilledema, and a 6-mm tonsillar descent was observed in the image tests. She was diagnosed with secondary intracranial hypertension coinciding with the symptoms of a Chiari malformation (MC).

DISCUSSION

Chiari malformation type I is the most common in this group of malformations, and is characterized by a greater than 5mm descent of the tonsils, being able to cause increased intracranial pressure and papilledema by blocking the flow of the cerebrospinal fluid. In this case, the MC was not the responsible for triggering the secondary intracranial hypertension, but a mere coincidence of both processes.

Unique cerebrovascular anomalies in Noonan syndrome with RAF1 mutation

Noonan syndrome is a common autosomal dominant neurodevelopmental disorder caused by gain-of-function germline mutations affecting components of the Ras-MAPK pathway. The authors present the case of a 6-year-old male with Noonan syndrome, Chiari malformation type I, shunted benign external hydrocephalus in infancy, and unique cerebrovascular changes. A de novo heterozygous change in the RAF1 gene was identified. The patient underwent brain magnetic resonance imaging, computed tomography angiography, and magnetic resonance angiography to further clarify the nature of his abnormal brain vasculature. The authors compared his findings to the few cases of Noonan syndrome reported with cerebrovascular pathology.

Chiari type 1 malformation and periventricular nodular heterotopia in a 6-year-old boy with congenital hemiplegia: a case report

A 6-year-old boy presented with weakness of the right upper and lower limbs, noted since infancy. Magnetic resonance imaging of the brain revealed periventricular nodular heterotopia lining the trigone and occipital horns of bilateral lateral ventricles along with herniation of the cerebellar tonsils below the foramen magnum suggestive of Chiari type 1 malformation. The association of periventricular nodular heterotopia with Chiari type 1 malformation has not been described earlier in children.

Expanding the SHOC2 mutation associated phenotype of Noonan syndrome with loose anagen hair: structural brain anomalies and myelofibrosis

Noonan syndrome is a heterogenous rasopathy typically presenting with short stature, characteristic facial features, cardiac abnormalities including pulmonic valve stenosis, ASD and hypertrophic cardiomyopathy (HCM), cryptorchidism, ectodermal abnormalities, and learning differences. The phenotype is variable, and limited genotype phenotype correlation exists with SOS1 mutations often associated with normal cognition and stature, RAF1 mutations entailing a high HCM risk, and certain PTPN11 mutations predisposing to juvenile myelomonocytic leukemia. The recently identified SHOC2 mutation (p.Ser2Gly) causes Noonan syndrome with loose anagen hair. We report five patients with this mutation. All had skin hyperpigmentation, sparse light colored hair, increased fine wrinkles, ligamentous laxity, developmental delay, and 4/4 had a structural cardiac anomaly. Hypotonia and macrocephaly occurred in 4/5 (80%); 3/5 (60%) had polyhydramnios, increased birth weight or required use of a feeding tube. Distinctive brain abnormalities included relative megalencephaly and enlarged subarachnoid spaces suggestive of benign external hydrocephalus, and a relatively small posterior fossa as indicated by a vertical tentorium. The combination of a large brain with a small posterior fossa likely resulted in the high rate of cerebellar tonsillar ectopia (3/4; 75%). Periventricular nodular heterotopia was seen in one patient with a thick and dysplastic corpus callosum. We report on the first hematologic neoplasm, myelofibrosis, in a 2-year-old patient with SHOC2 mutation. Myelofibrosis is exceedingly rare in children and young adults. The absence of a somatic JAK2 mutation, seen in the majority of patients with myelofibrosis, is noteworthy as it suggests that germline or somatic SHOC2 mutations are causally involved in myelofibrosis.

Association between Noonan syndrome and Chiari I malformation: a case-based update

BACKGROUND

Chiari I malformations (CM-I) have been associated with a variety of developmental abnormalities in the literature. A few cases of CM-I in patients with Noonan syndrome (NS) have been reported; however, opinion remains divided as to whether the observed association is coincidental.

DISCUSSION

Six previous cases of CM-I in patients with NS have been described in the literature. Many of these had other neurological abnormalities; however, neurological problems are not a prominent part of earlier descriptions of NS. A statistically significant association between NS and CM-I is difficult to obtain at present due to availability and logistical issues with scanning many asymptomatic patients. Although we believe a link exists between CM-I and NS, there is little understanding on how NS may cause CM-I. The most logical cause would be posterior fossa abnormality; however, the most common genetic mutation in NS tends to cause frontal and facial abnormalities, and the posterior fossa tends to be relatively spared. Other genetic mutations may also affect the posterior cranium and thus create the appropriate conditions for a CM-I to develop.

ILLUSTRATIVE CASE

We report a case of CM-I in a 9-year-old patient with Noonan syndrome, severe scoliosis and syringomyelia.

CONCLUSION

We believe that CM-I is a part of Noonan syndrome; however, statistical validation of this opinion is necessary.

Chiari type 1 anomaly in pseudohypoparathyroidism type Ia: pathogenetic hypothesis

AIM

This study aims to report a patient with Chiari type 1 malformation (CM1) occurring in the context of pseudohypoparathyroidism type 1a (PHP-Ia) that we believe represents the first instance of this association in the current literature.

CASE REPORT

The authors describe the case of a 6-year-old girl diagnosed with PHP-Ia who presented an associated tonsillar descent. During the follow-up, the skull vault and the occipital squama became extremely thickened at the same time as the tonsillar herniation showed a marked regression.

DISCUSSION

Chronic tonsillar descent has been reported in diverse genetic and metabolic diseases of bone. A constant finding in PH-Ia consists of changes that mainly involve the bones of the patients' hands and feet. Cerebral anomalies have also been documented in PHP-Ia, especially cerebral calcifications, but in contrast involvement of the skull bones has seldom been described in this condition. The authors briefly discuss the probable role played by the observed skull changes in the origin and subsequent regression of the tonsillar descent in this child.

CONCLUSIONS

We suggest that CM1 may develop in patients with PHP-Ia and that it should be actively sought, especially in individuals diagnosed with PHP-Ia presenting with neurological manifestations. Probably, the seeming rarity of chronic tonsillar descent in PHP-Ia is due to the fact that many patients with this condition are rarely investigated with magnetic resonance.