The significance of hindbrain herniation reversal following prenatal repair of neural tube defects.

OBJECTIVE: The aim of this study was to determine whether reversal of hindbrain herniation (HBH) on MRI following prenatal repair of neural tube defects (NTDs) is associated with reduced rates of ventriculoperitoneal (VP) shunt placement or endoscopic third ventriculostomy (ETV) within the 1st year of life. METHODS: This is a secondary analysis of prospectively collected data from all patients who had prenatal open repair of a fetal NTD at a single tertiary care center between 2012 and 2020. Patients were offered surgery according to inclusion criteria from the Management of Myelomeningocele Study (MOMS). Patients were excluded if they were lost to follow-up, did not undergo postnatal MRI, or underwent postnatal MRI without a report assessing hindbrain status. Patients with HBH reversal were compared with those without HBH reversal. The primary outcome assessed was surgical CSF diversion (i.e., VP shunt or ETV) within the first 12 months of life. Secondary outcomes included CSF leakage, repair dehiscence, CSF diversion prior to discharge from the neonatal intensive care unit (NICU), and composite neonatal morbidity. Demographic, prenatal sonographic, and operative characteristics as well as outcomes were assessed using standard univariate statistical methods. Multivariate logistic regression models were fit to assess for independent contributions to the primary and secondary outcomes. RESULTS: Following exclusions, 78 patients were available for analysis. Of these patients, 38 (48.7%) had HBH reversal and 40 (51.3%) had persistent HBH on postnatal MRI. Baseline demographic and preoperative ultrasound characteristics were similar between groups. The primary outcome of CSF diversion within the 1st year of life was similar between the two groups (42.1% vs 57.5%, p = 0.17). All secondary outcomes were also similar between groups. Patients who had occurrence of the primary outcome had greater presurgical lateral ventricle width than those who did not (16.1 vs 12.1 mm, p = 0.02) when HBH was reversed, but not when HBH was persistent (12.5 vs 10.7 mm, p = 0.49). In multivariate analysis, presurgical lateral ventricle width was associated with increased rates of CSF diversion before 12 months of life (adjusted OR 1.18, 95% CI 1.03-1.35) and CSF diversion prior to NICU discharge (adjusted OR 1.18, 95% CI 1.02-1.37). CONCLUSIONS: HBH reversal was not associated with decreased rates of CSF diversion in this cohort. Predictive accuracy of the anticipated benefits of prenatal NTD repair may not be augmented by the observation of HBH reversal on MRI.

Surgical management of Chiari malformation type 1 associated to MCAP syndrome and study of cerebellar and adjacent tissues for PIK3CA mosaicism.

BACKGROUND: Subjects with Megalencephaly-Capillary Malformation-Polymicrogyria syndrome (MCAP) can present with a Chiari Malformation Type 1 and resulting alterations in cerebrospinal fluid (CSF) dynamics, which may require surgical treatment. The aim of this paper is to describe the features of children with MCAP who underwent surgical decompression for CM1, and to explore the PIK3CA variant allele frequency (VAF) identified in cerebellar parenchyma and other adjacent structures. METHODS: This study reviewed two cases of children with CM1 and MCAP who underwent surgical decompression treatment. These two cases were part of a national cohort of 12 MCAP patients who had CM1, due to their surgical eligibility. Tissue samples were obtained from the cerebellar tonsils and adjacent anatomical structures during the surgical procedures. Samples were then subsequently analyzed for PIK3CA postzygotic variants. RESULTS: In both cases, alterations in CSF dynamics, specifically hydrocephalus and syringomyelia, were observed and required surgical treatment. PIK3CA targeted sequencing determined the VAF of the postzygotic variant in both cerebellar and adjacent bone/connective tissues. DISCUSSION: The recognition of a CM1 comorbidity in MCAP patients is of paramount importance when considering personalized treatment options, especially because these patients are at higher risk of developing complications during surgical decompression surgery. The variable PIK3CA VAF identified in the different analyzed tissues might help explain the heterogeneous nature and severity of anomalies observed in the volume of the posterior fossa structures in MCAP patients and associated CSF and venous disorders.

Ventral Tonsillar Herniation Predicts Headaches in Adults With Chiari Malformation.

BACKGROUND: Radiographic characterization of Chiari malformation (CM) has historically focused on caudal tonsillar herniation (CH) below the foramen magnum. Previously, we published evidence linking ventral tonsillar herniation (VH) and medullary symptoms in very young children. We sought to extend that investigation by studying the radiographic and clinical significance of VH in adults diagnosed with CM. METHODS: We retrospectively reviewed adults with cerebellar ectopia who underwent posterior fossa decompression with or without duraplasty (PFD/D) at our institution. VH was defined as tonsils crossing a line bisecting the caudal medulla at the level of the foramen magnum on axial MRI. Degree of VH was measured as distance between this bisecting line and the ventral tip of the herniated tonsil. Dorsal brainstem compression was qualitatively determined by assessing for obliteration of CSF space between the dorsal brainstem and the tonsils. RESULTS: Out of 89 cases reviewed, 54 had some degree of VH. Compared with those without VH, the VH group was significantly older in age and more likely to also present with dorsal brainstem compression and headaches. No correlation was observed between degrees of CH and VH in the VH group. The degree of VH significantly decreased 3 months after PFD/D. CONCLUSIONS: VH is relatively common in CM patients and might be an important independent radiographic metric to evaluate and consider as part of the decision-making process, especially in those presenting with Chiari-like symptomatology referable to the medulla but who do not meet the traditional criteria of cerebellar ectopia greater than 5 mm.

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.

Ectopia amigdalina cerebelosa borderline en un niño con cefalea. Caso clínico / Borderline cerebellar tonsillar ectopia in a child with headache. Case report

La cefalea es un síntoma que conlleva un malestar signifcativo y deterioro funcional en quienes lo sufren con frecuencia, tanto en la infancia como en la edad adulta. Algunas afecciones se asocian con una mayor frecuencia de cefaleas. La ectopia amigdalina cerebelosa borderline, defnida como la protrusión de las amígdalas cerebelosas por foramen magnum), es una de esas afecciones. Aunque no está claro el signifcado clínico de esta entidad como causa de cefalea, hay estudios que informaron su asociación en el 16% de los pacientes. Se presenta el caso de un paciente de 9 años que acudió a la consulta por padecer una cefalea frontal de 5 años de evolución. Se diagnosticó ectopia amigdalina cerebelosa borderline mediante una resonancia magnética. Se describe este caso dado lo atípico de la presentación de esta entidad en la infancia.

Frequent headache is a symptom that leads to signifcant distress and functional impairment, both in childhood and in adulthood. Some medical conditions are associated with a higher frequency of headaches. Borderline cerebellar tonsillar ectopia which may be defned as the downward extension of cerebellar tonsils of < 5 mm below the foramen magnum is among these conditions. Although questions persist about the clinical signifcance of this rare entity on headache, there are studies reporting severe headache syndrome in 16% of these patients. We report a 9-year old male patient, who presented to our clinic with a frontal headache of 5 years' duration, and was found to have borderline cerebellar tonsillar ectopia on magnetic resonance imaging. To the best of our knowledge, there has not been a reported case of this coexistence at this early stage of life. We would like to contribute to the literature, owing to the very rare and atypical presentation of this entity in the early childhood period.

Ectopia amigdalina cerebelosa borderline en un niño con cefalea. Caso clínico / Borderline cerebellar tonsillar ectopia in a child with headache. Case report

La cefalea es un síntoma que conlleva un malestar signifcativo y deterioro funcional en quienes lo sufren con frecuencia, tanto en la infancia como en la edad adulta. Algunas afecciones se asocian con una mayor frecuencia de cefaleas. La ectopia amigdalina cerebelosa borderline, defnida como la protrusión de las amígdalas cerebelosas por foramen magnum), es una de esas afecciones. Aunque no está claro el signifcado clínico de esta entidad como causa de cefalea, hay estudios que informaron su asociación en el 16% de los pacientes. Se presenta el caso de un paciente de 9 años que acudió a la consulta por padecer una cefalea frontal de 5 años de evolución. Se diagnosticó ectopia amigdalina cerebelosa borderline mediante una resonancia magnética. Se describe este caso dado lo atípico de la presentación de esta entidad en la infancia.(AU)

Frequent headache is a symptom that leads to signifcant distress and functional impairment, both in childhood and in adulthood. Some medical conditions are associated with a higher frequency of headaches. Borderline cerebellar tonsillar ectopia which may be defned as the downward extension of cerebellar tonsils of < 5 mm below the foramen magnum is among these conditions. Although questions persist about the clinical signifcance of this rare entity on headache, there are studies reporting severe headache syndrome in 16% of these patients. We report a 9-year old male patient, who presented to our clinic with a frontal headache of 5 years duration, and was found to have borderline cerebellar tonsillar ectopia on magnetic resonance imaging. To the best of our knowledge, there has not been a reported case of this coexistence at this early stage of life. We would like to contribute to the literature, owing to the very rare and atypical presentation of this entity in the early childhood period.(AU)