Midbrain-hindbrain involvement in septo-optic dysplasia

Morbidities and comorbidities associated with optic nerve hypoplasia and septo-optic-pituitary dysplasia

AIM

To quantify optic nerve hypoplasia (ONH) and septo-optic-pituitary dysplasia (SOD) morbidities and comorbidities.

METHOD

A retrospective population-based study with a case-control design was undertaken using administrative health data from Manitoba, Canada. Cases were 124 patients with ONH or SOD (70 males, 54 females; age range 6 months-36 years 8 months [mean 13 years, SD 7 years 2 months]) diagnosed from 1990 to 2019, matched to 620 unrelated population-based controls (350 males, 270 females; age range 0-36 years 8 months [mean 12 years 5 months, SD 7 years 2 months]) on birth year, sex, and area of residence. Additionally, 76 cases with ONH or SOD (46 males, 30 females; age range 2 years 5 months-36 years 8 months [mean 13 years 11 months, SD 7 years 3 months]) were matched one-to-one with sibling controls (40 males, 36 females; age range 7 months-33 years 1 month [mean 11 years 8 months, SD 7 years 3 months]). We used χ2 or Fisher's exact tests to test for differences in prevalence in morbidities and comorbidities between cases and controls; odds ratios (ORs) with 95% confidence intervals (CIs) were estimated. Cox proportional hazards models were used to test for differences in subgroups of cases; hazard ratios and 95% CIs were estimated.

RESULTS

Visual impairment and visual impairment with hypopituitarism were core morbidities associated with ONH and SOD cases respectively compared to unrelated controls (OR = 58.6, 95% CI = 22.5-152.5; OR = 243.4, 95% CI = 32.9-1799.0 respectively). Developmental delay or intellectual disability (OR = 6.9, 95% CI = 3.3-14.4), autism spectrum disorder (OR = 4.0, 95% CI = 2.0-8.3), epilepsy (OR = 14.9, 95% CI = 6.1-36.5), cerebral palsy (OR = 40.9, 95% CI = 14.0-119.6), and mood or anxiety disorders (OR = 1.7, 95% CI = 1.0-2.8) were the comorbidities more common among cases with ONH and SOD. Cases matched to siblings showed similar results except for mood and anxiety disorders.

INTERPRETATION

Visual impairment and visual impairment with hypopituitarism are the main morbidities in patients with ONH and SOD respectively, while developmental delay or intellectual disability, autism spectrum disorder, epilepsy, cerebral palsy, and mood or anxiety disorders are important comorbidities.

Septo-optic dysplasia plus: A case report for reviewing and recognizing this condition

Septo-optic dysplasia is a congenital neurological condition with multifactorial etiology, characterized by septum pellucidum agenesis and/or corpus callosum dysgenesis, hypoplasia of the chiasm or optic nerves, and hormonal dysfunction with pituitary or hypothalamic alterations. Diagnosis requires two of these criteria and magnetic resonance is the imaging test of choice. Most cases present with abnormalities of cortical development in the form known as septo-optic dysplasia plus. While seizures and neurodevelopmental disorders are the dominant neurological manifestations, this entity is highly heterogeneous and has multiple clinical and radiological findings to consider. We present the case of a 35-year-old man with a history of cranioencephalic trauma in childhood and remission for refractory focal epilepsy associated with cognitive deficit. During the initial examination, the simple cranial tomography showed septum pellucidum agenesis and corpus callosum dysgenesis. Brain magnetic resonance imaging revealed agenesis of the septum pellucidum, irregularity and anomalous thickening of the cerebral cortex in frontal lobes and perisylvian region, heterotopic gray matter in frontal lobes and left fronto-insular region, mild supratentorial ventriculomegaly, atypical appearance of the corpus callosum rostrum, and hypoplasia of the chiasm and optic nerves. Although agenesis of the septum pellucidum was the key finding in this case, it is not present in all patients. The relevance of magnetic resonance imaging for the detailed evaluation of other involved structures, highlighting optic nerve hypoplasia, is fundamental in the radiologist’s diagnostic workup and this entity recognition.

Neuroimaging Features in Children with Optic Nerve Hypoplasia and Septo-Optic-Pituitary Dysplasia

BACKGROUND

Optic nerve hypoplasia (ONH) and septo-optic-pituitary dysplasia (SOD) are common causes of congenital visual impairment. Our primary aim was to investigate the prevalence of abnormal neuroimaging features in patients with these disorders in Manitoba, Canada, and compare them with published reports.

METHODS

A retrospective neuroimaging review was performed in patients resident in Manitoba with ONH/SOD.

RESULTS

There were 128 patients (M = 70) with ONH/SOD who had neuroimaging. Their mean age (SD) at the end of the study was 13.2 (7.5) years. Males were significantly more likely to have bilateral ONH and a small optic chiasm size, while females were more likely to have a left ONH and a small left optic chiasm size on neuroimaging (p = 0.049). ONH and small optic chiasm size were seen in most patients on neuroimaging. Absent septum pellucidum was noted in 40%, small pituitary gland size in 28%, neuronal migration disorders (NMD) in 20% (>1 type and bilateral in 13 cases), corpus callosum abnormalities were present in 9%, while olfactory bulbs-tracts and olfactory sulci were absent in 8.6% of cases. Unilateral ONH was not significantly associated with other structural brain abnormalities, while NMD were significantly associated with other midline brain abnormalities including a symmetrically small optic chiasm size.

CONCLUSION

The prevalence of structural neuroimaging abnormalities in our cohort with ONH/SOD was generally in the same range reported in other studies with corpus callosum abnormalities being relatively less common in our study. Bilateral NMD were relatively common among patients with NMD. The association between sex and ONH laterality requires further study.

Neurodevelopmental impairments in children with septo-optic dysplasia spectrum conditions: a systematic review

BACKGROUND

Septo-optic dysplasia (SOD) is a rare condition diagnosed in children with two or more of the following: hypopituitarism, midline brain abnormalities, and optic nerve hypoplasia. Children with SOD experience varied visual impairment and endocrine dysfunction. Autistic-like behaviours have been reported; however, their nature and prevalence remain to be fully understood. The present systematic review aimed to explore the type and prevalence of neurodevelopmental impairments in children with SOD spectrum conditions.

METHODS

The search was conducted in PubMed, EMBASE, and PsycInfo. Hand-searching reference lists of included studies was conducted. All peer-reviewed, observational studies assessing behavioural and cognitive impairments or autism spectrum disorder (ASD) symptoms in children (< 18 years) with SOD, optic nerve hypoplasia, and SOD-plus were included. Studies were excluded if they did not report standardised measures of neurodevelopmental impairments or ASD outcomes.

RESULTS

From 2132 screened articles, 20 articles reporting data from a total of 479 children were included in prevalence estimates. Of 14 studies assessing cognitive-developmental outcomes, 175 of 336 (52%) children presented with intellectual disability or developmental delay. A diagnosis of ASD or clinical level of symptoms was observed in 65 of 187 (35%) children across five studies. Only five studies assessed for dysfunction across behavioural, emotional, or social domains and reported impairments in 88 of 184 (48%) of children assessed.

LIMITATIONS

Importantly, high heterogeneity among the samples in relation to their neuroanatomical, endocrine, and optic nerve involvement meant that it was not possible to statistically assess the relative contribution of these confounding factors to the specific neurodevelopmental phenotype. This was further limited by the variation in study designs and behavioural assessments used across the included studies, which may have increased the risk of information bias.

CONCLUSIONS

This systematic review suggests that the prevalence of neurodevelopmental impairments in children within the SOD spectrum may be high. Clinicians should therefore consider including formal assessments of ASD symptoms and neurodevelopmental impairments alongside routine care. There is, additionally, a need for further research to define and validate a standardised battery of tools that accurately identify neurodevelopmental impairments in SOD spectrum conditions, and for research to identify the likely causal mechanisms.

Delineating septo-optic dysplasia

BACKGROUND

Septo-optic dysplasia (SOD), once a variable triad of septum pellucidum defects (SPDs), optic nerve hypoplasia (ONH), and hypopituitarism, has had multiple findings added, with uncertain causes, definitions, and limits.

METHOD

Literature review.

RESULTS

SOD is a complex vascular sequence with confounders.

CONCLUSIONS

Proximal anterior cerebral artery trunk disruptions cause overlapping primary effects, giving ONH alone most often, and isolated SPD less. ONH disruptions can spread to pituitary, SPD disruptions to the cerebral cortex, causing schizencephaly and related anomalies. Pituitary defects are rare without ONH, and cortical findings are rare without SPD. Extensions are unidirectional, so isolated pituitary or cortical defects are separate from SOD. Micro- an- ophthalmia, a suggested ONH variant, is not part of SOD. Disruption by-products can affect development, causing cognitive and endocrine issues, and structural anomalies such as corpus callosum thinning, ventriculomegaly, and hippocampal and olfactory findings. Limbic extensions may also contribute to the same structural defects as by-products. Midline CNS developmental anomalies can act as disruptive foci, most likely through vascular variants, but have separate pathogenesis. Relative frequencies of specific pituitary hormone defects change as SOD rates increase. Increasing relative rates of midline CNS developmental defects and cortical anomalies are consistent with rising levels of exogenous exposures sensitizing to midline predispositions.

Hypothesis: By-products of vascular disruption carried in the CSF affect prenatal brain development

Prenatal CNS disruptions can be associated with physically separate findings. Examples include cognitive issues in septo-optic dysplasia and sporadic and WNT1-related unilateral cerebellar hypoplasia, and physical findings such as thinning of the corpus callosum, ventriculomegaly, hippocampal abnormalities, olfactory tract and bulb hypoplasia, and distant cortical dysplasias with schizencephaly. Similar effects to toxicities with intraventricular hemorrhage in prematurity could occur earlier in development. CSF transportation of disruption by-products would provide access to vulnerable areas through inflammatory effects on blood-brain barrier permeability. Outcomes are influenced by location and volume of byproducts in the CSF, timing, transport, and inflammatory responses. A particular association of vermis disruption with cognitive issues may be related to CSF flow distortions that avoid toxin dilutions in the third ventricle. Symmetrical contralateral cortical dysplasia with schizencephaly may reflect immunovascular field-related vulnerabilities seen in situations such as vitiligo.

Advances in differential diagnosis and management of growth hormone deficiency in children

Growth hormone (GH) deficiency (GHD) in children is defined as impaired production of GH by the pituitary gland that results in growth failure. This disease might be congenital or acquired, and occurs in isolation or in the setting of multiple pituitary hormone deficiency. Isolated GHD has an estimated prevalence of 1 patient per 4000-10,000 live births and can be due to multiple causes, some of which are yet to be determined. Establishing the correct diagnosis remains key in children with short stature, as initiating treatment with recombinant human GH can help them attain their genetically determined adult height. During the past two decades, our understanding of the benefits of continuing GH therapy throughout the transition period from childhood to adulthood has increased. Improvements in transitional care will help alleviate the consequent physical and psychological problems that can arise from adult GHD, although the consequences of a lack of hormone replacement are less severe in adults than in children. In this Review, we discuss the differential diagnosis in children with GHD, including details of clinical presentation, neuroimaging and genetic testing. Furthermore, we highlight advances and issues in the management of GHD, including details of transitional care.

Important Tools for Use by Pediatric Endocrinologists in the Assessment of Short Stature

Assessment and management of children with growth failure has improved greatly over recent years. However, there remains a strong potential for further improvements by using novel digital techniques. A panel of experts discussed developments in digitalization of a number of important tools used by pediatric endocrinologists at the third 360° European Meeting on Growth and Endocrine Disorders, funded by Merck KGaA, Germany, and this review is based on those discussions. It was reported that electronic monitoring and new algorithms have been devised that are providing more sensitive referral for short stature. In addition, computer programs have improved ways in which diagnoses are coded for use by various groups including healthcare providers and government health systems. Innovative cranial imaging techniques have been devised that are considered safer than using gadolinium contrast agents and are also more sensitive and accurate. Deep-learning neural networks are changing the way that bone age and bone health are assessed, which are more objective than standard methodologies. Models for prediction of growth response to growth hormone (GH) treatment are being improved by applying novel artificial intelligence methods that can identify non-linear and linear factors that relate to response, providing more accurate predictions. Determination and interpretation of insulin-like growth factor-1 (IGF-1) levels are becoming more standardized and consistent, for evaluation across different patient groups, and computer-learning models indicate that baseline IGF-1 standard deviation score is among the most important indicators of GH therapy response. While physicians involved in child growth and treatment of disorders resulting in growth failure need to be aware of, and keep abreast of, these latest developments, treatment decisions and management should continue to be based on clinical decisions. New digital technologies and advancements in the field should be aimed at improving clinical decisions, making greater standardization of assessment and facilitating patient-centered approaches.

Neuropathology of Septo-optic Dysplasia: A Report of 4 Autopsy Cases

Septo-optic dysplasia (SOD) is defined by the presence of 2 or more features in a diagnostic triad: (1) optic nerve hypoplasia, (2) pituitary dysfunction, and (3) midline forebrain anomalies. SOD arises due to diverse pathogenetic mechanisms including acquired and genetic factors, and it shows considerable clinical and phenotypic variability. Our knowledge of SOD is incomplete in part because of a paucity of published neuropathology data, so we reviewed the autopsy neuropathology of 4 SOD patients. All patients met SOD criteria according to the triad. Additional neuropathologic findings included malformations involving non-forebrain structures and possible secondary phenomena. Autopsies demonstrate that SOD patients often have additional neuropathologic findings beyond the triad and we feel that use of the term SOD-complex appropriately underscores this diversity and its likely clinical impact. This study suggests that autopsies enhance our understanding of SOD and may be an asset in performing needed clinical and phenotypic correlation studies.

Septo-optic dysplasia

Septo-optic dysplasia (SOD) or de Morsier's syndrome is a rare congenital disorder characterized by a classic triad of: (a) optic nerve hypoplasia, (b) agenesis of septum pellucidum and corpus callosum, and (c) hypoplasia of the hypothalamic-pituitary axis. This chapter will outline the key information regarding the etiology and epidemiology of this syndrome with a focus on its comprehensive management. Particular attention will be paid to the diagnostic stage and the most relevant differential diagnosis, before moving to the complexities of its treatment. In fact, although SOD is not curable, many aspects of this syndrome can be improved through a tailored multidisciplinary approach consisting in hormonal replacement, corrective ophthalmological surgery, management of epileptic seizures, and active neuropsychological support.

Review of the MRI brain findings of septo-optic dysplasia

AIM

To report the magnetic resonance imaging (MRI) findings from a retrospective case analysis of children with septo-optic dysplasia (SOD), a rare congenital disorder characterised by any combination of midline brain defects, optic nerve hypoplasia (ONH), and hypothalamic-pituitary dysfunction.

MATERIALS AND METHODS

SOD was defined radiologically as complete or partial septum pellucidum (SP) absence with hypoplasia of at least one of the optic nerves and/or chiasm. Local MRI databases were searched for SOD cases in children over an 18-year period, and studies reviewed by two consultant paediatric neuroradiologists. The extent of structural SP, optic nerve, chiasm, and hypothalamic-pituitary involvement was recorded, along with coexisting brain abnormalities.

RESULTS

Forty-eight cases of SOD were found; 44/48 (92%) demonstrated complete SP absence whereas 4/48 (8%) had partial absence. Eight of 48 cases (17%) exhibited unilateral ONH. Fifty-one percent of cases, where the pituitary was identified on MRI, demonstrated a structural pituitary abnormality, which included an ectopic posterior bright spot in 6%. The olfactory nerves were hypoplastic in 5/48 cases (10%). Twenty-seven of the 48 cases (56%) had another brain abnormality, resulting from some form of cortical formation abnormality/schizencephaly in 21/48 (44%).

CONCLUSION

A high rate of associated brain abnormalities was found in the present cohort, including structural pituitary abnormalities in 51% and cortical formation abnormalities/schizencephaly in 44%. This suggests there is not a single cause for SOD, rather SOD is the phenotypic end point from multiple aetiological events. Individual children with SOD may have coexisting intracranial abnormalities, and, hence, high-quality MRI is required in all.

Midbrain-Hindbrain Boundary Morphogenesis: At the Intersection of Wnt and Fgf Signaling

A constriction in the neural tube at the junction of the midbrain and hindbrain is a conserved feature of vertebrate embryos. The constriction is a defining feature of the midbrain-hindbrain boundary (MHB), a signaling center that patterns the adjacent midbrain and rostral hindbrain and forms at the junction of two gene expression domains in the early neural plate: an anterior otx2/wnt1 positive domain and a posterior gbx/fgf8 positive domain. otx2 and gbx genes encode mutually repressive transcription factors that create a lineage restriction boundary at their expression interface. Wnt and Fgf genes form a mutually dependent feedback system that maintains their expression domains on the otx2 or gbx side of the boundary, respectively. Constriction morphogenesis occurs after these conserved gene expression domains are established and while their mutual interactions maintain their expression pattern; consequently, mutant studies in zebrafish have led to the suggestion that constriction morphogenesis should be considered a unique phase of MHB development. We analyzed MHB morphogenesis in fgf8 loss of function zebrafish embryos using a reporter driven by the conserved wnt1 enhancer to visualize anterior boundary cells. We found that fgf8 loss of function results in a re-activation of wnt1 reporter expression posterior to the boundary simultaneous with an inactivation of the wnt1 reporter in the anterior boundary cells, and that these events correlate with relaxation of the boundary constriction. In consideration of other results that correlate the boundary constriction with Wnt and Fgf expression, we propose that the maintenance of an active Wnt-Fgf feedback loop is a key factor in driving the morphogenesis of the MHB constriction.

Neuroimaging Findings in Pediatric Genetic Skeletal Disorders: A Review

Genetic skeletal disorders (GSDs) are a heterogeneous group characterized by an intrinsic abnormality in growth and (re-)modeling of cartilage and bone. A large subgroup of GSDs has additional involvement of other structures/organs beside the skeleton, such as the central nervous system (CNS). CNS abnormalities have an important role in long-term prognosis of children with GSDs and should consequently not be missed. Sensitive and specific identification of CNS lesions while evaluating a child with a GSD requires a detailed knowledge of the possible associated CNS abnormalities. Here, we provide a pattern-recognition approach for neuroimaging findings in GSDs guided by the obvious skeletal manifestations of GSD. In particular, we summarize which CNS findings should be ruled out with each GSD. The diseases (n = 180) are classified based on the skeletal involvement (1. abnormal metaphysis or epiphysis, 2. abnormal size/number of bones, 3. abnormal shape of bones and joints, and 4. abnormal dynamic or structural changes). For each disease, skeletal involvement was defined in accordance with Online Mendelian Inheritance in Man. Morphological CNS involvement has been described based on extensive literature search. Selected examples will be shown based on prevalence of the diseases and significance of the CNS involvement. CNS involvement is common in GSDs. A wide spectrum of morphological abnormalities is associated with GSDs. Early diagnosis of CNS involvement is important in the management of children with GSDs. This pattern-recognition approach aims to assist and guide physicians in the diagnostic work-up of CNS involvement in children with GSDs and their management.

Assessment of fetal optic chiasm: an echoanatomic and reproducibility study

OBJECTIVES

Our aims were: (1) to perform an echoanatomic correlation study, in order to confirm that the structure identified as the optic chiasm (OC) on ultrasound (US) is indeed this anatomical structure; (2) to assess and compare the reproducibility of two- (2D) and three-(3D) dimensional US in measurement of the OC in normal fetuses; and (3) to assess whether the spatial orientation of the OC changes with increasing gestational age.

METHODS

For the echoanatomic study, the OC was studied in a neonatal specimen, deceased at 29 + 4 weeks, by passing a suture around the OC and visualizing the supposed OC structure on US while pulling gently on the suture. The reproducibility study included 39 women with normal pregnancy at 20-33 weeks undergoing routine obstetric US examination. After the routine exam, the OC was visualized on 2D-US, and a 2D image and 3D volume dataset were stored for offline measurement. On the 2D images, the diameters of the OC decussation and the optic tract proximal to the transducer were measured. For the 3D volume dataset, multiplanar image correlation with volume contrast imaging (VCI) was used to measure both these diameters and the chiasmocallosal angle (CCA). Two operators each took two sets of measurements of the diameters on 2D- and 3D-US, and intra- and interoperator variability were analyzed using Cronbach's alpha intraclass correlation coefficient (ICC), while a single operator took two sets of CCA measurements for assessment of intraoperator variability. Differences in CCA with increasing gestational age were also analyzed by regression, and CCA measurements were divided into three groups according to gestational age and their means compared by one-way ANOVA.

RESULTS

During the echoanatomic experiment, when the sling suture was pulled, the hyperechoic X-shaped structure just below the circle of Willis identified on 2D-US as the OC was displaced slightly and was eventually cut by the sling, confirming its identity as the OC. Intraoperator variability was low and almost identical for the two operators and the two imaging modalities for measurement of the decussation (ICC for 2D-US: 0.96 vs 0.95; 3D-US: 0.95 vs 0.96), but less so for the optic tract (ICC for 2D-US: 0.95 vs 0.91; 3D-US: 0.94 vs 0.83). Interoperator variability was low for the decussation (2D-US: 0.92; 3D-US: 0.92), but higher for the optic tracts (ICC for 2D-US: 0.80; 3D-US: 0.78). The difference between the mean measurement of the two operators was not statistically significantly different for the decussation, but it was for the optic tracts (P = 0.04). The CCA increased steadily between 20 and 30 gestational weeks and plateaued thereafter, at least until 33 weeks.

CONCLUSIONS

The hyperechoic structure evident on 2D- and 3D-US, just below the circle of Willis, is indeed the OC. 2D-US is apparently as good as 3D-US for visualization of the OC. However, only measurement of the decussation showed low intra- and interoperator variability, whereas measurement of the optic tract is of questionable variability. As gestation advances between 20 and 30 weeks, the OC becomes more oblique in orientation. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Two-dimensional visualization and measurement of the fetal optic chiasm: improving counseling for antenatal diagnosis of agenesis of the septum pellucidum

OBJECTIVE

To develop an objective method for visualizing and measuring the fetal optic chiasm (OC) using transvaginal two-dimensional (2D) ultrasound in the coronal plane and to report measurements in fetuses with agenesis of the septum pellucidum (SP).

METHODS

This was a prospective cross-sectional study of 115 morphologically normal fetuses in low-risk pregnancies, between 21 and 30 weeks' gestation. The OC was measured in a coronal plane at the level of the third ventricle and was seen as a horizontally aligned dumbbell-shaped structure of moderate echogenicity. In addition, OC measurements from eight fetuses with agenesis of the SP and complete follow-up were compared with the reference range.

RESULTS

OC measurements were obtained in 110/115 normal fetuses and showed that OC increases linearly with gestational age. Our method of measurement demonstrated good intraobserver repeatability and excellent interobserver reproducibility. Among the eight fetuses with agenesis of the SP, five had normal OC measurements and five had normal vision postnatally. Pregnancy continued to term in all cases and the follow-up period varied from 6 months to 7 years.

CONCLUSION

Our study demonstrates that it is possible to visualize and measure the OC directly on a 2D ultrasound coronal plane. In fetuses with agenesis of the SP, the morphology and width of the OC visual pathway could prove a relevant tool for assessing its development. It would also help in the difficult task of providing antenatal counseling when faced with the diagnosis of agenesis of the SP. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.