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.

CNS Malformations in the Newborn

Structural brain anomalies are relatively common and may be detected either prenatally or postnatally. Brain malformations can be characterized based on the developmental processes that have been perturbed, either by environmental, infectious, disruptive or genetic causes. Fetuses and neonates with brain malformations should be thoroughly surveilled for potential other anomalies, and depending on the nature of the brain malformation, may require additional investigations such as genetic testing, ophthalmological examinations, cardiorespiratory monitoring, and screening laboratory studies.

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.

Hypoxia: A teratogen underlying a range of congenital disruptions, dysplasias, and malformations

In this review, we explore evidence that hypoxia in the developing human fetus can lead not only to the more commonly accepted disruptive-type defects, but also patterns of anomalies that suggest that hypoxia can exert a more classic teratogenic effect, using the brain as one example. We review neuropathology in the context of intrauterine hypoxia, particularly as it relates to carbon monoxide poisoning, in utero strokes, and homozygous alpha-thalassemia. In general, the associated brain injuries resemble those seen with other causes of hypoxic-ischemic injury. Fetal strokes during development usually lead to loss of brain tissue in areas that do not follow a typical embryologic pattern, and therefore are considered disruptions. However, there is also evidence that fetal brain ischemia can cause more classically recognized patterns of abnormal embryonic neuronal migration and organization such as polymicrogyria, cortical dysplasia, or dysgenesis, including select types of focal cortical dysplasia. This study summarizes available literature and evidence to raise clinicians' awareness regarding the association between hypoxia and congenital anomalies, including brain malformations.

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.

Management of transient central diabetes insipidus with intravenous desmopressin in a premature infant with gastroschisis and septo-optic dysplasia: A case report

Central diabetes insipidus (CDI) may occur in the setting of intracranial abnormalities that affect the hypothalamus-pituitary system. It occurs rarely in neonates, especially in the premature population, and represents a challenging disease process to treat pharmacologically. Little is known regarding the treatment options in premature infants, including dose and route of administration of intravenous desmopressin (DDAVP). We present a case of a late premature male infant with gastroschisis and septo-optic dysplasia who developed transient CDI. He was treated with intravenous DDAVP but required frequent laboratory monitoring and a multidisciplinary approach, and ultimately his CDI resolved. Although there are minimal guidelines regarding the appropriate formulation and dosage of DDAVP for management of CDI in infants, we initiated the lowest dose available and titrated the medication based on close monitoring of urine output and serum sodium levels in order to successfully treat his transient CDI.

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.

Whole genome sequencing unveils genetic heterogeneity in optic nerve hypoplasia

Optic nerve hypoplasia (ONH) is a congenital malformation with a reduced number of retinal ganglion cell axons in a thin optic nerve. It is a common cause of visual impairment in children and ONH is associated with neurodevelopmental disorders, pituitary hormone deficiencies, and brain malformations. In most cases, the aetiology is unknown, but both environmental factors and genetic causes have been described. This study aimed to identify genetic variants underlying ONH in a well-characterised cohort of individuals with ONH. We performed array comparative genomic hybridization and whole genome sequencing in 29 individuals with ONH. Rare variants were verified by Sanger sequencing and inheritance was assessed in parental samples. We identified 11 rare single nucleotide variants (SNVs) in ten individuals, including a homozygous variant in KIF7 (previously associated with Joubert syndrome), a heterozygous de novo variant in COL4A1 (previously described in an individual with porencephaly), and a homozygous variant in COL4A2. In addition, one individual harboured a heterozygous variant in OPA1 and a heterozygous variant in COL4A1, both were inherited and assessed as variants of unknown clinical significance. Finally, a heterozygous deletion of 341 kb involving exons 7-18 of SOX5 (associated with Lamb-Schaffer syndrome) was identified in one individual. The overall diagnostic yield of pathogenic or likely pathogenic variants in individuals with ONH using whole genome sequencing was 4/29 (14%). Our results show that there is a genetic heterogeneity in ONH and indicate that genetic causes of ONH are not rare. We conclude that genetic testing is valuable in a substantial proportion of the individuals with ONH, especially in cases with non-isolated ONH.

Septo-optic dysplasia with amniotic band syndrome sequence: a case report

INTRODUCTION

De Morsier syndrome, or septo-optic dysplasia, is a rare, heterogeneous, complex condition with a highly variable phenotype. It is characterized by optic nerve hypoplasia, pituitary gland hypoplasia, and midline brain abnormalities, including absence of septum pellucidum and corpus callosum dysgenesis. Diagnosis is made clinically by the presence of any two or more features from the clinical triad.

CASE PRESENTATION

We report a case of a premature African newborn male baby born to nonconsanguineous parents who presented to our institution with agenesis of the septum pellucidum, unilateral optic nerve hypoplasia, and pituitary stalk hypoplasia. However, he had intact central endocrine function. He also presented with limb defects due to constricting amniotic band syndrome. Other dysmorphic features were low-set ears, microcephaly, and bilateral talipes equinovarus. He otherwise had a normal neurological examination result. Over time, he had an adequate weight gain and was managed by a multidisciplinary team.

CONCLUSION

De Morsier syndrome still represents a diagnostic challenge, despite advances in neuroimaging and genetic studies, due to the heterogeneous nature of the disorder. This case adds to existing knowledge on the vascular pathogenesis of septo-optic dysplasia.

Hearing Loss in Pediatric Septo-Optic Dysplasia

OBJECTIVE

To identify and characterize hearing loss (HL) in children with septo-optic dysplasia (SOD).

METHODS

Otologic and audiometric data for patients less than 18 years of age identified as having SOD who were seen in the Children's Healthcare of Atlanta-Scottish Rite Hospital clinic between 2013 and 2017 were collected and reviewed through a HIPAA-compliant medical record search. Relevant literature was also reviewed with the assistance of Medline.

RESULTS

Sixty-four patients with SOD were identified, and 7 of those patients (10.9%) were diagnosed with hearing loss. Type of hearing loss was sensorineural (SNHL) in 5 patients (63%), mixed (MHL) in 1(14%), and conductive (CHL) in 1(14%). Bilateral loss presented in 60% (3/5) of SNHL patients, while the rest demonstrated unilateral loss. Unilateral findings included cochlear nerve deficiency (1) and atresia/microtia (1). Tympanostomy tubes were required in 57% (4/7) of SOD children with hearing loss. Amplification was successfully implemented in 86% (6/7).

CONCLUSIONS

Hearing loss was found in nearly 11% of SOD children, and SNHL was identified as (63%) the predominant form of loss. To our knowledge, this is the first retrospective review of hearing loss in a pediatric SOD cohort and the first to report of cochlear nerve deficiency and atresia/microtia in this population. Based on these findings, early identification of hearing loss with imaging when appropriate and treatment of otitis in this population is recommended.

Epidemiology of septo-optic dysplasia with focus on prevalence and maternal age - A EUROCAT study

Septo-optic nerve dysplasia is a rare congenital anomaly with optic nerve hypoplasia, pituitary hormone deficiencies and midline developmental defects of the brain. The clinical findings are visual impairment, hypopituitarism and developmental delays. The aim of this study was to report prevalence, associated anomalies, maternal age and other epidemiological factors from a large European population based network of congenital anomaly registries (EUROCAT). Data from 29 full member registries for the years 2005-2014 were included, covering 6.4 million births. There were 99 cases with a diagnosis of septo-optic dysplasia. The prevalence of septo-optic dysplasia in Europe was calculated to lie between 1.9 and 2.5 per 100,000 births after adjusting for potential under-reporting in some registries. The prevalence was highest in babies of mothers aged 20-24 years of age and was significantly higher in UK registries compared with other EUROCAT registries (P = 0.021 in the multilevel model) and the additional risk for younger mothers was significantly greater in the UK compared to the rest of Europe (P = 0.027). The majority of septo-optic dysplasia cases were classified as an isolated cerebral anomaly (N = 76, 77%). Forty percent of diagnoses occurred in fetuses with a prenatal diagnosis. The anomaly may not be visible at birth, which is reflected in that 57% of the postnatal diagnoses occurred over 1 month after birth. This is the first population based study to describe the prevalence of septo-optic dysplasia in Europe. Septo-optic dysplasia shares epidemiological patterns with gastroschisis and this strengthens the hypothesis of vascular disruption being an aetiological factor for septo-optic dysplasia.

Septo-optic Dysplasia : Assessment of Associated Findings with Special Attention to the Olfactory Sulci and Tracts

PURPOSE

Septo-optic dysplasia is a congenital disorder consisting of optic nerve hypoplasia and absent septum pellucidum. While associated anomalies have been described, olfactory sulcus and bulb-tract hypoplasia have been scantily reported and was the focus of this study.

METHODS

The picture archival and communications system and radiology information system (PACS-RIS) was searched over 15 years for patients with suspected septo-optic dysplasia (n = 41) and cerebral magnetic resonance imaging (MRI). Included patients had coronal (≤3 mm), axial (≤4 mm), and sagittal (≤4 mm) imaging reviewed by two staff neuroradiologists by consensus. Both olfactory sulcus and bulb-tract hypoplasia were ascribed a grade of 0 (normal) to 3 (complete hypoplasia). Other associated congenital anomalies were recorded, if present. Incidence of anomalies were compared to age-matched and gender-matched control patients.

RESULTS

Out of 41 septo-optic dysplasia patients 33 were included (mean age = 120.7 months), with 8 excluded due to isolated septum pellucidum absence (n = 5), isolated bilateral optic hypoplasia (n = 2), or inadequate imaging (n = 1). An olfactory sulcus was hypoplastic on one or both sides in 14/33 (42.4%). Olfactory bulb hypoplasia was noted in one or both tracts in 15/33 (45.4%). A significant correlation was found between degree of olfactory sulcal and bulb-tract hypoplasia (ρ = 0.528, p = 0.0009). Other anomalies were: anterior falx dysplasia (n = 16, 48.5%), incomplete hippocampal inversion (n = 14, 42.4%), polymicrogyria (n = 11, 33.3%), callosal complete or partial agenesis (n = 10, 30.3%), schizencephaly (n = 8, 24.2%), ectopic posterior pituitary (n = 6, 18.2%), and nodular heterotopia (n = 4, 12.1%). Of the age-matched control patients 10/33 (30.3%) had at least mild anterior falx hypoplasia, and 1 control patient was noted to have unilateral incomplete hippocampal inversion (IHI); none of the age-matched control patients had olfactory sulcus or bulb-tract hypoplasia.

CONCLUSION

Olfactory sulcus and bulb-tract hypoplasia are fairly common in septo-optic dysplasia and can be discordant between sides. Of the other associated anomalies, anterior falx dysplasia seems to be the most common.

Clinical and Radiologic Spectrum of Septo-optic Dysplasia: Review of 17 Cases

We retrospectively reviewed the clinical and radiologic characteristics of 17 individuals with septo-optic dysplasia (SOD) and attempted to identify correlations between imaging findings, clinical features, and neurodevelopmental outcome. Surprisingly, only 1 (6%) individual was classified as classic SOD (with septum pellucidum/corpus callosum dysgenesis), 3 (18%) as SOD-like (with normal septum pellucidum/corpus callosum) and the majority, 13 (76%), as SOD-plus (with cortical brain malformation). Cortical abnormalities included schizencephaly, polymicrogyria, and gray matter heterotopias. All individuals had optic nerve hypoplasia, 11 (65%) had endocrinologic deficits, and 13 (76%) had abnormal cerebral midlines. Seven individuals (41%) had all 3 features. Neurodevelopmental outcome was abnormal in 13 (78%), ranging from mild to severe developmental delay. Individuals with SOD-plus did not have more severe neurologic deficits than individuals with classic or SOD-like subgroups. Thus, SOD is clinically and radiologically heterogeneous, and cortical abnormalities are very common. Neurodevelopmental deficits are very prevalent, and of wide-ranging severity.

Classical and non-classical causes of GH deficiency in the paediatric age

Growth hormone deficiency (GHD) may result from a failure of hypothalamic GHRH production or release, from congenital disorders of pituitary development, or from central nervous system insults including tumors, surgery, trauma, radiation or infiltration from inflammatory diseases. Idiopathic, isolated GHD is the most common sporadic form of hypopituitarism. GHD may also occur in combination with other pituitary hormone deficiencies, and is often referred to as hypopituitarism, combined pituitary hormone deficiency (CPHD), multiple pituitary hormone deficiency (MPHD) or panhypopituitarism. Children without any identifiable cause of their GHD are commonly labeled as having idiopathic hypopituitarism. MRI imaging is the technique of choice in the diagnosis of children with hypopituitarism. Marked differences in MRI pituitary gland morphology suggest different etiologies of GHD and different prognoses. Pituitary stalk agenesis and ectopic posterior pituitary (EPP) are specific markers of permanent GHD, and patients with these MRI findings show a different clinical and endocrine outcome compared to those with normal pituitary anatomy or hypoplastic pituitary alone. Furthermore, the classic triad of ectopic posterior pituitary gland, pituitary stalk hypoplasia/agenesis, and anterior pituitary gland hypoplasia is generally associated with permanent GHD. T2 DRIVE images aid in the identification of pituitary stalk without the use of contrast medium administration. Future developments in imaging techniques will undoubtedly reveal additional insights. Mutations in a number of genes encoding transcription factors - such as HESX1, SOX2, SOX3, LHX3, LHX4, PROP1, POU1F1, PITX, GLI3, GLI2, OTX2, ARNT2, IGSF1, FGF8, FGFR1, PROKR2, PROK2, CHD7, WDR11, NFKB2, PAX6, TCF7L1, IFT72, GPR161 and CDON - have been associated with pituitary dysfunction and abnormal pituitary gland development; the correlation of genetic mutations to endocrine and MRI phenotypes has improved our knowledge of pituitary development and management of patients with hypopituitarism, both in terms of possible genetic counseling, and of early diagnosis of evolving anterior pituitary hormone deficiencies.

Septo-Optic Dysplasia

Septo-optic dysplasia (de Morsier syndrome) is a rare intracranial malformation characterized by the absence of the septum pellucidum with optic disk hypoplasia. Associated clinical symptoms include hypothalamic-pituitary dysfunction and varying degrees of visual impairment. Although the exact etiopathology is unknown, some researchers postulate that septo-optic dysplasia is the result of a vascular disruption sequence, an environmental anomaly, an autosomal-recessive inheritance, or a genetic abnormality. The associated intracranial malformations with septo-optic dysplasia are agenesis of the corpus callosum, schizencephaly, and lobar holoprosencephaly. To detect septo-optic dysplasia and its associated anomalies, sonographers must scan beyond the routine axial views in utero as well as the standard, neonatal axial, coronal, and sagittal views.

Absent cavum septum pellucidum: a review with emphasis on associated commissural abnormalities

The cavum septum pellucidum (CSP) is an important fetal midline forebrain landmark, and its absence often signifies additional underlying malformations. Frequently detected by prenatal sonography, absence of the CSP requires further imaging with pre- or postnatal MRI to characterize the accompanying abnormalities. This article reviews the developmental anatomy of the CSP and the pivotal role of commissurization in normal development. An understanding of the patterns of commissural abnormalities associated with absence of the CSP can lead to improved characterization of the underlying spectrum of pathology.

Septo-optic dysplasia associated with congenital persistent fetal vasculature, retinal detachment, and gastroschisis

PURPOSE

The purpose of this study was to report the association of septo-optic dysplasia, persistent fetal vasculature, retinal detachment, and gastroschisis in a preterm neonate.

METHODS

This is a case report.

RESULTS

A female preterm neonate was found to have septo-optic dysplasia, with optic nerve hypoplasia, tripartite splitting of the vessels at the optic nerve, an ectopic pituitary gland, and absence of the septum pellucidum associated with persistent fetal vasculature, a retinal detachment, and gastroschisis.

CONCLUSION

Septo-optic dysplasia may also be associated with other ophthalmic findings and other developmental malformations as the authors report in this case. Follow-up should consist of a multidisciplinary approach with radiologic and endocrinology consultation.

The identification and measurement of autistic features in children with septo-optic dysplasia, optic nerve hypoplasia and isolated hypopituitarism

This study aimed to highlight the occurrence of autism spectrum disorders (ASDs) in children with septo-optic dysplasia (SOD) and optic nerve hypoplasia (ONH). A cross-sectional study was designed, including 28 children with SOD and 14 children with ONH. Clinician diagnosis of ASD was reported in 14 children. The Social Communication Questionnaire (SCQ) reported that 23 children met the cut-off point for ASD, and 9 children met the cut-off point for autism. Greater levels of intellectual disability and visual loss were reported in children with ASD in comparison to those without ASD, but, of the two, intellectual disability was a better predictor for ASD. The SCQ lost its sensitivity and specificity in children who had greater visual loss which highlights a requirement for a measure that is sensitive to visual loss. It is also recommended that children with SOD/ONH would benefit from routine screening for ASDs.

Vascular cerebral anomalies associated with Septo-Optic Dysplasia. A case report

We describe a case of Septo-Optic Dysplasia (SOD) characterized by the presence of anomalous cerebral vessels. In our young patient the classical features of SOD were associated with vascular anomalies including absence of the vein of Galen, right Rosenthal vein leading to the superior petrosal sinus, and anomalous origin of the anterior choroidal arteries. These findings have never been associated with SOD in the literature but their revelation supports the hypothesis of a vascular disruption as a possible cause of the SOD.

Incidental discovery of subtle-variant septooptic dysplasia in an adult with headaches: a novel case with pathophysiologic implications

Septooptic dysplasia (SOD) is a congenital central nervous system malformation syndrome classically associated with the triad of agenesis of the septum pellucidum, optic nerve hypoplasia, and pituitary abnormalities. It has been suggested that SOD may result from in utero vascular insults. We present the case of an adult male with personal and family histories of intracranial vascular pathology in whom SOD was incidentally discovered, and we describe how the specific abnormalities in this case could be related to vascular pathology.

Schizencephaly prevalence, prenatal diagnosis and clues to etiology: a register-based study

OBJECTIVES

To establish the prevalence and antenatal diagnosis of schizencephaly in the UK.

METHODS

Data on schizencephaly were extracted from six regional congenital anomaly registers.

RESULTS

Thirty-eight cases of schizencephaly were identified in 2 567 165 livebirths and stillbirths, giving a total prevalence of 1.48/100 000 births (95% CI, 1.01-1.95). Eighteen (47% (95% CI, 31-63%)) of the 38 cases were identified antenatally. No affected fetus had an abnormal karyotype identified. A high proportion of cases of schizencephaly occurred in younger mothers: 63% were aged 24 years or less, significantly higher (P < 0.0001) than the corresponding proportion (26%) of mothers in England and Wales. The majority of cases were not identified until after 22 weeks of pregnancy. Additional anomalies associated with vascular disruption sequences were found in eight cases which had septo-optic dysplasia or absent septum pellucidum, one of which also had gastroschisis.

CONCLUSIONS

Schizencephaly occurs more frequently in the fetuses of younger mothers. It is often associated with septo-optic dysplasia, suggesting that the two conditions may share a common origin, arising as a result of destructive processes that cause changes in the brain which only become apparent on ultrasound in the second half of pregnancy.

Septo-optic dysplasia-plus and dyskinetic cerebral palsy in a child

Septo-optic dysplasia (SOD), also called De Morsier's syndrome, is a highly heterogeneous condition comprising a spectrum of central nervous system malformations that involves in various degrees the optic nerves, the hypothalamic-pituitary axis, and other midline structures such as the septum pellucidum and the corpus callosum. In a discrete number of cases, schizencephaly, agenesis of the corpus callosum or other cortical malformations are associated (SOD-plus). The authors present a 6-year-old boy with dyskinetic cerebral palsy (athetoid-dystonic subtype) associated with SOD-plus. Cranial magnetic resonance imaging (cMRI) revealed the total absence of septum pellucidum, optic nerve hypoplasia, hypoplasia of the corpus callosum and right occipital cortical dysplasia. The patient was diagnosed with septo-optic dysplasia-plus syndrome based on the cMRI findings. To the best of our knowledge, this is the first reported case in which defects of midline brain structures, like in SOD-plus, are associated with a significant hyperkinetic movement disorder such as dyskinesia.

Septo-optic dysplasia plus: a patient with diabetes insipidus

The association of septo-optic dysplasia and cortical dysplasia is described as septo-optic dysplasia-plus. Reports on patients with septo-optic dysplasia-plus have been rare. We describe a 4-year-old girl with septo-optic dysplasia-plus syndrome, characterized by septo-optic dysplasia with schizencephaly, pachygyria, and diabetes insipidus.

Septo-optic dysplasia with bilateral congenital corneal anesthesia

Septo-optic dysplasia, or de Morsier syndrome, is characterized by optic nerve hypoplasia with an absent septum pellucidum and/or pituitary abnormalities. Congenital corneal anesthesia is a rare disorder that has been associated with many neurological disorders. Here we present a patient with both conditions who was successfully treated with permanent lateral tarsorrhaphy and aggressive lubrication. To our knowledge, congenital corneal anesthesia has not been reported in association with septo-optic dysplasia. The purpose of this report is to make pediatric ophthalmologists aware of a potential association since the diagnosis of congenital corneal anesthesia is often difficult and delayed.

Septo-optic dysplasia

This review summarises the key clinical features of septo-optic dysplasia (SOD), the significant inroads that progress in genetics has made into our understanding of the aetiology of the condition over the last decade, and the pitfalls and challenges that we face in the management of these phenotypically variable patients.

Two cases of septo-optic dysplasia-plus syndrome with epilepsy and mirror hand movements

Septo-optic dysplasia (SOD) is a rare developmental anomaly first described by Reeves. It is a heterogeneous condition defined loosely by any combination of optic nerve hypoplasia, pituitary hypoplasia, and midline neuroradiological malformations. The etiology of SOD remains unclear. SOD-plus is the association of SOD and disorders of neuronal organization. Herein we describe two patients with SOD-plus syndrome characterized by SOD with epilepsy and multiple skeletal and central nervous system abnormalities. These two cases indicate that SOD results from disorders in multiple developmental stages. In addition, this is the first report of SOD-plus syndrome with mirror hand movements. Advances in neuroradiological evaluation techniques enable the detection of associated central nervous system abnormalities that can be special characteristics for the diagnosis of the spectrum of SOD-plus.

Refining clinical phenotypes in septo-optic dysplasia based on MRI findings

Septo-optic dysplasia (SOD) is a heterogeneous brain midline anomaly associated with ophthalmological, endocrinological, and/or neurodevelopmental symptoms. The clinical phenotype correlates with abnormal brain magnetic resonance imaging (MRI) findings. However, variations of the septum pellucidum (SP) appearance and their clinical impact have not been studied in depth. Sixty-eight patients with optic nerve hypoplasia (ONH) were investigated for the presence of associated SP anomalies and correlations between clinical findings and their MRI abnormalities established. Thirty patients had either complete (n = 22) or partial (n = 8) absence of the SP. Pituitary hormone deficiencies were present in 64% or 25% of the cases, respectively. Neurological symptoms did not occur in patients with SP remnants or unilateral ONH. Hippocampus abnormalities (43%) that have not been described before in SOD and falx abnormalities (17%) correlated significantly with neurological symptoms and developmental delay (p < 0.05 and p < 0.01, respectively). Maternal age at birth was low (21.2 years) and drug abuse during pregnancy was reported in 27% of the patients. Twelve patients with pituitary anomaly and ONH but normal SP showed similar clinical and MRI features, and were classified as SOD-like. The remaining 26 patients were not assigned to SOD. We conclude that unilateral ONH and SP remnants are associated with a milder SOD phenotype. Hippocampus abnormalities and falx abnormalities seem to constitute important features of severe clinical disease, irrespective of SP appearance. Our anamnestic data support the hypothesis of vascular disruption during embryogenesis.

A patient with septo-optic dysplasia plus

Septo-optic dysplasia (SOD) is an uncommon developmental disorder involving variable midline brain structures, characterized by optic nerve hypoplasia, dysgenesis of septum pellucidum, and pituitary-hypothalamic dysfunction such as growth hormone deficiency. The phenotype is highly variable and the clinical presentation may be mild or extremely severe. Other distinct features, which occur especially when cerebral cortical abnormalities are also present (SOD-plus), consist of significant generalized developmental delay and/or spastic motor deficits. We report a case of SOD-plus with mild cortical dysplasia which was revealed to be thickening of bilateral insular cortex without schizencephaly by MRI, and there was no sign or symptom of cortical dysfunction except for one episode of brief seizure.

Early midline interactions are important in mouse optic chiasm formation but are not critical in man: a significant distinction between man and mouse

The optic chiasm is one of the most popular models for studying axon guidance. Here axons make a key binary decision either to cross the midline to innervate the contralateral hemisphere or to remain uncrossed. In rodents, midline interactions between axons from the two eyes are critical for normal development, as early removal of one eye systematically disrupts hemispheric projections from the remaining eye, increasing the crossed projection at the expense of the uncrossed. This is similar to the abnormal decussation pattern seen in albinos. This pattern is markedly different in marsupials where early eye removal has no impact on projections from the remaining eye. These differences are related to the location of the uncrossed projection through the chiasm. In rodents these axons approach the midline whereas in marsupials they remain segregated laterally. We provide anatomical evidence in man suggesting that, unlike in rodents, uncrossed axons are confined laterally and do not mix in each hemi-chiasm, which is a pattern similar to that found in marsupials. Further, we demonstrate electrophysiologically, using visual cortical evoked potentials, that the failure of one eye to develop in man has no impact on the hemispheric projections from the remaining eye. These data demonstrate that the mechanisms regulating chiasmal development in man differ from those in rodents but may be similar to those in marsupials. We suggest that mouse models of the organization and development of the optic chiasm are not common to placental mammals in general.

Retinal function in infants with optic nerve hypoplasia: electroretinograms to large patterns and photopic flash

AIMS

Optic nerve hypoplasia (ONH), which is defined as a congenital deficiency of retinal ganglion cells, may also involve more distal layers of the retina. We investigated electrophysiological function of the retina in ONH using electroretinograms (ERGs).

METHODS

ERGs were recorded from 48 subjects (3.5-35 months) with unilateral or bilateral ONH. Pattern reversal (4 degrees checks) was presented under chloral hydrate sedation, using an optical system to correct a cycloplegic refraction. A photopic flash stimulus was also used. Fundus photographs were used to measure the disk diameter/disk macula ratio (DD/DM), and to document other clinical signs. Eyes were classified as moderate (0.15-0.3) or severe (<0.15) ONH, and those with DD/DM greater than 0.3 were used as reference eyes.

RESULTS

Pattern ERG recording was completed in 89 eyes and was detectable in 80% of eyes with ONH (61/76 tested) and in all 13 reference eyes. Photopic flash ERGs were of good quality in all eyes. The severity of ONH correlates with the amplitude of the photopic flash b-waves and with the amplitude of the N95 component of the pattern ERG (P<0.01). However, the ERGs to large patterns were well preserved (>3.5 microV) in 10 of 35 eyes with severe ONH. Tortuous retinal vessels in eyes with either moderate or severe ONH were associated with smaller amplitude photopic b-waves and markedly diminished or undetectable pattern ERGs.

CONCLUSIONS

This study supports the hypothesis that retinal dysfunction distal to the ganglion cells is common in ONH, but is not predictable on the basis of ONH severity alone. Additionally, tortuous retinal vessels in ONH may be a sign associated with retinal dysfunction.

Schizencephaly: heterogeneous etiologies in a population of 4 million California births

Schizencephaly is a rare congenital brain defect characterized by gray matter lined clefts of the cerebral mantle, frequently accompanied by other defects of the CNS such as absence of the corpus callosum. This study in a California population of >4 million births from 1985-2001 found a population prevalence of 1.54/100,000. Among 63 cases, there was an association with young parental age in isolated schizencephaly (RR 3.9 mothers; 5.8 fathers), which was also seen in mothers but not fathers of non-isolated cases (RR 3.2). Monozygotic twins may also be at increased risk for schizencephaly (RR 2.1). One third of cases had a non-CNS abnormality, over half of which could be classified as secondary to vascular disruption, including gastroschisis, bowel atresias, and amniotic band disruption sequence. Other apparent rare causes included chromosomal aneuploidy, non-random associations, and unusual syndromes. Our observations suggest that schizencephaly has heterogeneous etiologies many of which are vascular disruptive in origin.

Hypopituitarism and neurodevelopmental abnormalities in relation to central nervous system structural defects in children with optic nerve hypoplasia

OBJECTIVE

Optic nerve hypoplasia (ONH) is a heterogeneous disease with variable findings of pituitary insufficiency, CNS and neurodevelopmental abnormalities. We characterized the spectrum of endocrinopathy in a cohort of children with ONH and attempted to correlate the presence of different midline CNS findings with the degree of hypopituitarism. The correlation of variable CNS abnormalities with the presence of a seizure disorder and neurodevelopmental delay was also examined.

METHODS

Charts of 56 patients with ONH referred to our endocrine clinics between 1990 and 2000 were reviewed. Neurodevelopmental assessment was based on questionnaires sent to families during the study period.

RESULTS

Forty-six patients (82%) had hypopituitarism, with growth hormone deficiency being the most common endocrinopathy. All patients with diabetes insipidus, hypocortisolism, and hypogonadotropin hypogonadism also had combined pituitary hormone deficiency. Evolving pituitary hormone deficiency was observed in two of 37 patients diagnosed with hypopituitarism in the first 3 years of life. No single midline CNS finding correlated with the presence of hypopituitarism or a seizure disorder. However, hydrocephalus or a seizure disorder was more commonly seen in patients with developmental delay.

CONCLUSION

ONH is a heterogeneous disorder with possible multifactorial etiologies. All patients with this diagnosis deserve a comprehensive endocrine and neurodevelopmental evaluation.

Maternal age in patients with septo-optic dysplasia

AIM

To determine whether patients with septooptic dysplasia (SOD) are of normal birth weight and gestation but are born to mothers who are significantly younger than average.

METHODS

Retrospective study of 30 patients with SOD attending the Royal Hospital for Sick Children, Glasgow. Birth data for the Scottish population were used for comparison.

RESULTS

Mean birth weight was 3.42 (range 2.66-4.18) kg. One patient was born preterm while the rest were born at term. Data for the Scottish population were available from 1979 onwards and 26 patients born after this year were selected for analysis. Median maternal age in this group was 21 (range 16-41) years, significantly lower than the median maternal age for Scotland of 27.12 (range 25.8-28.6) years (95% CI 4.8-8.0 years).

CONCLUSION

Patients with SOD are of normal birth weight and gestation but are born to mothers who are significantly younger than average.

Septo-optic dysplasia with digital anomalies?a recurrent pattern syndrome

A distinct form of septo-optic dysplasia (SOD) comprises limb malformations in addition to the characteristic CNS and ocular abnormalities. To date, there have been 4 reports, citing 5 affected patients with this combined phenotype. We now add a further case and present neuroradiological images of the CNS findings in this condition. The striking consistency of the limb malformations and their overlap with the Streeter's band phenotype is emphasized.

Septo-optic dysplasia and amniotic bands: Further evidence for a vascular pathogenesis

Septo-optic dysplasia (SOD) is a heterogeneous disorder. While most cases represent an isolated defect, SOD has also been seen in association with mutations in single genes, as a part of multiple congenital anomaly syndromes and with exposure to various teratogens. We report a boy with features of SOD who also has limb defects suggestive of amniotic bands. This case, in addition to others in the literature, provides evidence for a vascular pathogenesis of SOD in some individuals. This hypothesis is also supported by the sporadic occurrence of SOD and its association with decreased maternal age, vascular teratogens, and neuropathologic findings suggestive of vascular insults.

Hereditary porencephaly: clinical and MRI findings in two Dutch families

Familial porencephaly is a rare disorder causing motor impairment, hemiplegia, mental retardation and epilepsy in variable degrees. Two families with porencephaly and apparently dominant inheritance are reported. Brain MRI findings are reviewed and described in seven affected individuals. Most patients also show white matter abnormalities in the cerebral hemisphere, also contralateral to the cystic lesion. In the first family an obligate carrier was identified who did not have a cystic lesion but clear abnormalities of the white matter. Although a predisposition for thrombophilia has previously been reported, we did not observe any genetic, environmental or epigenetic predisposition for the porencephaly. The lesions are most compatible with a deep venous thrombosis/ischemic event occurring in a late stage of pregnancy, not necessarily aggravated by perinatal asphyxia.

Septo-optic dysplasia with digital anomalies associated with maternal multidrug abuse during pregnancy

We describe a 16-year-old female affected by septo-optic dysplasia (SOD) with digital anomalies as additional feature. This rare developmental anomaly of midline brain structures can result from different pathogenetical events, including mutations of the homeo box gene HESX1, recently suggested as the etiological cause at least in a subset of patients. The absence of mutational involvement of this gene in our patient led us to consider, in alternative terms of pathogenesis, the maternal multidrug abuse occurring during pregnancy. Our report, in accord with previous experimental evidences, points out that illicit drug use might have played a causative role in brain development anomalies, thus our patient could represent an additional case of birth defects caused by a prenatal toxic exposure. The neurologic abnormalities and the clinical history of the patient are extensively reviewed. The need to include the SOD phenotype amongst the possible teratogenic effects of multidrug abuse is evidenced.

Genetics of brain development and malformation syndromes

The identification of the specific genes responsible for several childhood neurologic disorders has provided a framework with which to understand key development stages in human brain development. Common genetic disorders of brain development include septo-optic dysplasia, schizencephaly, holoprosencephaly, periventricular heterotopia, lissencephaly, and Joubert syndrome. For each of these disorders, a critical step in brain development is interrupted. The identification of the responsible genes is providing scientists a window into the key modulators of brain development, and providing clinicians the opportunity to offer genetic testing to individual patients and their families.