Septo-optic dysplasia: the clinical insignificance of an absent septum pellucidum

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.

A Prolonged Treatment Associated With Absent Septum Pellucidum in Neonatal Abstinence Syndrome: A Case Report

Neonatal abstinence syndrome (NAS) involves a widely variable treatment course among affected individuals. Prognostic indicators that would help predict length of hospital stay and individualize treatment would be valuable to newborns, parents, and hospital staff, including advanced practice registered nurses. We describe a newborn with a prolonged NAS treatment course necessitating high doses of opioids and phenobarbital, found to have an isolated absent septum pellucidum (ASP). We hypothesize a mechanism for an association between an ASP and a difficult NAS treatment course. Should this be substantiated by other cases, it could provide a valuable prognosticator and indicate alternate treatment pathways.

Congenital Brain Malformations: An Integrated Diagnostic Approach

Congenital brain malformations are abnormalities present at birth that can result from developmental disruptions at various embryonic or fetal stages. The clinical presentation is nonspecific and can include developmental delay, hypotonia, and/or epilepsy. An informed combination of imaging and genetic testing enables early and accurate diagnosis and management planning. In this article, we provide a streamlined approach to radiologic phenotyping and genetic evaluation of brain malformations. We will review the clinical workflow for brain imaging and genetic testing with up-to-date ontologies and literature references. The organization of this article introduces a streamlined approach for imaging-based etiologic classification into malformative, destructive, and migrational abnormalities. Specific radiologic ontologies are then discussed in detail, with correlation of key neuroimaging features to embryology and molecular pathogenesis.

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.

Neuroimaging and endocrine disorders in paediatric optic nerve hypoplasia

Purpose

Optic nerve hypoplasia (ONH) is one of the leading causes of blindness among children. The purpose of this retrospective study is to determine the risk factors and association between brain MRI findings, pituitary abnormalities and endocrine disorders with the presence of ONH.

Methods

A retrospective review of patients seen at paediatric ophthalmology clinics from January 2006 to December 2016 at Children’s Hospital and Medical Center and the University of Nebraska Medical Center was performed. All patients with a documented diagnosis of ONH or septo-optic dysplasia were identified. MRI and endocrinology results were analysed by masked examiners.

Results

Out of 77 patients, overall incidence of abnormal pituitary on MRI was 35.1% and the incidence of endocrine abnormalities was 37.7%. Of the 57 patients with bilateral ONH, 23 (40.4%) had an abnormal pituitary while 4 of the 20 patients (20.0%) with unilateral ONH had an abnormal pituitary on MRI. The sensitivity and specific of brain MRI as signs of endocrinopathy are 67.9% and 83.3%, respectively.

Conclusion

This study has determined that abnormal MRI findings do not have the sensitivity to predict endocrinopathy, nor does a normal MRI rule out possible endocrine abnormalities. When patients with ONH present with normal neurological examinations, normal endocrine workup and normal developmental milestones, a MRI of the brain may be deferred until new indications arise. Regardless of the MRI status, children with ONH should have a comprehensive endocrine evaluation and continue to have routine endocrine follow-up.

Septo-optic Dysplasia Complex with Omphalocele, Pre-maxillary Agenesis and Encephalocele

Septo-optic dysplasia complex (SODC) is a rare congenital anomaly, characterized with absence of septum pellucidum, optic nerve hypoplasia with or without pituitary dysfunction. Various midline defects are also associated with SODC in addition to its classical findings. We report, for the first time a rare presentation of SODC which is associated with pre-maxillary agenesis along with sphenoidal encephalocele and omphalocele. The case showed resulting median cleft lip and palate along with other multiple congenital defects including hydrocele, inguinal hernia, micropenis and a wide mediastinum.

Optic nerve hypoplasia in children and adolescents; prevalence, ocular characteristics and behavioural problems

PURPOSE

To report prevalence, ocular characteristics and coexisting behavioural problems in children and adolescents with optic nerve hypoplasia (ONH), which is a common cause of visual impairment in children in western countries, often associated with neurological or endocrinological problems and where autism has been reported in severe cases with blindness.

METHODS

This is a population-based cross-sectional study of patients <20 years of age who had been diagnosed with ONH and lived in the county of Stockholm in December 2009. Ophthalmological assessments including fundus photographs with optic disc analyses were made. A questionnaire was used to screen for behaviour and development.

RESULTS

The prevalence of ONH in all living children <18 years of age in Stockholm was 17.3/100 000 with a prevalence of visual impairment (<0.3) of 3.9/100 000. In total, 66 patients, median age 9.3 years (0.6-19.4), 36 with bilateral and 30 with unilateral ONH, were included in the current study; 53 were re-examined clinically, group A, and 13 agreed to retrospective analyses of existing medical records, group B. Analyses of the optic discs were made in fundus photographs from 53 patients comparing a semi-automated (Retinal Size Tool) and a manual method (Zeki). There was a strong curvilinear correlation (r(S)  = -0.91 p < 0.0001 for both eyes). Behavioural problems were more common (p < 0.05) in bilateral ONH.

CONCLUSION

Optic nerve hypoplasia is a common ocular malformation with a prevalence of 17.3/100 000 children and adolescents <18 years of age in Stockholm. Unilateral ONH seems as common as bilateral.

Optic nerve hypoplasia syndrome: a review of the epidemiology and clinical associations

OPINION STATEMENT

BACKGROUND

Optic nerve hypoplasia (ONH) has developed into a leading cause of congenital blindness. The frequently associated features of hypopituitarism and absent septum pellucidum were felt to have embryonic linkage as "septo-optic dysplasia" or "de Morsier's syndrome." More recent studies have suggested these associations are independent of one another. This review provides an assessment of the historical and recent evidence linking neuroradiologic, endocrinologic and developmental morbidity in patients with ONH. The prenatal risk factors, heritability, and genetic mutations associated with ONH are described.

RESULTS

Recognition of the critical association of ONH with hypopituitarism should be attributed to William Hoyt, not Georges de Morsier. De Morsier never described a case of ONH or recognized its association with hypopituitarism or missing septum pellucidum. Hypopituitarism is caused by hypothalamic dysfunction. This, and other more recently identified associations with ONH, such as developmental delay and autism, are independent of septum pellucidum development. Other common neuroradiographic associations such as corpus callosum hypoplasia, gyrus dysplasia, and cortical heterotopia may have prognostic significance. The predominant prenatal risk factors for ONH are primiparity and young maternal age. Presumed risk factors such as prenatal exposure to drugs and alcohol are not supported by scrutiny of the literature. Heritability and identified gene mutations in cases of ONH are rare.

CONCLUSION

Children with ONH require monitoring for many systemic, developmental, and even life-threatening problems independent of the severity of ONH and presence of brain malformations including abnormalities of the septum pellucidum. "Septo-optic dysplasia" and "de Morsier's syndrome" are historically inaccurate and clinically misleading terms.

Reappraisal of the optic nerve hypoplasia syndrome

BACKGROUND

Optic nerve hypoplasia (ONH) has been described as an increasingly prevalent cause of congenital blindness. Its association with hypopituitarism and absent septum pellucidum has been recognized for more than 40 years as "septo-optic dysplasia" or "de Morsier syndrome." More recent studies have suggested that these associations are independent of one another. This review was designed to assess the historical and recent evidence for associations of neuroradiologic, endocrinologic, and developmental problems in patients with ONH.

EVIDENCE ACQUISITION

Historical and contemporary literature review.

RESULTS

The medical literature does not support the notion that Georges de Morsier ever described a case of ONH or recognized its association with hypopituitarism or missing septum pellucidum. Recognition of the critical association of ONH with hypopituitarism should be attributed to William Hoyt. Hypopituitarism and other more recently identified associations with ONH, such as developmental delay, hypothalamic dysfunction, and autism, are independent of septum pellucidum development. Other common neuroradiographic associations, such as corpus callosum hypoplasia, gyrus dysplasia, and cortical heterotopia, may have prognostic significance.

CONCLUSIONS

Children with ONH need to be monitored for many systemic, developmental, and even life-threatening problems independent of the status of the septum pellucidum. "Septo-optic dysplasia" and "de Morsier syndrome" are historically inaccurate and clinically misleading terms that should be abandoned.

Pediatric outcome of children with the prenatal diagnosis of isolated septal agenesis

BACKGROUND

Isolated Septal Agenesis (SA) is a rare disease with clinical outcomes (especially neurological outcomes) that are unknown. The purpose of this study was to evaluate the clinical outcome of these children.

METHODS

We conducted a retrospective multicenter study of 17 children with an isolated SA or SA combined with a moderate ventricular dilatation (VD) that was diagnosed antenatally and confirmed by a magnetic resonance imaging (MRI) performed in the antenatal period.

RESULTS

Of the 17 children, 14 had normal neurological examinations, 2 had language development delay and visuo-spatial dyspraxia, and 3 of the 17 children had behavioral problems. Eight children had neuropsychological evaluations, and the results were normal in six cases. There were 3 cases of septo-optic dysplasia (SOD) diagnosed postnatally, which highlighted the difficulties in assessing the optic tract and hypothalamic-pituitary region in antenatal imaging. Language delay and behavioral disorders were the main abnormalities at follow-up.

CONCLUSION

The discovery of an isolated SA reveals the difficulties of prenatal diagnosis to correlate the neurological and functional prognosis to morphological findings. The prognosis seemed to be good. It appears necessary to improve the diagnostic performance of fetal brain imaging and to follow-up these children prospectively to assess their long-term cognitive-behavioral outcomes.

Brain imaging studies in Leber's congenital amaurosis: new radiologic findings associated with the complex trait

Purpose

To report the incidence and new findings of abnormal brain imaging studies associated with patients initially diagnosed with Leber's congenital amaurosis (LCA) without definite systemic abnormalities and to determine the need for brain imaging studies in these patients.

Methods

A retrospective review of medical records was performed in 83 patients initially diagnosed as LCA and without definite systemic abnormalities before the age of 6 months in 2 tertiary referral centers. Brain magnetic resonance imaging was performed in 31 of 83 patients (37.3%).

Results

Six of 31 patients (19%) had radiologically documented brain abnormalities. Two patients had cerebellar vermis hypoplasia, 1 patient showed an absence of septum pellucidum, 2 subjects showed mild external hydrocephalus, and 1 patient was found to have a small cerebellum.

Conclusions

Approximately one fifth of the LCA patients in whom brain imaging was performed were associated with brain abnormalities, including the absence of septum pellucidum, which has not been documented in the literature. Brain imaging is mandatory in patients primarily diagnosed with LCA, even without definite neurologic or systemic abnormalities.

The corpus callosum, the other great forebrain commissures, and the septum pellucidum: anatomy, development, and malformation

There are three telencephalic commissures which are paleocortical (the anterior commissure), archicortical (the hippocampal commissure), and neocortical. In non-placental mammals, the neocortical commissural fibers cross the midline together with the anterior and possibly the hippocampal commissure, across the lamina reuniens (joining plate) in the upper part of the lamina terminalis. In placental mammals, a phylogenetically new feature emerged, which is the corpus callosum: it results from an interhemispheric fusion line with specialized groups of mildline glial cells channeling the commissural axons through the interhemispheric meninges toward the contralateral hemispheres. This concerns the frontal lobe mainly however: commissural fibers from the temporo-occipital neocortex still use the anterior commissure to cross, and the posterior occipito-parietal fibers use the hippocampal commissure, forming the splenium in the process. The anterior callosum and the splenium fuse secondarily to form the complete commissural plate. Given the complexity of the processes involved, commissural ageneses are many and usually associated with other diverse defects. They may be due to a failure of the white matter to develop or to the commissural neurons to form or to migrate, to a global failure of the midline crossing processes or to a selective failure of commissuration affecting specific commissural sites (anterior or hippocampal commissures, anterior callosum), or specific sets of commissural axons (paleocortical, hippocampal, neocortical commissural axons). Severe hemispheric dysplasia may prevent the axons from reaching the midline on one or both sides. Besides the intrinsically neural defects, midline meningeal factors may prevent the commissuration as well (interhemispheric cysts or lipoma). As a consequence, commissural agenesis is a malformative feature, not a malformation by itself. Good knowledge of the modern embryological data may allow for a good understanding of a specific pattern in a given individual patient, paving the way for better clinical correlation and genetic counseling.

Neuroradiographic, endocrinologic, and ophthalmic correlates of adverse developmental outcomes in children with optic nerve hypoplasia: a prospective study

BACKGROUND

Developmental delay has been reported to occur with optic nerve hypoplasia, a leading cause of pediatric blindness, but has not been systematically examined for its prevalence and correlation with associated pathologies of optic nerve hypoplasia.

OBJECTIVE

The purpose of this study was to determine the developmental outcomes of children with optic nerve hypoplasia and the correlation of development with neuroradiographic, endocrinologic, and ophthalmic findings.

METHODS

We conducted a prospective analysis of 73 subjects diagnosed with optic nerve hypoplasia at <36 months of age for developmental outcomes at 5 years of age. Subjects underwent neuroradiographic imaging, endocrinologic testing and examination, and ophthalmologic examination; developmental outcomes were assessed by using the Battelle Developmental Inventory.

RESULTS

At 5 years of age, developmental delay was present in 71% of subjects with optic nerve hypoplasia. Of patients with unilateral (18%) and bilateral optic nerve hypoplasia, 39% and 78%, respectively, experienced developmental delay. Corpus callosum hypoplasia and hypothyroidism were significantly associated with poor outcome in all of the developmental domains and an increased risk of delay. Absence of the septum pellucidum was not associated with adverse development. Six subjects had neither a neuroradiographic nor an endocrinologic abnormality, and of those, 4 were developmentally delayed.

CONCLUSIONS

These prospective data confirm the significant association of developmental delay with optic nerve hypoplasia and identify corpus callosum hypoplasia and hypothyroidism as strong correlates. A diagnosis of optic nerve hypoplasia warrants neuroradiographic and endocrinologic testing for risk factors of delay and developmental assessments for early intervention planning.

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.

Endocrinological and auxological abnormalities in young children with optic nerve hypoplasia: a prospective study

OBJECTIVE

To determine the prevalence of endocrinopathies, neuroradiographical findings, and growth derangements in young children with optic nerve hypoplasia (ONH).

STUDY DESIGN

A prospective observational study examined the prevalence of endocrinopathies at study enrollment and growth patterns in children with ONH. Subjects (n = 47, mean +/- SD 15.2 +/- 10.6 months) were followed until 59.0 +/- 6.2 months of age.

RESULTS

The prevalence of endocrinopathies was 71.7%: 64.1% of subjects had growth hormone (GH) axis abnormalities, 48.5% hyperprolactinemia, 34.9% hypothyroidism, 17.1% adrenal insufficiency, and 4.3% diabetes insipidus (DI). Endocrinopathies were not associated with ONH laterality, absence of the septum pellucidum, or pituitary abnormalities on neuroimaging. End height standard deviation score (SDS) was similar to start length SDS independent of GH surrogate status. A significant increase in end weight SDS was found for the cohort (p < .001). A body mass index (BMI) >85th percentile was noted in 44.4% of the cohort and in 52.1% of subjects with GH axis abnormalities. Initial hyperprolactinemia was positively associated with increased end BMI SDS (p = .004).

CONCLUSIONS

These prospective findings confirm the high prevalence of pituitary endocrinopathies in children with ONH reported in previous retrospective studies. Our data reveal that some of these children maintain normal height velocity despite GH axis abnormalities, and, as a group, they are at high risk for increased BMI.

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.

Optic nerve axons: life and death before birth

In the 2004 Bowman Lecture, I give a panegyric for Sir William Bowman, an estimate of the importance and the epidemiology of anterior visual pathway developmental disorders, followed by a history of the anterior visual system. I review the normal development of the optic nerve and chiasm and the main developmental disorders: Optic Nerve Aplasia, Optic Nerve Hypoplasia and Achiasmia.

Congenital disorders of the optic nerve: excavations and hypoplasia

The principal congenital abnormalities of the optic disc that can significantly impair visual function are excavation of the optic disc and optic nerve hypoplasia. The excavated optic disc abnormalities comprise optic disc coloboma, morning glory syndrome, and peripapillary staphyloma. Optic nerve hypoplasia manifests as a small optic nerve, which may or may not be accompanied by a peripapillary ring (the double ring sign). In addition, the optic disc cupping, which occurs as a sequel to some cases of periventricular leucomalacia, can arguably be classified as a type of optic nerve hypoplasia. All of these conditions can be unilateral or bilateral and can impair visual function mildly or severely. It is essential that children with poor vision due to any of these conditions are managed by treating refractive errors, giving occlusion therapy in selected cases, and optimising the conditions at home and at school in an attempt to ensure that impaired vision does not impede development or education.

Regulation of affect by the lateral septum: implications for neuropsychiatry

Substantial evidence indicates that the lateral septum (LS) plays a critical role in regulating processes related to mood and motivation. This review presents findings from the basic neuroscience literature and from some clinically oriented research, drawing from behavioral, neuroanatomical, electrophysiological, and molecular studies in support of such a role, and articulates models and hypotheses intended to advance our understanding of these functions. Neuroanatomically, the LS is connected with numerous regions known to regulate affect, such as the hippocampus, amygdala, and hypothalamus. Through its connections with the mesocorticolimbic dopamine system, the LS regulates motivation, both by stimulating the activity of midbrain dopamine neurons and regulating the consequences of this activity on the ventral striatum. Evidence that LS function could impact processes related to schizophrenia and other psychotic spectrum disorders, such as alterations in LS function following administration of antipsychotics and psychotomimetics in animals, will also be presented. The LS can also diminish or enable fear responding when its neural activity is stimulated or inhibited, respectively, perhaps through its projections to the hypothalamus. It also regulates behavioral manifestations of depression, with antidepressants stimulating the activity of LS neurons, and depression-like phenotypes corresponding to blunted activity of LS neurons; serotonin likely plays a key role in modulating these functions by influencing the responsiveness of the LS to hippocampal input. In conclusion, a better understanding of the LS may provide important and useful information in the pursuit of better treatments for a wide range of psychiatric conditions typified by disregulation of affective functions.

Optic nerve hypoplasia in cholestatic infants: a multiple case study

PURPOSE

To present four infants with optic nerve hypoplasia and cholestasis.

METHODS

All patients underwent detailed ophthalmological and hepatological assessment. Their endocrinological and neuroradiological examinations were re-evaluated.

RESULTS

All four infants presented with cholestasis and were subsequently found to have optic nerve hypoplasia. One child was blind according to the WHO definition and two had low vision. The fourth child had unilateral optic nerve hypoplasia and was too young to be assessed with optotypes. All four children had central nervous system and/or endocrine dysfunction. However, only one child had septo-optic dysplasia. The longterm outcome of liver disease seemed favourable in all children.

CONCLUSION

Early assessment by a paediatric ophthalmologist as well as a multidisciplinary approach is of great importance in cholestatic infants.

Unreported anatomical variation of septum pellucidum

During gross anatomy dissections of the brain, a developmental abnormality of the septum pellucidum was found in a 31-year-old male cadaver. Other parts of the central nervous system in this cadaver were normal in every aspect. Histological samples were taken from the neighboring areas of this abnormality, and they were examined under light microscope and scanning electron microscope. In this abnormality of the septum pellucidum, the two laminae of the septum pellucidum were fused together and there was a hole located 1 cm anterior to its apex. The maximum diameter of the hole was 0.5 cm in the sagittal plane and 0.6 cm in the vertical plane. In the light microscopic and scanning electron microscopic examinations, the free margin of this foramen was regular, and the surrounding tissue was intact and histologically unique to the septum pellucidum. Ependymal cells were present at the free margin of the foramen. Cavum vergae, cavum septum pellucidum, and agenesis of the septum pellucidum are described in the literature. These three abnormalities are seen in cadavers usually with histories of schizophrenia and other psychiatric or neurologic disorders. In a retrospective study, the cadaver with this abnormality had a history of schizophrenia and no history or signs of any kind of brain or head operation. As far as we could ascertain, the abnormality described here has not been reported previously.

Visual-evoked potential evidence of chiasmal hypoplasia

PURPOSE

To show that chiasmal hypoplasia or aplasia need not be an isolated developmental anomaly and to examine the spectrum of associated clinical findings to explore the possibility that these patients may represent a phenotypic manifestation of a developmental gene anomaly.

DESIGN

An observational case series.

PARTICIPANTS

Five infants, between several weeks and 7 months of age, in whom the electrophysiologic characteristic of chiasmal hypoplasia had been noted were included.

METHODS

Flash electroretinography and flash and pattern visual-evoked potentials (VEPs) were elicited from all patients. Clinical ophthalmologic examinations, including funduscopy, were performed, and all patients had magnetic resonance imaging (MRI) brain scans.

MAIN OUTCOME MEASURES

The occipital distribution of monocular VEP response peaks was studied. The symmetry of lateral channel responses was compared for monocular stimulation.

RESULTS

All five patients had a crossed asymmetry in the monocular VEP occipital distribution, which is consistent with a paucity of fibers crossing at the chiasm. The MRI findings supported this electrophysiologic observation, illustrating degrees of chiasmal hypoplasia and variable coincidence of other midline abnormalities of the brain. Optic disc appearances varied from normal to hypoplastic and colobomatous.

CONCLUSIONS

The ophthalmologic and MRI findings of five patients who showed a crossed asymmetry in monocular flash VEPs are consistent with a paucity of axons crossing at the chiasm. The similarities between achiasmia in humans and mice due to a Pax2 gene anomaly are discussed.

Neuroimaging in children with congenital disorders of the peripheral visual system

The study investigates the neurological substrate in children with congenital disorders of the peripheral visual system (CDPVS), i.e. disorders of the anterior visual pathways and the globe. The design is retrospective; brain MRI and/or CT scans were traced and reviewed for 79 of 254 children with CDPVS on our database. The neuroradiological findings were considered in the context of degree of visual impairment (profound [PVI] and severe [SVI]), developmental outcome (setback and non-setback), and mode of imaging (MRI and CT). Scans were abnormal in 40 of 79 (51%) children; 23 of 40 (58%) had more than one lesion; and in some children lesions not previously reported were found. The number of abnormalities per child was significantly higher in the PVI than the SVI group (P<0.05); the level of significance varied according to the method of scanning (MRI, P<0.001; CT, ns). Seven children were known to have had developmental setback; significantly more brain abnormalities per child were found in the group with setbacks than in the group without (P<0.001). Eighty-six percent (24 of 28) of MRI compared with 38% (22 of 58) of CT scans were abnormal. MRI detected more lesions per child than CT (P< 0.001). Thus, a significant amount of brain pathology occurs in children with CDPVS. The number of lesions varies directly with degree of visual impairment and both correlate with developmental outcome. As brain pathology will be only one of many factors influencing developmental progress in visually impaired children, prospective multifactorial studies of the CDPVS population, which include MRI studies of the neurological substrate, will be required to clarify the latter.

The clinical, neuroradiographic, and endocrinologic profile of patients with bilateral optic nerve hypoplasia

PURPOSE

The purpose of the study was to expand on ophthalmologic and endocrinologic data and report the neuroimaging findings of 35 patients with bilateral optic nerve hypoplasia (BONH).

METHODS

A retrospective chart review of 35 children with BONH was conducted. Data on visual acuity, refractive error, and presence of nystagmus and strabismus were collected. Twenty-six children underwent full-endocrinologic evaluation and magnetic resonance imaging or computed tomography scanning.

RESULTS

The male:female ratio was 2:1. Ten percent of eyes had visual acuity of 20/60 or better, whereas 34% had no light perception. Eighty-six percent of eyes had acuity less than 20/200, and 80% of patients were legally blind. Most patients (86%) had nystagmus or strabismus or both. Forty-six percent had absence of the septum pellucidum and corpus callosum on neuroimaging. Twenty-seven percent of patients had endocrinologic abnormalities, with growth hormone deficiency being the most common. Panhypopituitarism occurred in 11.5% of children.

CONCLUSIONS

Although the visual prognosis of children with BONH generally is poor, 10% of such patients have excellent acuity. In contrast to previous reports, endocrine abnormalities were seen in only one quarter of patients, and the full-blown deMorsier syndrome (septo-optic dysplasia with panhypopituitarism) was seen in only 11.5% of patients with BONH.

Role of cavum septum pellucidum in akinetic mutism of hydrocephalic children

Two children 9 and 13 years of age with histories of aqueductal stenosis developed akinetic mutism after multiple shunt revisions. The girl had spontaneous relief of her akinetic mutism 1 month later, after parenteral antibiotics and multiple shunt revisions. The akinetic mutism of the boy was resistant to antiparkinsonian therapy before megadosage of bromocriptine (120 mg/day). Both children had a prominent cavum septum pellucidum (CSP), which has rarely been involved in the pathogenesis of akinetic mutism. Because of the rapid shrinkage of the girl's CSP after shunt revision, but not that of the boy even after stereotactic fenestration of the wall of his CSP, their eventual outcomes were different. Wide CSP (WCSP) may play an important role in the occurrence of akinetic mutism in hydrocephalic patients.

Septo-optic dysplasia associated with bilateral complex microphthalmos

An 8-month-old girl was examined because of corneal clouding and microphthalmos. The fundi of both eyes could not be visualized because of corneal clouding. Orbital and cranial computerized tomographic scanning and magnetic resonance imaging demonstrated bilateral microphthalmos and presumed retinal dysplasia, hypoplasia of the optic nerves and chiasm, agenesis of the septum pellucidum, thinning of corpus callosum, and a normal pituitary infundibulum. Cerebral cortex and white matter were unremarkable. Other ocular malformations were anterior segment dysgenesis in the right eye and congenital cataract or lens abnormality in the left eye. Endocrine studies revealed normal serum hormone levels. There were no colobomatous lesions and systemic anomalies suggestive of a coloboma syndrome. This case represents the rare association of septo-optic dysplasia with complex microphthalmos.

Congenital optic disk anomalies

Over the past decade, a wealth of information has accumulated pertaining to the diagnosis and management of patients with congenital optic disk anomalies. As new examples of each entity have been detailed, the diagnostic criteria for each anomaly have become more clearly defined. The advent of sophisticated noninvasive neuroimaging techniques has further refined our ability to accurately detect and categorize the associated CNS anomalies that complicate many of these conditions. In light of recent findings, this review will critically examine many of the well-entrenched concepts pertaining to the diagnosis, evaluation, and treatment of patients with congenital optic disk anomalies. In so doing, it will attempt to dispel some longstanding misconceptions that pervade the literature and obscure our understanding of the pathogenesis, neuroradiological associations, and systemic implications of each anomaly.

The septum pellucidum and spatial ability of children with optic nerve hypoplasia

Animal studies suggest that spatial skills are dependent on an intact septum pellucidum. This theory was tested by comparing patients who were visually impaired due to bilateral optic nerve hypoplasia: 13 with a septum pellucidum were compared with six children without a septum pellucidum. There was no difference in spatial ability. The finding of an absent septum pellucidum may only indicate the timing of a congenital brain insult, and it cannot be used to predict specific clinical, neuroendocrinological, cognitive or spatial abnormalities.