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

Appetite- and Weight-Regulating Neuroendocrine Circuitry in Hypothalamic Obesity

Since hypothalamic obesity (HyOb) was first described over 120 years ago by Joseph Babinski and Alfred Fröhlich, advances in molecular genetic laboratory techniques have allowed us to elucidate various components of the intricate neurocircuitry governing appetite and weight regulation connecting the hypothalamus, pituitary gland, brainstem, adipose tissue, pancreas, and gastrointestinal tract. On a background of an increasing prevalence of population-level common obesity, the number of survivors of congenital (eg, septo-optic dysplasia, Prader-Willi syndrome) and acquired (eg, central nervous system tumors) hypothalamic disorders is increasing, thanks to earlier diagnosis and management as well as better oncological therapies. Although to date the discovery of several appetite-regulating peptides has led to the development of a range of targeted molecular therapies for monogenic obesity syndromes, outside of these disorders these discoveries have not translated into the development of efficacious treatments for other forms of HyOb. This review aims to summarize our current understanding of the neuroendocrine physiology of appetite and weight regulation, and explore our current understanding of the pathophysiology of HyOb.

Risk factors in children with optic nerve hypoplasia and septo-optic dysplasia

AIM

To identify the risk factors for optic nerve hypoplasia (ONH) and septo-optic dysplasia (SOD).

METHOD

A retrospective, population-based study with case-control design was undertaken using the Population Research Data Repository at the Manitoba Center for Health Policy in Manitoba, Canada. Cases were 111 patients (63 males, 48 females; age range 1-35 years [mean 11 years 6 months, SD 7 years 2 months]) with ONH and SOD diagnosed from 1990 to 2019, matched to 555 unrelated population-based controls (315 males, 240 females; age range 1-35 years [mean 11 years 6 months, SD 7 years 2 months]) on year of birth, sex, and area of residence. Additionally, 75 cases (46 males, 29 females; age range 2-35 years [mean 12 years 6 months, SD 7 years 2 months]) with ONH and SOD were matched one-on-one with sibling controls (40 males, 35 females; age range 0-33 years [mean 11 years 7 months, SD 7 years 10 months], the rest did not have siblings). Several antenatal maternal risk factors associated with ONH and SOD were tested for their association with case and control group membership using adjusted odds ratios (ORs) and 95% confidence intervals (CIs) from a multivariate conditional logistic regression model. The outcome was the risk of developing ONH and SOD.

RESULTS

Maternal age at conception (OR = 0.91, 95% CI = 0.86-0.96), primigravida (OR = 3.39, 95% CI = 1.92-6.01), and smoking (OR = 2.86, 95% CI = 1.61-5.05) were independently associated with ONH and SOD in the cohort matched to unrelated controls (p < 0.001). In the sibling cohort, smoking was an important risk factor (OR = 3.65, 95% CI = 1.2-11.1, p = 0.02).

INTERPRETATION

Unmodifiable and modifiable antenatal maternal risk factors are associated with ONH and SOD. Our investigation suggests that several risk factors reported in previous studies may have been due to confounding bias and that maternal smoking during pregnancy is the main modifiable risk factor associated with ONH and SOD.

WHAT THIS PAPER ADDS

Historically, many antenatal risk factors have been associated with optic nerve hypoplasia (ONH) and septo-optic dysplasia (SOD). Population-based data with matched controls for potential confounding bias are lacking. Young maternal age at conception, primigravida, and smoking during pregnancy are the main risk factors for ONH and SOD using a population-based, case-control design.

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.

Prenatal diagnosis and outcome of fetuses with isolated agenesis of septum pellucidum: cohort study and meta-analysis

OBJECTIVE

To evaluate the postnatal outcome of children with a prenatal diagnosis of apparently isolated agenesis of the septum pellucidum (ASP).

METHODS

A retrospective cohort study of cases of prenatally diagnosed ASP followed in two tertiary centers and a meta-analysis combining data from the cohort study with data from published studies identified in a systematic review were carried out. Only cases with apparently isolated ASP on antenatal ultrasound and/or magnetic resonance imaging and with available postnatal follow-up data were considered eligible for inclusion. The following outcomes were analyzed: incidence of chromosomal anomalies, agreement between antenatal and postnatal findings, overall incidence of septo-optic dysplasia (SOD) and incidence of major neurological disability (motor, language, coordination or behavioral disorder or epilepsy) in non-SOD children. The incidence of SOD in infants with apparently normal optic pathways on antenatal imaging was also evaluated.

RESULTS

Fifteen cases of isolated ASP, with median postnatal follow-up of 36 months (range, 12-60 months), were selected from the two centers. Six previously published studies met the inclusion criteria for the systematic review and a total of 78 cases were eligible for the analysis, including the 15 cases from our series. Genetic tests were carried out antenatally in 30 fetuses, of which two had an abnormal result (pooled proportion, 9.0% (95% CI, 1.8-20.7%); I²  = 0%). Additional or discordant imaging findings were noted postnatally in 9/70 (pooled proportion, 13.7% (95% CI, 3.5-29.0%); I²  = 63.9%) cases. Of all 78 neonates with available follow-up, SOD was diagnosed postnatally in 14 (pooled proportion, 19.4% (95% CI, 8.6-33.2%); I²  = 51.2%). In 60 cases, the optic pathways were considered to be normal on antenatal imaging, and six of these (pooled proportion, 9.1% (95% CI, 1.1-24.0%); I²  = 62.0%) were diagnosed postnatally with SOD. Of the 46 infants with available neurological follow-up who were not affected by SOD, a major neurological disability was diagnosed in three (pooled proportion, 6.5% (95% CI, 0.5-18.6%); I²  = 40.1%).

CONCLUSIONS

In the vast majority of cases with a prenatal diagnosis of apparently isolated ASP, the prognosis is favorable. However, an additional anomaly is detected after birth in about 14% of cases and has a negative impact on clinical outcome. Detailed antenatal assessment of the brain and optic pathways is strongly recommended in order to identify the presence of associated anomalies. Antenatal visualization of apparently normal optic pathways does not rule out SOD. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Bosch-Boonstra-Schaaf optic atrophy syndrome mimicking septo-optic dysplasia in a 10-year-old child

We report a case of confirmed Bosch-Boonstra-Schaaf optic atrophy syndrome presenting with suspected optic nerve hypoplasia, corpus callosum agenesis, and low levels of insulin-like growth factor 1. This patient's presentation demonstrates the clinical overlap of Bosch-Boonstra-Schaaf Optic atrophy syndrome with septo-optic dysplasia and the importance of genetic testing for correct diagnosis.

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.

Delayed and Precocious Puberty: Genetic Underpinnings and Treatments

Delayed puberty may signify a common variation of normal development, or indicate the presence of a pathologic process. Constitutional delay of growth and puberty is a strongly familial type of developmental pattern and accounts for the vast majority of children who are "late bloomers." Individuals with sex chromosomal abnormalities frequently have hypergonadotropic hypogonadism. There are currently 4 known monogenic causes of central precocious puberty. The primary treatment goal in children with hypogonadism is to mimic normal pubertal progression, while the primary aims for the management of precocious puberty are preservation of height potential and prevention of further pubertal development.

High prevalence of pituitary hormone deficiency in both unilateral and bilateral optic nerve hypoplasia

AIM

This study examined the prevalence of neurological impairment and pituitary hormone deficiency (PHD) in patients with unilateral and bilateral optic nerve hypoplasia (ONH).

METHODS

A population-based cross-sectional cohort study of 65 patients (51% female) with ONH was conducted in Stockholm. Of these were 35 bilateral and 30 unilateral. The patients were below 20 years of age, living in Stockholm in December 2009 and found through database searching. The median age at the analysis of the results in January 2018 was 16.1 years (range 8.1-27.5 years). Neurological assessments and blood sampling were conducted, neuroradiology was reviewed and growth curves were analysed. Diagnoses of PHDs were based on clinical and biochemical evidence of hormone deficiency.

RESULTS

Neurological impairments were identified in 47% of the patients and impairments in gross and fine motor function were more prevalent in bilateral ONH (p < 0.001). In addition, 9% had cerebral palsy and 14% had epilepsy. The prevalence of PHD was 29 and 19% had multiple PHD.

CONCLUSION

Children with ONH had a high risk of neurological impairment, especially in bilateral disease. Both unilateral and bilateral ONH signified an increased prevalence of PHD and all these children should be endocrinologically followed up until completed puberty.

Pituitary Dysfunction in Pediatric Patients with Optic Nerve Hypoplasia: A Retrospective Cohort Study (1975-2014)

BACKGROUND/AIMS

The risk factors for pituitary hormone dysfunction (PHD) in children with optic nerve hypoplasia (ONH) are not well understood. This study identified the type, timing, and predictors of PHD in children with ONH.

METHODS

ONH patient charts were reviewed retrospectively. The incidence rate of PHD was calculated assuming a Poisson distribution. Predictors of PHD were identified through a multivariable Cox proportional hazards model.

RESULTS

Among 144 subjects with ONH, 49.3% (n = 71) developed PHD over 614.7 person-years of follow-up. The incidence was 11.55 (95% confidence interval [CI]: 9.02-14.57/100 person-years). The median time to first PHD was 2.88 (interquartile range: 0.02-18.72) months. Eighty-two percent developed their first PHD by their 5th and 90% by their 10th birthday, and 89% within 5 years of ONH diagnosis. Prematurity (adjusted hazard ratio [aHR]: 0.33; 95% CI: 0.1-1.07), blindness (aHR: 1.72; 95% CI: 1.03-2.86), maternal substance abuse (aHR: 1.51; 95% CI: 0.91-2.48), abnormal posterior pituitary (aHR: 3.8; 95% CI: 2.01-7.18), and hypoplastic/absent anterior pituitary (aHR: 2.52; 95% CI: 1.29-4.91) were significant predictors of PHD.

CONCLUSIONS

The clinical predictors of PHD included blindness, pituitary gland abnormalities, and maternal substance abuse. These predictors help clinical decision-making related to the need for and frequency of hormone testing in pediatric patients with ONH.

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.

Brain Malformations Do Not Predict Hypopituitarism in Young Children with Optic Nerve Hypoplasia

BACKGROUND

Optic nerve hypoplasia (ONH), a leading cause of pediatric blindness, is associated with brain malformations and hypopituitarism in the constellation known as septo-optic dysplasia. Neuroimaging is used to anticipate hypopituitarism, but with unconfirmed reliability. We report prospective findings on the association of hypopituitarism with brain malformations.

METHODS

Children (<24 months) with ONH (n = 146; 87% bilateral) underwent baseline MRI and annual examinations and hormonal testing. Hypopituitarism status at age 5 years was classified.

RESULTS

A total of 74% had brain malformation(s). Hypopituitarism (69%) was not associated with brain malformations (p = 0.351); this persisted after adjusting for the laterality of ONH and the timing of MRI (padj = 0.869). No association was noted for absent septum pellucidum (38%; p = 0.073), corpus callosum abnormality (51%; p = 0.625), and major malformations (22%; p = 0.407). A malformation conferred a positive predictive value of 71% (95% CI: 62%, 80%), and a negative predictive value of 37% (95% CI: 22%, 54%). Overall, 10% (n = 15) of the cohort presented with a triad of absent septum pellucidum, corpus callosum abnormality, and other major malformation; only half (n = 8) of these had hypopituitarism. All 13 subjects with pituitary malformations manifested hypopituitarism, conferring predictive values of 100% (positive) and 34% (negative).

CONCLUSIONS

Hypopituitarism and brain malformations are highly prevalent, but have unrelated associations with ONH. Brain MRI in infants and toddlers with ONH is an unreliable screen for hypopituitarism risk.

Prenatal ethanol exposure in mice phenocopies Cdon mutation by impeding Shh function in the etiology of optic nerve hypoplasia

Septo-optic dysplasia (SOD) is a congenital disorder characterized by optic nerve, pituitary and midline brain malformations. The clinical presentation of SOD is highly variable with a poorly understood etiology. The majority of SOD cases are sporadic, but in rare instances inherited mutations have been identified in a small number of transcription factors, some of which regulate the expression of Sonic hedgehog (Shh) during mouse forebrain development. SOD is also associated with young maternal age, suggesting that environmental factors, including alcohol consumption at early stages of pregnancy, might increase the risk of developing this condition. Here, we address the hypothesis that SOD is a multifactorial disorder stemming from interactions between mutations in Shh pathway genes and prenatal ethanol exposure. Mouse embryos with mutations in the Shh co-receptor, Cdon, were treated in utero with ethanol or saline at embryonic day 8 (E8.0) and evaluated for optic nerve hypoplasia (ONH), a prominent feature of SOD. We show that both Cdon^-/- mutation and prenatal ethanol exposure independently cause ONH through a similar pathogenic mechanism that involves selective inhibition of Shh signaling in retinal progenitor cells, resulting in their premature cell-cycle arrest, precocious differentiation and failure to properly extend axons to the optic nerve. The ONH phenotype was not exacerbated in Cdon^-/- embryos treated with ethanol, suggesting that an intact Shh signaling pathway is required for ethanol to exert its teratogenic effects. These results support a model whereby mutations in Cdon and prenatal ethanol exposure increase SOD risk through spatiotemporal perturbations in Shh signaling activity.

Increased Intraocular Pressure in a Patient With Septooptic Dysplasia: A Case Report

INTRODUCTION

Previous studies have described septooptic dysplasia (SOD) to describe patients who have optic nerve hypoplasia, the absence of septum pellucidum, and pituitary hypoplasia. Other rare ophthalmic associations have been described, such as low-tension glaucoma. We report the ocular findings of a patient with SOD who had high intraocular pressure (IOP) and glaucoma as a part of the syndrome.

OBJECTIVES

To report the ocular findings in a Puerto Rican patient with SOD and increased IOP.

PATIENTS AND METHODS

A patient with De Morsier syndrome underwent a comprehensive eye examination, Humphrey visual fields, and Stratus optical coherence tomography, and was referred for neuroradiologic examination. The patient had increased IOP, visual field loss, and asymmetric optic nerve hypoplasia. The IOP was lowered with topical hypotensive medications.

CONCLUSIONS

The patient with the De Morsier syndrome had poor visual acuity, high IOP, visual field, and optical coherence tomography results that were all compatible with glaucoma. Further studies comparing ocular findings in patients with several mutations leading to De Morsier syndrome are warranted. To our knowledge, this is the first report on a patient with glaucoma as a part of the syndrome.

Efficacy of growth hormone replacement on anthropometric outcomes, obesity, and lipids in children with optic nerve hypoplasia and growth hormone deficiency

Background

Hypopituitarism and obesity are causes of major lifelong morbidity in patients with optic nerve hypoplasia (ONH). Growth hormone deficiency (GHD) affects the majority of children with ONH, though the degree of deficiency and variability of early growth patterns range from early severe retardation to normal initial growth. The utility of early GH replacement for improving anthropometric, body composition, and lipid outcomes in patients with ONH and GHD, especially those with normal initial height velocity, is unknown. This study examines the effects of GH replacement in a cohort of children with ONH and GHD.

Methods

Controlled clinical trial from 2005–2014. The study included 17 children with ONH and untreated GHD. Those meeting criteria for growth deceleration were assigned to treatment with recombinant human growth hormone (n = 5) while those with normal height velocity were randomized either to treatment (n = 5) or to observation (no intervention, n = 7). Study duration was 3 years. Primary outcome measures included stature, weight, weight-for-stature, and BMI standard deviation score (SDS) at study completion.

Results

Subjects on GH, irrespective of entry growth trajectory, grew more on average in stature than controls by a difference of 0.98 SDS by study end; this effect persisted after adjusting for baseline overweight status. Treatment had an effect on weight SDS only after adjusting for initial overweight status, resulting in an average increase of 0.83 SDS more than controls. Subjects who were overweight at the outset experienced greater gains in both weight and stature SDS. Treatment had no statistically significant impact on weight-for-stature or BMI SDS. A reduction in body fat percentage was observed in those treated, both before (−6.1 %) and after (−4.3 %) adjustment for initial overweight status.

Conclusion

Early GH replacement has a positive effect on short-term statural outcomes in children with ONH and GHD, even in those exhibiting normal initial linear growth. Results were less conclusive regarding treatment effects on body composition and lipids.

Magnetic resonance imaging of optic nerve

Optic nerves are the second pair of cranial nerves and are unique as they represent an extension of the central nervous system. Apart from clinical and ophthalmoscopic evaluation, imaging, especially magnetic resonance imaging (MRI), plays an important role in the complete evaluation of optic nerve and the entire visual pathway. In this pictorial essay, the authors describe segmental anatomy of the optic nerve and review the imaging findings of various conditions affecting the optic nerves. MRI allows excellent depiction of the intricate anatomy of optic nerves due to its excellent soft tissue contrast without exposure to ionizing radiation, better delineation of the entire visual pathway, and accurate evaluation of associated intracranial pathologies.

Endocrine and pubertal disturbances in optic nerve hypoplasia, from infancy to adolescence

Background

Endocrinologic abnormalities are a common co-morbidity in patients with optic nerve hypoplasia (ONH), however the impact on puberty is unknown. The purpose of this study was to examine rates of endocrine dysfunction and pubertal disturbances in a pediatric population of ONH.

Methods

A retrospective chart review was conducted on a cohort of children with ONH between January 2005 and March 2013. Endocrine dysfunction was determined based on laboratory evidence of hormone deficiency or hormone replacement. Pubertal disturbances were characterized based on presence of micropenis, tanner staging, menarche and hormone replacement. Pituitary abnormalities were classified using MRI findings. Descriptive statistics were used, and comparisons between groups were performed using the chi-square test.

Results

During the study period, 101 patients underwent an endocrine evaluation (median age: 2.3 years [0.76 – 6.5]). Hypopituitarism was present in 73% of patients with growth hormone deficiency (56%) and hypothyroidism (54%) being the most common. Pubertal disturbances (n = 19) were common; micropenis in 31% (13/42) of males and 2% with precocious puberty. Half of adolescents (n = 4/8) were diagnosed with gonadotropin deficiency. Patients with MRI pituitary abnormalities were more likely to have endocrine dysfunction than those without (p = 0.004). The sensitivity and specificity of MRI pituitary abnormalities for hypopituitarism was 54% and 92%, respectively.

Conclusions

A significant proportion of children with ONH have endocrine dysfunction. The high frequency of pubertal disturbances in this study emphasizes the need for long-term monitoring of developing endocrinopathy. While pituitary gland abnormalities are a good predictor of endocrine dysfunction, a normal pituitary gland does not rule out endocrinopathy.

Neuroimaging and clinical features of patients with optic nerve hypoplasia in Taiwan

PURPOSE

To investigate the clinical and neuroradiographic features of Chinese patients with optic nerve hypoplasia (ONH).

METHODS

This was a retrospective case series study. The medical records and magnetic resonance imaging (MRI) studies of patients diagnosed with ONH from September 2001 to December 2013 in the neuro-ophthalmology clinic of Taipei Veterans General Hospital were reviewed.

RESULTS

A total of eight eyes of five patients with ONH were enrolled in this study (1 male, 4 females). The mean age at diagnosis was 14.5 ± 12.0 years (range 0.25-30 years). Ocular examination revealed approximately half of the eyes had tortuous retinal vessels. In MRI studies, all patients had midline brain abnormalities including ectopic posterior pituitary gland (60%), agenesis of septum pellucidum (20%), and Rathke's cleft cyst (20%). Two patients had endocrinopathies-one suffered from hypopituitarism and the other had hyperprolactinemia. Both of them showed ocular findings of tortuous retinal vessels.

CONCLUSION

A high prevalence of midline brain abnormalities was noted in ONH patients of Chinese ethnicity. The presence of tortuous retinal vessels in patients with a midline brain anomaly may indicate the occurrence of endocrinopathy.

Prenatal determinants of optic nerve hypoplasia: review of suggested correlates and future focus

Optic nerve hypoplasia (ONH), a congenital malformation characterized by an underdeveloped optic nerve, is a seemingly epidemic cause of childhood blindness and visual impairment with associated lifelong morbidity. Although the prenatal determinants of ONH are unknown, early case reports have led to a longstanding speculation that risky health behaviors (e.g., prenatal use of recreational drugs, alcohol) are a likely culprit. There has yet to be a systematic review of the epidemiology of ONH to assess the common prenatal features that may help focus research efforts in the identification of likely prenatal correlates. A review of the past 50 years of epidemiologic research was conducted to examine the prenatal features linked with ONH and provide direction for future research. There are select prominent prenatal features associated with ONH: young maternal age and primiparity. Commonly implicated prenatal exposures (recreational or pharmaceutical drugs, viral infection, etc.) were rare or uncommon in large cohort studies of ONH and therefore unlikely to be major contributors to ONH. Familial cases and gene mutations are rare. The preponderance of young mothers and primiparity among cases of ONH is striking, although the significance is unclear. Recent research suggests a potential role for prenatal nutrition, weight gain, and factors of deprivation. With the rapidly increasing prevalence of ONH, future research should focus on investigating the relevance of young maternal age and primiparity and exploring the recently suggested etiologic correlates in epidemic clusters of ONH.

Septo-optic dysplasia: fitting the pieces together

A 7-year-old boy was admitted for a general tonic-clonic seizure with severe hypoglycaemia (1.39 mmol/l). His medical history was remarkable for a congenital left eye strabismus, unilateral cryptorchidism and three previous episodes of hypoglycaemic seizures with inconclusive metabolical and neurological investigations. Physical examination revealed a hoarse tone voice, dry skin, cold extremities and height in the third percentile (target height between 50th and 85th percentile). Left wrist radiography revealed a bone age of 4.5 years ±6 months Laboratory studies confirmed growth hormone deficiency and central hypothyroidism. The brain MRI showed an ectopic neurohypophysis. Neuroophthalmology investigation revealed left optic nerve hypoplasia and septo-optic dysplasia was then diagnosed. Thyroid and recombinant growth hormone replacement were started showing clinical improvement. A detailed clinical history and a careful physical examination in children presenting with multiple clinical signs of hypopituitarism may lead to a timely diagnosis, avoiding clinical morbidity associated to untreated hormonal abnormalities.

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.

The eye as a window to rare endocrine disorders

The human eye, as an organ, can offer critical clues to the diagnosis of various systemic illnesses. Ocular changes are common in various endocrine disorders such as diabetes mellitus and Graves' disease. However there exist a large number of lesser known endocrine disorders where ocular involvement is significant. Awareness of these associations is the first step in the diagnosis and management of these complex patients. The rare syndromes involving the pituitary hypothalamic axis with significant ocular involvement include Septo-optic dysplasia, Kallman's syndrome, and Empty Sella syndrome all affecting the optic nerve at the optic chiasa. The syndromes involving the thyroid and parathyroid glands that have ocular manifestations and are rare include Mc Cune Albright syndrome wherein optic nerve decompression may occur due to fibrous dysplasia, primary hyperparathyroidism that may present as red eye due to scleritis and Ascher syndrome wherein ptosis occurs. Allgrove's syndrome, Cushing's disease, and Addison's disease are the rare endocrine syndromes discussed involving the adrenals and eye. Ocular involvement is also seen in gonadal syndromes such as Bardet Biedl, Turner's, Rothmund's, and Klinefelter's syndrome. This review also highlights the ocular manifestation of miscellaneous syndromes such as Werner's, Cockayne's, Wolfram's, Kearns Sayre's, and Autoimmune polyendocrine syndrome. The knowledge of these relatively uncommon endocrine disorders and their ocular manifestations will help an endocrinologist reach a diagnosis and will alert an ophthalmologist to seek specialty consultation of an endocrinologist when encountered with such cases.

Etiology and treatment of hypogonadism in adolescents

Adequate functioning at all levels of the hypothalamic-pituitary-gonadal axis is necessary for normal gonadal development and subsequent sex steroid production. Deficiencies at any level of the axis can lead to a hypogonadal state. The causes of hypogonadism are heterogeneous and may involve any level of the reproductive system. This review discusses various causes of hypogonadism, describes the evaluation of hypogonadal states, and outlines treatment options for the induction of puberty in affected adolescents. Whereas some conditions are clearly delineated, the exact etiology and underlying pathogenesis of many disorders is unknown.

Septo-optic dysplasia and other midline defects: the role of transcription factors: HESX1 and beyond

Septo-optic dysplasia (SOD) is a highly heterogeneous condition comprising variable phenotypes including midline and forebrain abnormalities, optic nerve and pituitary hypoplasia. Most instances of SOD are sporadic and several aetiologies including drug and alcohol abuse have been suggested to account for the pathogenesis of the condition. However, a number of familial cases have been described with an increasing number of mutations in developmental transcription factors including HESX1, SOX2, SOX3 and OTX2 being implicated in its aetiology. These factors are essential for normal forebrain/pituitary development, and disruptions to these genes could account for the features observed in SOD and other midline disorders. The variable phenotypes observed within the condition are most likely due to the varying contributions of genetic and environmental factors. This review will discuss the current knowledge about SOD. Further study of these and other novel factors may shed light on the complex aetiology of this condition.

Septo-optic dysplasia

Septo-optic dysplasia (SOD), also referred to as de Morsier syndrome, is a rare congenital condition, characterized by two of the classic triad features: midline brain abnormalities, optic nerve hypoplasia (ONH) and pituitary endocrine dysfunction. We report 5 children with SOD, originally referred to be evaluated due to short stature, who also presented bilateral optic nerve hypoplasia, nystagmus and development delay. In 4 of the patients, we identified neuroimaging abnormalities of the hypothalamo-pituitary axis such as anterior pituitary hypoplasia (3/5), ectopic posterior pituitary (4/5), thin or absent stalk (3/5) and empty sella (1/5). We also encountered diverse pituitary deficiencies: growth hormone (3/5), adrenocorticotropic hormone (3/5), thyroid-stimulating hormone (2/5) and antidiuretic hormone (1/5). Only one child presented intact pituitary function and anatomy. Although rare, SOD is an important cause of congenital hypopituitarism and it should be considered in children with optic nerve hypoplasia or midline brain abnormalities for early diagnosis and treatment.

Evolving central hypothyroidism in children with optic nerve hypoplasia

BACKGROUND

Children with optic nerve hypoplasia (ONH) are at high risk for early-onset congenital central hypothyroidism (CH); however, reports of evolving, late-onset CH are rare and poorly documented.

AIM

To examine the clinical and biochemical data of children with ONH who developed CH after documented normal thyroid function tests at an earlier age.

PATIENTS AND METHODS

Children who developed late-onset CH were selected for review from an observational study (n = 214) that examined clinical risk factors for endocrinological abnormalities in children with ONH.

RESULTS

Eight patients with ONH developed CH between the ages of 20-51 months. One child at age 28 months developed CH within 4 months of prior normal thyroid function tests. There were no associations among clinical, neuroradiographical, vision, and/or pituitary outcomes.

CONCLUSIONS

Children with ONH may develop CH over time, and surveillance thyroid function tests may be necessary as frequently as every four months.

Etiology and treatment of hypogonadism in adolescents

Adequate functioning at all levels of the hypothalamic-pituitary-gonadal axis is necessary for normal gonadal development and subsequent sex steroid production. Deficiencies at any level of the axis can lead to a hypogonadal state. The causes of hypogonadism are heterogeneous and may involve any level of the reproductive system. This review discusses various causes of hypogonadism, describes the evaluation of hypogonadal states, and outlines treatment options for the induction of puberty in affected adolescents. Whereas some conditions are clearly delineated, the exact etiology and underlying pathogenesis of many disorders is unknown.

Genetic forms of hypopituitarism and their manifestation in the neonatal period

The anterior pituitary gland is a central regulator of growth, reproduction and homeostasis. The development of the pituitary gland depends on the sequential temporal and spatial expression of transcription factors and signalling molecules. Naturally occurring and transgenic murine models have demonstrated a role for many of these molecules in the aetiology of congenital hypopituitarism. These include the transcription factors HESX1, PROP1, POU1F1, LHX3, LHX4, PITX1, PITX2, OTX2, SOX2 and SOX3. Mutations in any of the genes involved in pituitary development may result in congenital hypopituitarism, which manifests as the deficiency in one or more pituitary hormones. The phenotype can be highly variable and may consist of isolated hypopituitarism, or more complex disorders such as septo-optic dysplasia (SOD) and holoprosencephaly. Neonates with congenital hypopituitarism may present with non-specific symptoms, with or without associated developmental defects such as ocular, midline and genital abnormalities. Alternatively, they may be initially asymptomatic but at risk of developing pituitary hormone deficiencies over time. The overall incidence of mutations in known transcription factors in patients with hypopituitarism is low, indicating that many genes remain to be identified. Their characterization will further elucidate the pathogenesis of this complex condition and will shed light on normal pituitary development.

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.