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SEPTO-OPTIC DYSPLASIA

SEPTO-OPTIC DYSPLASIA. SOD: Definition. Variable combination of midline forebrain abnormalities, eye abnormalities and pituitary abnormalities Rare: reported incidence 1/50000; probably commoner 2/3 features to make the diagnosis Commoner in younger mothers. Forebrain abnormalities.

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SEPTO-OPTIC DYSPLASIA

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  1. SEPTO-OPTIC DYSPLASIA

  2. SOD: Definition • Variable combination of midline forebrain abnormalities, eye abnormalities and pituitary abnormalities • Rare: reported incidence 1/50000; probably commoner • 2/3 features to make the diagnosis • Commoner in younger mothers

  3. Forebrain abnormalities • In 75-80% of patients • Absence of septum pellucidum • Absence of corpus callosum • Cerebellar hypoplasia • Schizencephaly

  4. Consequences of forebrain anomalies • Fits • Behavioural difficulties • Learning difficulties • Developmental delay • Hemiplegia

  5. Optic nerve hypoplasia • Unilateral/bilateral • Bilateral commoner • Associated with anopthalmia/micropthalmia • Visual impairment variable - complete to compensated

  6. Pituitary gland • Develops from the oral cavity in the embryo and the brain (hypothalamus) • 5 different cell types in anterior pituitary producing 6 different hormones • Secretion of hormones regulated by hypothalamus

  7. Anterior pituitary gland • Growth hormone: growth and helps maintain normal blood sugar levels in children; increases bone strength, muscle mass and decreases fat mass and heart disease in adults • ACTH: regulates production of cortisol and androgens from adrenal glands; cortisol essential for normal well-being and to fight stress and infection

  8. Anterior pituitary gland • Prolactin: important for lactation, ?immune system • FSH, LH: important for puberty and fertility; LH important for normal development of males and for descent of testes into scrotum • TSH: important for regulation of thyroid gland and thyroxine production

  9. Posterior pituitary gland • Vasopressin: important for normal fluid balance - retains water by controlling reabsorption of water in kidney tubules • Oxytocin: important for parturition (birth) and ejection of milk

  10. Pituitary Hormone Deficiency • GH: poor growth with eventual short stature, possibly increased incidence of myocardial infarction • Prolactin: no lactation • ACTH: low cortisol leading to low blood sugar, lethargy, inability to fight stress and infection, low blood pressure, low sodium level in blood, collapse

  11. Pituitary Hormone Deficiency • FSH, LH: inadequate sexual development in males, lack of puberty, lack of fertility • TSH: lack of thyroxine with slowness, cold intolerance, constipation, growth failure, mental retardation if not picked up early • Vasopressin: diabetes insipidus with excessive urinary output

  12. Complexity of hypothalamo-pituitary development • Early puberty: can be explained on basis of hypothalamic involvement • Occasionally mixed involvement of hypothalamus and pituitary

  13. Clinical features of SOD • Conjugated jaundice • Neurological features • Variable visual loss • Impaired sense of smell • Endocrine features • Behavioural disturbances eg. autism • Sleep disturbance

  14. MRI SCANS OF SOD PATIENTS CONTROL SIBLING 2 SIBLING 1

  15. Management of SOD • Support from Neurologists and Opthalmologists: treatment of convulsions • Mainstay of treatment: endocrine

  16. Endocrine replacement • Growth hormone: daily subcutaneous injections • Hydrocortisone: X3 doses daily; adjustment with illness/stress • DDAVP: nasal/oral • Thyroxine • Ethinyloestradiol/testosterone

  17. Investigations • MRI scan of brain • Visual evoked responses/electroretinogram • Routine electrolyte measurement • Thyroid function tests • Pituitary function tests: glucagon/insulin/LHRH/TRH - in tertiary centres ideally • Fluid balance

  18. Monitoring • Evolving - new endocrine features may develop • Monitoring of growth rate at regular intervals • Monitoring through puberty • Regular checks of thyroid function, watch fluid balance

  19. Long-term outlook • Short stature • Developmental/intellectual impairment • Fits, hemiparesis etc • Impaired fertility • Visual impairment • Sleep/behavioural difficulties • Obesity

  20. Why do you get SOD? • Development of pituitary gland, forebrain, olfactory bulbs and eyes all from the same part of the early embryo. Problems occur at 3-6 weeks of gestation • Environment and teratogens • Familial cases: dominant or recessive

  21. Genetics of SOD • Mutations in HESX1: Dominant or recessive • Occasionally, one abnormal copy of gene carried with no phenotype in parent but child affected • Number of other developmental genes may also be involved: all extrapolated from animal studies

  22. Research • New genes involved in SOD: what is their function • Why the variability in severity • Sleep/wake cycles in children with SOD and hypothalamic involvement and the use of melatonin (10-18 year olds)

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