Disorders of the chiasm - No Slide Title
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DISORDERS OF THE CHIASM
1. Anatomy
2. Pituitary adenomas• Basophil adenoma• Acidophil adenoma• Chromophobe adenoma
3. Craniopharyngioma
4. Meningioma
Anatomy of chiasm and pituitary gland
Upper nasal fibres
Macular fibres
Lower nasal fibres
Anterior clinoid
Pituitary gland
III rd ventricle
Craniopharyngioma
Optic chiasm
Diaphragma sellae
Posterior clinoid
Dorsum sellae
Normal anatomical variations
Central - 80%
Prefixed - 10% Postfixed - 10%
Pituitary adenomas
Cushing syndrome
ACTHBasophil
Growth hormone
Acromegaly Gigantism
AmenorrhoeaInfertilityGalactorrhoea
HypoglandismImpotenceInfertilityGynaecomastiaGalactorrhoea
PROLACTINChromophobe
Acidophil
Cushing syndrome
• Moon face, pigmentation and hirsutism • Hypertension and diabetes
• Obesity, skin striae, bruising and muscle weakness• Ankle oedema and osteoporosis
Acromegaly
Enlargement of hands and feet Enlargement of lower jaw
Acromegaly
• Facial coarseness • Organomegaly
• Carpal tunnel syndrome and cardiomyopathy
• Hypertension, diabetes and gonadal dysfunction
Visual field defects in pituitary adenomas LE RE
HM
CF
Decussating fibresare most vunerable
MRI of pituitary adenoma
Sagittal
CoronalAxial
Treatment options for pituitary adenomas
RadiotherapySurgery
Transfrontal
Trans-sphenoidal Bromocriptine
Craniopharyngioma Presents
• In children with endocrine dysfunction• In adults with visual field defects
LE RE
HM
CF
The posteriorly crossingfibres are most vunerable
Craniopharyngioma
Meningioma
Typically affect middle-aged women
LE REJunctional scotoma
Tuberculum Sellameningioma
Olfactory groove meningioma
Sphenoid ridge meningioma