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