Optic Chiasm Slides PDF

OPTIC CHIASM OPTM 739  OPTIC CHIASM 25% of all brain tumors occur in chiasmal area Of these, ~50% present with initial complaint of visual loss  ANATOMY: CHIASM & PITUITARY Pituitary gland sets in sella turcica of...

OPTIC CHIASM OPTM 739  OPTIC CHIASM 25% of all brain tumors occur in chiasmal area Of these, ~50% present with initial complaint of visual loss  ANATOMY: CHIASM & PITUITARY Pituitary gland sets in sella turcica of sphenoid bone Diaphragma sellae is dura matter Optic chiasm sits ~10 mm above diaphragma sellae Anterior Posterior Clinoid Clinoid  POSITION OF OPTIC CHIASM Central (80%) Anterior Chiasm sits directly over pituitary gland Prefixed (10-16%) Chiasm sits anterior to pituitary gland Chiasm and optic tracts affected Postfixed (4-10%) Chiasm sits posterior to pituitary gland Chiasm and optic nerves affected POSITION OF OPTIC CHIASM  ETIOLOGIES OF CHIASMAL COMPRESSION Pituitary tumor (50-55%) Craniopharyngioma (20-25%) Meningioma (10%) Glioma (7%) Aneurysm rare PITUITARY ADENOMA Headache Vague blurring of vision VF defects Bitemporal (sup > inf) Junctional scotoma Incongruous homonymous hemianopia Diplopia “hemi-field slide”  PITUITARY ADENOMA 2 groups: Nonfunctional (non-secreting) Most common type of pituitary adenomas – 40% 70% of macroadenomas causing visual loss Hormone hypersecretion Prolactinomas and Growth Hormone most common  PITUITARY ADENOMA Normal Pituitary Macroadenoma PITUITARY ADENOMA Radiological Features: Macroadenoma protruding into sphenoid sinus Bone of floor thin and sometimes non-existent Enlarged, asymmetrical sella turcica  PITUITARY ADENOMA: TREATMENT Surgery Trans-sphenoidal Radiation Gamma Knife Proton Beam Medical therapy Bromocriptine Octreotide  PITUITARY GLAND: HORMONES Anterior Pituitary Adreno-corticotropic hormone (ACTH) Growth Hormone (GH) Melanocyte Stimulating Hormone (MSH) Thyroid Stimulating Hormone (TSH) Gonadotropins Follicle Stimulating Hormone (FSH) Luteinizing Hormone (LH) Prolactin Posterior Pituitary Oxytocin ADH  PROLACTINOMA 35% of all pituitary tumors Secretes prolactin 100-1000x normal levels Women Amenorrhea, galactorrhea, infertility Men Decreased libido, impotence, infertility, hypopituitarism, galactorrhea, gynocomastia Treatment: Medical treatment 1st line Bromocriptine Cabergoline  TSH-SECRETING ADENOMA Rare, but ~50% present with VF defects Two Types: Primary hypothyroidism leads to hyperplasia of pituitary thyrotroph cells and results in enlarged pituitary gland TSH secreting tumor leads to thyrotoxicosis – high circulating levels of T3 and T4 Thyroid Ophthalmopathy rare  GH-SECRETING ADENOMA Secretes excess growth hormone Adults: acromegaly Enlargement of hands/feet Enlargement of lower jaw, tongue Coarsening of facial features Children: gigantism Hyperthyroidism, diabetes, arthritis  ACTH-SECRETING ADENOMA Secretes excess ACTH Hormone responsible for cortisol production Cushing’s Disease Truncal obesity Thin skin and purple striae “Moon face” “Buffalo Hump” Small tumors Rarely cause chiasmal compression  PITUITARY APOPLEXY Spontaneous, rapid expansion of pituitary gland due to infarction or tumor Neuro-ophthalmic emergency Symptoms: Sudden and severe headache Sudden VA decrease/VF loss Diplopia Nausea, vomiting Often occurs with pituitary tumor, although ~80% do not know they have a pituitary tumor Sheehan’s syndrome  CRANIOPHARYNGIOMA ~3% of intracranial tumors 13.5% of all CNS tumors in children Derived from pituitary gland embryonic tissue Slow growing tumors Suprasellar region Tumors are solid, cystic or a combination  CRANIOPHARYNGIOMA: HYPOTHALAMUS DYSFUNCTION Children (female Headache, rapid onset vision loss, retro-orbital pain Optic nerve edema/optic nerve atrophy Treatment: surgery, radiation, chemotherapy Poor prognosis  ANEURYSM Location ICA OA ACA PCA Circle of Willis Rare cause of chiasmal compression CT scan and arteriography