Bitemporal hemianopsia

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Summary of Bitemporal hemianopsia

Bitemporal hemianopsia is the medical description of a type of partial blindness where vision is missing in the outer half of both the right and left visual field. It is usually associated with lesions of the optic chiasm, the area where the optic nerves from the right and left eyes cross near the pituitary gland.

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Bitemporal hemianopsia

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BITEMPORAL HEMIANOPSIA osms.it/bitemporal_hemianopsia PATHOLOGY & CAUSES ▪ Visional deﬁcit: lateral vision loss ▫ Optic chiasm lesions (commonly) ▪ Pathogenesis: ↑ sellar mass size → presses optic chiasm → impinges decussating visual ﬁbers (most medial) → bitemporal hemianopsia CAUSES ▪ Pituitary enlargement ▫ Hyperplasia (i.e. pregnancy or lactation); adenoma (speciﬁc, hormone-secreting pituitary hyperplasia); cyst; abscess ▪ Craniopharyngioma ▪ Meningioma (in sella turcica) ▪ Saccular aneurysm (anterior communicating artery) ▪ Primary malignancy ▫ Germ cell tumor (AKA ectopic pinealoma); chordoma; central nervous system (CNS) lymphoma COMPLICATIONS ▪ ↑ size → further impinges surrounding structures ▫ Cavernous sinus impingement → CN III, IV, VI → diplopia → ophthalmoplegia ▪ Dorsal extension of mass → dorsal midbrain impingement → Parinaud’s syndrome ▫ Upgaze paralysis ▫ Pinealomas (posterior, common) SIGNS & SYMPTOMS ▪ Vision loss ▫ Lateral ﬁelds, both eyes (may go unnoticed; chronic, progressive) ▪ Headache ▪ Diplopia 684 OSMOSIS.ORG ▪ Ophthalmoplegia (especially large mass lesions, pinealomas) ▪ Hormonal deﬁciency/excess (if pituitary growth is functional) DIAGNOSIS DIAGNOSTIC IMAGING MRI ▪ Visualize mass at area of optic chiasm; gadolinium-enhanced images aid elucidating pituitary tissue (↑ gadolinium uptake in pituitary) CT scan ▪ Less diagnostic; may reveal sellar calciﬁcation, mass TREATMENT MEDICATIONS ▪ Smaller, hormone-responsive adenomas (prolactinomas → dopamine agonists ﬁrstline therapy) SURGERY ▪ Neurosurgery: nasal aperture, posterior nasopharynx, sublabial (upper lip) incision accesses inferior aspect of cerebrum ▫ Fluoroscopic visualization: navigation, pituitary visualization ▪ First-line therapy for all other pituitary adenomas, sellar masses with meaningful visual ﬁeld impingement/other symptom severity

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Bitemporal hemianopsia

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A 50-year-old man comes to the office because of a 1-month history of progressive vision loss and chronic headaches. His medical history is relevant to high blood pressure and coronary artery disease. Upon medical interrogation, the patient also reports having a loss of sexual drive and alternating mood swings. The physical exam is noncontributory. His temperature is 36.4°C (97.5°F), pulse is 70/min, respirations are 15/min, blood pressure is 130/70 mmHg. A head CT scan with contrast reveals a large suprachiasmatic cyst with calcifications.

Which of the following visual pathway defects is most likely to be seen in this patient?

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