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What is Bitemoral hemianopia seen in: (PGI Nov 2009) and explain in detail?
Ans: A(Optic chiasmal lesion) "Central lesions of chiasmaQ are characterized by bitemporal hemianopiaQ & bitemporal hemianopic paralysis of pupillary reflexes . Lateral chiasmal lesionsQ salient features are binasa! hemianopia associated with binasal hemianopic paralysis of the pupillary reflexesQ"- Khurana4th/290Common Causes of Central Chiasmal Lesion areSuprasellaraneurysms, tumors of pituitary gland, craniopharyngiomaQ, suprasellar meningioma & glioma of third ventricle, third ventricular dilation due to obstructive hydrocephalus & chronic chiasmal arachnoiditisFig. Lesions of the visual pathways at the level of: 1. Optic nerve; 2. Proximal part of optic nerve; 3. Central Chiasma; 4. Laterla Chiasma (both sides}: 5. Optic tract; 6. Geniculate body; 7. Part of optic radiations in temporal lobe; 8. Part of optic radiations in parietal lobe; 9. Optic radiations: 10. Visual cortex sparing the macula; 11. Visual cortex, only macula.* Type of blindness depending on site of lesion || | HemianopiaQuadrantic hemianopia||| | | SiteCauseTypeHetronvmous hemianopiaHetronvmous hemianopiaHetronyrnous hemianopiaQ Inferior fibres of optic radiationTemporal lobe lesionQSuperior quadrantic hemianopiaQ (pie on sky )SiteTypeSiteTypeSiteTypeCentral chiasmaBitemporalhemianropiawithbitemporal paralysis of papillary reflexProximal part of optic nerveC/L hemianopia + All features of optic nerve lesion (i.e. complete blindness (I/L). abolition of direct light reflex (I/L) & consensual on C/L side)OptictractIncongruous homonymous hemianopia with C/L Wernicke's reactionSuperior fibres of optic radiationParietallobelesionQInferior qulrantic heminaopiaQ (pie on floor)LateralgcnicultatcbodyHomonymous hemianopia with sparing of papillary reflex LateralchiasmaBinasal hemianopia Q with hemianopicOpticradiation(total)Homonymous hemianopiad with sparing of papillary reflex & no optic atrophyparalysis ofpapillaryreflex AnterioroccipitalcortexCongmous homonymous hemianopia usually sparing macula