A 55-year-old man with poorly controlled hypertension and type 2 diabetes mellitus comes to the emergency department due to difficulty seeing. He has had blurry vision for the last 2 weeks, and 1 day ago he suddenly noticed a shadow develop across the visual field of his left eye. The patient has no recent headache, double vision, vertigo, light sensitivity, or nausea. On examination, pupils are equal and reactive to light. There is an area of reduced vision in the left eye. Funduscopic examination reveals a flame-shaped hemorrhage in the left temporal hemiretina. The transmission of visual information through which of the following neural structures will be disrupted?

Question

A 55-year-old man with poorly controlled hypertension and type 2 diabetes mellitus comes to the emergency department due to difficulty seeing.  He has had blurry vision for the last 2 weeks, and 1 day ago he suddenly noticed a shadow develop across the visual field of his left eye.  The patient has no recent headache, double vision, vertigo, light sensitivity, or nausea.  On examination, pupils are equal and reactive to light.  There is an area of reduced vision in the left eye.  Funduscopic examination reveals a flame-shaped hemorrhage in the left temporal hemiretina.  The transmission of visual information through which of the following neural structures will be disrupted?

Quizplus · Accepted Answer

11ec160b_35d4_752d_9249_65f20f377a15_MD0001_00 This patient has a hypertensive hemorrhage in the left temporal hemiretina. The left temporal hemiretina receives visual information from the nasal visual field of the left eye. This visual signal is transmitted via the left optic nerve to the lateral aspect of the optic chiasm. It then joins the visual signal from the right nasal hemiretina (receives visual information from the temporal visual field of the right eye) and travels via the left optic tract to the left lateral geniculate body in the thalamus. After this homonymous visual signal leaves the left lateral geniculate body, it travels via the ipsilateral optic radiations to the ipsilateral primary visual cortex for visual processing. (Choices A, C, G and E) The inferior colliculi and medial geniculate bodies are part of the auditory pathway. (Choice D) The medial optic chiasm contains crossing nerve fibers that transmit visual information from the bilateral nasal hemiretinas. (Choice F) The right lateral geniculate body receives visual information from the right temporal hemiretina and the left nasal hemiretina. Educational objective: Damage to the left temporal hemiretina will disrupt the transmission of visual information along the ipsilateral optic nerve, lateral optic chiasm, optic tract, lateral geniculate body, optic radiations, and primary visual cortex. __________ References: Anatomy of the visual pathways. (http://www.ncbi.nlm.nih.gov/pubmed/23733119)

A 55-Year-Old Man with Poorly Controlled Hypertension and Type 2