Homonymous Hemianopia Case Study

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The choroidal arteries are deep cerebral arteries that supply deep structures in the brain. The anterior choroidal artery is a branch of the internal carotid and it supplies the choroid plexus in the lateral ventricles, parts of the visual pathway, the putamen, the thalamus, and the hippocampus. The posterior choroidal artery is a branch of the posterior cerebral artery. It supplies blood to the choroid plexus of the third ventricle and parts of the thalamus and hippocampus. An occlusion of the choroidal arteries is a very serious event due to the many structures it supplies with blood. Occlusion will produce contralateral hemiplegia and hemisensory loss with homonymous hemianopia1. Homonymous hemianopia is a visual defect where a person …show more content…
When the artery becomes occluded there are two parts of the visual tract that are affected the most, the optic tract and the optic radiations. The optic tract conveys visual information from the optic chiasm to the lateral geniculate. From the lateral geniculate the visual information is carried along post-synaptic neurons that travel to the primary visual cortex, via the geniculocalcarine tract; this pathway is known as optic radiations1. Axons leaving the optic chiasm from the left are carrying information from the right visual field. Therefore if the left choroidal artery were to be compromised, then there is a chance that vision could be impaired on the right side. To test this you could have the patient track your finger in an “H” pattern, have them read off of an eye chart with both eyes open and then again with one eye open, and you could also have them look at a picture and describe it to you, or have them try to recreate it. If the person’s vision is impacted they will only be able to draw/ describe one half of the picture, they will also have a hard time tracking the finger and reading off of the chart because they are only able to see one half of their surroundings on both …show more content…
It is a basal ganglion in the central hemisphere that helps to control movement of the body. The putamen is located next to the globus pallidus and the caudate. When combined with the globus pallidus you have the lenticular nucleus, which is part of the Motor Loop. The Motor Loop basal ganglion regulates muscle contraction, muscle force, multi-joint movements, and movement selection and action. This works by the putamen receiving information from the premotor and motor cortex, which it passes on to the globus pallidus. The globus pallidus then sends output signals to the motor areas of the cerebral cortex to initiate the movement1. The Motor Loop does not interact with the lower motor neurons, it only acts on upper motor neurons and descending tracts to facilitate small, precise movements. When the Putamen is combined with the caudate we get the area of the brain known as the corpus striatum. The corpus striatum contributes to motor control. Virtually all inputs to the basal ganglia arrive via the corpus striatum. The corpus striatum is so important in motor control because it receives dopamine from the substantia nigra. Dopamine is a neurotransmitter that can be used as an excitatory to cause movement, or inhibitory to limit excessive movement. Without dopamine both excitatory and inhibitory actions suffer; patients have a hard time initiating movement and they develop a tremor. Dopamine also adjusts signals to output

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