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Old 12-08-2010
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Eye Which eye is normal?



Patient with anisocoria...

A. Diagnostic approach: key questions to ask in the evaluation of the patient with anisocoria
1. The first question to ask: Which eye is abnormal?
2. The second question to ask: Could the abnormal pupil be due to primary ocular disease?
3. If intraocular disease is not present, a neurologic cause of anisocoria is sought.
4. If the mydriatic (dilated) pupil is abnormal - is it an afferent (retina, optic nerve) or efferent (parasympathetic) lesion?
5. If the miotic (constricted) pupil is abnormal - is it a pre-ganglionic or post-ganglionic sympathetic lesion?

B. How do you determine which eye is abnormal?
1. In most patients with anisocoria, only one eye is abnormal.
Less often, both eyes are abnormal. May see with brain trauma (see later) or multiple separate primary ocular disease conditions.

2. How to look for pupil asymmetry
a. Examine from an arm's length away from patient so you can see both eyes simultaneously.
b. Dark room - use retroillumination to view tapetal reflex through pupils.

3. Which is abnormal - the miotic or mydriatic pupil?
a. Examine in light: if the mydriatic pupil fails to constrict, it is abnormal.
b. Examine in the dark: if the miotic pupil fails to dilate, it is abnormal.
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Old 12-08-2010
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After nearly drowning, an 82-year-old man suffers from severe hypoxia with resulting severe brain edema. This edema leads to raised intracranial pressure. When the pressure exceeds 200 mmHg, the medial temporal lobe begins to be compressed against the tentorium cerebelli. What is typically the first sign of such compression?

A Anisocoria contralateral to compression
B Anisocoria ipsilateral to compression
C Both pupils 56 mm and fixed
D External oculomotor ophthalmoplegia
E This condition has no effect on the eyes
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Old 12-09-2010
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D External oculomotor ophthalmoplegia

Parasympathetic fibers comprise the outermost fibers of the CN III, so it seems to be the correct answer.
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Old 01-23-2011
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i think the answer should be anisocoria of ipsilateral side.
reason: in uncal herniation (medial temporal lobe), parasympathetic effects precede the somatic effects as parasympathetic fibres are on the periphery.
so first is dilated pupil followed by the classical 'down and out' eye features.
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Old 01-23-2011
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Save It! C

edema cause increase intra cranial pressure, then this should effect both sides of medial temporal lobes leading to
bilateral dilated & fixed pupils
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Old 01-23-2011
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Quote:
Originally Posted by manphnx View Post
i think the answer should be anisocoria of ipsilateral side.
reason: in uncal herniation (medial temporal lobe), parasympathetic effects precede the somatic effects as parasympathetic fibres are on the periphery.
so first is dilated pupil followed by the classical 'down and out' eye features.

You are most correct.
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Old 01-24-2011
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Quote:
Originally Posted by dr z View Post
edema cause increase intra cranial pressure, then this should effect both sides of medial temporal lobes leading to
bilateral dilated & fixed pupils
ya! also quadriplegia. then it is called kernohan sign. the last stage of raised ict.
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