Anisocoria with a Constricted Pupil in the Affected Eye
Horner’s Syndrome
Causes:
Damage to the sympathetic pathway.
❖ Central (first neuron):
– Tumors.
– Encephalitis.
– Diffuse encephalitis.
❖ Peripheral (second neuron):
– Syringomyelia.
– Diffuse encephalitis.
– Trauma.
– Rhinopharyngeal tumors.
– Goiter.
– Aneurysm.
– Processes in the tip of the lung.
❖ Peripheral in the strict sense (third neuron):
– Vascular processes.
– Internal carotid aneurysm.
Clinical Picture:
❖ Miosis (approximately 1 – 2 mm difference) due to failure of the dilator pupillae muscle.
❖ Ptosis (approximately 1 – 2 mm difference) due to failure of the muscle of Müller.
❖ Enophthalmos due to failure of the rudimentary lower eyelid retractors. This makes the lower eyelid project so that the eye appears smaller. This condition only represents a type of pseudoenophthalmos.
❖ Decreased sweat gland secretion (only present in preganglionic disorders as the sweat glands receive their neural supply via the eternal carotid).
Diagnostic considerations:
❖ Direct and consensual light reflexes are intact, which distinguishes this disorder from a parasympathetic lesion); the pupil dilates more slowly (dilation deficit).
❖Near reflex is intact.
❖ Pharmacologic testing with cocaine eyedrops:
– Peripheral Horner’s syndrome:On the affected side, there is slight mydriasis (decrease in norepinephrine due to nerve lesion). On theunaffected side, there is significant mydriasis.
– Central Horner’s syndrome:On the affected side, the pupil is dilated. Onthe unaffected side, the pupil is also dilated (the norepinephrine in thesynapses is not inhibited).
Following Eyedrop Application (Unilateral Administration of a Miotic as in Glaucoma Therapy)
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