Horner's syndrome

(redirected from second order (peripheral) H's s)
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Horner's syndrome

Etymology: Johann F. Horner, Swiss ophthalmologist, 1831-1886
a neurological condition characterized by a constricted (miotic) pupil, ptosis, and facial anhidrosis, associated with a lesion in the spinal cord, with damage to a cervical nerve or any ascending part of the sympathetic outflow to the face/head. Signs are ipsilateral (same side) to the injury.
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Horner's syndrome: ptosis of the right eyelid

Horner's syndrome

The association, on one side, of a drooping upper eyelid, an apparently slightly sunken eyeball, a pupil reduced in size compared with the other, and absence of sweating on the same side of the face. This syndrome is an indication that certain nerves in the neck have been damaged, possibly by cancer. (Johann Friedrich Horner, 1831–1886, Swiss ophthalmologist)

Horner's syndrome

enophthalmos, ptosis of the upper eyelid, slight elevation of the lower lid, constriction of the pupil, and narrowing of the palpebral fissure caused by paralysis of the cervical sympathetic nerve supply.
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Horner's syndrome. By permission from Nelson RW, Couto CG, Small Animal Internal Medicine, Mosby, 2003

first order (central) H's s
caused by lesions within the parenchyma of the brain or spinal cord, before the synapse of sympathetic fibers within gray matter of thoracic segments T1 to T3.
second order (peripheral) H's s
involves the sympathetic trunk from its origin at T2 to T4 to the cranial cervical ganglion.
third order H's s
involves sympathetic fibers distal to the cranial cervical ganglion. Middle and inner ear disease can affect these fibers, which pass close to the tympanic bulla.
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