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Signs found in all patients on affected side of face include ptosis (drooping upper eyelid from loss of sympathetic innervation to the Müller muscle), upside-down ptosis (slight elevation of the lower lid), and miosis (constricted pupil) and dilation lag. Enophthalmos (the impression that the eye is sunk in) and anhidrosis (decreased sweating) on the affected side of the face, loss of ciliospinal reflex and blood shot conjunctiva may occur depending on the site of lesion.
In children Horner's syndrome sometimes leads to a difference in eye color between the two eyes (heterochromia). This happens because a lack of sympathetic stimulation in childhood interferes with melanin pigmentation of the melanocytes in the superficial stroma of the iris.
It is named after Johann Friedrich Horner, the Swiss ophthalmologist who first described the syndrome in 1869. Several others had previously described cases, but "Horner's syndrome" is most prevalent. In France, Claude Bernard is also eponymised with the condition being called "syndrome Bernard-Horner".
Horner's syndrome is usually acquired but may also be congenital (inborn) or iatrogenic (caused by medical treatment). Although most causes are relatively benign, Horner's syndrome may reflect serious pathology in the neck or chest (such as a Pancoast tumor or thyrocervical venous dilatation) and hence requires workup.
Horner's syndrome is due to a deficiency of sympathetic activity. The site of lesion to the sympathetic outflow is on the ipsilateral side of the symptoms. The following are examples of conditions that cause the clinical appearance of Horner's syndrome:
Three tests are useful in confirming the presence and severity of Horner's syndrome:
It is important to distinguish the ptosis caused by Horner's syndrome from the ptosis caused by a lesion to the oculomotor nerve. In the former, the ptosis occurs with a constricted pupil (due to a loss of sympathetics to the eye), whereas in the latter, the ptosis occurs with a dilated pupil (due to a loss of innervation to the sphincter pupillae). In an actual clinical setting, however, these two different ptoses are fairly easy to distinguish. In addition to the blown pupil in a CNIII (oculomotor nerve) lesion, this ptosis is much more severe, occasionally occluding the whole eye. The ptosis of Horner's syndrome can be quite mild or barely noticeable.
When anisocoria occurs and the examiner is unsure whether the abnormal pupil is the constricted or dilated one, if a one-sided ptosis is present then the abnormally sized pupil can be presumed to be the one on the side of the ptosis.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Horner's_syndrome". A list of authors is available in Wikipedia.|