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Horner's syndrome (also known as Bernard-Horner syndrome and oculosympathetic palsy) is a combination of symptoms that arises when a group of nerves known as the sympathetic trunk is damaged. The signs and symptoms occur on the same side as the lesion of the sympathetic trunk. It is characterized by miosis (a constricted pupil), ptosis (a weak, droopy eyelid), apparent anhidrosis (decreased sweating), with or without enophthalmus (inset eyeball). The nerves of the sympathetic trunk arise from the spinal cord in the chest, and from there ascend to the neck and face. The nerves are part of the sympathetic nervous system, a part of the autonomic (or involuntary) nervous system. Once the syndrome has been recognized, medical imaging and response to particular eye drops may be required to identify the location of the problem and the underlying cause. ==Signs and symptoms== Signs that are found in patients on the affected side of the face include * partial ptosis〔 * upside-down ptosis (slight elevation of the lower lid) * anhidrosis * miosis * pseudoenophthalmos (the impression that the eye is sunk caused by a narrow palpebral aperture) * pupillary dilation lag * loss of ciliospinal reflex * bloodshot conjunctiva, depending on the site of lesion. * unilateral straight hair (in congenital Horner's syndrome) * heterochromia iridum (in congenital Horner's syndrome) Interruption of sympathetic pathways leads to several implications. It inactivates the dilator muscle and thereby produces miosis. It inactivates the superior tarsal muscle which produces ptosis. It inactivates the orbitalis muscle which produces the effect of enophthalmos. It also reduces sweat secretion in the face. Sometimes there is flushing on the affected side of the face due to dilation of blood vessels under the skin. The pupil's light reflex is maintained as this is controlled via the parasympathetic nervous system. In children, Horner's syndrome sometimes leads to heterochromia, a difference in eye color between the two eyes.〔 This happens because a lack of sympathetic stimulation in childhood interferes with melanin pigmentation of the melanocytes in the superficial stroma of the iris. In veterinary medicine, signs can include partial closure of the third eyelid, or nictitating membrane. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Horner's syndrome」の詳細全文を読む スポンサード リンク
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