The syndrome in which sympathetic supply to face is effected causing: ptosis (unilateral), miosis (unilateral constricted pupil), anhydrosis (unilateral loss of ability to sweat), and unaffected light and accommodation reflex. The syndrome can present differently due to the different site of impairment of sympathetic system. First order neurons comprise of hypothalamus, brainstem, and cervical cord. Second order neurons travel through: T1 root ganglion, cervical sympathetic chain and superior cervical ganglion and third order neurons go from superior cervical ganglion to Muller muscles, pupil and sweat glands. When first order neurons are involved it’s a central lesion and effects face, trunk and upper limb. Second order involves pre ganglionic fibers: face involvement only. Third order are post ganglionic and effect all accept sweat glands.