A 22-year-old man had intermittent paroxysmal cyanoderma on the left side of his face and upper limb (Figure 1A) occasionally accompanied by bilateral ear redness and burning sensation for a month. The typical episode lasted for 10 minutes to 2 hours, followed by spontaneous recovery. The results of neurological examination indicated hypesthesia of the left face and arm. Pupils were symmetrical and equal in size with normal pupillary light reflex. Horner syndrome and mydriasis were absent. Cerebrospinal fluid, brain magnetic resonance angiography, computed tomography angiography of cervical arteries, enhanced magnetic resonance imaging, and skin sympathetic response testing had unremarkable results. Cervical magnetic resonance imaging showed a C5 to C6 herniated disc.