acephalgic

adjective

ace·​phal·​gic ˌā-sə-ˈfal-jik 

of a migraine

: characterized by visual disturbances (as flashing or flickering lights) without an accompanying headache

Approximately 20% of migraineurs may experience acephalgic attacks of migraine at one time or another.

—Donald M. Pedersen

see also acephalgic migraine