BLINK TO VISUAL THREAT DOES NOT HERALD CONSCIOUSNESS IN THE VEGETATIVE STATE

The blink response to visual threat is a standard bedside method for testing visual processing. In response to a sudden gesture directed toward the eyes, a person with a normal blink response will promptly contract both orbicularis oculi muscles to close the eyelids momentarily. There is no consensus as to whether blinking to visual threat (BVT) is purely reflex¹ or a cognitively mediated behavior that heralds consciousness; i.e., is incompatible with the diagnosis of the vegetative state (VS).^2,3 Some authors stated that “one should be extremely cautious in making the diagnosis of the VS when there is … response to threatening gestures.”⁴ Others stated that “react(ion) to visual threat” is a “compatible but atypical feature” of VS.⁵ Similarly, other guidelines stated that the “threat response is usually absent” in VS.⁶ Finally, BVT was not mentioned in some workgroup criteria on the minimally conscious state.⁷

The aim of the study was to determine the incidence of BVT in patients whose clinical features are in all other respects typical of the VS, as assessed by means of validated testing.⁷ We also investigated whether the presence of BVT in patients considered vegetative is predictive of recovery of consciousness.