When Andrei, a Ukrainian serviceman, was evacuated from the frontline in eastern Ukraine, he bore no visible injuries except a minor limp. But after an explosion rocked the vehicle he was travelling in, sending a violent blast wave rippling through his body, Andrei fell prey to a silent but pervasive battle wound: concussion. "I was seeing stars," says Andrei, who declined to give his last name, gesticulating loosely in an ambulance near the front-line town of Bakhmut, controlled by Russian forces. For front-line medics like Vasylyna, these are the tell-tale signs of "an insidious disease" that she says harms half of the servicemen deployed to the front. IMAGES AND SOUNDBITES ARRANGED IN SEQUENCES N°346X3M2