In a direct strike, the electrical currents in the flash channel passes directly through the victim. The alternating stroke currents behave more like AC electricity, where the energy travels on the surface of the conductor and at the frequency typical of lightning, "everything becomes a conductor", therefore the energy may pass relatively benignly "around" the body, minimizing injury.
Metallic objects in contact with the skin may "concentrate" the lightning's energy, given it is a better natural conductor and the preferred pathway, resulting in more serious injuries, such as burns from the super heated metal. At least two cases have been reported where a strike victim wearing an iPod suffered more serious injuries as a result.
However, during a flash, the alternating stroke current flowing through the channel and around the body will generate large electromagnetic fields and EMPs, which may induce electrical transients (surges) within the nervous system or pacemaker of the heart, upsetting normal operations. This effect might explain the cases where cardiac arrest or seizures followed a lightning strike that produced no external injuries. It may also point to the victim not being directly struck at all, but being very close to the strike termination.
Another effect of lightning on bystanders is to their hearing. The resulting shock wave of thunder can damage the ears. Also, electrical interference to telephones or headphones may result in damaging acoustic noise.