People with injuries to one limb sometimes report pain at the exact same spot on the opposite side. Doctors have often attributed this to overuse of the healthy limb. Neurologist Anne Louise Oaklander at Massachausetts General Hospital has shown the cause is far weirder: Nerve damage on one side actually creates a matching injury on the other side of the body. After noticing mirror-image pain in her patients with shingles, Oaklander cut nerve bundles in the hind paws of rats to see what would happen. Within a day, about half the nerves in the equivalent part of the other paw died.
Mirror nerve injuries are so precise that Oaklander concludes they must result from a specific neuronal signal. “This is most likely a mechanism that operates in health,” she says. “Perhaps it allows us to coordinate information coming from both sides of the body.” Linda Watkins, a pain expert at ...
