Increased tenderness in the left third intercostal space in adult patients with myalgic encephalomyelitis: a controlled study.
Puri, B K, Gunatilake, K D R, Fernando, K A C et al.·The Journal of international medical research·2011
Researchers examined the chests of 42 people with ME/CFS and 20 healthy people to look for physical signs. They found that 81% of people with ME/CFS had tenderness (pain when touched) in a specific area on the left side of their rib cage, while none of the healthy people had this tenderness. This suggests there may be a consistent physical finding that doctors could potentially use to help identify ME/CFS.