It is said that in dermatomyositis(DM) , proximal muscle weakness is seen earlier than distal muscle weakness. It is also said that , DM is due to damage to small blood vessels contributing to muscle injury.( from Robbin's textbook of pathology pg.no: 1238-1239, 10e)
Shouldn't the distal group of muscles being smaller show weakness earlier? Why inclusion body myositis does not follow the pattern as in DM?