The phrase "misshapen head" means that someone's head does not have a normal or regular shape. It could be lopsided, uneven, or distorted in some way. Full definition
While this advice has saved thousands of babies» lives, experts have noticed a fivefold increase in misshapen heads since then. (babycenter.com)
Flat Head Syndrome (also called plagiocephaly) may have a variety of causes; recently, though, there has been a significant increase in the number of misshapen heads (and other developmental problems) that are attributable to the pressure between a baby's head and their mattress (or pillow). (tinyfry.com)
The U.S. Congress forced NASA to wash its hands of SETI in 1993 after some congressmen mocked the whole idea of spending federal money to look for «little green men with misshapen heads,» as one of them put it. (science.sciencemag.org)