In David Copperfield, Dickens' description of Miss Mowcher is that of an achondroplastic dwarf.
In achondroplasia, the epiphyses, near the ends of the long bones, cannot produce their normal elongation. So the victim has a relatively normal head and torso, with very short arms and legs. Mental development is not impaired.
Here is a URL about the condition:
http://www.consultsos.com/pandora/achondro.htm