Why did Hepburn shake her head? Was it Parkinson's or something else?

An ailment recently discussed on television by her niece was not Parkinson's disease, but a progressive neurological disorder called essential tremor.Ms. Hepburn's was referred to as an inherited form of tremor.Each child of a parent with the disease has a 50 percent chance of inheriting a gene that causes it.There is no family history in some cases.