Well, I am a neurologist and it may be that the muscle spasms are
myoclonus, a contributing diagnostic hallmark of CJD. Rapidly
progressive dementia is also typical of this disease which is thought
to be caused by a non-viral transmissable protein called a 'prion'
protein. The EEG is usually helpful as it demonstrates triphasic sharp
waves over one or both hemispheres in this condition. Brain biopsy is
diagnostic but almost always never done as there is no treatment for
the condition at present. Literature on this may be available from the
Alzheimer's Disease and Related Disorders Association.