Parkinson's Disease & Parkinson's Plus Syndromes
Some conditions have clinical features that are similar to Parkinson's disease and may be confused with Parkinson's, especially early in the course of the disease. These conditions are called Parkinson's plus syndromes.
A severe viral disease called encephalitis lethargica affected almost 5 million people worldwide in the years just after World War I. This incident was portrayed by neurologist Dr. Oliver Sacks in the book, Awakenings, and in the movie made from this book.
Encephalitis lethargica disappeared during the 1920s, but not before it killed one-third of its victims and cast others into a seemingly catatonic state. This "sleeping sickness," as it was called in the United States, was postencephalitic parkinsonism, a disabling neurological disorder that often developed years after the acute phase of encephalitis lethargica had passed. Other viral infections, including western equine encephalomyelitis, eastern equine encephalomyelitis, and Japanese B encephalitis, have been known to cause parkinsonian symptoms as well, although rarely.
This condition is characterized by mild problems in the substantia nigra and severe damage to other parts of the brain that usually are less affected by primary Parkinson's disease. Patients with striatonigral degeneration often have greater muscular rigidity than Parkinson's patients, and their disease progresses rapidly.
Arteriosclerotic Parkinsonism or Pseudoparkinsonism
Arteriosclerotic parkinsonism is a condition in which multiple small strokes cause damage to blood vessels in the brain. This condition rarely causes tremors, but most people affected with it experience dementia. Drugs often used to treat parkinsonian symptoms are largely ineffective with pseudoparkinsonism.
Some toxins (poisonous substances) are known to cause parkinsonism. These include manganese dust, carbon disulfide, carbon monoxide, and a chemical known as MPTP (1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine).
Progressive Supranuclear Palsy (PSP)
Patients who have progressive supranuclear palsy have rigidity and bradykinesia, which may appear similar to early symptoms of Parkinson's disease. However, rigidity associated with PSP usually affects the trunk more than the limbs. Patients with progressive supranuclear palsy have a marked tendency to fall and usually do not experience tremor.
As the condition progresses, patients often develop a characteristic slowing of eye movements, loss of the ability to roll the eyes up or down, and a "suprised" facial expression.
Parkinsonian symptoms also may occur in conjunction with other neurological disorders. These diseases include progressive supranuclear palsy, Huntington's disease, Alzheimer's disease, Creutzfeldt-Jakob disease, and post-traumatic encephalopathy.