Parkinson's Disease - What are the Other Forms of Parkinsonism?
Other forms of parkinsonism include the following:
- Postencephalitic parkinsonism. Just after the first World War, a viral disease, encephalitis lethargica, attacked almost 5 million people throughout the world, and then suddenly disappeared in the 1920s. Known as sleeping sickness in the United States, this disease killed one third of its victims and in many others led to post-encephalitic parkinsonism, a particularly severe form of movement disorder in which some patients developed, often years after the acute phase of the illness, disabling neurological disorders, including various forms of catatonia. (In 1973, neurologist Oliver Sacks published Awakenings, an account of his work in the late 1960's with surviving post-encephalitic patients in a New York hospital. Using the then-experimental drug levodopa, Dr. Sacks was able to temporarily "awaken" these patients from their statue-like state. A film by the same name was released in 1990.) In rare cases, other viral infections, including western equine encephalomyelitis, eastern equine encephalomyelitis, and Japanese B encephalitis, can leave patients with parkinsonian symptoms.
- Drug-induced parkinsonism. A reversible form of parkinsonism sometimes results from use of certain drugs -- chlorpromazine and haloperidol, for example -- prescribed for patients with psychiatric disorders. Some drugs used for stomach disorders (metoclopramide) and high blood pressure (reserpine) may also produce parkinsonian symptoms. Stopping the medication or lowering the dosage causes the symptoms to abate.
- Striatonigral degeneration. In this form of parkinsonism, the substantia nigra is only mildly affected, while other brain areas show more severe damage than occurs in patients with primary Parkinson's disease. People with this type of parkinsonism tend to show more rigidity and the disease progresses more rapidly.
- Arteriosclerotic parkinsonism. Sometimes known as pseudoparkinsonism, arteriosclerotic parkinsonism involves damage to brain vessels due to multiple small strokes. Tremor is rare in this type of parkinsonism, while dementia -- the loss of mental skills and abilities -- is common. Antiparkinsonian drugs are of little help to patients with this form of parkinsonism.
- Toxin-induced parkinsonism. Some toxins -- such as manganese dust, carbon disulfide, and carbon monoxide -- can also cause parkinsonism. A chemical known as MPTP (1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine) causes a permanent form of parkinsonism that closely resembles Parkinson's disease. Investigators discovered this reaction in the 1980s when heroin addicts in California who had taken an illicit street drug contaminated with MPTP began to develop severe parkinsonism. This discovery, which demonstrated that a toxic substance could damage the brain and produce parkinsonian symptoms, caused a dramatic breakthrough in Parkinson's research: for the first time scientists were able to simulate Parkinson's disease in animals and conduct studies to increase understanding of the disease.
- Parkinsonism-dementia complex of Guam. This form occurs among the Chamorro populations of Guam and the Mariana Islands and may be accompanied by a disease resembling amyotrophic lateral sclerosis (Lou Gehrig's disease). The course of the disease is rapid, with death typically occurring within 5 years. Some investigators suspect an environmental cause, perhaps the use of flour from the highly toxic seed of the cycad plant. This flour was a dietary staple for many years when rice and other food supplies were unavailable in this region, particularly during World War II. Other studies, however, refute this link.
- Parkinsonism accompanying other conditions. Parkinsonian symptoms may also appear in patients with other, clearly distinct neurological disorders such as Shy-Drager syndrome (sometimes called multiple system atrophy), progressive supranuclear palsy, Wilson's disease, Huntington's disease, Hallervorden-Spatz syndrome, Alzheimer's disease, Creutzfeldt-Jakob disease, olivopontocerebellar atrophy, and post-traumatic encephalopathy.