There are many causes of tremors and other symptoms associated with Parkinson's disease and it may take time to make an accurate diagnosis. A neurologist who specializes in movement disorders is the best person to make or confirm a diagnosis. The following information describes other disorders that may be confused with Parkinson's.
Many of the conditions described in this section are extremely rare.
Essential Tremor (ET)
Sources: International Essential Tremor Foundation, The Mayo Clinic
Essential Tremor is a chronic neurological condition characterized by involuntary, rhythmic tremor of a body part. The most frequently affected areas of the body are the hands, arms and head, followed by the voice, tongue, legs, or trunk.
ET is considered a slowly progressive disorder although for some people it may be relatively non-progressive and the tremor may be mild throughout life. Essential tremor isn't caused by other conditions and it is a common movement disorder.
Medication is a common treatment and many people with ET benefit from drug therapy, however not everyone is a candidate for the medications used to treat ET.
Surgery may be suggested to treat ET but individuals are carefully selected as possible candidates for surgery and surgical intervention is usually reserved for patients with severe, disabling tremor.
Finally, lifestyle changes as well as physical and occupational therapy may help individuals better perform tasks that are affected by ET.
Some common medications can cause Parkinson-like symptoms. Medications frequently associated with the development of Parkinsonism (the name given to a group of disorders with similar features including four primary symptoms: tremor, rigidity, slowness of movement and postural instability) include antipsychotics, metaclopramide, reserpine, tetrabenazine and some blood pressure medications such as cinnarizine and flunarizine. Fortunately, the symptoms usually abate within weeks to months after discontinuing the problem medication.
This is one reason why it is very important to inform the medical staff in a hospital or clinic that you have Parkinson's and what medications you are taking. A Medication Card, which may be obtained from Parkinson Society British Columbia, is a very useful tool for keeping track of your medications. The card contains a clear message regarding medications that must not be taken by a person with Parkinson's.
Dementia with Lewy Bodies (DLB)
This disorder is characterized by early dementia, prominent hallucinations, changes in cognitive functioning throughout the day, and symptoms similar to Parkinson's disease. Other symptoms include difficulties with attention, problem solving, planning, and with recognizing figures and images.
See Lewy Body Dementia Association.
Progressive Supranuclear Palsy (PSP)
Early development of balance problems, frequent falls, rigidity or stiffness of the trunk of the body, and (eventually) eye-movement problems can be symptoms of PSP. Symptoms usually begin after age 50 and progress more rapidly than those associated with Parkinson's disease. The most characteristic eye movement abnormality is called vertical gaze paralysis, making looking up and looking down very difficult. People with PSP may experience frequent falls while walking down stairs because they cannot look down. Dementia, depression and alterations in mood may develop later in the disease. Speech therapy, physical therapy, and antidepressants may alleviate symptoms and while there is no specific treatment for PSP, some Parkinson's medications may provide some symptom relief.
See the Society for Progressive Supranuclear Palsy.
The following conditions are rare, and can be found on the website of the National Organization for Rare Disorders. See Rare Diseases.
Corticobasal Degeneration (CBD)
This is the least common cause of symptoms similar to Parkinson's is CBD. It often affects one side far more than the other and it may progress more rapidly than Parkinson's disease. The initial symptoms of CBD usually develop after age 60 and include asymmetric bradykinesia (uncontrolled movement focusing on one side or the other), rigidity, limb dystonia (abnormal, prolonged, and repetitive muscle contractions that may cause twisting or jerking), balance problems, and speech/language problems. There is often marked and disabling apraxia (the loss of ability to carry out an intended movement even though there is no weakness or sensory loss in the arm or leg). There is no specific treatment for CBD. Supportive treatment such as botulinum toxin for dystonia, antidepressant medications and speech and physical therapy may help. Levodopa and dopamine, seldom offer benefit.
Multiple System Atrophy (MSA)
MSA is a neurodegenerative disease of unknown cause. Initially it may be difficult to distinguish from Parkinson's disease, but it is far less common and progresses more rapidly. The average age of onset is in the mid-50s. Symptoms include one or a combination of the following: bradykinesia, poor balance, abnormal autonomic function, rigidity, or difficulty with coordination. Abnormalities of autonomic function include impotence, low blood pressure upon standing (orthostatic hypotension), excessive or reduced sweating, and constipation.
There are three different subtypes of MSA:
- Striatonigral degeneration (SND) is characterized by Parkinson's symptoms but without much tremor and with poor response to Sinemet.
- Shy-Drager syndrome is characterized by Parkinson's symptoms and autonomic abnormalities.
- Olivopontocerebellar atrophy (OPCA) may involve a lack of coordination and clumsiness which affect balance and gait.
Multiple small strokes can cause Parkinson's-like symptoms. People with this disorder are more likely to have gait difficulty rather than tremors and are more likely to have symptoms that are worse in the lower limbs rather than the upper limbs. Some will also report the abrupt onset of symptoms or give a history of a step form of symptom development (symptoms get worse, then plateau for a period, then get worse again). Treatment is the same as for Parkinson's disease, but the results are often not as positive.