Atypical parkinsonism refers to a set of symptoms similar to those seen in Parkinson’s disease, but caused by other disorders. Because the symptoms are similar, it can be difficult to distinguish between Parkinson’s disease and atypical parkinsonism without extensive diagnostic testing; misdiagnoses are common.
Symptoms of atypical parkinsonism
The symptoms of atypical parkinsonism are similar to those seen in Parkinson’s disease: muscle tremors while at rest, muscle stiffness, difficulty with balance and coordination while walking, and problems with fine motor control. Symptoms may be present only in the lower body or only on one side of the body, while Parkinson’s disease symptoms are usually present on both sides of the upper and lower body.
Causes of atypical parkinsonism
There are several diseases which can cause symptoms similar to Parkinson’s disease.
Drug-induced parkinsonism
There are some medications that block dopamine receptors in the brain. These medications can cause Parkinson’s-like symptoms because they are mimicking the effect of losing dopaminergic neurons in the brain. The American Parkinson’s Disease Association provides a list of medications that can cause parkinsonism. These medications are primarily anti-nausea and anti-psychotic therapies. Drug-induced parkinsonism can be treated by weaning patients off the medication that caused the symptoms and replacing it with a different treatment.
Vascular parkinsonism
Vascular parkinsonism is thought to be caused by a series of small strokes in areas of the brain that control motor movement. Often, patients with vascular parkinsonism will have symptoms such as tremors and muscle stiffness only in the lower portion of the body. Not all patients with vascular parkinsonism respond to levodopa treatments, but some do. Treatment usually focuses on reducing the risk of further strokes by managing blood pressure, cholesterol levels, and blood sugar levels, while maximizing exercise ability with physical therapy.
Multiple system atrophy (MSA)
MSA is similar to Parkinson’s disease in its early stages, but patients often also have problems with blood pressure and bladder control, which indicate a problem with the autonomic nervous system. Patients with MSA also frequently show signs of ataxia (a loss of muscle coordination, which can cause problems with walking, picking up objects, swallowing, talking, and eye movement). MSA may respond a little to levodopa treatment, but progresses more rapidly than Parkinson’s disease.
Dementia with Lewy bodies (DLB)
DLB is a condition that causes dementia and visual hallucinations. It is caused by the clumping or aggregation of proteins in the brain, called Lewy bodies. Lewy bodies also form in Parkinson’s disease, which makes it difficult to distinguish between the diseases. The main difference is the presence of dementia versus difficulties in movement. Late-stage Parkinson’s disease can also cause dementia, but in DLB, dementia and hallucinations begin very early on. Because DLB is so closely related to Parkinson’s and Parkinson’s disease dementia, the three conditions are often grouped as Lewy body disorders.
Progressive supranuclear palsy (PSP)
PSP is a neurodegenerative disease with many subtypes. Some PSP patients are prone to falls in early stages of the disease, and some have difficulty moving their eyes up and down. However, unless the eye characteristics are present, PSP is often very difficult to differentiate from Parkinson’s disease.
Corticobasal ganglionic degeneration (CBGD)
Patients with CBGD have Parkinson’s-like symptoms, but these may manifest on only one side of the body. There are sub-types of CBGD, which may manifest with different symptoms.
Treatment of atypical parkinsonism
Treatment for atypical parkinsonism is focused on minimizing symptoms and improving quality of life. Most forms of atypical parkinsonism will not respond to levodopa treatment, but other treatments may be useful. Patients should work with a neurologist to determine the best treatment (or combination of treatments) for their symptoms. Many patients can benefit from physiotherapy to minimize falls, and speech therapy to strengthen the muscles involved in speaking and swallowing.
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