What are atypical Parkinsonian disorders?
Atypical Parkinsonian disorders are progressive diseases that present with some of the signs and symptoms of Parkinson’s disease, but that generally do not respond well to drug treatment with levodopa. They are associated with abnormal protein buildup within brain cells.
The term refers to several conditions, each affecting particular parts of the brain and showing a characteristic course:
Dementia with Lewy bodies, characterized by an abnormal accumulation of alpha-synuclein protein in brain cells (“synucleinopathy”)
Progressive supranuclear palsy, involving tau protein buildup (“tauopathy”) affecting the frontal lobes, brainstem, cerebellum and substantia nigra
Multiple system atrophy, another synucleinopathy that affects the autonomic nervous system (the part of the nervous system that controls internal functions such as heartbeat, blood pressure, urination digestion), substantia nigra and at times the cerebellum
Corticobasal syndrome, a rare tauopathy that typically affects one side of the body more than the other and makes it difficult for patients to see and navigate through space
What are the symptoms of atypical Parkinsonian disorders?
Like classic Parkinson’s disease, atypical Parkinsonian disorders cause muscle stiffness, tremor, and problems with walking/balance and fine motor coordination.
Patients with atypical Parkinsonism often have some degree of difficulty speaking or swallowing, and drooling can be a problem. Psychiatric disturbances such as agitation, anxiety or depression may also be part of the clinical picture.
Dementia with Lewy bodies (DLB)
can cause changes in attention or alertness over hours or days, often with long periods of sleep (two hours or more) during the day. Visual hallucinations — typically of small animals or children, or moving shadows in the periphery of the visual field — are common in DLB. DLB is second only to Alzheimer’s disease as a cause of dementia in the elderly, and it most commonly affects patients in their 60s.
Patients with progressive supranuclear palsy (PSP) may have difficulties with eye movements, particularly when looking downward, and with balance — when descending stairs, for instance. Backward falls are common and may occur during the early course of the disease. PSP is not usually associated with tremor, unlike Parkinson’s disease.
Multiple system atrophy (MSA) can affect autonomic function, with urinary urgency, retention and incontinence, constipation, lightheadedness when standing (orthostasis) and significant otherwise unexplained erectile dysfunction in men. Patients may experience color and temperature changes in hands and feet, such as redness and coldness. When MSA affects the cerebellum, patients may have ataxia, characterized by a wide-based unsteady gait, and lack of coordination in the hands, feet or both.
The symptoms of corticobasal syndrome (CBS) often appear only on one side of the body. Dystonia (abnormal posture of the limbs) and myoclonus (sudden jerking) may occur. Some patients may have difficulties with simple arithmetic early on. Patients may suffer from an inability to demonstrate or recognize the use of common objects. For instance, a CBS sufferer may not be able to show how a hammer is used to strike a nail or how a spoon scoops food and directs it to the mouth. Another unusual symptom of CBS is alien limb phenomenon, in which the patient experiences his or her arm or leg as a foreign structure over which the patient has no control. Patients may repeatedly pick at buttons or zippers on their clothing without realizing it. Alien limb phenomenon can cause patients great fear and distress.
What are the risk factors for atypical Parkinsonian disorders?
Atypical Parkinsonian disorders are not currently thought to be genetic. Most cases arise from unknown causes, though some may be associated with long-term drug exposure or trauma.
Atypical Parkinsonism Diagnosis
To diagnose an atypical Parkinsonian disorder in a patient exhibiting symptoms, the doctor will start with a thorough history and neurologic exam, and determine the next course of action if Parkinson’s disease drug therapy does not resolve the problem.
He or she may use imaging techniques such as positron emission tomography (PET), magnetic resonance imaging (MRI) or methods that track dopamine transport in the brain (DAT-SPECT.)
Atypical Parkinsonism Treatment
Although research is deepening medical understanding of these disorders, atypical Parkinsonian disorders are progressive and as yet there are no treatments that effect a cure.
Supportive physical and occupational therapies can help patients cope with their symptoms, and maximizing the patient’s ability to swallow is particularly important. Psychiatric and other specific manifestations of these diseases may respond to medication.
Reviewed by Alexander Pantelyat, M.D.