Secondary parkinsonism refers to a group of disorders that have features similar to those of Parkinson disease but have a different etiology. Atypical parkinsonism refers to a group of neurodegenerative disorders other than Parkinson disease that have some features of Parkinson disease but have some different clinical features, different pathology, and a different response to treatment, and the prognosis is worse. Diagnosis is by clinical evaluation and response to levodopa. Treatment is directed at the cause when possible.
(See also Overview of Movement and Cerebellar Disorders.)
In secondary parkinsonism, the mechanism is blockade of or interference with dopamine’s action in the basal ganglia.
Atypical parkinsonism encompasses neurodegenerative disorders such as
Corticobasal ganglionic degeneration
Certain spinocerebellar ataxias
Etiology of Secondary and Atypical Parkinsonism
Parkinsonism results from medications, disorders other than Parkinson disease, or exogenous toxins.
The most common cause of secondary parkinsonism is
Use of medications that decrease dopaminergic activity
These medications include
Antipsychotics (eg, phenothiazine, thioxanthene, butyrophenone)
Medications that deplete dopamine
Outside the United States, cinnarizine and flunarizine
Etiology reference
1. Wang Z, Zhang Y, Hu F, et al: Pathogenesis and pathophysiology of idiopathic normal pressure hydrocephalus. CNS Neurosci Ther 26 (12):1230-1240, 2020. Epub 2020 Nov 26. doi: 10.1111/cns.13526
Symptoms and Signs of Secondary and Atypical Parkinsonism
Clinical features of secondary and atypical parkinsonism are similar to those of Parkinson disease (eg, resting tremor, rigidity, bradykinesia, postural instability).
Diagnosis of Secondary and Atypical Parkinsonism
Clinical evaluation
Poor response to levodopa therapy
For differential diagnosis, sometimes neuroimaging
Causes of parkinsonism can be identified by the following:
A thorough history, including occupational, medications and other substances, and family history
Evaluation for neurologic deficits characteristic of neurodegenerative disorders other than Parkinson disease
Neuroimaging when indicated
Deficits that suggest neurodegenerative disorders other than Parkinson disease include gaze palsies, signs of corticospinal tract dysfunction (eg, hyperreflexia), myoclonus, autonomic dysfunction (if early or severe), cerebellar ataxia, prominent dystonia, ideomotor apraxia (inability to mimic hand motions), early dementia, early falls, and confinement to a wheelchair.
Treatment of Secondary and Atypical Parkinsonism
Treatment of the cause
Physical measures
The cause of secondary parkinsonism is corrected or treated if possible, sometimes resulting in clinical improvement or disappearance of symptoms.
Physical measures to maintain mobility and independence are useful (as for Parkinson disease). Maximizing activity is a goal. Patients should increase daily activities to the greatest extent possible. If they cannot, physical or occupational therapy, which may involve a regular exercise program, may help condition them physically. Therapists may teach patients adaptive strategies, help them make appropriate adaptations in the home (eg, installing grab bars to reduce the risk of falls), and recommend adaptive devices that may be useful.
Good nutrition is essential.
Treatment references
1. Yoshiyama Y, Kojima A, Itoh K, Uchiyama T, Arai K: Anticholinergics boost the pathological process of neurodegeneration with increased inflammation in a tauopathy mouse model. Neurobiol Dis 2012 45 (1):329-336, 2012. doi: 10.1016/j.nbd.2011.08.017
2. Yoshiyama Y, Kojima A, Itoh K, et al: Does anticholinergic activity affect neuropathology? Implication of neuroinflammation in Alzheimer's disease. Neurodegener Dis 15 (3):140-148, 2015. doi: 10.1159/000381484
Key Points
Parkinsonism can be caused by medications, toxins, neurodegenerative disorders, and other disorders that affect the brain (eg, stroke, tumor, infection, trauma, hypoparathyroidism).
Suspect parkinsonism based on the clinical evaluation and differentiate it from Parkinson disease by the lack of response to levodopa; neuroimaging may be needed.
Check for deficits that suggest a neurodegenerative disorder other than Parkinson disease.
Correct or treat the cause if possible, and recommend physical measures to maintain mobility.
