(See also Overview of Movement and Cerebellar Disorders Overview of Movement and Cerebellar Disorders Voluntary movement requires complex interaction of the corticospinal (pyramidal) tracts, basal ganglia, and cerebellum (the center for motor coordination) to ensure smooth, purposeful movement... read more .)
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
Etiology of Secondary and Atypical Parkinsonism
Parkinsonism results from drugs, disorders other than Parkinson disease Parkinson Disease Parkinson disease is a slowly progressive, degenerative disorder characterized by resting tremor, stiffness (rigidity), slow and decreased movement (bradykinesia), and eventually gait and/or... read more , or exogenous toxins.
The most common cause of secondary parkinsonism is
Use of drugs that decrease dopaminergic activity
These drugs include
Antipsychotics (eg, phenothiazine, thioxanthene, butyrophenone)
Antiemetics and gastrointestinal drugs (eg, metoclopramide, prochlorperazine, cinitapride, clebopride)
Drugs that deplete dopamine (eg, tetrabenazine, reserpine)
Outside the US, 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
Clinical features of secondary and atypical parkinsonism are similar to those of Parkinson disease Symptoms and Signs Parkinson disease is a slowly progressive, degenerative disorder characterized by resting tremor, stiffness (rigidity), slow and decreased movement (bradykinesia), and eventually gait and/or... read more (eg, resting tremor, rigidity, bradykinesia, postural instability).
Diagnosis
Clinical evaluation
Poor response to levodopa therapy
For differential diagnosis, sometimes neuroimaging
To differentiate Parkinson disease from secondary or atypical parkinsonism, clinicians note whether levodopa results in dramatic improvement, suggesting Parkinson disease.
Causes of parkinsonism can be identified by the following:
A thorough history, including occupational, drug, 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 Conjugate Gaze Palsies A conjugate gaze palsy is inability to move both eyes together in a single horizontal (most commonly) or vertical direction. (See also Overview of Neuro-ophthalmologic and Cranial Nerve Disorders... read more , signs of corticospinal tract dysfunction (eg, hyperreflexia), myoclonus Myoclonus Myoclonus is a brief, shocklike contraction of a muscle or group of muscles. Diagnosis is clinical and sometimes confirmed by electromyographic testing. Treatment includes correction of reversible... read more , autonomic dysfunction Overview of the Autonomic Nervous System The autonomic nervous system regulates physiologic processes. Regulation occurs without conscious control, ie, autonomously. The 2 major divisions are the Sympathetic system Parasympathetic... read more 
(if early or severe), cerebellar ataxia Cerebellar Disorders Cerebellar disorders have numerous causes, including congenital malformations, hereditary ataxias, and acquired conditions. Symptoms vary with the cause but typically include ataxia (impaired... read more , prominent dystonia Dystonias Dystonias are sustained involuntary muscle contractions of antagonistic muscle groups in the same body part, leading to sustained abnormal posturing or jerky, twisting, intermittent spasms that... read more , ideomotor apraxia (inability to mimic hand motions), early dementia Dementia Dementia is chronic, global, usually irreversible deterioration of cognition. Diagnosis is clinical; laboratory and imaging tests are usually used to identify treatable causes. Treatment is... read more , early falls, and confinement to a wheelchair.
Treatment
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.
Drugs used to treat Parkinson disease are often ineffective or have only transient benefit. But amantadine or an anticholinergic drug (eg, benztropine) may ameliorate parkinsonism secondary to use of antipsychotic drugs. However, because these drugs may worsen cognitive decline and possibly increase tau pathology and neurodegeneration, their use should be limited (1 Treatment references 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... read more , 2 Treatment references 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... read more ).
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 drugs, 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.
