Atypical parkinsonism is a term that refers to diseases that share some features of parkinsonism (slowness of movement, muscle stiffness, tremor, or walking/balance problems), but tend to be more rapidly progressive, while less likely to respond to the drugs used to treat Parkinson disease (PD).
Early in disease, a person with atypical parkinsonism may have features that mimic PD, and this commonly will lead to a wrong diagnosis. Usually over time features unique to each form of atypical parkinsonism will declare themselves and therefore allow a doctor to correct the diagnosis. Forms of atypical parkinsonism are not usually genetic diseases, or at best do not appear to spread in a genetic pattern through families. The first four disorders discussed below were formerly called “Parkinson-plus” syndromes, though the name was changed in part due to the fact that they are not forms of Parkinson disease, thus a misleading term. Drug-induced, or tardive parkinsonism will not be discussed here, though these too, are forms of parkinsonism that are not PD. Also not discussed , due to the fact that they are very rare conditions which only sometimes mimic PD, are illnesses such as certain forms of spinocerebellar ataxia, neurodegeneration with brain iron accumulation, Fahr’s disease, the Westphal variant of Huntington disease, and many others. This article lists the illnesses which are usually implied when a doctor refers to atypical parkinsonism.
Corticobasal degeneration (CBD) (also known as corticobasal syndrome) typically affects one side of the body more than the other, classically resulting in apraxia, the inability to carry out learned movements in the absence of weakness or impaired sensation. For example, a person with CBD may not be able to turn a car key, use a spoon properly, or use scissors. In these patients another common issue is dystonia, a semi-sustained contraction of a pair of opposing muscles. Dystonia may cause painful twisting and cramp-like pain in a limb. Myoclonus, a sudden, brief, jerking movement, is common. Another unusual feature of CBD is alien limb phenomenon, wherein a person feels like an arm or leg is not their own, and they may not be able to control it. Similar to Alzheimer disease and PSP (below), CBD is a tauopathy, in which abnormal tau protein accumulations collect in key locations of the brain. Dystonia is treated with botulinum toxins (Botox, Dysport, Xeomin, or Myobloc). Myoclonus may sometimes be treated with levetiracetam (Keppra), valproic acid (Depakote), or clonazepam (Klonopin).
Dementia with Lewy bodies (DLB) is the second most common form of neurodegenerative dementia (after Alzheimer disease), and tends to start in the 50s, though it may occur at any age after 50. These patients have progressive cognitive problems in the first year of disease, with or before motor features as described above. The parkinsonism tends to be symmetric. Patients with DLB often describe illusions, in which one object or a pattern, takes on the appearance of something else. For example, one might see a person in the branches of a tree, or a face in a pattern on wallpaper. Visual hallucinations tend to come after illusions, and are common. Usually these are small animals or children, or moving shadows in the periphery of the visual field, so-called “passage hallucinations.” DLB patients tend to fluctuate, having good days and bad days (or weeks), which may be severe. These patients tend to have delusional thoughts, believing something that could not possibly be true, such as a newscaster talking directly to through the television. Paranoia is also common. And, importantly, these patients are very sensitive to neuroleptics, drugs which can cause parkinsonism, such as metoclopramide (Reglan),and the antipsychotic medications which block dopamine receptors. These drugs should be avoided in patients with DLB. Newer atypical antipsychotics may be tolerated in these patients. DLB is characterized by an abnormal accumulation of misfolded alpha-synuclein protein in brain cells, which result in Lewy bodies.
Multiple system atrophy (MSA) is a form of symmetric parkinsonism in which autonomic function tends to be biggest problem: urinary symptoms such as urgency, retention, or incontinence, sexual dysfunction, GI issues such as constipation, blood pressure problems resulting in lightheadedness when standing or after eating a large meal, or cardiac issues. Patients may notice red hands and feet, and they may feel they do not tolerate cold temperatures well. There are two main forms of MSA. MSA-C (formerly known as OPCA), affects the cerebellum and results in very poor balance, gait problems, and poor coordination. MSA-P (formerly known as striatonigral degeneration), mimics PD, but is more rapid and is unresponsive to dopaminergic medication because the disease harms the striatum, where dopamine is used. In MSA misfolded alpha-synuclein accumulates in key locations that are associated with damage. The low blood pressure issues are usually treated by stopping antihypertensives (blood pressure lowering medications), lowering doses of carbidopa/levodopa (if taken), liberalizing salt, and adding drugs such as midodrine, fludrocortisone (Florinef), or droxidopa (Northera).
Progressive supranuclear palsy (PSP) is a symmetric parkinsonian condition in which early eye movement problems (especially downgaze, such as looking down at your feet), and falls usually bring patients to the neurologist. In PSP there is typically no flexion of gait, and patients develop a high degree of rigidity of the spine, so-called “axial rigidity.” There is usually no tremor in PSP. PSP is a tauopathy similar to Alzheimer disease and CBD. The balance issues in PSP are initally treated with physical therapy. Sometimes the vision issues can be treated with prism glasses.
Vascular parkinsonism is usually caused by stroke or small vessel disease (damage to tiny blood vessels in the brain). In most cases gait/balance issues are the most prominent problems, and often it seems to be predominantly lower extremity disease. Tremor is uncommon in vascular parkinsonism, and dopaminergic medications are usually unhelpful. High blood pressure is the leading cause of small vessel disease.
If you or a loved one have an atypical form of parkinsonism, please see the article Janet Edmunson on the atypical parkinsonism support group.
