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The term parkinsonism refers to a cluster of four cardinal symptoms: slowness of movement (also called akinesia or bradykinesia), tremor (typically a rest tremor), muscle stiffness, and poor balance. Although all patients with Parkinson disease (PD) have parkinsonism, not all patients with parkinsonism have PD. There are a number of other conditions that can produce these symptoms and need to be taken into consideration by your neurologist when making a diagnosis.

Many of the questions your doctor asks and the tests he or she orders are intended to rule out conditions that mimic PD, which may require a different treatment approach or progress at a different rate. These mimics include other primary neurologic diseases that are associated with “red flags,” or symptoms that differentiate them from typical PD. These disorders cause atypical parkinsonism and are sometimes called Parkinson-plus syndromes. Parkinsonism can also be secondary to a medication side effect, certain types of toxins, vascular disease of the brain, trauma, encephalitis, or normal pressure hydrocephalus. What follows is an overview of some of the most important alternate causes of parkinsonism, other than idiopathic Parkinson disease.

Primary Causes of Atypical Parkinsonism

Like Parkinson disease, the conditions listed below are considered neurodegenerative diseases, meaning they cause gradually progressive symptoms due to loss of nerve cells and function in the brain. The cause of each of these conditions is unknown.

Multiple System Atrophy (MSA)

Multiple system atrophy (MSA) is a rare degenerative neurologic disorder that causes symmetric parkinsonism along with signs of dysfunction in other parts of the nervous system. MSA typically begins between ages 55-60, and does not run in families. In addition to parkinsonism, patients have problems with coordination and/or regulation of blood pressure, temperature, respiration and urologic function. These features are clues to the diagnosis. Medications used to treat PD are not very effective for the parkinsonism of MSA, but should still be tried in case some benefit can be achieved. The other features of MSA are also treated symptomatically, with medications to boost blood pressure and reduce incontinence, and CPAP machines to help regulate breathing at night. MSA progresses more quickly than regular PD, with falls occurring relatively early in the course. In patients who present with symmetric parkinsonism but no other features to suggest MSA, it may take time to evaluate the rate of progression and response to treatment before the diagnosis can be made.

Progressive Supranuclear Palsy (PSP)

If early falls and balance problems are present, another important diagnostic consideration is progressive supranuclear palsy (PSP). Similar to MSA, this rare disease can cause symmetric parkinsonism, usually without tremor, that progresses more quickly and is less responsive to treatment than typical PD. The most distinctive feature of PSP is the eye movement disorder, characterized by drastically reduced blinking, trouble opening the eyes, and difficulty moving the eyes up and down voluntarily. Patients with PSP are very prone to falls, often falling backwards. Despite this, patients often seem reckless in their walking, which may be a sign of the cognitive problems that accompany PSP. Patients may develop behavior changes/impulsivity and difficulty performing complex tasks. Speech and swallowing changes are also common in this disorder. As with MSA, treatment should be tried but is not very effective. There is anecdotal evidence supporting the use of amantadine to decrease falls. Patients with PSP also progress more rapidly than PD patients, and need to be monitored closely due to the risk of falls and choking. There are several trials underway looking for a medication that could slow progression of PSP.

Additional resource: Cure PSP: Foundation for PSP, CBD and related brain disorders www.psp.org

Corticobasal Degeneration (CBD)

Unlike PSP and MSA, which cause relatively symmetric symptoms, corticobasal degeneration (CBD) causes asymmetric rigidity and slowness of movement initially affecting one limb, usually an arm. A jerky tremor can occur, which can make it particularly difficult to distinguish from PD early on. Patients may describe the affected limb as “dead” or “useless,” or feel that the limb has a mind of its own – this is known as the “alien limb phenomenon.” Over time, the hand may become clenched in an uncomfortable position, which can be relieved with botulinum toxin injections into the affected muscles. Patients with CBD develop difficulty using even the good hand appropriately, and may also have sensory deficits. Speech and language problems and other cognitive changes are prominent features of this disorder. There is no cure for CBD, and, similar to MSA and PSP, treatment is aimed at the individual symptoms and preventing complications.

Additional resource: Cure PSP: Foundation for PSP, CBD and related brain disorders www.psp.org

Dementia with Lewy Bodies (DLB)

When hallucinations or problems with thinking and memory are present early in the course of parkinsonism, particularly if these symptoms are present without being on medication for PD, the diagnosis of dementia with Lewy bodies (DLB) needs to be considered. This disease is a challenge to manage because there is such a delicate balance between motor and cognitive symptoms: medications used to treat the motor symptoms (levodopa or other PD meds), tend to worsen hallucinations, and medications aimed at controlling hallucinations can drastically worsen movement. DLB is characterized by fluctuating levels of alertness, attention, and cognition. Hallucinations tend to be of a visual type, usually of people or animals, and are worse in the evening. Short term memory tends to be better preserved than in Alzheimer’s disease. Patients with DLB can benefit from medications such as donepezil and rivastigmine, which work to promote the brain chemical acetylcholine.

Additional resource: Lewy Body Dementia Association www.lbda.org
See Lewy Body Support Groups and Caregiver Support Groups on this site.

Secondary Causes of Parkinsonism

These conditions are not due to progressive loss of nerve cells and function, but rather are the result of some other problem that affects the areas of the brain where symptoms of Parkinson’s arise.

Drug-induced Parkinsonism

Drug-induced parkinsonism is most often caused by medications that block the brain chemical dopamine, which is necessary for regulating movement and many other brain functions. In Parkinson’s disease, the cells that make dopamine in the brain die off too quickly, resulting in a dopamine shortage. In drug-induced parkinsonism, the brain is able to produce dopamine, but it is prevented from doing its job by the medications. Drugs that have this effect are anti-psychotics, used to treat psychiatric conditions such as schizophrenia, bipolar disorder and severe depression, and anti-emetics like metoclopramide (Reglan), which are used to prevent nausea or improve digestion. Valproate, which is used for epilepsy or to prevent migraines, can also cause parkinsonism, as can certain cardiac medications. If a patient has parkinsonism and is currently taking one of these medications, the medication should be tapered off gradually. Your neurologist can work with your other physicians to find an alternate medication that is less likely to cause these side effects. It can take several months for the effects of these drugs to wear off, so patience and close monitoring are important.

Vascular Parkinsonism

When your physician orders an MRI or CT scan of the brain, it is in part to exclude the possibility of vascular parkinsonism. In this condition, hardening of the arteries occurs in the brain and causes poor blood flow to the areas that control walking and movement. This will have the appearance of strokes on a brain scan, even though patients may not have a history of a discrete event that was recognized as a stroke. Vascular parkinsonism is also referred to as “lower body parkinsonism” due to its tendency to cause prominent gait difficulties early in its course. This helps to distinguish it from typical PD. Vascular parkinsonism may respond partially to treatment with levodopa, which should be used in conjunction with physical therapy. It is also important to prevent further vascular damage by treating high blood pressure, high cholesterol and diabetes, and by taking aspirin or clopidogrel (Plavix) to prevent blood clotting.

Normal Pressure Hydrocephalus

Normal pressure hydrocephalus (NPH) is another PD mimic that causes prominent problems with walking and can be seen on a brain scan. This condition does not generally produce tremor or muscle rigidity, but the gait disorder of NPH can sometimes be confused with Parkinson’s disease. An MRI or CT will demonstrate dilation of the fluid-filled areas in the brain, called the ventricles. A lumbar puncture is typically performed next – this allows the gait to be tested after removal of some of the fluid that surrounds the brain and spinal cord. If gait improves after this test, the patient is referred to a neurosurgeon for placement of a shunt to allow continuous drainage of the excess fluid. In addition to a gait disorder, NPH can cause incontinence and problems with thinking and memory. The gait symptoms are the main indication for treatment, however, as the other symptoms do not reliably improve with shunting.


Because PD is still a clinical diagnosis, meaning we do not have a test that can prove or disprove someone has it, we rely on the clinical signs and symptoms, the response to treatment, and how patients do over time to determine the most accurate diagnosis. It is always a good idea to discuss any unusual symptoms you have noticed or concerns that you have with your doctor.