Some of the recurring questions, ones asked by many newly Parkinson disease (PD) patients, spouses, caregivers, family members, friends are:
These are legitimate questions by people who are confused by terms doctors use to convey differences (apparent to doctors) among seemingly similar disorders ( similar to patients). The doctors, in seeking to convey the differences often, inadvertently, create confusion. The purpose of this article is to a reasonable explanation of the terms.
is a disorder of slow (over many years) progression characterized by the presence in most (but not all) people of four main symptoms that are explained later in this article.
These symptoms are:
Most but not all of the symptoms respond to Sinemet (levodopa) or the dopamine agonists.
PD is characterized by specific changes in a region of the brain (the substantia nigra) at post mortem examination. In about 85% of people a neurologist trained in PD can match the symptoms to the changes in the brain.
refers to a group of disorders which in life, at one time during their evolution, may resemble PD. That is their symptoms and some of symptoms of PD resemble each other. The PD-Plus disorders may have other symptoms not found in PD. That is they’re called PD-Plus. The PD-Plus disorders differ from PD and differ from each other on post mortem examination. The PD-Plus disorders respond poorly or not at all to Sinemet or the dopamine agonists. At one time in their progression the PD-Plus disorders may be mistaken for PD and vice versa. The more common PD disorders are:
PD results from a loss of dopamine cells in a region of the brain called the substantia nigra.
These cells extend their processes (project) to another region of the brain called the striatum. The striatum consists of two parts: the caudate and the putamen. In PD, as distinct from the PD-like disorders, the cells that originate in the striatum are NOT lost nor injured. However, the processes (extensions) of the cells from the substantia nigra are lost as are the cell bodies in the substantia nigra. In PD the substantia nigra processes are lost to a greater degree in the putamen than in the caudate. In the PD-Plus disorders the processes are lost equally in the putamen and the caudate.
The above changes are detected on post-mortem examination. They cannot be detected in an office examination. Technologies called single photon emission computed tomography or SPECT and positron emission tomography or PET can measure biochemical changes in the striatum, changes which mirror the loss of dopamine cells in the substantia nigra. Using different isotopes alone and in combination, SPECT and PET are increasingly able to tell in life if a person has PD or a PD-like disorder. The expertise needed to use the different isotopes for distinguishing between PD and the PD-like disorder are not yet widely available.
In PD, on post-mortem examination, the loss of dopamine cells in the substantia nigra is accompanied by a marker present in most of the dying cells. This marker is found in a part of the cell called the cytoplasm. Under the microscope it appears as a round body, almost filling the cell. This is called a Lewy body, after Friedrich Lewy the doctor who first described it. How the Lewy body is formed, whether it is a sign of death or recovery, and the composition of the Lewy body are questions which science is seeking to answer. Such answers will bring us a long way forward toward understanding PD.
To diagnose PD, and not a PD-like disorder, there must be at least a 60% loss of dopamine cells and many if not most of them must contain Lewy bodies. In the PD-like disorders, there may be an equal or greater loss of dopamine cells but the dying cells do NOT contain Lewy bodies. It is as though a different process is killing them. The usually greater loss of dopamine cells in the PD-like disorders explains, in part, why they are less responsive to Sinemet, why if they do respond the response is less dramatic.
In PD, but not in the PD-like, the cells in the striatum are normal. Because the cells in the striatum are normal, the receptors for dopamine on these cells are normal. PD patients respond to dopamine agonists (drugs which act like dopamine on the receptors). In some of the PD-like disorders the cells in the striatum are injured or dead. And, in some of the PD-like disorders the cells in another brain region called the globus pallidus are injured or dead. The cells in the striatum extend their processes to the globus pallidus. Because in the PD-like disorders the cells in the striatum and the globus pallidus are injured or dead, the PD-like disorders respond poorly to agonists.
In life, during an office examination, the changes in the striatum and the globus pallidus cannot be detected. However, the response to Sinemet or an agonist can be detected. Thus sometimes when the diagnosis of PD or PD-like is unclear, a patient will be placed on Sinemet or an agonist as a test. The test can lasts until both doctor and patient are certain there is (or is not) a response.
PD starts slowly and progresses slowly. This mirrors the slow loss of dopamine cells. The PD-like disorders start and progress more rapidly. From onset of symptoms (often not appreciated except in retrospect) to diagnosis can be 2-4 years in PD, 1-2 years in the PD-like disorders. From diagnosis to need of symptomatic treatment may be 1-2 years in PD, less in the PD-like disorders.
With Parkinson's disease if dopamine agonists (Mirapex, Permax, Requip) are started first, approximately 80% of patients respond. Among patients who do not respond are patients originally diagnosed with PD but later diagnosed with a PD-like disorder. Thirty percent (30%) of patients treated with an agonist can be maintained on the agonist (without Sinemet) for up to 4 years. Such patients rarely develop dyskinesia. Seventy percent (70%) of patients treated with an agonist need Sinemet within 4 years. If Sinemet is started first, approximately 80% of patients respond and approximately half have dyskinesia. Among patients who respond minimally or not at all are patients originally diagnosed with PD but later diagnosed with a PD-like disorder. Such patients do not have dyskinesia.
A moderate to marked response to a dopamine agonist or Sinemet usually means PD. The development of dyskinesia usually means PD. A minimal or no response to a dopamine agonist or Sinemet usually (but not always) means a PD-like disorder. A relatively rapid course 1-2 years from onset of symptoms to diagnosis usually means a PD-like disorder. An exception are people over 70 years in whom PD progresses more rapidly. This reflects the superimposition of PD with its loss of dopamine cells on an age related loss of dopamine cells. Older people have a smaller reserve and thus their PD can progress more rapidly.
Before levodopa, or the dopamine agonists, before SPECT and PET, distinguishing PD from the PD-like disorders on the basis of an office examination could be done but not as accurately as today. PD is diagnosed on the basis of four main symptoms. Not all people have all four symptoms when they’re diagnosed. And not all people develop all four symptoms during the course of their PD. The four main symptoms are contrasted in PD and the PD-like disorders.
which the patient may feel as a stiffness or a "soreness" in a shoulder or a hip. The rigidity usually starts asymmetrically, more on one side than the other, more in the arms and legs than the neck and trunk. In the PD-like disorders, especially Progressive Supranuclear Palsy (PSP) the rigidity usually starts on both sides simultaneously is felt more in the neck and trunk and is rarely described as a "soreness. In Corticobasilar Degeneration (CBD) the rigidity, like in PD, may start asymmetrically, more on one side than the other, more in the arms and legs.
which the patient feels at rest with the arms relaxed and not moving. The resting tremor of PD usually starts asymmetrically. If a resting tremor is present, and marked, and is more on one side than the other, it is virtually specific for PD. A resting tremor is rarely present in the PD-like disorders.
Twenty percent (20%) of PD patients, usually in addition to a resting tremor, have a tremor when they extend their arms (called a postural or sustention tremor) or when they move their arms (called an action of kinetic tremor). And some patients have both a postural and action tremor. In half of patients with PD and a sustention tremor the tremor appears before the resting tremor and may be confused with a condition called Essential Tremor. Essential Tremor is perhaps 20 times more common than PD. In perhaps 10 % the tremor is sufficiently severe to require treatment. Rarely, ET becomes PD. Whether, in these instances, ET is a fore-runner of PD, or a co-incidence is, at present, unknown.
or slowness of movement is part of PD, and often part of the PD-like disorders especially PSP and Multiple System Atrophy (MSA). In PD the slowness of movement usually responds to Sinemet or the agonists. In the PD-like disorders the slowness of movement does not respond to Sinemet or the agonists. This is because, in the PD-like disorders the change in the brain are more extensive and wide-spread.
in PD results from a combination of slowness of movement of the legs and difficulty with balance. The slowness of movement, but not the difficulty with balance, responds to Sinemet and the agonists. When difficulty walking occurs in the PD-like disorders there is usually more and earlier difficulty with balance. This is why the difficulty walking in the PD-like disorders are much less likely to respond to Sinemet or the agonists. If a disorder begins with difficulty with balance the disorder is more likely to be a PD-like disorder.
PD and the PD-like disorders have other symptoms. The appearance in time of the particular symptom (early or late in the disorder) and the severity of the symptom in proportion to the four main symptoms may, sometimes, distinguish PD from the PD-like disorders. Among the more common symptoms are:
. Thirty percent (30%) of people with PD develop a dementia. This usually occurs after the diagnosis of PD is made. Dementia is more common after age 70. Dementia is usually not as frequent in PSP and MSA. Whether the absence of dementia is a feature of these disorders or whether people with these disorders do not live as long as people with PD (and so do not have time to develop dementia) is unknown. The dementia of PD is often, but not always, called Lewy Body Disease (abbreviated LBD) because Lewy bodies are seen in cells in brain regions outside the substantia nigra. If symptoms of dementia appear first and then symptoms of PD the disorder is called Lewy Body Disease. There’s a debate as to whether the appearance of PD symptoms then dementia and the appearance of dementia then PD symptoms are the same or different disorders. In some people dementia first than PD is called Alzheimer Disease with Parkinsonism.
Although at post-mortem examination differences between Lewy Body Disease and Alzheimer can be appreciated, in life the differences may not be. PD with dementia, Lewy Body Disease, and Alzheimer with Parkinsonism are sometimes called PD-Pplus or PD-like disorders.
. Some people with PD have difficulty moving their eyes. This usually occurs later in PD. The difficult in moving the eyes may not be apparent on an office examination but is apparent to the patient who has difficulty reading. In PSP the difficulty with eye movements appears early, and is apparent on an office examination. In some people with PSP the difficulty moving the eyes progresses to paralysis.
. This is also known as dysphagia and appears late in PD and in PSP and early in MSA. Difficulty swallowing results from involvement of the Autonomic Nervous System which regulates automatic activities such as swallowing.
An estimated 15 million Americans have swallowing problems. One of the most common causes is stroke although the condition can be also be associated with various neurological diseases.
Dysphagia makes it difficult or impossible to eat normally and affects both adults and children.
An estimated 60,000 people die each year from complications of dysphagia, including aspiration pneumonia. And some patients with severe dysphagia face spending the rest of their lives taking all their nourishment through a feeding tube.
A number of hospitals are offering an often overlooked treatment for some types of dysphagia. This treatment, called VitalStim Therapy is based on principles that have been successfully used in physical therapy for years. It uses neuromuscular electrical stimulation in combination with traditional physical therapy techniques to stimulate inactive swallowing musculature. The technique aids in helping patients create or re-learn functional muscle use patterns necessary to initiate or re-establish swallowing.
Dysphagia is a difficult condition to treat. It can often have a devastating impact on a person's life. According to some reports this technique has enabled some individuals who have not been able to eat for years to regain the ability to eat normally again. As with all treatments what works for someone else may or may not work in your case. Everyone is unique. Obtain the best medical advice you can obtain before starting any course of treatment.
or a drop in blood pressure on standing. This appears later in PD, is usually not disabling, and is usually related to drugs: Sinemet and the agonists. Postural hypotension appears early in MSA, may be disabling, and is not related to drugs. Postural hypotension results from involvement of the Autonomic Nervous System.
. This appears later in PD, in annoying but not disabling. This appears early in MSA and may progress to an inability to empty the bladder.
From the above PD and PD like disorders may be thought of as people who look alike because they dress alike. Underneath they are different, each from PD, and each from the other.