Parkinson’s Disease

General Illness Information

Medical Term: Parkinson’’s disease

Common Name: None Specified

Description: Parkinson’s disease (PD) is a chronic, progressive movement disorder which affects 1% of the population over the age of 65 years. This is a neurological disorder which becomes apparent as cells in a certain part of the brain (the basal ganglia), are lost. The disease is characterized by a tremor which is present at rest, increased muscle tone (stiffness) and/or a slowness in initiating movements.

The disease usually presents in people over the age of 50 years. In younger people without a family history of PD, symptoms like tremor are likely to be due to some other cause.

Causes: Unknown. There is accelerated loss of dopaminergic neurons in the part of the brain called substantia nigra— in normal people loss of neurons occurs at 0.5% as opposed to 1% in patients with Parkinsonism.

By definition, PD is a disease without a known cause. PD is thought to result partly from a genetic predisposition to the disease and partly from exposure to toxic substances in the environment (which are as yet unknown). If the constellation of symptoms is identical to PD, but a known environmental cause exists (e.g. carbon monoxide poisoning, a specific drug or medication, manganese exposure), then the disease is called “parkinsonism”, but not Parkinson’’s disease.

Prevention: At present, there is no medication or practice which is used to prevent PD.  Therefore, no medication is given to otherwise healthy people to prevent the disease. However, studies are being done on “neuroprotective treatments which, if used early in the course of the disease, may slow the progression of the disease.

The most promising of these neuroprotective treatments are:

• Selegiline (Eldepryl) – Selegiline is an antioxidant” therapy which may prevent damage to the affected part of the brain. At present, its “protective value is still a matter of debate, so discuss it with your physician if you are interested in this treatment.
• D3-Agonists (e.g. ropinirole; pramipexole) – These medications bind to specific (dopamine) receptors in the brain, thereby replacing the chemical (dopamine) which is in short supply in the brains of people with Parkinson’’s disease. Pramipexole is the only medication studied as a “protective drug” and it was not demonstrated to have a significant protective effect, but this may have been due to the relatively small number of people involved in the study. More studies are planned, with a larger number of subjects. Critics suggest that the above medications may treat the symptoms of the disease without necessarily slowing disease progression. In either case, these treatments are useful in early PD, because they can delay the need for a medication called levodopa. Your doctor will want to wait to prescribe levodopa until your symptoms are severe enough to require medical intervention, since this medication has many side-effects which increase with the duration of treatment.

Signs & Symptoms

• Resting Tremor – coarse” tremor which is present at rest (i.e. when one is still). This may affect one side of the body more than the other, and it often involves the arms more than the legs in the early stages. A “pill rolling tremor, which is a special sort of trembling of the thumb relative to the other fingers, is one of the classic signs of PD. The tremor may cause problems with tasks involving fine motor skills, such as buttoning clothes or cutting up food.
• Akinesia/Bradykinesia – A slowness in initiating movements. This may cause some difficulty in arising from a chair, beginning to walk from a standing position, and turning around to begin walking in another direction.  A decreased arm swing while walking may occur. “En bloc” turns (turning the whole body a few degrees at a time instead of quick pivoting) are characteristic.  The rate of blinking (of the eyes) is also noted to be slow.
• Rigidity – An increase in muscle tone, or stiffness, may be noted. The phrase “cogwheel rigidity is often used to describe a characteristic type of increase in muscle tone and jerkiness of movement which the physician might find on physical examination.
• Postural Instability and Gait Disturbances – This “postural instability” usually occurs later in the disease process. It causes some difficulty in righting oneself when balance is lost, and can result in falls and injuries. It also causes a disturbance of gait (walking pattern). This may involve foot shuffling, or other special patterns of walking. (Your physician may call this a. “festinating gait or retropulsive gait”.)
• Masked Facies – A loss of normal facial expression may be noted, giving the appearance of a “mask.
• Oily skin and/or a Rash (Seborrheic Dermatitis)
• Depression – occurs in about 20% of PD patients at some time during the course of the disease.
• Side effects of medication (especially levodopa/”L-dopa”) – include involuntary movements (dyskinesias), increased muscle tone (dystonias), freezing spells (inability to move, frozen in place”), “wearing off or on-off” motor fluctuations (increased PD symptoms, often near the time when the last dose of medication is wearing off), and hallucinations.

Risk Factors

• Age – Age is the most consistent risk factor for Parkinson’’s disease. The disease rarely occurs in people under the age of about 55 years.
• Male Gender – Men are affected four times more often than women.
• Genetics and Family History – No gene has been consistently associated with PD, with the exception of a particular, rare form of rapidly-progressive, early-onset PD, which tends to appear in patients at around the age of 40 years. In these cases a gene on chromosome 4 has been implicated. However, a family history of PD is still a recognized risk factor for the disease. People with an immediate family member with PD are 2 to 3 times more likely to develop PD than members of the general population.
• Environment and Toxin Exposure – Rural living, well water, pesticide exposure and various other factors have been studied, and have been found to increase the risk of acquiring PD.
• Smoking decreases the risk of acquiring PD in later life, BUT it substantially increases the risk of lung disease, heart disease, and many other health problems which will shorten lifespan and decrease the quality of life even more than PD.  It is NOT a recommended preventive measure for PD.

Diagnosis & Treatment

Parkinson’s disease is a diagnosis that is made by observation of the symptoms and their progression over time. The typical symptoms are: tremor, akinesia/bradykinesia, rigidity and/or postural instability. Often, the diagnosis of PD is presumed, and then confirmed when 2 or more of the above symptoms are present and other causes of parkinsonism have been ruled out.

The region of the brain that is affected is very small, and so it is not possible to see the changes on a CT scan or an MRI. There are no blood tests to diagnose this disorder (but blood tests are usually done to rule out other conditions).  If there is any doubt about the diagnosis, some physicians will recommend a trial of levodopa, a medication that should relieve the symptoms of PD. If the medication helps, then parkinsonism is diagnosed, and if no cause can be found, Parkinson’s disease is the final diagnosis. If the medication does not help, this is not parkinsonism (and therefore, not PD).

General Measures:

• Physical, occupational and speech therapy.
• Physical limitations require adjustments in the home e.g. special chairs, raised toilet seat, eating utensils and dressing oneself.

Medications:

Levodopa/Carbidopa (Sinemet or Sinemet CR) – The part of the brain which is affected in PD (the basal ganglia) normally helps to control movement. The cells in this region produce a chemical called dopamine (a neurotransmitter). As the cells become damaged, they produce less of this chemical. One of the treatments for PD is therefore a medication, levodopa/carbidopa (Sinemet or Sinemet CR), which helps to replace the missing chemical in the brain. Since levodopa has a number of side effects, its use is delayed until it is absolutely necessary. (See Signs and Symptoms, above, for a list of side effects associated with this medication.). In the meantime, conservative measures such as education/counselling, physical therapy and nutritional counselling are suggested.  Your physician may use other medications in the early stages of disease as well. These “early treatments” include:

Selegiline (Eldepryl) – This is a MAO-B (enzyme) inhibitor. It prevents the breakdown of the missing chemical”, dopamine. Side effects may preclude its use in elderly or confused patients.  This medication may help to slow the progression of the disease by protecting the dying cells from sustaining further damage.

Dopamine receptor agonists or agents that increase dopamine release – These medications include the D3-agonists ropinirole (Requip) and pramipexole, which bind special dopamine receptors and “act like dopamine, thereby serving the same function as the missing chemical. Bromocriptine and amantadine are other agents which increase dopamine release by stimulating the remaining cells in the affected part of the brain to produce more of the missing chemical. Side effects of these medications include somnolence and, in a small number of patients, hallucinations. You might be advised to avoid driving until you know how these medications affect your alertness.

If all else fails, and medical therapy does not work, then surgical methods may be used. Such techniques involve destroying areas of the brain that may cause tremor (pallidotomy) or prevent initiation of movement (thalamotomy), or implanting special electrical stimulators into the brain to perform the same function as the damaged basal ganglia. New therapies on the horizon include fetal nigral stem cell transplantation, whereby healthy cells are transplanted into the brain to replace the damaged ones.

Activity:

It is best to maintain a regular regimen of physical exercise.  Bed rest is not recommended. If you have difficulty walking, then choose activities where you are not likely to fall, but remember to stay as active as possible!

Diet:

No special diet is recommended. However, a balanced diet is recommended for general overall health maintenance, and your physician may recommend that you consult a dietitian to design a well-balanced diet which will keep you as well as possible.

If your symptoms are not responding well to medical therapy with levodopa/carbidopa (Sinemet), your physician will recommend that you eat low-protein meals or snacks around the time that you take your medication. This will help to increase your absorption of the medication. Since you need protein to stay healthy, this might mean that you end up eating your daily protein requirement in one meal (e.g. at dinnertime). This type of diet requires a lot of planning, and you will be referred to a dietitian to ensure that you will still be eating a balanced diet while following your doctor’’s recommendation.

Possible Complications :

Postural Instability and Falls – In the late stages of disease, postural instability may result. This can lead to an increasing number of falls and related injuries, and you may need to use a cane or walker or a wheelchair to ensure your own safety.

Depression and mood disturbances

Seborrheic dermatitis – This is a rash caused by overactivity of the oil glands in the skin. It is usually seen on the face.

Trouble speaking (dysarthria) or swallowing (dysphagia) – This may occur with tongue tremor, or inability to move the muscles of the mouth and tongue, but it usually does not occur until very late in the disease.

Side effects of medications – See above, under Diagnosis and Treatment.

Prognosis

The prognosis for PD is good. PD does not itself cause death, although PD patients are at increased risk for dying of other conditions, such as pneumonia. PD is a slowly progressive disease, and some people initially present with a hand tremor, which is the only symptom which is noted for the next 8 to 15 years. The disease may be staged in terms of severity according to various standardized scales (e.g. Hoehn and Yahr or UPDRS scales), and there is a typical time course of progression through the stages of the disease.

Typically, the early presentation involves mild symptoms such as tremor of an isolated body part (or body parts). These initial symptoms do not cause much disturbance of function and therefore do not generally require medication. After about 5 years, there is an increase in muscle tone (rigidity) and a difficulty in initiating movements. At this point, medication must be prescribed to alleviate symptoms and to maintain the ability to perform daily activities. After about 10 years, mobility is usually impaired and walking aids may be required. Higher doses of medication are generally needed, and symptoms may be incompletely alleviated, even with optimal treatment. At about 12 years, debilitating symptoms such as dysphagia (difficulty swallowing) may be present, and a wheelchair is often required (due to the inability to maintain posture and for reasons of general immobility).  Intractable side effects of medication are often present at these later stages of disease, and symptoms may not respond well to the medication.  At this time, the only successful treatment is surgical.

Other

Nothing Specified.

Posted by RxMed