Parkinson's Disease: Causes, Diagnosis and Treatment

2010-05-22
THE PUNCH Newspaper

Parkinson‘s disease, also known as Parkinson disease, PD, paralysis agitans, and shaking

palsy is a gradually progressive, degenerative neurologic disorder which typically impairs the patient‘s motor skills, speech, writing, as well as some other functions. Sufferers often have a fixed, inexpressive face, tremor at rest, slowing of voluntary movements (bradykinesia), an unusual posture, and muscle weakness. In extreme cases there is a loss of physical movement (akinesia).

Parkinson‘s disease is both chronic and progressive. Chronic means long-term, while progressive means it gradually gets worse.

Parkinsonism is a neurological syndrome characterized by tremor, rigidity, postural instability, and hypokinesia (decreased bodily movement). A syndrome is the association of several clinically recognizable features, signs, symptoms, phenomena or characteristics that often occur together. Parkinson‘s disease is the most common cause of Parkinsonism. Put simply - Parkinsonism includes the signs and symptoms that resemble Parkinson‘s disease.

While about 5% of individuals with Parkinson‘s disease are under the age of 40 years, the majority are over 50. When signs and symptoms develop in an individual aged between 21 and 40 years, it is known as Young-onset Parkinson‘s disease. Approximately 1 in every 20 patients diagnosed with PD is under 40 years of age. When signs and symptoms appear in people under 18 years of age, it is known as Juvenile Parkinson‘s disease. It affects both sexes; males slightly more than females.

According to the National Institutes of Health (NIH), USA, approximately 500,000 Americans are affected by Parkinson‘s disease; about 50,000 new diagnoses are made each year. The National Health Service (NHS), UK, estimates that about 120,000 people in the United Kingdom are affected.

As a significant number of elderly patient with early Parkinson‘s disease symptoms assume that their symptoms may form part of normal aging and do not seek medical help, obtaining accurate statistics is probably impossible. There are also a several different conditions which sometimes have comparable signs and symptoms to PD.

PD is named after James Parkinson (1755-1824), an English apothecary surgeon, paleontologist, geologist and political activist. In his most famous work An Essay on the Shaking Palsy (1817), he was the first person to describe paralysis agitans, which eventually was named after him.

Parkinson‘s disease belongs to a group of conditions called movement disorders. Movement disorders describe a variety of abnormal body movements that have a neurological basis, and include such conditions as cerebral palsy, ataxia, and Tourette syndrome. Parkinson‘s disease results from decreased stimulation of the motor cortex by the basal ganglia, typically caused by insufficient formation and action of dopamine.

There is no current cure for Parkinson‘s disease.

Treatment focuses on alleviating symptoms. Sometimes treatment may include surgery.

What are the signs and symptoms of Parkinson‘s disease?

Hands

A symptom is something the patient feels and describes, while a sign is something other people, such as the physician notice. For example, drowsiness may be a symptom while dilated pupils may be a sign.

Parkinson‘s disease causes problems with movement, cognitive problems, neurobehavioral problems, as well as sensory and sleep difficulties. The signs and symptoms usually begin gradually, slowly and often randomly (in no set order).

Each sufferer will be affected differently, with a unique set of symptoms. Patients also tend to respond differently to treatment. Symptom severity also varies enormously. Some patients may experience tremor (shaking) as their primary symptom, while others may not have tremors, but have balance problems. While the disease may develop slowly for some individuals, for others it progresses rapidly.

The four main signs and symptoms include slow physical movements (bradykinesia), shaking (tremor), muscle stiffness (rigidity) and postural instability (impaired balance and coordination). They are called the primary motor symptoms:

Primary motor symptoms:

- Bradykinesia (slowness of movement, slowed motion) - initiating movement, such as beginning to get up from a chair can become more difficult. The patient typically takes longer to carry out tasks. There is also a lack of coordination. The difficulty is not only with the execution of movement, but also with its planning and initiation. Bradykinesia is often tolerated by elderly patients, who think they are entering normal milestones of aging - such patients may eventually be diagnosed with PD later on, when other signs and symptoms develop.

- Resting tremor (shaking) - the characteristic shaking frequently starts in one hand, such as a back-and-forth rubbing of the thumb or forefinger (pill-rolling). Tremor may start in a foot or one side of the body, and less commonly in the jaw or face. Tremor is usually more likely to occur when that part of the body is resting - stress and/or anxiety may make the tremor more noticeable. However, substantial tremor is not always present in many patients. Other conditions may include tremor as one of their symptoms, such as multiple sclerosis, encephalitis (inflammation of the brain), or alcoholism. The presence of tremor does not necessarily mean the individual has Parkinson‘s disease. According to the Parkinson‘s Disease Foundation, USA, approximately 70% of people with Parkinson‘s experience a slight tremor in the early stages.

- Rigidity (muscle stiffness) - the muscles feel stiff. Doing some everyday tasks may be troublesome, such as getting out of a chair, rolling over in bed, using body language appropriately, or making fine finger movements. Most commonly, stiffness occurs in the limbs and neck. It can be so severe that the range of movements is severely undermined. Sometimes there is pain.

-Posture and balance - there may be instability when standing, or impaired balance and coordination. These symptoms, combined with bradykinesia significantly increase the risk of falling.

Secondary motor symptoms:

- A tendency to stoop, to lean forward

- Cramping

- Drooling

- Fatigue

- Handwriting may be very small and cramped (micrographia)

-Impaired fine motor dexterity (fine finger movements)

-Impaired motor coordination

-Involuntary movements and prolonged muscle contractions (dystonia)

-Loss of facial expression - some individuals may appear uninterested (not animated) when speaking, while others stare fixedly with unblinking eyes.

-Sexual dysfunction

-Speech problems - the sufferer may have a softer voice, utterances may come out more rapidly or slowly, or in a monotone. There may be repeated words or slurring.

-Swallowing difficulties (dysphagia)

-The arms may not swing when walking

Other signs and symptoms may include:

-Dementia - this may develop in the later stages of the disease. The patient may have memory and mental clarity problems. A person with Parkinson‘s is six times more likely to develop dementia, compared to other people.

-Sleep problems - which may be worsened by medications for Parkinson‘s disease. However, sleep problems are a core feature of the disease. The patient may be excessively sleepy during the day; there may be disturbances in REM (rapid eye movement) sleep, as well as insomnia.

-Constipation

-Depression

-Dysphagia (difficulty swallowing)

-Fatigue, tiredness, loss of energy

-Paresthesia - a sensation of tingling, pricking, or numbness of a person‘s skin (pins and needles)

-Reduced sensation of pain

-Reduced sense of smell

-Urinary incontinence (bladder weakness)

-Urinary retention (difficulty getting rid of urine)

What are the risk factors for Parkinson‘s disease?

A risk factor is something which increases the risk of developing a condition or disease. For example, obesity significantly raises the chances of developing diabetes type 2. Hence, obesity is a risk factor for diabetes type 2. Risk factors for Parkinson‘s disease include:

-Age - the older you get the greater the risk. Although Parkinson‘s disease can affect young people, this is exceptional.

-Genetics - a person who has a close relative (brother, sister, mother, father) with Parkinson‘s disease has a slightly higher risk of developing it himself/herself, compared to others. Even so, according to The Mayo Clinic, USA, the risk is still less than 5%.

-Gender - males are slightly more likely to develop Parkinson‘s disease compared to females.

-Toxin exposure - individuals who have been exposed to some chemicals, such as carbon monoxide, herbicides or pesticides have a slightly higher risk of developing Parkinson‘s disease, compared to other people.

-Some medications - such as antipsychotics used to treat severe paranoia and schizophrenia can cause Parkinsonism (symptoms that resemble Parkinson‘s disease).

What are the causes of Parkinson‘s disease?

The symptoms of Parkinson‘s disease are caused by a loss of nerve cells (dopaminergic cells) in a part of the brain called the substantia nigra (literally means ”black substance”). The dopaminergic cells are responsible for producing dopamine. Dopamine is a neurotransmitter; it helps transmit messages from the brain that control and coordinate body movements - dopamine allows the substantia nigra and another area of the brain, the corpus striatum to communicate; this communication coordinates proper muscle movement.

If the Dopaminergic cells in the brain are damage or perish, dopamine production goes down and the messages from the substantia nigra and the corpus striatum do not work properly. Parkinson‘s disease signs and symptoms appear when four-fifths of these nerve cells are lost. As dopamine levels continue to drop, the signs and symptoms of Parkinson‘s disease get worse.

Put simply:

-Parkinson‘s disease is caused by the degeneration or destruction of dopamine-producing nerve cells (dopaminergic cells), which in turn makes it harder for the brain to control and coordinate muscle movement.

Experts are not sure why the nerve cells that cause Parkinson‘s disease become damaged or die.

Diagnosing Parkinson‘s Disease

doctor with patient

There is no specific test for Parkinson‘s disease, making it sometimes a difficult condition to diagnose, especially early on. Parkinsonism - the group of signs and symptoms of Parkinson‘s disease - may have other causes, such as dementia with Lewy bodies, progressive supranuclear palsy, as well as some antipsychotic medication, toxins, head injuries, and some types of stroke.

A GP (general practitioner, primary care physician), usually the first health care professional people see, will base diagnosis on the signs and symptoms, the patient‘s medical history, as well as the results of a clinical examination.

Initially, when symptoms are mild during the early stages of Parkinson‘s disease, a GP will find it hard to definitively diagnose the condition. If Parkinson‘s is suspected, the GP will probably refer the patient to a specialist (neurologist).

It is vital that the doctor has experience with all the possible disorders than can masquerade as Parkinson‘s disease.

As part of their medical history, the physician will need to know about any drugs the patient is/was taking, and also whether any close family members have/had Parkinson‘s disease.

A neurological examination usually evaluates the patient‘s walking, coordination, and some simple hand tasks. The doctor may also check the patient‘s sense of smell. He/she may also prescribe a medication for Parkinson‘s disease - if it helps symptoms, it may help find out whether the individual has the disease.

The following tests may be ordered:

-Blood test - usually to rule out any other condition, such as abnormal thyroid hormone levels or liver damage.

-MRI or CT scan - to check for signs of a stroke or brain tumor. If there is/was no stroke or brain tumor, most MRI or CT scans of people with Parkinson‘s disease will appear normal.

-PET (positron emission tomography) scan - this imaging test may sometimes detect low levels of dopamine in the brain. As PET scans are expensive and not present in all hospitals, this option may sometimes not be available. PET is a highly specialized imaging technique which uses radioactive substances to create 3-dimensional colored images of those substances functioning in the body. Information about the body‘s chemistry can be gained with a PET scan, which is not the case with other imaging techniques.

-Two of the four main symptoms must be present - for a neurologist to consider a Parkinson‘s disease diagnosis, the patient must have two of the four main symptoms. They must be present over a specific period. The four main symptoms are:

-Tremor or shaking

-Bradykinesia - slowness of movement

-Rigidity (stiffness) of the arms, legs or trunk

-Postural instability - balance problems and possible falls

To recap, the following will be done to help a doctor diagnose Parkinson‘s disease:

-Look at a detailed medical history of the patient

-Carry out a physical exam

-Check medications currently being taken, and those taken in the past

-Carry out a detailed neurological exam, during which the patient performs tasks to asses agility of legs and arms, muscle tone, gait, and balance.

-Usually, results of an exam are entered into a table, called United Parkinson‘s Disease Rating Scale (UPDRS). UPDRS was created to comprehensively asses and document the examination of a patient with Parkinson‘s disease, and be able to compare data entered with future follow up examinations, or to communicate data with other neurologists.

-Observe the patient‘s response to Parkinson‘s disease medications (drugs that stimulate Dopamine production or imitate it). An example of a Parkinson‘s drug is levodopa.

A Parkinson‘s disease diagnosis is more likely if:

-Two of the four main Parkinson‘s symptoms have been present for some time

-Symptoms started on just one side of the body

-Tremor (shaking) is more evident at rest

-A Parkinson‘s drug (e.g. levodopa) produces a strong, positive response

The doctor may have to observe the patient for some time before symptoms are deemed to be consistently present. Clinical practice guidelines, which were introduced in the United Kingdom in 2006, state that diagnosis and follow-up of Parkinson‘s disease should be carried out by a specialist - usually a neurologist or geriatrician with an interest in movement disorders. A neurologist is a doctor who is specialized in the diagnosis and treatment of disorders of the nervous system. A geriatrician is a doctor who is specialized in the care of older and aging adults.

What are the treatment options for parkinson‘s disease?

Medication

There is currently (April, 2010) no cure for Parkinson‘s disease. Therapy focuses on treating the symptoms that undermine the patient‘s quality of life. As people have enormously varying symptoms and levels of severity, there is no standard or best treatment that applies to everybody.

Treatment approaches include medication, surgery, general lifestyle modifications (rest and exercise), physical therapy (UK: Physiotherapy), support groups, occupational therapy and speech therapy.

Medication - as most Parkinson‘s symptoms are caused by low levels of dopamine in the brain, most drugs are aimed at either replenishing dopamine levels, or mimicking its action - dopaminergic drugs do this. Dopaminergic medications reduce rigidity (muscle stiffness), improve speed, help with coordination, and lessen tremor (shaking). Taking dopamine itself does not help, because it cannot enter the brain.

-Levodopa - the most effective Parkinson‘s drug; is absorbed by the nerve cells in the brain and turned into dopamine. It is taken orally, in tablet or liquid form. Levodopa is combined with carbidopa to create Sinemet, a combination drug. Carbidopa prevents the levodopa from being destroyed by enzymes in the digestive tract; it also reduces levodopa side effects, such as nausea, vomiting, fatigue and dizziness. In the UK and the rest of Europe benserazide may be combined with levodopa (Madopar).

-As Parkinson‘s disease progresses the effects of levodopa may wear off and the doctor may have to increase the dosage. Increased dosage also raises the risk of developing side effects, which may include confusion, delusions, hallucinations, compulsive behavior, and dyskinesia (involuntary movements). Reducing the dosage will usually help with side effects, but with the risk that parkinsonism increases.

Side effects of selegiline may include:

-Dizziness

-Dry mouth

-Headaches

-Nausea

-Stomach pain

-Strange and/or vivid dreams

Side effects of rasagiline may include:

-Conjunctivitis

-Dizziness

-Fever, with joint and muscle aches (flu-like)

-Headache

-Indigestion

-Neck pain

-Runny nose

-Stomach pain

-COMT (catechol O-methyltransferase) inhibitors - this medication blocks the enzyme that breaks down levodopa, hence prolonging the effect of carbidopa-levodopa therapy.

-Anticholinergics - used for controlling tremor (shaking). Examples include trihexyphenidyl and benztropine (Cogentin). Some patients may find that the side effects are much greater than the slight benefits. Side effects may include urine retention, severe constipation, nausea and dry mouth. Male patients with an enlarged prostate have a higher risk of developing urine retention.

-Antivirals - may be used on its own during early-stage Parkinson‘s disease. May also be used alongside carbidopa-levodopa therapy later on. Side effects include ankle edema (swelling) and skin discoloration. An example of this drug is amantadine (Symmetrel).

-Physical therapy (UK: physiotherapy) - exercise is crucial for maintaining function. Physical therapy can help the patient improve mobility, range of motion, as well as muscle tone. Physical therapy cannot stop the progression of Parkinson‘s disease, but it can help the patient cope and feel better. The physical therapist can help relieve muscle stiffness and joint pain through movement and exercise. A qualified physical therapist (UK: physiotherapist) can help the patient improve balance and gait.

-Speech therapy - according to the National Health Service (NHS), UK, approximately half of all Parkinson‘s patients experience communication problems, such as slurred speech and poor body language. A speech and language therapist can help with the use of language and speech. Patients with swallowing difficulties may also be helped by a speech therapist.

-Occupational therapy - an occupational therapist can pinpoint everyday life problems and help work out practical solutions. Examples include getting dressed, or getting the shopping done.

Surgery

-Deep brain stimulation - a surgical procedure used to treat several disabling neurological symptoms, such as tremor, rigidity, stiffness, slowed movement and walking difficulties.

-An electrode is implanted deep inside the brain, where movement is controlled. A pacemaker-like device (neurostimulator), which controls the amount of stimulation delivered by the electrode, is placed under the skin in the upper chest. A wire travels under the skin and connects the neurostimulator to the electrode.

-Electrical impulses are sent from the neurostimulator, along the wire, and into the brain via the electrode. They interfere with the electrical signals that cause symptoms, effectively blocking them.

-Deep brain stimulation is generally used when the patient is in the advance stages of Parkinson‘s disease, and has unstable medication responses.

-The procedure has some risks, including brain hemorrhage and infection. Patients who do not respond to carbidopa-levodopa therapy do not benefit from deep brain stimulation.

- Thalamotomy - the thalamus is destroyed (lesioned) or removed by cutting (ablated). The thalamus is a tiny part of the brain. The proecedure may help reduce tremor. Thalamotomy is rarely performed these days. It may be used for patients with tremor who have not responded to medication. The procedure does not improve slow movement, walking difficulties or speech problems.

Alternative Therapies

Alternative therapies - according to the National Health Service (NHS), UK, up to 40% of patients with Parkinson‘s disease in the UK use some type of alternative therapy, such as massage, acupuncture or herbal remedies. Patients using herbal remedies and/or supplements should tell their doctor - some may interact with Parkinson‘s medications.

Nutrition: some patients with Parkinson‘s disease suffer from constipation. A diet high in fiber, as well as adequate fluid consumption is important for reducing the number of incidences as well as severity of constipation.

Postural (orthostatic) hypotension: low blood pressure when changing position - is another problem experienced by some Parkinson‘s disease patients. Doctors may advise an increase in salt and fluid intake, as well as avoiding products with caffeine in the evening, eating many small meals a day, and abstaining from alcoholic drinks.

If the patient loses weight - a common problem with Parkinson‘s disease - he/she may be referred to a dietitian.

What are the possible complications of Parkinson‘s disease?

silhouette of a man

Chewing and swallowing (dysphagia) difficulties - more commonly affects people during the later stages of the disease.

Depression, anxiety - sometimes depression may occur before other Parkinson‘s symptoms appear. According to the National Parkinson‘s Foundation, USA, it is thought that up to 50% of patients with PD experience a mood disturbance at some point during their illness.

Sexual dysfunction: some patients experience a drop in libido (sex drive). Sexual dysfunction affects more males than females.

Sleep: patients often wake up during the night. A significant number of individuals with Parkinson‘s disease find it hard to fall asleep. Being sleepy and falling asleep during the day is also common.

Urinary incontinence or retention: some patients may leak while others find it hard to pee properly. Sometimes this may be due to medications used to treat Parkinson‘s disease.

Medications: some Parkinson‘s disease medications can cause:

- Hypotension when standing up (blood pressure drops upon standing from seated or lying position)

-Involuntary twitching/jerking of arms and legs

-Hallucinations

-Drowsiness

- Obsessive compulsive behavior



 

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