Parkinson’s Disease – Diagnosis, Symptoms, and Treatment

What is Parkinson's Disease?

Parkinson's disease is a degenerative neurologic condition that typically causes progressive tremor, slowed movement, muscle stiffness, and trouble walking. Eventually, individuals may develop behavioral changes.  Most people develop symptoms during middle age (around age 56).

The condition usually starts with shaking or tremor in one arm.  Over time, patients may become physically disabled without the ability to perform daily activities. This condition is a relatively common cause of falls in the elderly.

What Causes Parkinson's Disease?

Parkinson's disease is caused by the degeneration of nerve cells in a specific brainstem region called the substantia nigra.  This part of the brain is responsible for generating dopamine, an essential molecule for the smooth pursuit of movement.

The most common form of Parkinson's disease is called sporadic Parkinson's disease – this accounts for about 90% of cases.  Sporadic Parkinson's disease is related to specific genetic abnormalities. Family members of people with this condition have a higher likelihood of developing the disease.

In some cases, people may develop features such as tremor, slow movement, and muscle stiffness due to another condition such as:

•         Stroke
•         Traumatic brain injury
•         Medication use – Antipsychotics

The most commonly prescribed drugs associated with Parkinson's features include the long-term use of Haldol – haloperidol, Risperdal - risperidone), or certain nausea medications (Reglan - metoclopramide).  These medications are less likely to cause symptoms if used at low doses and for a short period.

How Common is Parkinson's Disease?

It affects approximately 0.1-0.5% of Americans.  About 1 million people in the United States have this condition.  It typically affects people around age 56 and is rare before age 30.  This condition frequently requires referral to a Neurology specialist.

Signs and Symptoms

The most common features of Parkinson's disease include:

•         Resting Tremor
•         Slow movement (bradykinesia)
•         Muscle stiffness (rigidity)
•         Instability
•        Shuffling Gait

These symptoms slowly progress over time.  Patients may have difficulty performing tasks such as brushing, feeding, bathing, and clothing.  They may eventually not be able to take care of their daily activities due to reduced mobility and function.  Over time, patients can develop personality changes and memory loss.  The most common cause of death in patients with Parkinson's disease is pneumonia, a bacterial lung infection.

Your doctor will often evaluate specific findings on your physical examination, such as how fast you can move.  They will also usually test for muscle rigidity, muscle strength, sensation, and reflexes.  They may have you stand with your eyes closed to check your balance.

A common feature is shaking of the hand or upper limb at rest (also known as resting tremor).  This shaking or tremor usually improves with purposeful movements such as grabbing objects.  It can involve other parts of the body, such as the head and even the voice.

Your doctor may also test your memory by asking your name, date, where you are, and who the current president is.  Sometimes they will perform a detailed memory test where you are asked to remember specific words and repeat them and copy various figures using a pen or pencil.  They may even ask you to draw a clock.

Diagnosis

Parkinson's disease is diagnosed based on symptoms, family history, and physical examination findings.  Your doctor will usually obtain an MRI of your brain to evaluate for other conditions that could be responsible for your symptoms, such as brain tumor or stroke.  Newer imaging techniques are being performed, such as the DaTSCAN, which specifically evaluates the amount of dopamine in the substantia nigra – the abnormal brain region in Parkinson's disease. The only way doctors know you have Parkinson's disease, for sure, is if they perform a brain autopsy after death.

Your doctor will also likely order blood tests such as a CMP (comprehensive metabolic panel), CBC (complete blood cell count), vitamin B12 level, and thyroid hormones.  They will also usually check your cholesterol levels and screen for diabetes.

Parkinson's Disease Treatment

If Parkinson's disease features occur due to medication use such as antipsychotics (e.g., Haldol, Risperdal, Reglan), these medications are typically discontinued if possible.

Parkinson's disease therapy goals are to increase the patient's ability to move and socially function – this includes reducing the risk of falls.  The most commonly prescribed drugs used to treat sporadic Parkinson's disease include:

•       Sinemet (Levodopa/Carbidopa)
•       Parlodel (Bromocriptine)
•       Prascend (Pergolide)
•       Mirapex (Pramipexole)
•       Requip (Ropinirole)
•       Comtan (entacapone)
•       Tasmar (tolcapone)

These drugs generally work by increasing dopamine levels or activating dopamine receptors in the brain – remember, the loss of dopamine in the brain is the cause of Parkinson's disease.

References:

1.     Gazewood JD, Richards DR, Clebak K. Parkinson's disease: an update. Am Fam Physician. 2013 Feb 15;87(4):267-73. - http://edelweisspublications.com/edelweiss/article/motor-symptoms-parkinsons-disease-review-literature-npr-18-108.pdf
2.     Beitz JM. Parkinson's disease: a review. Front Biosci (Schol Ed). 2014 Jan 1;6:65-74. - https://europepmc.org/article/med/24389262