by Thomas A. Viola, RPH, CCP
He was most certainly one of our favorite patients. John was always quick with a joke or funny anecdote, and a broad smile that always brightened our moods. As a local police officer and one of our most loyal customers, John stopped in regularly to check on us, and we looked forward to his visits. During his visits, John always made sure to seek me out, shake my hand with his characteristic viselike grip, and ask how I was. It was a simple act of kindness that I truly appreciated over the years.
When John announced he was retiring and moving to Florida, we were all happy for him, but we knew we'd miss him terribly. We made John promise to stop in and visit us whenever he came back to town. A few years later, as I arrived one day to start my late shift, I was surprised and delighted to find him seated in the waiting area of our pharmacy. His wife was just completing her purchase.
"Hey, John!" I said, extending my hand for our customary shake. "It's great to see you again! How have you been?"
However, there was no quick wit and no broad smile. He just stared at me with a blank expression and said nothing. He made no effort to shake my hand. I was completely dismayed. Had he forgotten me already? Had something happened just before I greeted him?
A few moments later, John's face contorted slightly and he finally smiled and said, "Tom." He stood up from the chair, very slowly and unsteadily, and took a few shuffling steps toward me. He extended his hand and it trembled as he tried to hold it there. I grasped his hand. The viselike grip was gone. As I shook his hand, it felt more like I was steadying him and supporting him than greeting him. I looked at his wife and the tears welled up in her eyes, confirming the diagnosis already forming in my mind.
Parkinson's disease is a chronic, progressive degenerative disorder of the central nervous system. It is associated with the degeneration and loss of dopamine-producing neurons in the nigrostriatal portion of the brain, as well as the formation of destructive lesions and loss of function in the limbic, motor, and autonomic systems. Parkinson's disease is characterized by the presence of Lewy bodies, structures that are strongly correlated with neuron degeneration that are considered a diagnostic marker for the disease.
Parkinson's disease leads to decreased controlled motor function and balance, mood and behavior disorders, and reduced quality of life. It results from a combination of genetic and other contributing factors. People with parents or siblings diagnosed with Parkinson's disease have a greater chance of developing it themselves. Other contributing factors to the development of the disease include oxidative damage to the brain from free radicals, trauma from stroke, brain tumor, or head injury, exposure to environmental toxins (such as pesticides), and occupational hazards (such as chronic exposure to manganese and mercury). Over 1.5 million people in the U.S. have been diagnosed with Parkinson's disease, with 50,000 new cases diagnosed annually.
Typically, symptoms appear in patients older than 50, although some variants of the disease affect patients under the age of 40. Many patients report a variety of nonmotor symptoms associated with the disease years before the onset of motor symptoms. By the time symptoms are noticeable, there is approximately 60% to 80% loss of dopamine-producing cells in the substantia nigra and other areas of the brain.
Primary symptoms of Parkinson's disease include resting tremor, muscle rigidity, slow movement, reduced facial expression, and gait instability. Resting tremor of the hands is the most noticeable symptom. The tremor can be unilateral or bilateral and produces a "pill-rolling" movement of the thumb and the opposing fingers, as well as handwriting changes. The tremor disappears with the motion of the hand and worsens with fear, anxiety, and excitement. Tremors may also affect the jaw, tongue, and eyelids.
Muscle rigidity often manifests as reduced swinging of the arms, foot dragging, and shuffling while walking. This is often accompanied by stooped posture and overall imbalance. Normally smooth muscle movements are replaced with a ratchet type of movement, commonly known as "cogwheel rigidity." Other movement disturbances associated with Parkinson's disease, known as dyskinesia, include two syndromes that are very disturbing to most patients. The first, akinesia, refers to a significant reduction or absence of spontaneous movement, resulting in "freezing," or a sudden inability to initiate movement. The second, bradykinesia, refers to an overall slowness of movement, often manifested as reduced facial expression or "facial mask." Another related syndrome, akathisia, a subjective feeling of restlessness, is equally disturbing and often manifested as restless leg syndrome.
In addition to these symptoms, many patients with Parkinson's disease experience pain, orthostatic hypotension, bowel and bladder dysfunction, cognitive impairment and dementia, mood disturbances and depression, insomnia and fatigue, visual disturbances, and sexual dysfunction.
Patients with Parkinson's disease display a number of orofacial manifestations, secondary to motor and sensory deficits with dental implications. Many patients experience profound dysphagia, making the normal swallowing of food, water, or saliva difficult. Even expectorating toothpaste and mouthwash can be challenging. This leads to aspiration of small amounts of food or liquid and possible aspiration pneumonia. Gastrointestinal muscles may also be affected, resulting in gastroesophageal reflux disease.
Patients with Parkinson's disease may experience either xerostomia or excessive saliva production and drooling. These symptoms may be a result of the disease or an adverse effect of the medications. Patients with xerostomia are at risk for dental decay, especially root caries. Patients with excessive drooling, sometimes as a result of slowed swallowing, are at risk for fungal infections at the corners of the mouth and irritation from frequent blotting of the lips and mouth. Burning mouth syndrome is also common in Parkinson's patients. It is often exacerbated by medications, xerostomia, poor oral hygiene, and candidiasis, as well as dietary changes and reduced nutritional status since these patients often experience dysfunction in their taste and olfactory senses.
Parkinson's disease patients present unique challenges for the dental team in rendering dental treatment. Patients with Parkinson's disease may experience exaggerated trembling and involuntary shaking; thus proper precautions should be taken to prevent needlestick injury. These patients have difficulty with movement and ambulation and often experience orthostatic hypotension. Proper chair positioning and the use of soft restraints are essential for adequate support and to stabilize the patient in a comfortable position. Slow adjustments should be used to ensure that the patient has time to adjust to different chair positions.
Many patients with Parkinson's disease experience physical and mental fatigue and bowel dysfunction. Dental treatment plans involving extended chair time will need to be modified to allow for frequent rests and restroom trips. Patients with Parkinson's disease often experience anxiety, mood disorders, and compulsive behaviors, which, depending on their level of control may result in reduced tolerance and cooperation. Adequate anesthesia, good pain control, and anxiety and stress-reduction techniques are essential in treating these patients.
Patients with Parkinson's disease have varying degrees of dyskinesia of the hands and face, which is often associated with poor oral hygiene and increased incidence of infections of oral tissues. Dental treatment plans may require modification based on a patient's ability to cleanse the oral cavity. Patients may have difficulty remembering details and, thus, written instructions may be warranted.
As John and his wife prepared to leave our pharmacy that day, I looked him in the eye and wished him well. As I shook his hand, I knew I was saying goodbye not only for that day, but also for days to come. Worsening cognitive and motor skills will eventually steal
Pharmacology for Parkinson's
Pharmacologic therapy of Parkinson's disease is aimed at increasing dopamine levels in the brain. Dopamine itself cannot be administered because it does not cross the blood-brain barrier. Levodopa, the immediate precursor of dopamine, is metabolized to dopamine in both brain and peripheral tissues. The combination of levodopa with carbidopa, a peripheral metabolic inhibitor, in the drug Sinemet, is the most effective treatment for Parkinson's disease available. Dopamine agonist drugs, such as pramipexole (Mirapex) and ropinirole (Requip), mimic the action of dopamine in the brain. Unfortunately, adverse effects of these medications mimic symptoms of the disease, including dyskinesia and confusion. Psychosis (hallucinations and delusions) and impulse control disorder have also been reported.
Used in combination with levodopa, Tasmar (tolcapone) and Comtan (entacapone) are two medications that block the enzyme catechol-O-methyl-transferase (COMT) to prevent levodopa breakdown in the intestine, thus allowing more of the levodopa to reach the brain. Entacapone is also available as a carbidopa/levodopa/entacapone combination (Stalevo).
Selegiline (Eldepryl) and rasagiline (Azilect) are two medications that block the enzyme monoamine oxidase type B (MAO-B) to inhibit the breakdown of dopamine in the brain, and therefore increase its concentration. Adverse effects of these medications again mimic those of the disease, including dyskinesias and psychosis. COMT inhibitors and epinephrine may potentially interact, so epinephrine should be used with caution in patients taking these medications. No such precaution exists for MAO-B inhibitors.
Anticholinergic drugs, such as trihexyphenidyl (Artane) and benztropine (Cogentin), block the effects of acetylcholine to rebalance its levels with dopamine. They are also useful for the treatment of the tremor and drooling associated with Parkinson's disease. Unfortunately, adverse effects of these medications also mimic symptoms of the disease, including impaired memory, confusion, and hallucinations. Xerostomia, constipation, and urinary retention are also common adverse effects.
THOMAS A. VIOLA, RPh, CCP, In addition to his daily practice of the profession of pharmacy, Thomas A. Viola, RPh, CCP, also serves the professions of dentistry, dental hygiene, and dental assisting as an educator, published writer, and professional speaker. As an educator, Viola is a member of the faculty of seven dental hygiene and dental assisting programs, as well as several national board exam review courses. Visit Viola’s website: www.tomviola.com.
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