Parkinson's Disease: Causes and Symptoms

Parkinson's Disease Overview

• Parkinson's Disease (PD) is a gradually worsening neurodegenerative condition.
• PD is now recognized as a complex disorder with various features, not just a motor system disorder.
• PD occurs due to widespread dopamine depletion in the substantia nigra.
• The substantia nigra is involved in movement, reward, and addiction.
• The loss of dopamine results in increased inhibition of the thalamus as well as reduced excitatory input to the motor cortex
• This leads to tremor at rest, rigidity, bradykinesia, and postural instability.
• Lewy bodies in the remaining nigral neurons are a pathological hallmark of the disease after death.
• The decline in dopamine-generating cells adversely affects movement and balance.

Problem and Population

• PD is idiopathic, progressive, chronic, and incurable.
• It is characterized by bradykinesia combined with rest tremor and rigidity.
• The mean age at diagnosis is 70.5 years.
• Men are 1.5 times more likely than women to develop PD.
• PD has been found in all ethnic populations studied.

Incidence and Prevalence

• PD is the second most common neurodegenerative disease after Alzheimer's.
• It affects approximately 5 million people worldwide.
• There is a rapid increase in incidence after the age of 65.
• PD is uncommon in people younger than 40 years of age.
• Population prevalence is approximately 1% at age 60 and 4% by age 80.
• PD affects 0.3% of the general population.
• Risk doubles if a first-degree relative has PD.

Impact of Parkinson's Disease

• As high as 41% of older patients with PD have dementia.
• Dementia is often associated with Lewy bodies.
• Visual hallucinations, delusions, and paranoia are common in advanced stages of the disease.
• Depression is the most common psychiatric illness seen in PD.
• Depression has a negative impact on mobility and quality of life.
• Sexual dysfunction is greater in men with PD.
• Daytime sleepiness can be a hazard for patients still driving.

Classical Presentation

• Cardinal signs include resting tremors, rigidity, bradykinesia and akinesia
• Postural changes include loss of equilibrium, stooped posture, and short shuffling steps.
• Neuroendocrine symptoms include glucose and insulin resistance
• Neuroendocrine symptoms also include bone metabolism and weight changes.
• Dopamine-producing cells degenerate in the substantia nigra.
• Degeneration of dopamine neurons also occurs in the basal ganglia and frontal cortex
• There is depletion of gamma-aminobutyric acid (GABA) and acetylcholine levels.

Diagnoses - Subjective Data

• Patients or their families may report fatigue, depression, mood change, lack of sleep
• Patients or their families may report skin breakdowns, skin injury, sweating, or lack of tears
• Patients or their families may report ptosis, impaired vision, speech change, and tremors in the face
• Patients or their families may report drooling, lack of cough, constipation, and inability to swallow
• Patients or their families may report urinary incontinence, nocturia, frequency, urgency, and decreased sexual capacity
• Patients or their families may report no movement or freezing time, changes to handwriting, and muscle weakness, incoordination in speech
• Patients report repetitive pill rolling, propulsive gait, short shuffling steps with acceleration, and mental symptoms

Diagnoses - Physical Exam

• Physical exam includes assessment of mask like face or expressionless appearance
• Physical exam includes the skin for breakdowns, bruising, dry skin, and turgor
• Physical exam includes assessment of Diplopia, Ptosis, impaired vision, speech, decreased tongue movement
• Physical exam includes assessment of Oculogyric crisis, blepharospasm, and decreased lacrimation
• Physical exam includes assessment of orhostatic hypotension, aspiration, and lung sounds
• Physical Exam includes assessment of the ability to swallow, gag reflex, quality of voice, dysphagia
• Physical Exam includes the patient being awake, alert, and oriented x3
• Physical Exam includes bloodwork and CT scans to rule out metabolic syndromes

Diagnosis

• Clinical diagnosis includes a minimum of two of the four cardinal signs of PD.
• The cardinal signs are tremor, muscle rigidity, bradykinesia, and postural instability.
• Exclusion criteria to be considered include secondary Parkinsonism as a result of drug exposure
• Exclusion criteria also includes repeated stroke, head injuries, and Parkinsonion type syndrome
• There are no true tests or screenings for Parkinson's Disease
• Diagnosis is based on history, physical, and neurological exam
• The doctor looks for shaking, tremors, bradykinesia, rigidity, and posture instability

Geriatric Considerations

• PD is the second most common neurodegenerative disease in the elderly.
• 1.6% of Americans or 36 million medicare beneficiaries over the age 65 are treated yearly
• PD is more common in males due to neuro protective effects of estrogen.
• People of of Asian or African descent are half risk compared to the white population.

Follow Up/Referral

• Patients are to follow up with primary care physician
• Patients are to be refered to a neurologist
• Patients are to seek support from family and friends
• Patients are encouraged to join support groups.

Pharmacological Treatment

• Sinemet (carbidopa-levodopa) doses: 100/10mg, 100/25mg, to a dose of 250/25mg.
• Dopamine agonist agents include Mirapex with a typical dose of 0.5-1.5mg PO TID.
• Requip (ropinirole) dosages are IR from 0.25-8mg titrated or ER from 2-24mg titrated.
• MAO B Inhibitors include Zelapar (selegiline) from 1.25-2.5 mg.
• COMT Inhibitors include Comtan (entacapone) at 200mg PO BID-QID
• COMT Inhibitors also include Tasmar (tocapone) at 100 mg PO TID.
• Anticholinergics include Cogentin (benztropine) at 1-2 mg PO/IM/IV qhs.
• Amantadine is also a treatment option given at 100mg PO BID.

Side Effects and Complications

• Carbidopa-Levodopa can cause nausea, lightheadedness, and orthostatic hypotension.
• Dopamine Agents may cause sleepiness, compulsive behaviors, and hallucinations.
• MAO B Inhibitors can cause headaches, nausea, and insomnia.
• COMT Inhibitors may cause dyskinesia, vomiting, diarrhea, and nausea.
• Anticholinergics can cause dry mouth, impaired urination, confusion, and impaired memory.
• Amantadine may cause ankle and skin swelling, as well as purple mottling of the skin.

Surgical Intervention

• Deep brain stimulation (DBS) delivers electrical impulses to a targeted area of the brain.
• DBS disrupts abnormal brain activity responsible for motor symptoms.
• This procedure is done under neurosurgical, neurology, and neuropsychological collaboration.
• Strict inclusion/exclusion criteria ensure that only suitable PD patients undergo DBS.

Non Pharmacological Intervention

• Patient/Caregiver Education on disease, progression, safety
• PT/OT to maximize function
• Regular physical activity
• Speech therapy
• Diet and Nutrition
• Psychosocial support