WORLD PARKINSONS DISEASE AWARENESS DAY - 11th APRIL 2019
Parkinsons Disease (PD) is one of the most common neurologic disorders, affecting approximately 1% of individuals older than 60 years and causing progressive disability that can be slowed, but not halted, by treatment. The incidence of Parkinsons Disease has been estimated to be 4.5-21 cases per 100,000 population per year, and estimates of prevalence range from 18 to 328 cases per 100,000 population. The incidence and prevalence of Parkinsons Disease increase with age, and the average age of onset is approximately 60 years and it is about 1.5 times more common in men than in women.
Most cases of Parkinsons Disease (Idiopathic Parkinsons Disease [IPD]) are hypothesized to be due to a combination of genetic and environmental factors. However, no environmental cause has yet been proven. A known genetic cause can be identified in approximately 10% of cases, and these are more common in younger-onset patients.
Environmental causes :
Environmental risk factors commonly associated include use of pesticides, living in a rural environment, consumption of well water, self injection with MPTP, exposure to herbicides, and proximity to industrial plants or quarries.
Genetic factors :
Genetic factors appear to be very important when the disease begins at or before age 50 years. A total of 18 loci in various genes have now been proposed. Mutations within 6 of these loci (SNCA, LRRK2, PRKN, DJ1, PINK1, and ATP 13A2) are well-validated causes of familial parkinsonism.
In a large cohort study, researchers found that individuals with Type 2 Diabetes had a 32% increased risk of developing later Parkinson's Disease than those without Diabetes. The relative increase was greater in patients with diabetic complications and in younger individuals with Type 2 Diabetes aged 25 to 44 years.
Common early symptoms of Parkinsons Disease include tremor, bradykinesia, rigidity, and postural instability.
• Tremor is most often described by patients as shakiness or nervousness and usually begins in one upper extremity and initially may be intermittent.
• Bradykinesia refers to slowness of movement. Truncal bradykinesia results in slowness or difficulty in rising from a chair, turning in bed, or walking. If walking is affected, patients may take smaller steps and gait cadence is reduced.
Other features include:
• Decreased arm swing on the first-involved side
• Decreased facial expression
• Sleep disturbances
• RBD, in which there is a loss of normal atonia during REM sleep
• Decreased sense of smell
• Symptoms of autonomic dysfunction, including constipation, sweating abnormalities, sexual dysfunction, and seborrheic dermatitis
• A general feeling of weakness, malaise, or lassitude
• Depression or anhedonia
• Slowness in thinking
• Excessive salivation
• Urinary urgency
• Decreased sense of smell
No laboratory or imaging study is required in patients with typical presentation. Such patients are aged 55 years or older and have a slowly progressive and asymmetric parkinsonism with resting tremor and bradykinesia or rigidity. Patients who do not have tremor or with atypical presentation should generally be considered for Magnetic Resonance Imaging (MRI) evaluation to exclude brain lesions such as stroke, tumor, or demyelination.
Serum ceruloplasmin concentration is obtained as a screening test for Wilson disease in patients younger than 40 years who present with parkinsonian signs.
PET and SPECT
Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT) are useful diagnostic imaging studies, but these are not routinely required.
At the onset of motor signs, patients with Parkinsons Disease show an approximately 30% decrease in18 F-dopa (fluorodopa) uptake on PET imaging in the contralateral putamen.
Ioflupane (Datscan) is a radiopharmaceutical agent that is indicated for striatal dopamine transporter visualization using SPECT brain imaging to assist in the evaluation of adults with suspected Parkinsonian syndromes.
Symptomatic anti-Parkinson medications usually provide good control of motor signs for 4-6 years. After this, disability often progresses despite best medical management, and many patients develop long-term motor complications, including fluctuations and dyskinesias.
• Levodopa/carbidopa: The gold standard of symptomatic treatment
• Monoamine oxidase (MAO)–B inhibitors: Can be considered for initial treatment of early disease
• Other dopamine agonists (eg, ropinirole, pramipexole): Monotherapy in early disease and adjunctive therapy in moderate to advanced disease
• Anticholinergic agents (eg, trihexyphenidyl, benztropine): Second-line drugs
Treatment for nonmotor symptoms
• Sildenafil : For erectile dysfunction
• Laxatives: For constipation
• Modafinil: For excessive daytime somnolence
• Donepezil, Rivastigmine: Dementia
• SSRIs: Depression
• Benzodiazepines: Sleep disorders
Deep Brain Stimulation(DBS)
DBS has become the surgical procedure of choice for Parkinsons Disease for the following reasons:
• It does not involve destruction of brain tissue
• It is reversible
• It can be adjusted as the disease progresses or adverse events occur
• Bilateral procedures can be performed without a significant increase in adverse event