Overview of Parkinsons disease?
Parkinson’s disease (PD), or simply Parkinson’s, is a chronic degenerative disorder of the central nervous system that affects both the motor system and non-motor systems. The symptoms usually emerge slowly, and as the disease progresses, non-motor symptoms become more common. Early symptoms are tremor, rigidity, slowness of movement, and difficulty with walking. Problems may also arise with cognition, behaviour, sleep, and sensory systems. Parkinson’s disease dementia is common in advanced stages.
What is the cause of Parkinsons disease?
Parkinson disease (PD) is the leading cause of parkinsonism, a syndrome clinically manifested by rest tremor, rigidity, bradykinesia, and postural instability. PD is one of the most common neuro-degenerative diseases and a major cause of neurologic morbidity and mortality worldwide.
The exact cause or trigger of neurodegeneration in PD is still unknown in the majority of cases.
The clinical features of PD arise partly from progressive degeneration of an important brain chemical called dopamine producing neurons. These neurons are mainly located in a deep-seated part of brain known as basal ganglia.
But degeneration of other neurons is implicated in many motor and nonmotor symptoms. Thus, dopamine depletion and loss of other neurotransmitters account for the classic motor as well as a wide range of nonmotor and neuropsychiatric symptoms that affect function and quality of life.
There are certain risk factors associated with PD, mainly:
1. Age – Age is the most important risk factor for PD. The incidence and prevalence rise steadily in adults beginning in the fifth decade [1]
2. Sex – Males have a higher risk of PD than females by a ratio of approximately 1.4:1 [2]
3. Genetics – A family history of PD in a first-degree relative is associated with a two- to threefold increase in the risk of PD [3]
4. Environmental exposures – A large number of environmental exposures have been identified as risk factors for PD, example:
a) Exposure to pesticides [3]
b) Exposure to air pollution, including nitrogen dioxide and fine particulate matter [4]
c) Farming or agriculture work [3]
d) The use of well water [3]
e) Reduced levels of dietary and sunlight-derived vitamin D [5]
5. Comorbidities – A variety of medical and psychiatric illnesses in early or mid-life have been associated with increased risk of PD in observational studies. Among the most consistently identified risk factors are:
a) Excess body weight and metabolic syndrome [6,7]
b) Type 2 diabetes mellitus [8]
c) History of traumatic brain injury [9]
What are the symptoms of Parkinsons disease?
PD is characterized by three core clinical features: tremor, bradykinesia, and rigidity.
1. Tremor – The tremor in PD is a type of rest tremor, meaning that it is most noticeable when the affected body part is supported against gravity and not engaged in purposeful activities. Other conditions like essential tremor more commonly cause action tremor, which occurs with voluntary muscle contraction and movement.
The tremor in the upper extremity is called “pill-rolling” because of the way the thumb and fingers appear to be rolling a small object between them.
Tremor severity usually decreases with purposeful action and is most severe at rest.
2. Bradykinesia – Bradykinesia means generalized slowness of movement but also refers to decreased amplitude of movements. “Weakness,” “incoordination,” and “tiredness” are often used to describe the decreased ability to initiate voluntary movement.
In the arms, patients often complain of difficulty performing simple tasks, such as buttoning clothes, tying shoelaces, double clicking a computer mouse, typing, or lifting coins from a pocket or purse.
In the legs, common complaints include dragging the legs, short steps, or a feeling of unsteadiness. Patients may also have difficulty standing up from a chair or getting out of a car.
3. Rigidity – Rigidity is an increased resistance to passive movement about a joint. Rigidity can affect any part of the body and may contribute to complaints of stiffness and pain. Features of PD that results from rigidity includes decreased arm swing with walking, and the typical stooped posture.
Patients may have cogwheel rigidity, which refers to a jerky pattern of resistance and relaxation as the examiner moves the limb through its full range of motion.
Other important symptoms include: –
4. Postural instability – refers to a tendency of frequent falling. It usually appears late in the course of PD. Patients who fall early in the course of the illness most likely have another parkinsonian syndrome, which are atypical and more dangerous forms such as progressive supranuclear palsy or multiple system atrophy (MSA), rather than PD.
5. Non-motor symptoms – there are important non-motor symptoms which are seen in patients with PD. These features include the following:
1) Mood disorders including depression, anxiety, and apathy/abulia – Depression is the most common psychiatric disturbance seen in PD [10], up to 50 percent of patients have depressive symptoms.
Anxiety is the next most frequent psychiatric disturbance and is estimated to occur in approximately 30 to 40 percent of patients [11]
2) Sleep disturbances – Up to 80 percent of patients with PD have one or more sleep disorders, including insomnia, restless legs syndrome (RLS), and rapid eye movement (REM) sleep behaviour disorder (RBD) [6]
3) Cognitive dysfunction and dementia – prevalence of dementia increases with the duration of the disease.
4) Psychotic symptoms (hallucinations and delusions) – Psychosis occurs in 20 to 40 percent of drug-treated patients with PD, and visual hallucinations are the most common psychotic symptom [8]
5) Fatigue – fatigue is reported by approximately one-third of patients at diagnosis and becoming more prevalent as the disorder progresses [12]
6) Autonomic dysfunction – included orthostatic hypotension, urinary dysfunction, sexual dysfunction.
7) Olfactory dysfunction – Olfactory dysfunction is very common in PD and can manifest as deficits in odour identification, discrimination, and detection [13]
8) Gastrointestinal dysfunction
9) Pain and sensory disturbances – Painful sensory symptoms are reported in up to half of patients with PD. The pain can be lancinating, burning, or tingling, and can be generalized or localized to different areas of the body, including the face, abdomen, genitals, and joints [14]
What is the treatment of Parkinsons disease?
Management of PD requires careful consideration of the patient’s symptoms and signs, age, stage of disease, degree of functional disability, and level of physical activity and productivity.
A wide range of symptomatic pharmacologic, nonpharmacologic, and surgical therapies are available to maximize motor and nonmotor function and quality of life throughout the disease course
Spectrum of dopaminergic therapies — Dopaminergic therapy is the mainstay of pharmacologic treatment for PD. Given below is the list of dopaminergic medications
1) Levodopa, most commonly in the form of carbidopa-levodopa
2) Dopamine agonists (DAs; pramipexole and ropinirole)
3) Monoamine oxidase type B (MAO B) inhibitors (rasagiline, safinamide, and selegiline)
4) Amantadine, a dopamine promoter with anticholinergic effects
Selection is based on patient characteristics (age, comorbidities), disease severity, and drug efficacy and side effects.
When to initiate therapy – All pharmacologic therapies for PD are symptomatic. Treatment should generally begin when motor symptoms are affecting function and quality of life.
Preferred therapy for most patients – In most patients with early PD seeking control of motor symptoms, levodopa is the initial therapy of choice. Among dopaminergic therapies, levodopa has superior effects on motor function, activities of daily life, and quality of life and is often the best tolerated, especially in older adults
EXERCISE AND PHYSICAL THERAPY: Regular exercise promotes a feeling of physical and mental wellbeing; it is especially valuable due to the chronic nature of PD and its associated progressive motor limitations. In patients with PD, exercise may help to slow motor progression, improve nonmotor symptoms, and alleviate secondary orthopaedic effects of rigidity and flexed posture such as shoulder, hip, and back pain [15]
The available evidence suggests that regular aerobic exercise has a positive impact on PD [16]
References:
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- Jankovic J, Schwartz KS, Ondo W. Re-emergent tremor of Parkinson’s disease. J Neurol Neurosurg Psychiatry 1999; 67:646.
- Deuschl G, Bain P, Brin M. Consensus statement of the Movement Disorder Society on Tremor. Ad Hoc Scientific Committee. Mov Disord 1998; 13 Suppl 3:2.
- Zetusky WJ, Jankovic J, Pirozzolo FJ. The heterogeneity of Parkinson’s disease: clinical and prognostic implications. Neurology 1985; 35:522.
- Tinazzi M, Fasano A, Geroin C, et al. Pisa syndrome in Parkinson disease: An observational multicenter Italian study. Neurology 2015; 85:1769.
- Barone P, Antonini A, Colosimo C, et al. The PRIAMO study: A multicenter assessment of nonmotor symptoms and their impact on quality of life in Parkinson’s disease. Mov Disord 2009; 24:1641.
- Politis M, Wu K, Molloy S, et al. Parkinson’s disease symptoms: the patient’s perspective. Mov Disord 2010; 25:1646.
- Fénelon G, Mahieux F, Huon R, Ziégler M. Hallucinations in Parkinson’s disease: prevalence, phenomenology and risk factors. Brain 2000; 123 ( Pt 4):733.
- Chou KL, Messing S, Oakes D, et al. Drug-induced psychosis in Parkinson disease: phenomenology and correlations among psychosis rating instruments. Clin Neuropharmacol 2005; 28:215.
- Aarsland D, Larsen JP, Lim NG, et al. Range of neuropsychiatric disturbances in patients with Parkinson’s disease. J Neurol Neurosurg Psychiatry 1999; 67:492.
- Scott BM, Eisinger RS, Burns MR, et al. Co-occurrence of apathy and impulse control disorders in Parkinson disease. Neurology 2020; 95:e2769.
- Alves G, Wentzel-Larsen T, Larsen JP. Is fatigue an independent and persistent symptom in patients with Parkinson disease? Neurology 2004; 63:1908.
- Tissingh G, Berendse HW, Bergmans P, et al. Loss of olfaction in de novo and treated Parkinson’s disease: possible implications for early diagnosis. Mov Disord 2001; 16:41.
- Goetz CG, Tanner CM, Levy M, et al. Pain in Parkinson’s disease. Mov Disord 1986; 1:45.
- Comella CL, Stebbins GT, Brown-Toms N, Goetz CG. Physical therapy and Parkinson’s disease: a controlled clinical trial. Neurology 1994; 44:376.
- Shulman LM, Katzel LI, Ivey FM, et al. Randomized clinical trial of 3 types of physical exercise for patients with Parkinson disease. JAMA Neurol 2013; 70:183.