From the Guidelines
Parkinson's disease diagnosis should be based on clinical features, including motor symptoms such as resting tremor, bradykinesia, and rigidity, as well as non-motor symptoms like autonomic dysfunction and behavioral changes, with imaging used as an essential diagnostic tool to rule out other conditions 1.
Clinical Presentation
The clinical presentation of Parkinson's disease is characterized by progressive degeneration of the dopaminergic neurons in the substantia nigra/striatum, leading to motor symptoms such as:
- Resting tremor
- Bradykinesia (slowness of movement)
- Rigidity in limbs
- Postural instability Non-motor symptoms can include:
- Autonomic dysfunction
- Behavioral changes
- Dementia
- Depression
- Anxiety
- Sleep disturbances
- Cognitive changes
- Constipation
- Loss of sense of smell
Diagnosis
Diagnosis is primarily clinical, based on a neurological examination and medical history, as there is no definitive test for Parkinson's disease 1. Physicians look for at least two of the four cardinal motor symptoms, particularly asymmetric presentation (symptoms starting on one side of the body).
Diagnostic Tools
Neurologists may use the UPDRS (Unified Parkinson's Disease Rating Scale) to assess symptom severity. Response to levodopa medication can also support diagnosis. Brain imaging like MRI or CT scans may be used to rule out other conditions but cannot confirm Parkinson's disease 1. In some cases, DaTscan (dopamine transporter scan) may help differentiate Parkinson's disease from similar conditions.
Differential Diagnosis
It is essential to consider other Parkinsonian syndromes, such as multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD), which can present with similar symptoms 1. MSA can be subdivided into three distinct clinical subtypes: MSA-P (striatonigral degeneration), MSA-C (olivopontocerebellar atrophy), and MSA-A (Shy-Drager syndrome). PSP is the most common atypical Parkinsonism, with a prevalence of around 5/100,000 1. CBD initially presents with asymmetric limb clumsiness and progresses to include unilateral limb rigidity and dystonia.
Treatment
Early diagnosis is crucial, as treatment with medications like levodopa/carbidopa, dopamine agonists, or MAO-B inhibitors can help manage symptoms effectively, though they don't slow disease progression 1. Physical therapy, exercise, and speech therapy are also important components of treatment that should begin early in the disease course.
From the Research
Parkinson's Disease Symptoms
- The symptoms of Parkinson's disease include tremor, muscle rigidity, bradykinesia, and postural instability 2, 3, 4, 5
- Tremor-predominant Parkinson's disease is characterized by prominent tremor of one or more limbs with a relative lack of significant rigidity and bradykinesia 2
- Other clinical features of Parkinson's disease include secondary motor symptoms, non-motor symptoms, and autonomic dysfunction 3
Diagnosis of Parkinson's Disease
- There is no definitive test for the diagnosis of Parkinson's disease, and the disease must be diagnosed based on clinical criteria 3, 6
- The diagnosis of Parkinson's disease is based on the presence of cardinal signs such as rest tremor, bradykinesia, rigidity, and loss of postural reflexes 3
- The International Parkinson and Movement Disorder Society (MDS) task force has proposed diagnostic criteria for Parkinson's disease, which include the use of non-motor symptoms as additional diagnostic features and the adoption of the concept of prodromal PD 6
Motor Features of Parkinson's Disease
- The most characteristic motor feature of Parkinson's disease is bradykinesia, and other cardinal motor features include tremor, rigidity, and postural instability/gait changes 4
- Additional motor features common to the disease include dystonia, postural abnormalities, speech and swallowing dysfunction, and levodopa-related dyskinesias 4
- The pathophysiology of many of these motor features remains poorly understood 4
Epidemiology and Pathophysiology
- Parkinson's disease is the second most prominent neurodegenerative movement disorder after Alzheimer's disease, involving 2-3% of the population aged above 65 years 5
- The disease is mainly triggered by the depletion of dopaminergic neurons located in substantia nigra pars compacta (SNpc) in the region of basal ganglia 5
- Analysis of various causes of Parkinson's disease is essential for an accurate examination of the disease, including tremors and rigidity 5