Parkinson's Disease Flashcards
Definition of Parkinson’s Disease
Parkinson’s disease is a chronic and progressive neurological disorder characterized by the degeneration of dopamine-producing neurons in substantia nigra.
This leads to a deficiency of dopamine
Pathomechanism of Parkinson’s Disease
Loss of dopamine-producing neurons in the substantia nigra. This results in an imbalance of neurotransmitters, particularly dopamine in basal ganglia.
The depletion of dopamine leads to disrupted signaling within the basal ganglia and impairs the coordination and regulation of movement.
Causes of Parkinson’s Disease
Genetic factors: Mutations in the LRRK2, SNCA, PARK2, and PINK1 genes, have been associated with an increased risk of developing PD. However, genetic factors account for a small percentage of cases.
Environmental factors: Exposure to certain environmental toxins, such as pesticides, herbicides, and heavy metals.
Symptoms of Parkinson’s Disease
Motor symptoms:
Resting tremor: Typically, a rhythmic tremor that occurs while at rest, usually starting in the hand or fingers and spreading to other body parts.
Bradykinesia: Slowness of movement, including difficulty initiating movement, reduced arm swing during walking, and overall slowing of voluntary movements.
Rigidity: Increased muscle stiffness and resistance to passive movement.
Postural instability: Impaired balance and coordination, leading to a tendency to stoop, instability while walking, and an increased risk of falls.
Non-motor symptoms:
Cognitive changes: Cognitive impairment, including problems with memory, attention, and executive function.
Depression and anxiety
Sleep disturbances: Insomnia, REM sleep behavior disorder, and excessive daytime sleepiness.
Autonomic dysfunction: Constipation, urinary problems, orthostatic hypotension (low blood pressure upon standing), and excessive sweating.
Diagnosis and differential diagnosis of Parkinson’s Disease
UK Brain Bank Criteria:
Bradykinesia: Slowness of movement and/or progressive reduction in speed and amplitude during repetitive actions.
Resting tremor: Typically a pill-rolling tremor at a frequency of 4-6 Hz, most commonly affecting the hands.
Rigidity: Increased resistance to passive movement of the limbs.
Asymmetrical onset: Symptoms begin on one side of the body.
Persistent asymmetry: The asymmetry of symptoms is maintained throughout the course of the disease.
Excellent response to levodopa: There is a noticeable and sustained improvement in motor symptoms with levodopa therapy.
Additionally, the UK Brain Bank Criteria consider the absence of atypical features such as early postural instability, repeated falls within the first year, or prominent autonomic dysfunction. These features would suggest an alternative diagnosis, such as a parkinsonian-plus syndrome.
Movement Disorder Society (MDS) Criteria:
MDS Criteria take into account not only motor symptoms but also non-motor symptoms and response to dopaminergic therapy. The criteria are divided into three levels of certainty:
Level 1: Clinically established PD: This requires the presence of bradykinesia plus at least one of the following criteria: rest tremor, rigidity, or an excellent response to levodopa.
Level 2: Clinically probable PD: This category incudes cases that have bradykinesia plus at least one supportive criterion, such as a unilateral onset, a positive response to levodopa, or a progressive course.
Level 3: Clinically possible PD: This category includes cases that have bradykinesia as the only criterion or cases that do not meet the criteria for Levels 1 or 2 but still have features suggestive of PD.
-Additional tests may include:
Response to dopaminergic therapy: A positive response to dopaminergic medications can support the diagnosis of PD.
Neuroimaging: Brain imaging, such as MRI or DaTscan (a dopamine transporter imaging test), may be performed to rule out other causes of parkinsonism and evaluate for any structural abnormalities.
Treatment of Parkinson’s Disease
Medications:
Dopamine replacement therapy, such as levodopa(1st line)
Dopamine agonists, MAO-B inhibitors, and COMT inhibitors, may also be prescribed to enhance dopamine function or manage specific symptoms.
Deep brain stimulation (DBS): In cases where medication alone is insufficient to control symptoms, DBS may be considered. It involves the implantation of electrodes in specific brain regions to help regulate abnormal neural activity and improve motor symptoms.
Physical therapy: Physical therapy and exercise programs can help improve mobility, flexibility, balance, and overall physical function.
Occupational therapy: Occupational therapy focuses on improving daily activities, fine motor skills, and functional independence.
Speech therapy: Speech therapy may be beneficial for individuals experiencing speech and swallowing difficulties.
Complications of Parkinson’s Disease
Postural instability and gait disturbances can increase the risk of falls and injuries.
Impaired swallowing can lead to aspiration pneumonia and malnutrition.
Cognitive decline: Some individuals with PD may develop dementia or experience cognitive decline over time.
Psychiatric complications: Depression, anxiety, and psychosis can occur in individuals with Parkinson’s disease.
Sleep disorders: PD is associated with sleep disturbances, such as insomnia and REM sleep behavior disorder.
