Parkinson's Disease Overview

Parkinson's Disease Overview

• Parkinson's Disease (PD) is a common, progressive neurodegenerative disorder impacting movement.
• It's characterized by a loss of dopamine-producing cells in a specific brain region, the substantia nigra.
• The exact cause of cell death isn't fully understood.
• Approximately 80% of dopamine-producing neurons are lost before symptoms noticeably emerge.

Analogy of Nervous System

• The thalamus functions like an accelerator for movement.
• The basal ganglia acts as the brake on movement.
• Imbalance in these functions causes difficulties with movement regulation.

Basal Ganglia Impairment

• Imbalances in basal ganglia function can lead to problems with motor control and coordination.
• Excessive inhibition results in hypokinetic disorders like PD (too little movement).
• Insufficient inhibition causes hyperkinetic disorders like Huntington's Disease and athetoid cerebral palsy.

Pathology of Parkinson's Disease

• Death of dopamine-producing neurons in the substantia nigra compacta (SNc) is a crucial feature.
• Microscopic protein deposits, called Lewy bodies, appear inside dopamine-producing neurons.

Parkinson's Disease - Brain Structure

• The substantia nigra appears diminished in size in individuals with Parkinson's disease, as seen in cross-sectional brain images.

Effects on Movement

• Reduced dopamine levels lead to enhanced inhibition of the thalamus by basal ganglia.
• This results in reduced activity within the motor cortex, which leads to diminished and slowed voluntary movements.

Effects on Posture

• An additional basal ganglia motor circuit controls posture.
• Dysfunction in this circuit leads to over-contraction of postural muscles.
• This causes stiffness and rigidity in muscles that control posture.

Characteristics of Parkinson's Disease

• Common motor characteristics include:
  • Muscular rigidity (cogwheel/lead-pipe)
  • Bradykinesia (slow movements)
  • Tremors (resting or postural)
  • Difficulty with voluntary and smooth movement initiation and termination.
  • Postural instability (balance issues).

Additional Symptoms

• Shuffling gait.
• Kyphotic posture.
• Mask-like facial expression (hypomimia).
• Speech problems (monotonous, slurred, reduced volume, difficulty with diction and expression).
• Fine motor impairment.
• Freezing episodes.
• Dyskinesia (irregular movements).

Gait

• Parkinson's gait is characterized by short, shuffling steps, with reduced stride length and step length.
• Other gait abnormalities include slower movement, flexion of the trunk and hips, reduced trunk rotation, reduced arm swing, increased double stance, decreased heel strike, decreased toe clearance.
• There are problems with the initiation, freezing of gait, and termination of movements (festination).

Pharmacological Treatments

• Drug therapy, such as L-dopa, initially helps replace dopamine, alleviating symptoms.
• However, effectiveness diminishes as the disease progresses.
• On/off effect is a common side effect of L-Dopa therapy. "Off" periods are when the drug is no longer effectively treating symptoms, resulting in a return of movement problems (tremors, rigidity, slow movement).

Surgical Treatments

• Transplantation of fetal brain tissue and deep brain stimulation are surgical options for treating severe cases.

Rehabilitation

• Rehabilitative therapies are often vital to manage Parkinson's.

This quiz provides an overview of Parkinson's Disease, a progressive neurodegenerative disorder affecting movement. It discusses the loss of dopamine-producing cells, the role of the basal ganglia in motor control, and the impact of imbalances in these functions. Test your knowledge on the pathology and symptoms related to Parkinson's Disease.