Overview of PD

What is Parkinson's disease?

Parkinson’s disease (PD) is a brain disorder associated with a loss of dopamine nerve cells in a brain region called the basal ganglia. The basal ganglia consist of a network of nuclei or nerve circuits involved in motor control. The figure below illustrates key regions of the basal ganglia. Dopamine nerve cells are located in the substantia nigra. This nucleus, in turn, projects to other regions within the motor circuit including the caudate nucleus, putamen, thalamus and subthalamic nuclei. One of the primary tasks for these nerve cells is the planning, initiation, and control of movement.

Basal -ganglia

Motor symptoms of PD emerge as these nerve cells degenerate. In fact it is estimated that between 60 to 70% of dopamine nerve cells are lost before the initial motor symptoms are noticed.

Motor symptoms typically begin on one side of the body and over time 'spread' to the other side. These include:

Rest tremor
Postural Instability

Are there non-motor symptoms?

Nonmotor symptoms are listed below. These symptoms can precede the earliest motor symptoms:

  • Loss of smell
  • Depression or anxiety
  • Constipation
  • RLS
  • REM Sleep disorder

Occur after diagnosis throughout the disease:

  • Cognitive symptoms- executive dysfunction
  • Behavioral symptoms- depression, anxiety, apathy
  • Pain- Restless leg syndrome, burning sensation, spasm
  • Autonomic dysfunction- constipation, bladder control problems, low blood pressure, temperature dysregulation and sexual dysfunction
  • Sleep- REM sleep disorder, poor sleep, sleep apnea

Parkinson's medications can also worsen non-motor symptoms:

  • Confusion and visual hallucinations
  • Sedation
  • Impulsivity control
  • Lightheadedness due to low blood pressure
  • Nausea
  • Leg swelling

Monique L. Giroux, MDMonique L. Giroux, MD
Guest Blogger, Former Medical Director of NWPF