Chapter 13 - Parkinson's Disease

Question 1

Epidemiology of Parkinson’s

Answer 1

• most common among elderly, avg age of onset is 55 y.o.
• higher prevalence in men

Question 2

Morphological patterns of Parkinson’s

Answer 2

• affected areas include:
  
  • substantia nigra (loses pigment due to neuronal loss)
  • locus coeruleus
  • basal ganglia, cortex brainstem, spinal cord

Question 3

Main/Direct Pathway

Answer 3

decrease D1 receptors

Question 4

Indirect Pathway

Answer 4

increase D2 receptors

Question 5

Biochemical patterns of Parkinson’s

Answer 5

• mainly affects DA
• Norepi and 5-HTA also affected
• Lewy bodies present - NOT the same as Lewy dementia

Question 6

What correlate to the pigment loss in the substantia nigra and locus coeruleus?

Answer 6

Lewy bodies and Lewy neurites

Question 7

Motor features of Parkinson’s

Answer 7

• resting tremor (usually starts small, like with a finger)
• rigidity (shuffle when walking, facial masking, blink less)
• bradykinesia (diff. initiating motor plans and w/ fine motor movement)
• postural instability (tested w/ Riding reflex)
• gait disturbance

Question 8

Other clinical features of Parkinson’s (sensorimotor and mood)

Answer 8

• depression (could be due to low levels of norepinephrine and serotonin)
• dementia (towards late stage, NOT a dementia)
• Hallucinations and psychotic behavior (due to increased activity in indirect pathway)
• REM-related sleep disorders
• olfactory disturbance (early sign, occurs before motor symptoms)

Question 9

Etiology of Parkinson’s

Answer 9

• exact cause unknown, but there are theories:
• oxidative damage (increase of free radicals causes cell death)
• environmental toxins (chronic exposure to insecticides and pesticides)
• genetic predisposition (very rare, involves gene encoding for alpha synuculein)

Question 10

Diagnosis of Parkinson’s

Answer 10

• Bradykinesia must be present w/ at least two of the following: limb muscle rigidity, resting tremor, or postural instability
• must eliminate secondary causes like: drug related, stroke, AZ, or Lewy body disease

Question 11

Time course of Parkinson’s

Answer 11

• mild stage lasts approx 5 years, pt experiences balance and gait impairment, begins to consider medication
• after 5 years, pt has motor fluctuations, dyskinesias, and behavioral or cognitive changes

Question 12

Clinicopathologic correlations in Parkinson’s

Answer 12

• neuronal loss in the substantia nigra must exceed 50% before motor symptoms appear
• 80-90% neurons are lost by the end of disease

Question 13

Treatment of Parkinson’s (motor symptoms)

Answer 13

• Levodopa (L-dopa)
  
  • precursor for dopamine
  • w/n 5 years, pt becomes less sensitive/responsive to the medication, and motor symptoms return

Question 14

Treatment of Parkinson’s (psychiatric symptoms)

Answer 14

• antipsychotics can be used to treat hallucinations, but can worsen motor symptoms
  
  • however, Seroquel can reduce psychosis

Question 15

What three regions are targeted for surgical intervention (lesioning)?

Answer 15

• thalamus
• globus pallidus
• subthalamic nucleus

Question 16

What is typically the best surgical intervention for Parkinson’s?

Answer 16

• deep brain stimulation to areas that will stop tremors