Parkinsons disease basal ganglia neuroanatomy

1. Parkinson’s
Disease
Dr. Irtaza Rehman
(Author of the book The Extraordinary Life)

3. Learning objectives
• To clear concepts about physiological anatomy
of basal ganglia
• To understand pathophysiology & S/S of
Parkinson’s disease
• To solve 2 MCQS at the end of class

4. Q. What is basal ganglia?
Ans. Group of
subcortical nuclei deep
to cerebral hemispheres
or at the base of the
forebrain.
Responsible primarily for motor control

6. Basal ganglia
Consists of :
Caudate
Putamen
Globus pallidus
Subthalamic nucleus
Substantia nigra
Neostriatum (C + P)
Lentiform (G + P)
Corpus striatum ( C + Lentiform)
Paleostriatum (G)

7. Functions:
• Planning of multiple parallel/sequential patterns
• Modulation/scaling of movement
• Performs subconsciously learned movements
• Last second movements
Basal ganglia

8. Q. What is the
relation of basal
ganglia with internal
capsule?
Ans. The striatum is divided by the internal
capsule into the caudate nucleus and
putamen. The caudate nucleus lies medial to
the internal capsule, while the putamen is
located lateral to it

9. Basal Ganglia

10. Q. Which part of basal
ganglia receive major
excitatory input from
cerebral cortex but it
itself doesn’t send axons
to cortex?
A. Substantia nigra
B. Globus pallidus
C. Caudate
Ans. A

11. • Striatum communicates with
the thalamus and cerebral
cortex by two opposing
pathways
• Indirect pathway = Inhibitory
• Direct pathway = Excitatory
Basal ganglia
Dopamine Inhibits Indirect (D2) – Dopamine Excites Direct (D1)
OVERALL EXCITATORY

12. Direct Pathway

13. InDirect Pathway

14. Glutamate
GABA GABA

15. Glutamate
GABA
GABA
Glutamate
GABA

16. • Both basal ganglia pathways
utilize 2 GABA neurons in
series, and a “disinhibition”
• Dopamine drives the direct
pathway; Acetylcholine drives
the indirect pathway
Basal ganglia

17. All basal ganglia
connections are with
ipsilateral cortex
That’s why Basal ganglia
lesions are present
contralaterally
Basal ganglia

18. Q. What is the major input center of
basal ganglia?
• Ans: Striatum
Q. What is the major output center of
basal ganglia?
• Ans: Globus pallidus

19. Basal ganglia
Lesion
Direct pathway Indirect pathway
Underactive cortex overactive cortex
Decreased movements Increased movements

20. Q. Lesions of direct
pathway lead to
decrease in ?
• A. Velocity of movements
• B. Amplitude of movements
Ans. Both 

21. Case
History:
• A 67 year-old man had noticed involuntary shaking
of his right hand when he was not doing anything.
This abnormal movement disappeared when he
started using his hand. Of, late, family and friends
were also complaining that he looked and moved
slow, which was quite unlike to him because he had
an athletic personality.

22. On Exam: He had
Expressionless face
Resting tremors of his right hand
Decreased swinging movements of right upper
limb on walking
Marked rigidity
Case

23. Did You Know: Mohammad Ali was
diagnosed with Parkinson’s disease

24. Parkinson’s disease
• Lesion of direct pathway
• Degeneration of dopaminergic neurons
(depigmentation) of substantia nigra
• Hypokinetic disturbances: Slowing/absence of
spontaneous movements
• Problems in initiating movements: reduced
velocity & magnitude of movements.
Pathophysiology

26. Parkinson TRAP your body
• Tremor (pill rolling resting tremor)
• Rigidity (cogwheel)
• Akinesia (or bradykinesia)
• Postural instability
Parkinson’s disease
Cardinal signs

28. Imbalance of D & Ach causes tremors, rigidity & akinesia

29. • Stooped posture
• Expressionless mask like face
• Depression, Dysphagia
• Dementia (late finding)
• Small handwriting (micrographia)
Parkinson’s disease

30. Gait
• Shuffling gate: A type of gait (walking) characterized
by dragging one's feet along or without lifting the feet
fully from the ground.
• Accelerating/festinating gait: similar to a shuffling
gait. Unlike a shuffling gait, a person is in a stooped
position at all times. Their center of gravity is always too
far forward, so to avoid falling the person takes short,
shuffled steps
Parkinson’s disease

34. Composed of α-synuclein (intracellular
eosinophillic inclusions)
Parkinson’s disease

35. Q. Is Parkinson’s
disease same as
parkinsonism?
• Ans. Parkinson’s disease is always Parkinsonism but
Parkinsonism is not always Parkinson’s disease.
• Parkinsonism is a motor syndrome that manifests as
rigidity, tremors, and bradykinesia
• 80% Parkinsonism is caused by Parkinson’s disease

36. Parkinsonism
Known causes of parkinsonism:
• Parkinson’s disease (80%)
• Infections
• Vascular insults
• Toxic insults (MPTP: contaminant in illegal drugs)

37. • Treatment:
• L-Dopa: Dopamine precursor
• Anticholinergics: Inhibit effect of Ach on
indirect pathway
Parkinson’s disease

38. Types of Tremors

39. Q. Which of the following
structures has a primary
function to coordinate rate,
range, force, and direction of
movement?
A. Primary motor cortex
B. Premotor and supplementary motor cortex
C. Prefrontal cortex
D. Basal ganglia
E. Cerebellum
Ans. E

40. Q. A 45 year old man presents with involuntary facial
grimaces and movements of the fingers. His mother
had had similar symptoms beginning at about the
same age. Her disorder had progressed to dancing
movements, writhing of the arms and legs and
eventually coma and death. Which of the following is
most characteristics of this disease?
A. Degeneration of UMN & LMN
B. Dopamine depletion & depigmentation of subst. Nigra
C. Increased number of trinucleotide repeats in a gene on Ch#4
D. Neurofibrillary tangles and amyloid plaques in cerebral cortex
E. Pick bodies, characterized by round intracytoplasmic inclusions
consisting of neurofilaments
Ans. C

47. Jazakumullahu Khair ♥
(May ALLAH swt reward you with goodness)