The document discusses nervous system dysfunction, including syncope, fatigue, dizziness and vertigo, and neurologic causes of weakness and paralysis. It provides epidemiology, pathophysiology, diagnostic approaches and management strategies for different conditions. Key topics covered include vasovagal and orthostatic syncope, distinguishing peripheral from central causes of dizziness, differentiating upper and lower motor neuron disorders, and evaluating fatigue based on various potential etiologies.

1. HARRISON’S HOUR
NERVOUS SYSTEM
DYSFUNCTION

2. OBJECTIVES
• To be able to identify and distinguish different types of nervous system dysfunction
• To know the pathophysiology behind each condition
• To establish a definitive approach to management

3. TABLE OF CONTENTS
01
02
03
04
SYNCOPE FATIGUE
NEUROLOGIC CAUSES
OF WEAKNESS AND
PARALYSIS
DIZZINESS AND VERTIGO

4. SYNCOPE
01

5. EPIDEMIOLOGY AND NATURAL HISTORY
Cardiac (structural)
Neurally mediated /
Vasovagal syncope
35% cumulative
incidence
Higher mortality
10% cardiac cause
Women > Men
Genetic basis
Peak 10-30 y/o, median 15 y/o
The likelihood of hospitalization and mortality risk are higher in older adults.
/
Jameson, L., Fauci, A., Kasper, D., Hauser, S., Longo,D., Loscalzo, J., Harrison’s
Principles of Internal Medicine, 21st edition. New York: Mc Graw Hill; 2018

6. PATHOPHYSIOLOGY
Decreased
vagal nerve
activity
50
mmHg
Blood pooling
500-1000 mL
Increased
sympathetic
outflow
Compensatory
reflex response
Oiseth, S., Jones, L., Maza, E.. Syncope. Achieve Mastery of medical Concepts.
https://www.lecturio.com/concepts/syncope/
CO,
SVR

7. W
Wieling
et
al:
Symptoms
and
signs
of
syncope:
a
review
of
the
link
between
physiology
and
clinical
clues.
Brain
132:2630,
2009

8. Jameson, L., Fauci, A., Kasper, D., Hauser, S., Longo,D., Loscalzo, J., Harrison’s
Principles of Internal Medicine, 21st edition. New York: Mc Graw Hill; 2018
I. NEURALLY MEDIATED SYNCOPE
• Final pathway of reflex arc
• Transient change in autonomic
efferent activity
• Premonitory features
Cardiac output
 Parasympathetic outflow

9. Jameson, L., Fauci, A., Kasper, D., Hauser, S., Longo,D., Loscalzo, J., Harrison’s
Principles of Internal Medicine, 21st edition. New York: Mc Graw Hill; 2018
• Cornerstone of management
- REASSURANCE
- EDUCATION
- AVOIDANCE
- EXPANSION
• Isometric counterpressure
maneuvers
• Cardiac pacemaker is rarely
beneficial

10. Jameson, L., Fauci, A., Kasper, D., Hauser, S., Longo,D., Loscalzo, J., Harrison’s
Principles of Internal Medicine, 21st edition. New York: Mc Graw Hill; 2018
II. ORTHOSTATIC HYPOTENSION
• Autonomic failure
• Slow decline in pressure
• Non-specific symptoms due to sudden
postural change
• “Synucleinopathies”, Peripheral
neuropathies
Vagal tone
 Compensatory tachycardia

11. Jameson, L., Fauci, A., Kasper, D., Hauser, S., Longo,D., Loscalzo, J., Harrison’s
Principles of Internal Medicine, 21st edition. New York: Mc Graw Hill; 2018
• Reduction in SBP of at least 20 mmHg
or DBP of at least 10 mmHg
• Treatment interventions:
- Removal of reversible causes
- Non-pharmacologic
- Pharmacologic (as Midodrine
and l-dihydroxyphenylserine)
- Supplementary agents
(Pyridostigmine, Ocreotide, EPO)

12. Jameson, L., Fauci, A., Kasper, D., Hauser, S., Longo,D., Loscalzo, J., Harrison’s
Principles of Internal Medicine, 21st edition. New York: Mc Graw Hill; 2018
III. CARDIAC SYNCOPE
I. ARRHYTHMIAS
Bradyarrhythmia
• Sinus node dysfunction (tachycardia-
bradycardia syndrome)
• Bradycardia or Asystole (Stokes-
Adams attack)
Ventricular tachyarrhythmia
Inherited channelopathies

13. Jameson, L., Fauci, A., Kasper, D., Hauser, S., Longo,D., Loscalzo, J., Harrison’s
Principles of Internal Medicine, 21st edition. New York: Mc Graw Hill; 2018
II. STRUCTURAL HEART DISEASE
• Vagal overactivity
• Arrhythmogenesis
• Treatment interventions:
- Cardiac pacing
- Anti-arrhythmic drugs
- Cardioverter-defibrillator
- Holter monitoring

14. DIZZINESS AND
VERTIGO
02

15. DIAGNOSTIC ALGORITHM: TiTrATE
Muncie,
H.L.,
Sirmans,
S.M.,
James,
E.,Dizziness:
Approach
to
Evaluation
and
mnagement.
Americal
Family
Physician
2017;
95(3):
154-162
Jameson,
L.,
Fauci,
A.,
Kasper,
D.,
Hauser,
S.,
Longo,D.,
Loscalzo,
J.,
Harrison’s
Principles
of
Internal
Medicine,
21st
edition.
New
York:
Mc
Graw
Hill;
2018
<1 min and
typically 15–20s
Free-floating
otoconia
Epley maneuver

16. DIAGNOSTIC ALGORITHM: TiTrATE
Muncie,
H.L.,
Sirmans,
S.M.,
James,
E.,Dizziness:
Approach
to
Evaluation
and
mnagement.
Americal
Family
Physician
2017;
95(3):
154-162
Jameson,
L.,
Fauci,
A.,
Kasper,
D.,
Hauser,
S.,
Longo,D.,
Loscalzo,
J.,
Harrison’s
Principles
of
Internal
Medicine,
21st
edition.
New
York:
Mc
Graw
Hill;
2018
No trigger
Excess endolymph
Diuretics and sodium
restriction
Non-ablative surgery

17. DIAGNOSTIC ALGORITHM: TiTrATE
Muncie,
H.L.,
Sirmans,
S.M.,
James,
E.,Dizziness:
Approach
to
Evaluation
and
mnagement.
Americal
Family
Physician
2017;
95(3):
154-162
Jameson,
L.,
Fauci,
A.,
Kasper,
D.,
Hauser,
S.,
Longo,D.,
Loscalzo,
J.,
Harrison’s
Principles
of
Internal
Medicine,
21st
edition.
New
York:
Mc
Graw
Hill;
2018
Hours to weeks
Common
Motion sensitivity
Migraine features
Anti emetics

18. DIAGNOSTIC ALGORITHM: TiTrATE
Muncie,
H.L.,
Sirmans,
S.M.,
James,
E.,Dizziness:
Approach
to
Evaluation
and
mnagement.
Americal
Family
Physician
2017;
95(3):
154-162
Jameson,
L.,
Fauci,
A.,
Kasper,
D.,
Hauser,
S.,
Longo,D.,
Loscalzo,
J.,
Harrison’s
Principles
of
Internal
Medicine,
21st
edition.
New
York:
Mc
Graw
Hill;
2018
Days to weeks
Trauma or toxic exposure

19. Jameson, L., Fauci, A., Kasper, D., Hauser, S., Longo,D., Loscalzo, J., Harrison’s
Principles of Internal Medicine, 21st edition. New York: Mc Graw Hill; 2018

20. Muncie,
H.L.,
Sirmans,
S.M.,
James,
E.,Dizziness:
Approach
to
Evaluation
and
mnagement.
Americal
Family
Physician
2017;
95(3):
154-162

21. Rapid eye movement => PERIPHERAL
No eye movement => CENTRAL
HEAD-IMPULSE
NYSTAGMUS
Horizontal => PERIPHERAL
Vertical / torsional => CENTRAL
TEST OF SKEW
Vertical deviation => Abnormal result
Muncie, H.L., Sirmans, S.M., James, E.,Dizziness: Approach to Evaluation and
mnagement. Americal Family Physician 2017; 95(3): 154-162

22. Rapid eye movement => PERIPHERAL
No eye movement => CENTRAL
HEAD-IMPULSE
NYSTAGMUS
Horizontal => PERIPHERAL
Vertical / torsional => CENTRAL
TEST OF SKEW
Vertical deviation => Abnormal result
Muncie, H.L., Sirmans, S.M., James, E.,Dizziness: Approach to Evaluation and
mnagement. Americal Family Physician 2017; 95(3): 154-162

23. Rapid eye movement => PERIPHERAL
No eye movement => CENTRAL
HEAD-IMPULSE
NYSTAGMUS
Horizontal => PERIPHERAL
Vertical / torsional => CENTRAL
TEST OF SKEW
Vertical deviation => Abnormal result
Muncie, H.L., Sirmans, S.M., James, E.,Dizziness: Approach to Evaluation and
mnagement. Americal Family Physician 2017; 95(3): 154-162

24. Rapid eye movement => PERIPHERAL
No eye movement => CENTRAL
HEAD-IMPULSE
NYSTAGMUS
Horizontal => PERIPHERAL
Vertical / torsional => CENTRAL
TEST OF SKEW
Vertical deviation => Abnormal result
Muncie, H.L., Sirmans, S.M., James, E.,Dizziness: Approach to Evaluation and
mnagement. Americal Family Physician 2017; 95(3): 154-162

25. Jameson, L., Fauci, A., Kasper, D., Hauser, S., Longo,D., Loscalzo, J., Harrison’s
Principles of Internal Medicine, 21st edition. New York: Mc Graw Hill; 2018

26. FATIGUE
03

27. Jameson, L., Fauci, A., Kasper, D., Hauser, S., Longo,D., Loscalzo, J., Harrison’s
Principles of Internal Medicine, 21st edition. New York: Mc Graw Hill; 2018
DIFFERENTIAL DIAGNOSIS
Psychiatric disease Cardiovascular disorder
Neurologic disease Pulmonary disorders
Sleep disorders Malignancy
Endocrine disorders Hematologic disorders
Liver and Kidney disease Immune-mediated diorders
Obesity Pregnancy
Physical inactivity Disorders of unclear cause
Malnutrition Drugs
Infection

28. Jameson, L., Fauci, A., Kasper, D., Hauser, S., Longo,D., Loscalzo, J., Harrison’s
Principles of Internal Medicine, 21st edition. New York: Mc Graw Hill; 2018
DIFFERENTIAL DIAGNOSIS
Psychiatric disease Cardiovascular disorder
Neurologic disease Pulmonary disorders
Sleep disorders Malignancy
Endocrine disorders Hematologic disorders
Liver and Kidney disease Immune-mediated diorders
Obesity Pregnancy
Physical inactivity Disorders of unclear cause
Malnutrition Drugs
Infection

29. NEUROLOGIC
CAUSES OF
WEAKNESS AND
PARALYSIS
04

30. UPPER MOTOR NEURON PATHWAY
• Distal > proximal
• Axial movements are spared UNLESS severe
and bilateral
• Normal rhythmicity, but repetitive movements
• Corticobulbar = lower face and tongue
Muncie,
H.L.,
Sirmans,
S.M.,
James,
E.,Dizziness:
Approach
to
Evaluation
and
mnagement.
Americal
Family
Physician
2017;
95(3):
154-162
Jameson,
L.,
Fauci,
A.,
Kasper,
D.,
Hauser,
S.,
Longo,D.,
Loscalzo,
J.,
Harrison’s
Principles
of
Internal
Medicine,
21st
edition.
New
York:
Mc
Graw
Hill;
2018

31. LOWER MOTOR NEURON PATHWAY
• Decrease in number of muscle fibers
• Absent stretch reflex = spindle afferent
fibers
• Fasciculations vs Fibrillation potentials
• Delayed recruitment of motor units
Muncie,
H.L.,
Sirmans,
S.M.,
James,
E.,Dizziness:
Approach
to
Evaluation
and
mnagement.
Americal
Family
Physician
2017;
95(3):
154-162
Jameson,
L.,
Fauci,
A.,
Kasper,
D.,
Hauser,
S.,
Longo,D.,
Loscalzo,
J.,
Harrison’s
Principles
of
Internal
Medicine,
21st
edition.
New
York:
Mc
Graw
Hill;
2018

32. Muncie,
H.L.,
Sirmans,
S.M.,
James,
E.,Dizziness:
Approach
to
Evaluation
and
mnagement.
Americal
Family
Physician
2017;
95(3):
154-162
Jameson,
L.,
Fauci,
A.,
Kasper,
D.,
Hauser,
S.,
Longo,D.,
Loscalzo,
J.,
Harrison’s
Principles
of
Internal
Medicine,
21st
edition.
New
York:
Mc
Graw
Hill;
2018

33. Muncie,
H.L.,
Sirmans,
S.M.,
James,
E.,Dizziness:
Approach
to
Evaluation
and
mnagement.
Americal
Family
Physician
2017;
95(3):
154-162
Jameson,
L.,
Fauci,
A.,
Kasper,
D.,
Hauser,
S.,
Longo,D.,
Loscalzo,
J.,
Harrison’s
Principles
of
Internal
Medicine,
21st
edition.
New
York:
Mc
Graw
Hill;
2018

34. Muncie,
H.L.,
Sirmans,
S.M.,
James,
E.,Dizziness:
Approach
to
Evaluation
and
mnagement.
Americal
Family
Physician
2017;
95(3):
154-162
Jameson,
L.,
Fauci,
A.,
Kasper,
D.,
Hauser,
S.,
Longo,D.,
Loscalzo,
J.,
Harrison’s
Principles
of
Internal
Medicine,
21st
edition.
New
York:
Mc
Graw
Hill;
2018

35. Muncie,
H.L.,
Sirmans,
S.M.,
James,
E.,Dizziness:
Approach
to
Evaluation
and
mnagement.
Americal
Family
Physician
2017;
95(3):
154-162
Jameson,
L.,
Fauci,
A.,
Kasper,
D.,
Hauser,
S.,
Longo,D.,
Loscalzo,
J.,
Harrison’s
Principles
of
Internal
Medicine,
21st
edition.
New
York:
Mc
Graw
Hill;
2018

36. Jameson, L., Fauci, A., Kasper, D., Hauser, S., Longo,D.,
Loscalzo, J., Harrison’s Principles of Internal Medicine, 21st
edition. New York: Mc Graw Hill; 2018
Muncie, H.L., Sirmans, S.M., James, E.,Dizziness: Approach to
Evaluation and mnagement. Americal Family Physician 2017;
95(3): 154-162
RESOURCES

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