(17) Nervous System Tables Flashcards
Tables 17-1 and 17-2 not done
p. 774-777
Vasovagal Syncope (the common faint) & Vasodepressor Syncope: Mechanism
For vasovagal syncope: reflex withdrawal of sympathetic
tone and increased vagal tone causing drop in blood
pressure and heart rate
For vasodepressor syncope: same mechanism but no
vagal surge or drop in heart rate
Baroreflexes normal
Vasovagal Syncope (the common faint) & Vasodepressor Syncope: Precipitating Factors
Strong emotion such as fear or
pain, prolonged standing, hot
humid environment
Vasovagal Syncope (the common faint) & Vasodepressor Syncope: Predisposing Factors
Fatigue, hunger, preload reduction from
dehydration, diuretics, vasodilators
Vasovagal Syncope (the common faint) & Vasodepressor Syncope: Prodromal Manifestations
Usually >10 s. Palpitations,
nausea, blurred vision, warmth,
pallor, diaphoresis, lightheadedness
Vasovagal Syncope (the common faint) & Vasodepressor Syncope: Postural Associations
Usually occurs when
standing, at times
when sitting
Vasovagal Syncope (the common faint) & Vasodepressor Syncope: Recovery
Prompt return of consciousness after lying down, but pallor, weakness, nausea, and slight confusion may persist for a time Most common type of syncope
Orthostatic hypotension: definition
drop in SBP >20 or DBP >10 within 3 min of standing
Orthostatic hypotension:
mechanism
Gravitationally mediated redistribution and pooling of
300–800 mL blood in the lower extremities and
splanchnic venous system, caused by decreased venous
return and an excessive fall in cardiac output, or by an
inadequate vasoconstrictor mechanism (with inadequate
release of norepinephrine)
Hypovolemia, a diminished blood volume insufficient to
maintain cardiac output and blood pressure
Orthostatic hypotension:
precipitating factors
standing up
standing up after hemorrhage or dehydration
Orthostatic hypotension:
predisposing factors
Aging; central and peripheral neuropathies:
Parkinson disease, multiple system atrophy;
Lewy body disease diabetes, amyloidosis;
antihypertensive vasodilator drugs; prolonged
bed rest
Bleeding from the GI tract or trauma, potent
diuretics, vomiting, diarrhea, polyuria
Orthostatic hypotension:
prodromal manifestations
Lightheadedness, dizziness,
cognitive slowing, fatigue
Often none
Light-headedness and
palpitations (tachycardia) on
standing up
Orthostatic hypotension:
postural associations
Occurs soon after
standing
Supine hypertension
is common
Occurs soon after
standing up
Orthostatic hypotension:
recovery
Prompt return to normal when
lying down
Improves with volume repletion
Cough Syncope:
mechanism
Neurally mediated, possibly from reflex vasodepressorbradycardia
response; cerebral hypoperfusion,
increased CSF pressure also proposed
Cough Syncope:
precipitating factors
Severe paroxysm of coughing
cough syncope:
predisposing factors
COPD, asthma, pulmonary hypertension.
Typically occurs in overweight middle-aged
patients
cough syncope:
prodromal manifestations
Often none except for cough;
blurred vision, light-headedness
may occur
cough syncope:
postural associations
May occur in any
position
cough syncope:
recovery
Prompt return to normal after a
few seconds
Micturition Syncope:
mechanism
Vasovagal response, sudden hypotension proposed
Micturition Syncope:
precipitating factors
Emptying the bladder after
getting out of bed to void
Micturition Syncope:
predisposing factors
Nocturia, usually in elderly or adult men
Micturition Syncope:
prodromal manifestations
Often none
Micturition Syncope:
postural associations
Commonly just after
(or during) voiding
after standing up
Micturition Syncope:
recovery
Prompt return to normal
Table 17-3 Cardiovascular Disorders and Disorders Resembling Syncope not done
pg. 778-779