2. The autonomic nervous system (ANS) is the system that controls nonstriated muscles
and glands.
There are three divisions of the ANS:
1. sympathetic (thoracolumbar),
2. parasympathetic (craniosacral), and
3. Enteric
Autonomic functions are beyond voluntary control and for the most part
beneath consciousness
11. SYMPTOMS OF AUTONOMIC DYSFUNCTION
• Clinical manifestations can result from loss of function, overactivity, or
dysregulation of autonomic circuits.
• Disorders of autonomic function should be considered in all patients with
unexplained orthostatic hypotension, syncope, sleep dysfunction, altered
sweating (hyperhidrosis or hypohidrosis), constipation, upper
gastrointestinal symptoms (bloating, nausea, vomiting of old food),
impotence, or bladder disorders (urinary frequency, hesitancy, or
incontinence).
• Symptoms may be widespread or regional in distribution.
12.
13.
14. FEATURES OF AUTONOMIC FAILURE
ORTHOSTATIC HYPOTENSION
Is defined as a fall in SBP of at least 20 mm hg or fall in DBP of at least 10 mm hg within 3 min of standing or
head up tilt to at least 60 degree angle.
Presyncopal symptoms such as lightheadedness or dizziness, palpitation, weakness, blurred visison, nausea
vomiting or may be syncope.
POST PRANDIAL HYPOTENSION
is defined as a fall in SBP of more than 20 mm hg occurring within 2 hr after a meal.
Freeman et al.2011
Lipsitz et al, 1983; mathius 1991
15. SUPINE HYPERTENSION
Many patients with autonomic failure have this SBP >/=150 & DBP >/= 90 mm hg
in many cases >200 mm hg
Can remain undetected as pressure is often measured seated
RESTING TACHYCARDIA-
fixed high HR, non responsive to moderate exercise , stress, sleep
EXERCISE INTOLERANCE- blunted HR response to exercise
QTc PROLONGATION >450ms in males, >460 ms in females
REVERSE DIPPING & NON DIPPING PATTERNS
In healthy subjects – nightly drop in BP
In Diabetic AN- increased BP with increased sympathetic tone
16. CLINICAL GOALS OF TESTING
1. TO EVALUATE THE PRESENCE , SEVERITY, DISTRIBUTION OF AUTONOMIC
DYSFUNCTION
2. TO DETECT AUTONOMIC FAILURE RESTRICTED TO A SINGLE SYSTEM OR SPECIFIC
AREA
3. TO DIAGNOSE AND EVALUATE ORTHOSTATIC INTOLERANCE
4. TO MONITOR THE COURSR AND TREATMENT OF DYSAUTONOMIA
5. AS AN INSTRUMENT IN RESEARCH STUDIES
17. AUTONOMIC FUNCTION TESTS
• CARDIOVASCULAR AUTONOMIC FUNCTION
• SUDOMOTOR FUNCTION
• PUPILLARY FUNCTION
• BLADDER FUNCTION
• GIT FUNCTIONS
18. CARDIOVASCULAR AUTONOMIC FUNCTION TESTS
• POSTURAL CHALLENGE TEST
• VALSALVA MANEUVER
• COLD PRESSOR TEST
• ISOMETRIC HANDGRIPTEST
• DEEP BREATHING TEST
• BP DURING AND AFTER EXERCISE
• CAROTID SINUS MASSAGE
• HEART RATE VARIABILITY
• BP VARIABILITY
• BAROREFLEX SENSITIVITY
• PULSE WAVE VELOCITY
• SYMPATHETIC SKIN RESPONSE
• PLASMA CATECHOLAMINE LEVEL
19. DEEP BREATHING TEST(DBT)
HEART RATE VARIATION DURING DEEP BREATHING
• Breating at 6 cycles/ min. For 5 min.
(performed while lying down)
• Each breath should be smooth deep and slow
• Over 120 beats are analysed
• E:I ratio is the ratio between longest RR interval and shortest RR interval
• NORMAL E:I RATIO >/= 1.21
24. POSTURAL CHALLENGE TEST
HEAD UP TILT TEST
PI(Sometimes known as 30:15) calculated using RR interval after standing up from recumbent
PI = longest RR interval between 20-40 beats
shortest RR between 5-25 beats
NORMAL >/= 1.04
BORDERLINE 1.01-1.03
ABNORMAL </= 1.0
25. Physiological basis
• Standing puts hydrostatic stress on venous return causing venous pooling
• BP drops. This activates the baroreflex
• Heart rate increases in 10-20 seconds
• Heart rate decreases later 25-35 seconds
30. VALSALVA MANEUVER
TECHNIQUE-
• SUPINE POSITION
• FORCED EXPIRATION AGAINST A CLOSED
GLOTTIS TO BUILD AN INTRATHORACIC
PRESSURE
• INTRATHORACIC PRESSURE SHOULD BE 40 MM
HG HELD FOR 15 SECONDS(RECORDING IN
FINOMETER)
31.
32.
33. PHYSIOLOGICAL BASIS
• BP changes in phase I and III are purely mechanical
• Phase II BP drop is due to reduction in venous return and the tachycardia is due to the baroreflex
• Mediated initially by vagal withdrawl and subsequently by increased sympathetic discharge
• Phase IV is due to the increase in venous return overshooting the BP and baroreflex mediated bradycardia
36. longest RR in phase IV
VALSALVA RATIO = shortest RR in phase II
VR normal >/= 1.21
borderline 1.1-1.20
abnormal </= 1.10
37. ISOMETRIC HANDGRIP TEST
• 30% of the Maximum voluntary contraction (MVC) using a hand dynamometer is maintained
for 3 minutes.
• Blood pressure is recorded at 1st min. 2nd min., 3rd min. and after 2 min of release
• Highest DBP during test –baseline DBP
DBP rise >/=16 mm hg normal
11-15 mm hg borderline
</= 10 mm hg abnormal
Handgrip muscle contraction increases the generalized sympathetic tone elevating the BP and
increase in heart rate is due to parasympathetic withdrawl.
38. INTERPRETATION OF CARTs
• Avoid using single test for interpretation
• Ideally use all five tests
• One abnormal test or two borderline tests EARLY CAN
• Two or more abnormal test DEFINITIVE CAN
• Presence of orthostatic hypotension SEVERE CAN
40. QUANTITATIVE SUDOMOTOR AXON REFLEX TESTING (QSART)
• It measures postganglionic small nerve fibre functions where nerve
conductions studies are normal
• The use of multiple recording sites helps in evaluating the distribution of the
sweating abnormality
• QSWEAT is the commercially available FDA approved version
• Normative percentiles values are currently available for both QSART and
QSWEAT
• Low PA. et al Ann Neural 1983;14:573-80
41. TECHNIQUE:
• Four multi compartmental
capsules are applied on the
forearm, proximal leg, distal leg
and foot
• A.ch is iontophorised in
compartment C activating a local
axon reflex stimulating the sweat
gland under this compartment.
• Sweat output is collected from
compartment A and is measured
in microlitres/cm2
44. THERMOREGULATORY SWEAT TEST (TST)
TECHNIQUE:
• Alizarin S powder
• Infrared heat lamps
• Oral temperature: if not fully sweating , an increase of 1.0 degree
centigrade or to reach 38.0 degree centigrade whichever is highest is
required
• Sensor feedback loop control of heating rate
• Digital image processing
45.
46.
47.
48.
49.
50. BEDSIDE AUTONOMIC FUNCTION TESTS
FOR CARDIOVASCULAR REFLEXES
1. SUPINE AND STANDING BP
2. CHANGE IN HEART RATE WITH POSTURE
3. RESPIRATION ASSOCIATED SINUS ARRHYTHMIA
4. MENTAL STRESS TEST
5. ICE WATER TEST
6. HAND GRIP MANEUVER
FOR PUPILLARY CHANGES
1. COCAINE AND HYDROXYAMPHETAMINE TEST
FOR SUDOMOTOR FUNCTION
1. MINOR’S TEST
2. SPOON TEST
51. Important advise for patients preparation before autonomic testing
The following should be discontinued
48 hr before
Anticholinergics, sympathomimetics, parasympathomimetics, minerelocorticoids, diuretics
24 hr before
Sympatholytics
12 hr before
Alcohol and analgesics
At the morning of the examination
No wearing of tight clothes or support stockings
3 hr before
Nicotine, coffee, food
52. Management of autonomic failure
• Aimed at specific treatment of the cause and
alleviation of symptoms.
• Of particular importance is the removal of drugs
or amelioration of underlying conditions that
cause or aggravate the autonomic symptoms,
especially in the elderly.
56. PHARMACOLOGIC INTERVENTION
1. Midodrine a directly acting α1-agonist that does not cross the blood-brain barrier.
• It has a duration of action of 2–4 h.
• The usual dose is 5–10 mg orally tid, but some patients respond best to a decremental dose (e.g., 15 mg on
awakening, 10 mg at noon, and 5 mg in the afternoon). Midodrine should not be taken after 6 P.M.
• Side effects include pruritus, uncomfortable piloerection, and supine hypertension especially at higher doses.
2. Pyridostigmine appears to improve OH without aggravating supine hypertension by enhancing ganglionic
transmission (maximal when orthostatic, minimal supine).
3. Fludrocortisone will reduce OH, but it aggravates supine hypertension. At doses between 0.1 mg/d and 0.3 mg
bid orally, it enhances renal sodium conservation and increases the sensitivity of arterioles to NE.
• Susceptible patients may develop fluid overload, congestive heart failure, supine hypertension, or hypokalemia.
• Potassium supplements are often necessary with chronic administration of fludrocortisone.
• Sustained elevations of supine BP >180/110 mmHg should be avoided.
57. TREATMENT OPTIONS FOR POSTPRANDIAL HYPOTENSION
NON PHARMCOLOGICAL
1. Instruct patients to self monitor BP
2. Frequent, small, low-carbohydrate meals may diminish splanchnic shunting of
blood after meals and reduce postprandial OH
3. Avoid use of abdominal binder or elastic waist high high stocking when supine
4. Avoid fluid intake at bedtime
5. Avoid pressor agents before bedtime
6. Rest in reclining chair with feet on floor during the day
7. Raise head of the body by 6 to 9 inch during nighttime
58. PHARMACOLOGICAL
1. Prostaglandin inhibitors (ibuprofen or indomethacin) taken with meals
2. Midodrine (10 mg with the meal) can be helpful.
3. The somatostatin analogue octreotide can be useful in the treatment of
post-prandial syncope by inhibiting the release of gastrointestinal
peptides that have vasodilator and hypotensive effects.
The subcutaneous dose ranges from 25 μg bid to 200 μg tid.
59. SUMMARY
1. Autonomic disorders are well recognized entity
2. If diagnosed can be treated to improve quality of life
3. Most of the Tests are simple and non invasive
4. Patients need to be prepared for the test for proper results
60. REFERENCES:
1. Ganong’s Review Of Medical Physiology , 26th Edition
2. Guyton And Hall Textbook Of Medical Physiology, 14th Edition
3. Harrison’s Textbook Of Internal Medicine, 21st Edition
4. Bradley And Daroff’s Neurology In Clinical Practice, 8th Edition
5. Snell’s Neuroanatomy, 8th Edition
6. Dejong's The Neurologic Examination, 8th Edition
7. Electrodiagnostic Assessment Of The Autonomic Nervous System: A Consensus Statement Endorsed By The
American Autonomic Society: Clinical Neurophysiology Vol. 132, Feb 2021 666-682
8. Autonomic Function Tests: Some Clinical Applications; J Clin Neurol, 2013
9. Fealey Rd Et Al, Mayo Clin. Proc. 1989; 64: 617-28
10.Low PA. Et Al Ann Neural 1983;14:573-80
11. Freeman Et Al.2011
12.Lipsitz Et Al, 1983; Mathius 1991
13.D. Clausa, R. Schondorf :Sympathetic Skin Response; 1999 International Federation Of Clinical
Neurophysiology
14.Kucera P., Goldenberg Z , Kurca E : SSR: Review Of Method And Its Clinical Use : Bratist Lek Listy 2004
15.Ben M.W Illigens, MD And Christopher H. Gibbons, Sweat Testing To Evaluate Autonomic Function: Clin Ayton
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