The%20autonomic%20nervous%20system%20dysfunction

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The autonomic nervous system dysfunction

• Tamer Belal,MD.PHD
• Neurology Department
• Mansoura University Hospitals

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Autonomic system Divisions
Sympathetic nervous system (fight or flight)

• Diverts blood flow away from the
  gastro-intestinal (GI) tract and skin via
  vasoconstriction
• Blood flow to skeletal muscles and the lungs is
  enhanced (by as much as 1200 in the case of
  skeletal muscles)
• Dilates bronchioles of the lung, which allows for
  greater alveolar oxygen exchange
• Increases heart rate and the contractility of
  cardiac cells (myocytes), thereby providing a
  mechanism for enhanced blood flow to skeletal
  muscles
• Dilates pupils and relaxes the ciliary muscle to
  the lens, allowing more light to enter the eye
  and far vision
• Provides vasodilation for the coronary vessels of
  the heart
• Constricts all the intestinal sphincters and the
  urinary sphincter
• Inhibits peristalsis
• Stimulates orgasm

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Autonomic system Divisions
Parasympathetic nervous (Rest and digest)

• Dilate blood vessels leading to the GI tract,
  increasing blood flow
• Constrict the bronchiolar diameter when the need
  for oxygen has diminished
• Dedicated cardiac branches of the vagus and
  thoracic spinal accessory nerves impart
  parasympathetic control of the heart
• During accommodation, causes constriction of the
  pupil and contraction of the ciliary muscle to
  the lens, allowing for closer vision
• Stimulates salivary gland secretion, and
  accelerates peristalsis, mediating digestion of
  food and, indirectly, the absorption of nutrients
• The PNS is also involved in the erection of
  genital tissues via the pelvic splanchnic nerves
  24.
• The PNS is responsible for stimulating sexual
  arousal

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Central control of the Autonomic NS
Amygdala main limbic region for
emotions -Stimulates sympathetic activity,
especially previously learned fear-related
behavior -Can be voluntary when decide to recall
frightful experience - cerebral cortex acts
through amygdala -Some people can regulate some
autonomic activities by gaining extraordinary
control over their emotions Hypothalamus main
integration center Reticular formation most
direct influence over autonomic function
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Classification
Localized disorders Affect an organ or region
of the body but they may be part of generalized
disease, such as gustatory sweating in diabetes
mellitus
Generalized disorders often affect systems, such
as those involved in blood pressure control and
thermoregulation. They can be primary when the
cause is often unclear, or secondary when
associated with a specific disease or its
complications
Drugs are a common cause of autonomic
dysfunction, either because of their
pharmacological effects or because of autonomic
nerve damage. Damage to the autonomic nervous
system often causes irreversible abnormalities
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Clinical features
Clinical features of autonomic disease cover a
wide spectrum and result from Underactivity or
Overactivity. Sympathetic adrenergic failure
causes orthostatic (postural) hypotension and
ejaculatory failure in the male Sympathetic
cholinergic failure causes anhidrosis
Parasympathetic failure causes dilated pupils,
fixed heart rate, sluggish urinary bladder,
atonic large bowel and, in the male, erectile
failure
In some disorders, particularly in neurally
mediated syncope, there may be a combination of
over-activity and under-activity, with
bradycardia caused by increased parasympathetic
activity and hypotension brought about by
withdrawal of sympathetic activity
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System
Cardiovascular
Cardiovascular Postural hypotension Supine hypertension
Cardiovascular Lability of blood pressure Paroxysmal hypertension
Cardiovascular Tachycardia Bradycardia
Sudomotor
Sudomotor Hypohidrosis or anhidrosis Hyperhidrosis
Sudomotor Gustatory sweating
Sudomotor Hyperpyrexia Heat intolerance
Alimentary
Alimentary Xerostomia Dysphagia
Alimentary Gastric stasis Dumping syndromes
Alimentary Constipation Diarrhoea
Urinary
Urinary Nocturia Frequency
Urinary Urgency incontinence
Urinary Retention
Sexual
Sexual Erectile failure Ejaculatory failure
Sexual Retrograde ejaculation
Eye
Eye Pupillary abnormalities Ptosis
Eye Alachryma Abnormal lachrymation with food ingestion
Clinical manifestations of autonomic dysfunction
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Cardiovascular system
Orthostatic hypotension
Orthostatic or postural hypotension is defined as
a fall in blood pressure of 20 mmHg systolic or
10 mmHg diastolic on sitting, standing or during
60 head-up tilt. In neurogenic orthostatic
hypotension, levels of plasma noradrenaline do
not rise when upright, as occurs in normal
subjects . Hypoperfusion of organs, especially
above heart level such as the brain, cause the
malaise, nausea, dizziness and visual
disturbances that often precede loss of
consciousness.
A variety of symptoms result from hypoperfusion
elsewhere. Neck pain in a coat-hanger
distribution (suboccipital and shoulder regions)
differs from other types of neck pain by
developing when upright. It is relieved by
sitting or lying flat
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Cerebral hypoperfusion Dizziness Visual
disturbances Blurred tunnel Scotoma Greying
out blacking out Colour defects Syncope Cognitiv
e deficits Muscle hypoperfusion Paracervical and
suboccipital (coat-hanger) ache Lower
back/buttock ache Subclavian steal-like
syndrome Renal hypoperfusion Oliguria Spinal cord
hypoperfusion Non-specific Weakness, lethargy,
fatigue Fall
Symptoms of orthostatic hypotension and impaired
perfusion
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Cardiovascular system
Syncope without orthostatic hypotension
Syncope has many causes (autonomic, cardiac,
neurogenic and metabolic). Autonomic causes of
syncope without orthostatic hypotension include
neurally mediated syncope, where there is
transient hypotension and bradycardia. There are
three major forms vasovagal syncope, carotid
sinus hypersensitivity and situational syncope.
Blood pressure falls because of sympathetic
withdrawal while heart rate falls because of
increased vagal activity.
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Cardiovascular system
Orthostatic intolerance with posturally induced
tachycardia
When orthostatic intolerance occurs without
orthostatic hypotension, but with a substantial
rise in heart rate (of over 30 beats/ minute),
the term postural tachycardia syndrome (PoTS)
is used. It predominantly affects women below the
age of 50 years. Symptoms include marked
dizziness on postural change or modest exertion
syncope may occur.
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Cardiovascular system
Hypertension
Unlike hypotension, hypertension typically causes
few symptoms other than headaches and these
only occasionally. In high spinal cord
lesions, severe paroxysmal hypertension can
develop as part of autonomic dysreflexia, when an
uninhibited increase in spinal sympathetic
activity is caused by contraction of the urinary
bladder, irritation of the large bowel, noxious
cutaneous stimulation or skeletal muscle spasms.
In tetanus, hypertension in ventilated
patients may be precipitated by muscle spasms or
tracheal suction.
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Cardiovascular system
Hypertension
Intermittent hypertension may occur in the
GuillainBarré syndrome, porphyria, posterior
fossa tumours and phaeochromocytoma , often
without any evident precipitating
cause. Hypertension in the supine position may
complicate orthostatic hypotension in pure
autonomic failure (PAF). The mechanisms include
impaired baroreflex activity, adrenoceptor
supersensitivity, an increase in central blood
volume because of a shift from the periphery and
the effects of drugs used to prevent orthostatic
hypotension .
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Cardiovascular system
Heart rate disturbances
Bradycardia, along with hypertension, may occur
in cerebral tumours with or without raised
intracranial pressure and during autonomic
dysreflexia in high spinal cord injuries In PoTS,
tachycardia usually is associated with head-up
postural change and exertion
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Sudomotor system
Anhidrosis or hypohidrosis is common in PAF and
differences in sweating may first be noticed
during exposure to warm temperatures
Alimentary system
Reduced salivation and a dry mouth (xerostomia)
occur in autonomic disease. Constipation is
common in PAF. Diarrhoea also may occur as result
of overflow. Diarrhoea, especially at night, can
be a distressing problem in diabetes mellitus
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Kidneys and urinary tract
Nocturnal polyuria is a frequent symptom in PAF.
The causes include restitution of blood pressure
sometimes to elevated levels while supine,
redistribution of blood from the peripheral into
the central compartment. Autonomic disease can
cause urinary frequency, urgency, incontinence
or retention. Ureteric reflux predisposes to
renal damage, especially in the presence of
infection
Sexual function
Failure of erection ( parasympathetic damage) may
cause impotence. Retrograde ejaculation may
occur, especially if there are urinary sphincter
abnormalities. Priapism resulting from abnormal
spinal reflexes may occur in patients with spinal
cord lesions.
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Eyes and lacrimal glands
Mild ptosis is part of Horners syndrome.
pupillary abnormalities may occur with autonomic
involvement, miosis in Horners syndrome and
dilated myotonic pupils in HolmesAdie syndrome
Impaired tear production may occur in PAF,
sometimes as part of a presumed sicca or
Sjögrens syndrome, along with diminished
salivary secretion. Excessive and inappropriate
lacrimation occurs in crocodile tears syndrome
(gusto-lacrimal reflex)
Respiratory system
Involuntary inspiratory sighs, stridor and
snoring of recent onset are more frequent .
Nocturnal apnoea is caused by involvement of
brainstem respiratory centres
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Facial and peripheral vascular changes
Facial pallor with an ashen appearance with fall
of pressure in postural hypotension, Restoration
of colour follows promptly on assuming the supine
position In longstanding tetraplegia,
hypertension during autonomic dysreflexia is
often accompanied by fl ushing and sweating over
the face and neck Harlequin syndrome there is
vasodilatation and anhidrosis on one side of the
face caused by sympathetic impairment, with
sparing of the pupil. Raynauds phenomenon may be
seen in both PAF and MSA, for uncertain
reasons. In erythromelalgia there is limb
discomfort with vascular changes
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Clinical examination
The combination of a detailed history and
physical examination is crucial in determining if
autonomic disease is present, in ascertaining
the probable underlying diagnosis, and also for
interpreting the results of autonomic tests in
the context of the associated disorder
Measurement of blood pressure, both lying and
standing (or sitting), is needed to determine if
orthostatic hypotension is present, as is
recording the pulse rate changes in patients
with PoTS
The extent and distribution of the neurological
abnormalities provide important clues to
underlying central or peripheral autonomic
disorders. Examination of other systems, as in
hepatic disease or diabetes, is necessary along
with urine testing for glucose and protein
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Investigations
The aims of investigations in autonomic
dysfunction are twofold.
The first relates to diagnosis
The second is to understand the
pathophysiological basis of disturbed autonomic
function, as this often forms the basis of
treatment strategies and their evaluation.
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Investigations
Cardiovascular

• Pressor stimuli (isometric exercise, cold
  pressor, mental arithmetic)
• Head-up tilt (60º) standing Valsalva
  maneouvre
• Heart rate responses deep breathing,
  hyperventilation, standing,
• Liquid meal challenge
• Exercise testing
• Carotid sinus massage
• Plasma noradrenaline supine and head-up tilt or
  standing
• Noradrenaline alpha-adrenoceptors,
• Cardiac sympathetic innervation

Outline of investigations in autonomic disease
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Endocrine

• Clonidine alpha-2 adrenoceptor agonist
  noradrenaline suppression growth hormone
  stimulation

Sudomotor

• Central regulation thermoregulatory sweat test
• Sweat gland response to intradermal
  acetylcholine, quantitative sudomotor reflex
  test, localized sweat test
• Sympathetic skin response

Outline of investigations in autonomic disease
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Gastrointestinal

• Video-cine-fluoroscopy, barium studies,
  endoscopy, gastric emptying studies,
• lower gut studies

Renal function and urinary tract

• Day and night urine volumes and sodium/potassium
  excretion
• Urodynamic studies, intravenous urography,
  ultrasound examination,
• sphincterelectromyograph

Outline of investigations in autonomic disease
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Sexual function

• Penile plethysmography
• Intracavernosal papaverine

Respiratory

• Laryngoscopy
• Sleep studies to assess apnoea and oxygen
  desaturation

Eye and lacrimal function

• Pupil function, pharmacological and physiological
• Schirmers test

Outline of investigations in autonomic disease
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Management
Management strategy in autonomic failure
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Management
Approaches to management of orthostatic
hypotension
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