Autonomic Dysfunctions
-
Upload
twinkle-salonga -
Category
Documents
-
view
235 -
download
0
Transcript of Autonomic Dysfunctions
-
8/20/2019 Autonomic Dysfunctions
1/41
Disorders of the Autonomic Nervous System
Althea P. Tampos, M.D.
-
8/20/2019 Autonomic Dysfunctions
2/41
-
8/20/2019 Autonomic Dysfunctions
3/41
Physiologic and Pharmacologic Considerations:
Has only sympathetic postganglionic fibers:1. Sweat glands
2. Cutaneous blood vessels
3. Hair follicles
Only preganglionic sympathetic innervation:
1. Adrenal medulla
Neurohumoral Transmission
-
8/20/2019 Autonomic Dysfunctions
4/41
Neurohumoral Transmission Acetycholine (Ach)
Terminals of all preganglionic fibers
Skeletal muscle fibers
All postganglionic parasympathetic fibers:
Receptors:
1. Nicotinic – skeletal muscles; blocked by tubocurarine
2. Muscarinic – innervated organs; antagonized byatropine
Some postganglionic sympathetic (sweat glands)
-
8/20/2019 Autonomic Dysfunctions
5/41
Neurohumoral Transmission
Noerpinephrine (NE) – postganglionic sympathetic fibers
Adrenergic receptors
1. Alpha – vasoconstriction, relaxation of gut, dilation of pupils
1. Alpha1 – postsynaptic
2. Alpha 2 – presynaptic, decrease release of transmitters
2. Beta – vasodilation, relaxation of bronchi, increased heartrate and contractility
1. Beta 1 – increases heart rate and contractility
2. Beta 2 – relaxes smooth muscles of bronchi, bloodvessels of skeletal muscles
-
8/20/2019 Autonomic Dysfunctions
6/41
Central Regulation
1. Brainstem –1. Nucleus tractus solitarius – main visceral afferent
1. CN X (nodose ganglion) carry cardiovascular, respi-
2. CN IX (petrosal ganglion) ratory and GI afferents,baroreceptor and chemo-receptor info.
3. Caudal subnuclei – main receiving site for viscerosensoryfibers, receives baroreceptor and chemoreceptor info.
Projects to hypothalamus, amygdala, insular cortex,pontine and medullary nuclei
-
8/20/2019 Autonomic Dysfunctions
7/41
Central Regulation
2. Cerebrum
1. Hypothalamus – integrates ANS and limbic system via:
1. Direct pathway
1. Ventromedial – prefrontal (temperature, sweating)2. Cingulate cortices - voluntary control of bladder and
bowel
3. Insular cortex – cardiac arrythmias, alteration ofvisceral functions
4. Limbic lobe – visceral brain2. Pituitary – endocrine glands
-
8/20/2019 Autonomic Dysfunctions
8/41
Regulation of Blood Pressure
Baroreceptors (afferent components)
Sensitive to decrease in pulse pressure
1. Carotid sinus – rapidly responsive, responds to beat-to-beatchanges
2. Aortic arch – longer response time, discriminate only larger andmore prolonged alterations in pressure
Alterations in blood volume1. Right heart chamber
2. Pulmonary vessels
Afferent fibers – CN IX and X; motor nucleus of vagus nerve
Terminal ganglion – nucleus of tractus solitarius
Main sympathetic flow – via greater splanchnic nerve to celiacganglion
Renal Juxtaglomerular cells – release renin which stimulatesangiotensin production and influence aldosterone producion
-
8/20/2019 Autonomic Dysfunctions
9/41
Regulation of bladder function
Parasympathetic innervation
S2-S4
Muscarinic acetycholine receptors of detrusor muscles
Sympathetic innervation
Detrusor muscle
T10-T12
From inferior mesenteric ganglia through hypogastricnerve to pelvic plexus
Supplies beta adrenergic receptors at bladder dome
Internal sphincter
Alpha receptors
Internal sphincter and base of basal trigone
External urethral and anal sphincter – innervated by pudendalnerve from S2-S4; Ventrolateral part of Onuf’s nucleus
-
8/20/2019 Autonomic Dysfunctions
10/41
Central regulation of bladder functions:
Micturition centers:
1. Pontomesencephalic tegmentum
2. Frontal lobe ( paracentral region)
-
8/20/2019 Autonomic Dysfunctions
11/41
Examination of ANS
Postural Hypotension
Fall in BP of >30mmHg systolic and 15mmHg diastolic
Increase heart rate
Failure of above responses – vagal dysfunction
Bladder Function Test
cystometogram
-
8/20/2019 Autonomic Dysfunctions
12/41
Tests for vasomotor function:
Normal skin temperature : 31-33 ˚C Cold pressor test
immerse hand in cold water for 1 – 5 min
Increase systolic BP to 15-20 and diastolic BP to 10 -15mmHg
Sustained isometric contraction test
Hand grip for 5 min
Increase HR and BP
Test for GI function
Barrium swallow
-
8/20/2019 Autonomic Dysfunctions
13/41
Test for sudomotor functions
Galvanic skin resistance test
Lacrimal function
Schirmer test – Normal: wet area in filter paper is15 mm
If < 15 mm suggest keratoconjunctivitis
-
8/20/2019 Autonomic Dysfunctions
14/41
Acute Autonomic Paralysis
Dysautonomic Polyneuropathy
Pure Pandysautonomia
Both sympathetic and parasympathetic systems areaffected mainly at postganglionic level
Somatosensory and motors fibers are spared
Idiopathic
(+) antibodies against ganglionic acetylcholinereceptors
-
8/20/2019 Autonomic Dysfunctions
15/41
Signs and symptoms:
1. Anhidrosis
2. Orthostatic hypotension
3. Paralysis of pupillary reflexes
4. Loss of lacrimation and salivation
5. Impotence
6. Impaired bladder and bowel dysfunction (urinary
retention, postprandial bloating, ileus orconstipation)
7. Loss of pilomotor or vasomotor responses in skin(flushing and heat intolerance)
-
8/20/2019 Autonomic Dysfunctions
16/41
Treatment:
IVIg
Plasma exchange
Variants:
Sympathetic orthostatic hypotension
Postural orthostatic tachycardia syndrome
-
8/20/2019 Autonomic Dysfunctions
17/41
Idiopathic Orthostatic Hypotension
Degenerative disease of middle and late adult life
Lesions involve
mainly postganglionic sympathetic neurons
Preganglionic lateral horn neurons of thoracic and spinalhorn neurons degenerate
Signs and symptoms:
1. Orthostatic hypotension
2. Impotence
3. Anhidrosis
4. Atonicity of bladder
-
8/20/2019 Autonomic Dysfunctions
18/41
2 types (multiple system atrophy):
1. Postganglionic type
NE is decreased in supine and standing position becauseof failure of damaged nerve terminals to synthesize or
release catecholamines2. Central type
1. Striatonigral degeneration or Shy-Drager syndrome –autonomic failure was associated with Parkinsoniansyndrome and cytoplasmic inclusions in sympathetic
neurons
2. Olivopontocerebellar degeneration – involves stiatum,cerebellum,pons and medulla
-
8/20/2019 Autonomic Dysfunctions
19/41
Treatment:
Sleep with elevation of head
Mineralocorticoids:
Fludrocortisone acetate
Midrodine
Elastic/compression stockings
-
8/20/2019 Autonomic Dysfunctions
20/41
Peripheral Neuropathy With
Secondary Orthostaic Hypotension Acute and chronic peripheral neuropathies affect
autonomic fibers
Diabetes, alcoholic-nutritional, amyloid, GBS, heavymetal and toxic neuropathies
Hyponatremia maybe secondary to release of anti-diuretic hormone
-
8/20/2019 Autonomic Dysfunctions
21/41
Diabetic Neuropathy
Impotence
Constipation
Diarrhea (especially at night)
Hypotonia of bladder Gastroparesis
Orthostatic hypotension
Sensory polyneuropathy
Argyll-Robertson pupils
-
8/20/2019 Autonomic Dysfunctions
22/41
Pathophysiology
Vacuolization of sympathetic ganglionic neurons
Cell necrosis and inflammation Loss of myelinated fibers in vagi and white rami
communicantes
Loss of lateral horn cells in spinal cord
-
8/20/2019 Autonomic Dysfunctions
23/41
-
8/20/2019 Autonomic Dysfunctions
24/41
Pathophysiology:
Deficiency of neurons in superior cervical ganglion andlateral horn of spinal cord
Mutation in gene IKAP Failure of embryonic migration or formation of first and
second order sympathetic neurons
-
8/20/2019 Autonomic Dysfunctions
25/41
Autonomic Failure in Elderly
65 years and above
Orthostatic hypotension
Lability of temperature Loss of sewating of lower parts of body and
increased sweating of head and arms
Impotence and incontinence
-
8/20/2019 Autonomic Dysfunctions
26/41
Horner or Oculosympathetic
Syndrome Triad:
1. Ptosis
2. Miosis
3. Anhydrosis Pathophysiology includes interruption of:
postganglionic sympathetic fibers along internal carotidartery
superior cervical ganglion
preganglionic fibers between their origin inintermediolateral horn cells (C8-T2) spinal segments andsuperior cervical ganglion
Descending , uncrossed hypothalamospinal fibers integmentum of brainstem
-
8/20/2019 Autonomic Dysfunctions
27/41
Common causes:
1. Neoplastic or inflammatory involvement of cervicallymph nodes or proximal part of brachial plexus
2. Surgical or trauma to cervical structures
3. Carotid artery dissections
4. Syringomyelia or trauma of second thoracic spinalsegments
5. Infarcts or other lesions of lateral part of medulla
-
8/20/2019 Autonomic Dysfunctions
28/41
Other manifestations:
Heterochromia iridis
Harlequin effect
Ross syndrome
Combination of segmental anhidrosis and Adie pupil
-
8/20/2019 Autonomic Dysfunctions
29/41
Sympathetic and ParasympatheticParalysis in Tetraplegia and Paraplegia
Complete lesion in C4/C5 and upper thoracic (aboveT6)
Usual causes:
Traumatic necrosis of spinal cord
Infarction
Necrotic myelitis
Tumors
Acute cervical cord transection – abolishedsensorimotor, reflex, and autonomic functions ofspinal cord
-
8/20/2019 Autonomic Dysfunctions
30/41
Spinal shock:
Acute cervical cord transection – abolishedsensorimotor, reflex, and autonomic functionsof spinal cord
Hypotension
Loss of sweating
Piloerection
Paralytic ileus and gastric atony
Paralysis of bladder
Decrease plasma epinephrine andnorepinephrine
-
8/20/2019 Autonomic Dysfunctions
31/41
Mass reflex
Flexor spasms of legs and involuntaryemptying of bladder are associated with:
marked rise in BP
Bradycardia
Sweating
pilomotor reactions in parts below cervicalsegment (autonomic dysreflexia)
-
8/20/2019 Autonomic Dysfunctions
32/41
Autonomic crises
Sympathetic storm
Abrupt over activity of sympathetic andparasympathetic nervous systems – hypertensionand midriasis coupled with signs of CNSexcitation
Maybe caused by drugs as:
Phenylpropanolamine Cocaine
Tricyclic antidepressants Cholinergic blockers
-
8/20/2019 Autonomic Dysfunctions
33/41
-
8/20/2019 Autonomic Dysfunctions
34/41
Severe head injury with hypertensive cerebral
hemorrhage
Syndromes of unopposed sympathetic-adrenal medullaryhyperactivity
Mechanisms:
1. Outpouring of adrenal catecholamines with acutehypertension and tachycardia
2. Cushing response – brainstem mediated vasopressor reaction(hypertension, bradycardia, slow, irregular breathing)
3. Extreme hypertension, profuse diaphoresis, pupillary
dilatation usually arising during diencephalic autonomicseizures
Myocardial abnormalities maybe due to norepinephrineand cortisol surge
-
8/20/2019 Autonomic Dysfunctions
35/41
Disorders of Sweating
Hyperhydrosis:
Results from overactivity of sudomotor nerve
Botulinum toxin
Interruption of postganglionic sympatheticfibers
-
8/20/2019 Autonomic Dysfunctions
36/41
Raynaud Syndrome
Episodic, painful blanching of fingers probably dueto digital artery spasm
Age of onset: 14 years
Pallor, cyanosis, and rubor discoloration of fingersor toes
Brought about by cold or emotional stress
Numbness, paresthesias, burning sensation
Maybe associated with connective tissue diseases:scleroderma, rhematoid disease
Maybe due to obstructive arterial disease, minortrauma
-
8/20/2019 Autonomic Dysfunctions
37/41
Treatment:
Avoidance of cold exposure
Drugs that an cause vasoconstriction ( clonidine)
Calcium channel blockers (nifedipine)
-
8/20/2019 Autonomic Dysfunctions
38/41
Disturbances of bladder function
complete destruction of cord below T12
No awareness of state of fullness, voluntary initiation ofmicturition is impossible; bladder distends as urine
accumulates until there is overflow incontinence, voidingis possible only by Crede maneuver, saddle aneshesia,loss of bulbocavernosus and anal reflexes as well astendon reflexes
Disease of sacral motor neurons in spinal gray
matter, anterior sacral roots or peripheral nervesinnervating the bladder
Same as in I but sacral and bladder sensations are intact
-
8/20/2019 Autonomic Dysfunctions
39/41
Frontal lobe incontinence
Supranuclear hyperactivity of detrusor and precipitantevacuation
Nocturnal enuresis
Urinary incontinence during sleep
Delay in acquiring inhibition of micturition
Interruption sensory afferent fibers from bladder
-
8/20/2019 Autonomic Dysfunctions
40/41
Therapy of disordered micturition:
Bethanicol – for flaccid bladder paralysis; contractsdetrusor by stimulating its muscarinic cholinergicreceptors
Propatheline, atropine – for spastic bladder paralysis; act
as muscarinic antagonist
Alpha1synpathomimetic blocking drugs (terazosin,doxazosin) – relax urinary sphincter and facilitate voiding
Intermittent catheterization
Implantation of sacral anterior root stimulator
-
8/20/2019 Autonomic Dysfunctions
41/41
Disturbances of Bowel Function
Congenital Megacolon ( Hirschsprung Disease)
Affects mainly male infants and children
Congenital absence of ganglionic cells in the myentericplexus
Often involves internal anal sphincter and rectosigmoid
Most serious complication: enterocolitis and has highmortality