Autonomic Nervous System

Front 1

ANS overview

Back 1

Front 2

SNS Preganglionic Fibres Neurons to...

Back 2

–Paravertebral ganglia; paired, bilaterally along vertebral column
3 cervical, 11 thoracic, 4 lumbar, 4 or 5 sacral
–Prevertebral ganglia : midline, anterior to aorta, spinal column
coeliac, aorticorenal and mesenteric
–previsceral ganglia; small collections of sympathetic ganglia located close to target structures

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NTs in SNS

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Front 4

Parasympathetic nervous system

Back 4

•Craniosacral outflow
•Cranial nerves III, VII, IX, X
–CN III fibres Edinger-Westphal nucleus midbrain, periphery of CNIII, exit with nerve to IO, ciliary ganglion
–Preganglionic fibres for VII from superior salivary nucleus, leave VII at geniculate ganglion
–DMV in medulla preganglionic fibres to essentially all organ systems in chest and abdomen
•Sacral cord levels 2,3,4
–Cell bodies intermediolateral cell column
–Postganglionic fibres to bladder and bowel and reproductive organs

Front 5

Ganglia in ANS

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Front 6

Effects of ANS on organs

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Front 7

Horners Syndrome
- causes

Back 7

causes horners:
- vascular
- physical damage to the sympathetics along the course (mesh along the carotid, lesion in the brain stem, along T1, or paravertebral length...)

Front 8

Course of Sympathetics to the eye
- lesion sites

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Front 9

MVA horners syndrome + neck pain

Back 9

think carotid dissection

Front 10

Cardiovascular reflexes: easily tested in clinical setting

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Parasympathetic
•Heart rate response to deep breathing (vagal afferent and efferents)
•Heart rate response to Valsalva (INC> thoracic pressure thus DEC. VR)
Sympathetic
•Blood pressure response to postural change (eg tilt-up)
•Heart rate response to postural change
•Blood pressure response to Valsalva

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Baroreceptor Reflex

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Front 12

Normal Tilt table test

Back 12

Slight inc. in HR AND BP

Front 13

COnvulsive Syncopy

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if the BP is low for long enough
- eg faint and dont get flat quick enough

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Causes of Syncopy

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Front 15

Vasovagal

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called a vasovagal due to bardycardic response BUT in fact the cause is due to the abrupt withdrawal of SNS that actually causes it and not the vagus

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Key historical points in the evaluation of
syncope

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• Situation
• Prodrome
– diaphoresis, warmth, lightheadedness
– focal neurological deficit
– chest pain, shortness of breath
– Witness reports
• Witness reports
• Post event residua
• Past history
• Family history
• Medications

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Current investigations used to assess syncope

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• thorough history , examination and ECG yields a
diagnosis in 50%
• Ambulatory ECG monitoring
• ECHO
• Exercise testing
• EPS
• Tilt table testing
• Other
– EEG
– coronary angiography

Front 18

Tilt testing: indications

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Established
• Recurrent unexplained syncope
• Single episode in high risk individuals
• Further evaluation where a cause is established but where NMS would affect treatment plans
Debated
• convulsive syncope vs seizures
• recurrent unexplained falls
• follow up evaluation to assess therapy of NMS
Not warranted
• single episode of syncope with clear vasovagal features
• syncope with established cause where NMS would not effect therapy

Much better test than active staning (using muscles) but not v.specific because some normal people will faint

Front 19

Tilt testing: method

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• fasting vs non, IV hydration vs not
• beat to beat blood pressure recordings
• 60-80% head up tilt
• 30-45 min initial drug free tilt
• ?? Role of provocative medication (isoprenaline,
nitroglycerin, clomipramine)
• reproducibility varies (35-85% most studies 65-85%)

Front 20

Tilt testing: optimum duration

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Front 21

SNS Syncopy

Back 21

no drop in HR just abrupt withdrawal of SNS causing the syncopy

Front 22

Mixed SNS and PSNS Syncopy

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Front 23

Treatment of neurally mediated syncope

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•Nonpharmacologic: salt and water loading, resistance training lower limbs
•Beta blockade (blocks the INC. HR that initates the problem)
•Fludrocortisone
•SSRIs
•Adrenergic agonists
•cardiac pacing for refractory vasovagal (not vasodepresor)

Front 24

•48F
•20year history of diabetes
•Lightheadedness on standing, presyncope with prolonged standing
•Constipation, reflux, bloating after meals
•Marked face sweating with minimal exertion, extreme fatigue in hot weather
•Problems driving at night

Back 24

- baroreceptors not working
- GI dysmotility
- can only sweat in her face (peripheral neuropathy and so the ANS is affected and always the long nerves are always affected first
- chronotropic fibres still functioning, they are short fibres

Front 25

Autonomic neuropathy WITHOUT somatic neuropathy

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–acute pandysautonomia (post infection)
–subacute autonomic neuropathy- autoimmune autonomic ganglionopathy, paraneoplastic autonomic neuropathy
–Limited cholinergic neuropathy- chronic anhidrosis, chronic enteric neuropathy

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Autonomic Neuropathy + Somatic neuropathy

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–Diabetes (danger is that these people lose the Sx recognition fro hypoglaceamic attacks)
–Amyloidosis (primary and secondary)
–Guillain Barre Syndrome
–Porhyria
–Familial dyautonomia, hereditary sensory and autonomic neuropathy

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Autonomic neuropathy Sx

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•Postural lightheadedness
•Heat intolerance
•Erectile dysfunction
•GI dysmotility- bloating, constipation, diarrhoea
•Bladder dysfunction- retention, incontinence
•Glare sensitivity

Front 28

Acute autonomic neuropathies

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•Acute pandysautonomia
–paraneoplastic
–idiopathic
•Botulism
•GBS
•porphyria
•drugs and toxins

Front 29

Acute pandysautonomia

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•various restricted forms
–acute cholinergic neuropathy
–postural tachycardia syndrome
–GI motility disorders
•many likely to be immune mediated
•recovery usually only partial
•reports of response to IVIG, PEx, steroids
•may follow viral or other febrile illness (? 50%)
•uncommon
•acute or subacute onset
•widespread sympathetic and parasympathetic failure
•rarely pure autonomic but relative sparing of somatic fibres

CASE:
•24F
•Well until July 2011
•Presumed viral illness with high fevers, myalgia
•2 weeks later
–severe abdominal bloating
–Constipation
–Sensitivity to light
–Marked heat intolerance
–Postural lightheadedness

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Subacute autonomic neuropathies

Back 30

•paraneoplastic
•autoimmune
•diabetes
•drugs and toxins

Front 31

Chronic autonomic neuropathies

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•amyloid
•Diabetes
•chronic pandysautonomia (paraneoplastic,idiopathic)
•sensory neuronopathy with autonomic failure (idiopathic, paraneoplastic, Sjögrens)
•pure autonomic failure
•familial dysautonomia

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Chronic autonomic neuropathies
PAtterns

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•Distal sympathetic
–small fibre neuropathy
–other peripheral neuropathies
•Cholinergic
–LEMS
–chronic idiopathic anhidrosis
–Adie's, Chagas’
•Adrenergic
–(inc DßH deficiency, NGF deficiency)

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Anhydrosis above T1

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horners

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Sweating on one side of the face

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classic medullary stroke
- vertigo
- hiccups
- slurred speech
- horners syndrome

Front 35

Multiple Systems Atrophy

Back 35

•Striatonigral
•Olivopontocerebellar
•Pyramidal
•Natural history: usually do not survive more than 6-8 years
•Prevalence 5-15 per 100,000
•Onset middle to old age (two large series median 53, range 33-76)
•M:F 2:1
•Most common presentation autonomic failure and parkinsonism
Rigidity and bradykinesia> tremor
No, poor or poorly sustained response to l-dopa (?29% respond at some stage, maintained in only 13%)
Mild cerebellar or pyramidal signs may be present
•OH is the rule: present at first evaluation or within a year of development of parkinsonism

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Orthostatic Hypotension

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Symptoms
–Often vague : blurred vision, neck ache , muddled thinking etc
–Worse on first arising (esp after excessive nocturia), after meals (always worse after meals or EtoH due to excess vasodilation) , in heat, with exercise, with duration of standing
Treatment:
•non pharmacological measures
–elevation of head of bed (brain gets used to the lower BP thus in the morning there isnt the big drop)
–physical manoeuvres
–compression garments
•Fludrocortisone
•sympathomimetic agents
–ephedrine, psuedoephedrine
– midodrine (selective alpha agonist)
•non specific pressor agents
– caffeine, ergot derivatives, somatostatin analogs
•prostaglandin synthetase inhibitors, indomethacin, ibuprofen

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Pure Autonomic Failure DDx

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•Major differentials MSA and Parkinsonism
•Absence of neurological findings (NB autonomic features may be the first signs in MSA too so serial assessment needed):No cerebellar, pyramidal or extrapyramidal features
•Low supine plasma NA with little increase on standing and marked response to infusion
•PAF less progressive and generally less disabling, slow if any progression over 10-15 years
• Disease of peripheral (postganglionic, predominantly sympathetic) ANS

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Carotid Sinus Hypersensitivity

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more common in elderlydue to atherosclerosis changes
- in young people the have to have a more toght collar or something else to provoke it
- massage of caotids drops BP and HR

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small fibre neuropathy: causes

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•idiopathic
•impaired glucose tolerance
•diabetes
•HIV neuropathy
•amyloid
•paraneoplastic neuropathy
•paraproteinaemic neuropathy
•hereditary neuropathies

Front 40

small fibre neuropathy: symptoms

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•characteristically constant burning pain: superficial, mainly soles of feet, worse at night (or at rest- when there are no other inputs))
•prickling sensations, sometimes itch
•lancinating pains usually starting in feet and shooting up legs
•dull, deep seated aching pain in the feet
•episodic abnormal heat/cold sensation
•allodynia (light touch becomes painful)

Front 41

small thinly myelinated Ad and unmyelinated C fibre dysfunction

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–disturbed pain and temperature sensation
–dysesthesia, burning pain
–disturbed autonomic function

Front 42

•large myelinated fibre (Aa, Ab) dysfunction

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–numbness, hypoesthesia, reduced proprioception and vibration
–reduced deep tendon reflexes
–variable motor deficit