7.2 ANS & Sympathetic Blocks Flashcards
Differences between
cerebrospinal and autonomic nervous systems
Stimuli
Concerned with response
to external stimuli
Concerned with response to internal stimuli
Differences between
cerebrospinal and autonomic nervous systems
subdivision
Subdivisions are:
CNS: central (brain and spinal cord)
PNS: peripheral nerves
Subdivisions are:
Sympathetic
Parasympathetic
Differences between
cerebrospinal and autonomic nervous systems
Control
Under voluntary/conscious control
Under involuntary/subconscious control
Differences between
cerebrospinal and autonomic nervous systems
myelination
Mostly myelinated neurons Both myelinated and unmyelinated neurons
Differences between
cerebrospinal and autonomic nervous systems
Fibre relay
No relay of fibres in ganglia
Fibres relay in peripheral ganglia before supplying target organs
Differences between
cerebrospinal and autonomic nervous systems
Lowermost efferent
Hence lowermost efferent in CNS
Lowermost efferent in peripheral ganglia
Are the two division of ANS always opposing
Although most often,
the two divisions of the autonomic nervous
system have opposing actions,
this is not always the case.
What is dual innervation with regards to ans
Many organs have ‘dual innervation’,
and the two divisions, sympathetic
and parasympathetic, work synergistically to maintain
homeostasis.
PS active when
Parasympathetic division
predominates in resting conditions
usually inhibitory,
SNS active when
while the sympathetic division
takes over during stress
usually stimulatory
Is (ACh) is always stimulatory?
At preganglionic neurons, acetylcholine (ACh) is always stimulatory,
while it can be either stimulatory or inhibitory at postganglionic
neurons.
What is norEpi usual action
Norepinephrine at postganglionic sympathetic terminals is usually stimulatory
single-organ innervations ANS
parasympathetic only
parasympathetic only – lacrimal glands
single-organ innervations ANS
sympathetic only
sympathetic only –
adrenal medulla, arterioles in skin, viscera and kidney
Sympathetic
Origin
Origin
Thoracolumbar (T1–L2) outflow
Sympathetic
Location of ganglia
Location of ganglia
Paraverterbral,
prevertebral
suprarenal medulla
Sympathetic
Preganglionic fibres
Length
Myelination
Neurotransmitter
Short
Myelinated
Acetylcholine
Sympathetic
Postganglionic fibres
Length
Myelination
Neurotransmitter
Postganglionic fibres
Long
Unmyelinated
Usually norepinephrine and sometimes ACh
Sympathetic
Divergence and effects
Divergence and effects
Widespread ‘mass action’ effects
Sympathetic
General fxn
General functions
Fight or flight
Parasympathetic
Origin
Cranio (
CNIII, VII, IX, X)
Sacral (S1,2,3) outflow
Parasympathetic
Location of ganglia
Near terminal organs or
intramural
Parasympathetic
Preganglionic fibres
Length
Myelination
Neurotransmitter
Long
Myelinated
Acetylcholine
Parasympathetic
Postganglionic fibres
Length
Myelination
Neurotransmitter
Short
Unmyelinated
Always ACh
Parasympathetic
Divergence and
effects
Localised and discrete’ effects
Parasympathetic
General functions
Rest and repose
Do SNS neurons always release NorEpi
sometimes, the
postganglionic neurons of
the sympathetic system may
release ACh;
for example,
sweat glands and
smooth muscles of skin and
blood vessels.
sympathetic division has the following organisational features
originates
Originates from thoracolumbar outflow,
i.e. neurons in
lateral grey horns
of T1–L2.
Their axons enter the
ventral roots of spinal segments.
Where do sns axons relay
These axons may relay in:
Paravertebral ganglia
Prevertebral ganglia
Suprarenal medulla
Plexus:
cardiac, pulmonary, oesophageal, hypogastric
Paravertebral ganglia
Paravertebral (or lateral) ganglia:
on either side of vertebral body.
Three cervical (superior, middle and inferior),
12 thoracic,
two to four lumbar,
four to five sacral and one coccygeal
(join in midline to form
ganglion impar).
Prevertebral ganglia
Prevertebral (or collateral) ganglia:
coeliac,
superior mesenteric
and inferior mesenteric ganglia.
They form their respective plexuses.
Suprarenal medulla:
Suprarenal medulla:
modified sympathetic ganglia.
The chromaffin cells (postganglionic neurons)
do not have postganglionic fibres.
They are neural crest derivatives
Do all spinal nerves have a white ramus
what about grey
They receive preganglionic fibres
from the white ramus while passing
on the postganglionic fibres
through the grey ramus.
Since the outflow is received from T1–L2,
only these spinal nerves have white ramus,
while others do not.
However, all spinal nerves have a grey ramus.
What happens after entering white prams to preganglionic sns
path
After entering the white ramus,
preganglionic fibres of the
sympathetic division of ANS
may course along any of the following paths
Synapse in the corresponding paraverterbral ganglia
Ascend or descend in the sympathetic chain
Pass through paraverterbral ganglia without relaying to synapse
Synapse in the corresponding paraverterbral ganglia.
Synapse in the corresponding paraverterbral ganglia.
The postganglionic fibres
join the spinal nerves
through the grey ramus,
to relay to the blood vessels
of the skin and skeletal muscles,
and in
sweat glands.
Ascend or descend in the sympathetic chain
Ascend or descend in the sympathetic chain to
relay in other paraverterbral ganglia.
This is the cause for the
widespread action of
the sympathetic division.
Pass through paraverterbral ganglia
Pass through paraverterbral ganglia
without relaying
to synapse in the
peripheral ganglia such as
prevertebral ganglia or
suprarenal glands
Sympathetic nerve supply of different body parts
Head and neck T1–T2 Upper limb T2–T5 Thoracic viscera T1–T4 Abdominal viscera T4–L2 Pelvic viscera T10–L2 Lower limb T11–L2 Suprarenal medulla T5–T8
Is there a craniosacral sympathetic outflow?
there is no craniosacral sympathetic outflow.
Hence they derive
sympathetic supply through
nearest sympathetic ganglia.
Cervical areas receive sympathetic
supply through upper-thoracic segments,
while the sacral
(pelvic) areas receive same through lower thoracolumbar segments
parasympathetic system originates
parasympathetic system originates
in the brain stem (CNIII, VII, IX, and X)
and
the sacral spinal segments
(S2–S4 – nervi erigentes).
Hence,
it is often called the craniosacral outflow
What carries most of PS /
The vagus nerve (CNX) carries
75% of the distribution of
parasympathetic division.
What is the diff vs SNS and ganglia
location
length
Unlike sympathetic ganglia,
parasympathetic ganglia are
quite distant from the brainstem
& cord,
often located directly on the
effector organ itself.
Thus the preganglionic fibres are longer,
while the postganglionic fibres are shorter
the sensory nerve supply of the viscera travels how
Sensory information from the
viscera travels via GVA –
general visceral afferents.
GVA
They are fibres that use the ANS
efferents as a conveyor belt
to send sensory information
from the viscera to higher centres
Do GVA Use only Sympathetic efferents
They mostly use the sympathetic efferents,
but parasympathetic efferents are
also used (CNIX, X, and sacral nerves).
Is viscera involved in referred pain
They do not relay in the peripheral ganglia.
We are not aware of these sensations
unless they cross the pain threshold.
This may then lead to referred pain.
FIGURE 7.6 Projections of parasympathetic nervous system
FIGURE 7.6 Projections of parasympathetic nervous system
Sympathetic reflexes
Cardioaccelerator reflex
Vasomotor reflex
Pupillary reflex
Ejaculation
Parasympathetic reflexes
Distension reflexes:
Distension reflexes:
Gastric and intestinal reflex
Defecation reflex
Urination reflex
Parasympathetic reflexes
heart eyes
willy
Baroreceptor reflex
Direct light reflex
Consensual light reflex
Sexual arousal
Parasympathetic reflexes
eating etc
Swallowing reflex
Vomiting reflex
Coughing reflex
stellate ganglion block
Cervical sympathetic ganglia
how many
Cervical sympathetic ganglia are three in number:
superior,
middle
and
inferior.
Cervical sympathetic ganglia
Communicate via grey how
They communicate via
grey rami with
C1–C4, C5–C6 and C7– C8 spinal segments.
Cervical sympathetic ganglia
have they white rami?
what do they form
They have no white rami.
The inferior cervical ganglia are fused with upper thoracic (T1 usually) to form the stellate ganglia.
The stellate ganglia lie at level of
where in relation to Vert A / BP sheath Subclav A
The stellate ganglia lie at the level of
transverse process of the C7 vertebra.
It lies in front of vertebral artery,
brachial plexus sheath and
neck of the first rib.
Subclavian artery lies at or above it
For a stellate ganglion block
Patient position
whats palpated
what is moved
For a stellate ganglion block,
the patient lies supine with the neck
slightly extended.
The Chassaignac tubercle (C6) is palpated between
the sternocleidomastoid muscle and the trachea at cricoid level.
The operator then pushes the carotid artery laterally.
For a stellate ganglion block
Needling technique
redirection
injection
After raising a skin wheal,
a 22-gauge,
5-cm needle with a 10-mL syringe attached is
inserted perpendicularly until the tip contacts the C6 transverse process.
The needle is then withdrawn 1–2 mm and is fixed.
After careful aspiration,
10 mL of local anaesthetic solution
is injected in 1- mL increments.
For a stellate ganglion block
Signs of success
Signs of success:
Horner syndrome, anhidrosis, injection of the conjunctiva, nasal congestion, vasodilatation and increased skin temperature.
For a stellate ganglion block
Complications
Complications:
haematoma,
bleeding,
pneumothorax,
intravascular injections,
seizures,
spinal cord trauma,
unintended nerve blocks
(vagus, phrenic, brachial plexus, recurrent laryngeal),
QTc alterations
Quirk about stellate block location and injection
stellate ganglion lies at C7 (or below),
but is blocked at C6 as this is safer.
Vertebral artery and subclavian artery at lower levels may increase the risk at C7.
Hence a high-volume injection at C6 is expected to do the job
Indications and contraindications for stellate ganglion block
Painful states
Painful states
Complex regional pain syndrome types I and II Refractory angina Phantom limb pain Herpes zoster Shoulder/hand syndrome Post-frostbite Angina
Indications and contraindications for stellate ganglion block
Vascular insufficiency
Vascular insufficiency
Raynaud’s syndrome Scleroderma Frostbite Obliterative vascular disease Vasospasm Trauma Emboli
Indications and contraindications for stellate ganglion block
Contraindications
Contraindications
Coagulopathy Recent myocardial infarction Pathological bradycardia Glaucoma
Organs supply:
1
Thoracic
2
Abdominal
3
pelvic organs
1
thoracic organs are supplied by cardiac plexus
2
abdominal organs by coeliac plexus
3
pelvic organs are supplied by the hypogastric plexus
Coeliac plexus
is it the biggest
what does it supply
to where
coeliac is the largest.
It is also known as the solar plexus
supplies all abdominal organs and intestines
up to the splenic flexure.
How many coeliac ganglia
Where found
Lie
The coeliac ganglia are between
two and 10 (average five) in number
and lie anterior to the aorta
at T12–L1 level on either side.
The supra-renal glands / stomach / pancreas lie where in relation to coeliac plexus
The supra-renal glands lie lateral to
celiac plexus while
the stomach and pancreas
are located anterior to it.
The celiac plexus receives sympathetic supply
The celiac plexus receives its
sympathetic supply through
the greater splanchnic nerve
(T5–T6 to T9–T10),
lesser splanchnic nerve
(T10–T11)
and least splanchnic nerve (T11–T12).
The celiac plexus receives
its parasympathetic supply
The celiac plexus receives
its parasympathetic supply
from the
left and right vagal trunks.
How does it allow pain relief Coeliac plexus
The celiac plexus also transits
the visceral afferents,
which accounts for pain relief
following celiac plexus block.
The main indication for coeliac
plexus block is
The main indication for coeliac
plexus block is pancreatic cancer pain.
Various approaches have been described for coeliac plexus:
Various approaches have been described for coeliac plexus:
1
posterior (most common) –
retrocrural, transcrural or transaortic
2
posterior paramedian
3
anterior approach
4
endoscopic approach
Posterior retrocrural approach:
patient position
Posterior retrocrural approach:
patient is given prone position,
and a pillow under the abdomen
is used to eliminate lumbar lordosis.
Posterior retrocrural approach:
landmarks
Then lines connecting the T12 spine
with points 7–8 cm lateral at the
lower edges of the 12th ribs
are drawn forming a flattened isosceles triangle
Posterior retrocrural approach:
describe
After raising a skin wheal,
a 20-G, 10–15 cm needle is
inserted on the left side at 45° angle
toward the body of L1.
Bony contact should be made at an
average depth of 7–9 cm
(superficial bony contact at 5–6 cm means hitting transverse process and should never be accepted).
The needle is then withdrawn and redirected
to slide off the tip past the vertebral body anterolaterally.
It is then advanced 1.5–2 cm past this point to feel transmitted aortic pulsations along the needle
(which allows the finger holding it to act as a pressure transducer).
Once this depth is ascertained, the right-sided needle is inserted in a similar fashion to a depth of 1.0–1.5 cm farther than the left.
After checking for blood, CSF and urine, a test dose is given. The main dose is given after this incrementally.
FIGURE 7.8 Performing a coeliac plexus block (posterior retrocrural approach)
Risk of PTX with Coeliac plexus block increased how
identifying the 11th rib instead of the 12th rib significantly increases
the risk of pneumothorax!
Regarding the coeliac plexus, the following are true
1
It provides sympathetic supply to abdominal organs
2
It lies anterior to aorta at T12–L1 level
3
It receives parasympathetic supply through the vagus
Complications of celiac plexus block
Vascular
Sympathetic block:
hypotension
Haematoma
Bleeding
Aortic/inferior vena cava puncture
Paraplegia (due to puncture of artery of Adamkiewicz)
Complications of celiac plexus block
Neurological
Lumbar plexus block,
Spread to epidural space
Intrathecal spread
Complications of celiac plexus block
Damage to visceral
Kidney,
ureter,
adrenal,
bowel,
stomach,
Pneumothorax
Chylothorax
Complications of celiac plexus block
infections
unopposed parasympathetic: diarrhoea
alcohol intoxication or acetaldehyde syndrome.
Indications of various blocks
Blocks Indications
Stellate ganglion
Stellate ganglion
see previous question
Hyperhydrosis
Limb lymphoedema
Indications of various blocks
Solar plexus (coeliac)
Solar plexus (coeliac)
Pancreatic cancer pain
Indications of various blocks
Hypogastric plexus
Hypogastric plexus
Pelvic cancer pain
Indications of various blocks
Lumbar sympathetic block
Lumbar sympathetic block
Complex regional pain syndrome
Vascular occlusive disorders
Indications of various blocks
Ganglion impar (coccyx)
Ganglion impar (coccyx)
Coccydynia
